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Method and system for context-based adaptive binary arithmetic coding

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CN100454339C
CN100454339C CN 200610088709 CN200610088709A CN100454339C CN 100454339 C CN100454339 C CN 100454339C CN 200610088709 CN200610088709 CN 200610088709 CN 200610088709 A CN200610088709 A CN 200610088709A CN 100454339 C CN100454339 C CN 100454339C
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method
system
context
based
adaptive
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CN1866297A (en )
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M·卡策维茨
R·库尔切伦
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诺基亚有限公司
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Abstract

一种图像编码方法,其中图像被分成了具有多个像素的块。 An image encoding method, wherein an image is divided into blocks having a plurality of pixels. 对像素块执行变换编码操作以便产生相应的变换系数值块,其中对所述变换系数值块进行扫描,以便产生一个经过扫描的系数值阵列,所述阵列由具有第一和第二数字的多个数字对表示。 Perform a transform on the pixel block coding operation to produce corresponding transformed block of coefficient values, wherein the transform coefficient values ​​of scanning block, through the array of values ​​to produce a scan line, said array having a plurality of first and second digital numbers to represent. 第一和第二数字指派到了表示所述数字对的多个上下文(14)之一。 The first and second plurality of context numbers assigned to the one (14) representative of the number pairs. 在这里,根据一个数字对的第一数字而将另一个数字对的第一数字指派给一个上下文。 Here, the first number by the first digit of a digit pair and the other pair is assigned to a digital context. 可替换地,一个数字对中的第二数字是基于数字对(16)中的第一数字而被指派给一个上下文的。 Alternatively, a number of the second number is the digit pair (16) is assigned to the first digital a context-based. 此外还确定了一个指示变换系数值块中非零系数值数目的数字,并且将其指派给一个上下文。 In addition, determining an indication of non-zero transform coefficient value based block number of the digital values, and assign it to a context.

Description

基于上下文的自适应二进制算术编码的方法和系统 Context-based adaptive binary arithmetic coding method and system

本申请是申请号为02822672.0的专利申请的分案申请。 The present application is a divisional application No. 02822672.0 of patent applications. 技术领域 FIELD

本发明一般地涉及静止图像和视频序列压缩,尤其涉及一种基于上下文的自适应二进制算术编码方法和系统。 The present invention relates generally to compression of still images and video sequences, particularly to a method and adaptive binary arithmetic coding system based on the context.

背景技术 Background technique

未压缩形式的数字图像包含了一个图像像素或图元的阵列。 Form uncompressed digital image contains a pixel or image element of the array of FIG. 例如,在一种以四分之一通用中间格式(QCIF)著称的常用数字图像格式中,图像或帧包含了排列在一个176 x 144像素的阵列中的25, 344 个像素。 For example, in one to Quarter Common Intermediate Format (QCIF) commonly known in the digital image format, the image or frame arranged in an array comprising a 176 x 144 pixel 25, 344 pixels. 每个像素依次由一定数量的比特表示,它们传送的是关于像素明亮度(亮度)和/或颜色(色度)的信息。 Each pixel in turn represented by a certain number of bits, which are transmitted and / or information regarding the pixel brightness (luminance) color (chromaticity) of. 此外还存在表示数字图像中的亮度和/或色度的不同方案。 There is also the different embodiment represented in the digital image brightness and / or chromaticity. 通常使用的则是所谓的YUV颜色模型。 Commonly used is the so-called YUV color model. 其中亮度或Y分量表示像素亮度,并且像素颜色由U和V标记的两个色度或色差分量来表示。 Wherein the luminance or Y component represents the brightness of a pixel, and the pixel color is represented by two chrominance or color difference components U and V mark. 此外还通常用到那些以表示光的三原色的分量为基础的其他颜色模型,例如RGB(红,绿,蓝)颜色模型。 In addition, other commonly used color models that three primary colors of light component represented based, for example, RGB (Red, Green, Blue) color model. 然而,与基于原色的颜色模型相比,基于亮度/色度表示的颜色模型则更具优势。 However, compared with the primary colors of the color model, color model based on the luminance / chrominance representation is an advantage. 这些优势源自于人类视觉系统更易于感受到光亮变化而不是颜色变化的特性。 These advantages derived from the characteristics of the human visual system is easier to feel the changes instead of bright color change. 而YUV颜色模型通常为色度分量(U, V)使用了一个低于亮度分量(Y)的空间分辨率,由此利用了这种特性。 And YUV color models typically use less than a luminance component (Y) spatial resolution for the chrominance components (U, V), whereby the use of this feature. 这样就可以在不显著降低所察觉图像质量的情况下减少表示图像色彩信息所需要的信息量。 This can, without significantly reducing the image quality perceived reduction in information amount to represent the image information of the color desired.

色度分量的较低空间分辨率通常是借助于二次抽样来实现的。 Lower spatial resolution of the chrominance components is usually achieved by means of subsampling. 通常, 一个16 x 16图像像素的块由四个包含了亮度信息的8 x 8像素的块表示,相应色度分量分别由一个8 x 8像素的块来表示,其中所述块表示一个与亮度分量中的16 x 16像素的块等价的图像区域。 Typically, the luminance information contains four 8 x 8 blocks of pixels in a 16 x 16 pixel block indicated by one block corresponding chrominance components are 8 x 8 pixels is represented, wherein the block represents a luminance 16 x component of the image area equivalent to the block of 16 pixels. 因此色度分量在x和y方向上由一个大小为2的因数来进行空间二次抽样。 Thus chrominance components in the x and y directions by a factor of two spatially subsampled by one size. 最终得到的四个8 x 8像素的亮度块以及2个在空间上与之对应的8 x 8 像素的色度块的组合通常称为一个YUV宏块,或者简称为宏块。 Four 8 x 8 pixel luminance blocks and combinations of 8 x 8 pixel chrominance blocks in the finally obtained two spatially corresponding thereto is commonly referred to as a YUV macroblock, or simply referred to as macroblocks. 而QCIF The QCIF

图像包括11 x 9个宏块。 Image comprises 11 x 9 macroblocks. 如果用8位(也就是0到255这个范围中的数字)分辨率来表示亮度块和色度块,那么,用于表示与每个宏块相关联的亮度和色度信息所需要的总比特数为6 x ( 8 x 8 x 8 ) = 3072比特。 If the luminance blocks and chrominance represented by eight blocks (i.e. numbers that range from 0 to 255) resolution, then the total bits used to represent the luminance and chrominance information associated with each macroblock required number 6 x (8 x 8 x 8) = 3072 bits. 因此,用于表示QCIF格式图像所需要的比特数为99 x 3072 = 304, 128比特。 Thus, the number of bits used to represent the desired image format QCIF is 99 x 3072 = 304, 128 bits.

应该了解的是,即使是在如上所述使用一个大小为2的因数来对数字图像的两个色度分量进行二次抽样的情况下,中等大小(例如17 4 It should be appreciated that, even when the size of a factor of 2 as described above to subsample the chrominance components of two digital images, medium size (e.g., 174

x 1"像素)的未压缩图像也会需要大量比特来供显示所用。这意味着以未压缩格式保存数字图像所需要的存储器数量将会过度。此外,举例来说,如杲经由一个具有中等或较低可用带宽的数据通信网络来传送静止图像,那么传输时间将会很长或者网络有可能会发生阻塞。如果希望实时发送作为数字视频序列的一系列图像,那么带宽需求甚至会更为严格。例如,以每秒30帧的速率传送一个使用了YUV颜色模型表示并包括一系列未压缩QCIF格式图像的数字序列需要用到9Mb/s x 1 "pixels) uncompressed image requires a large amount of bits will be used for display. This means that the number of memory stored in digital format uncompressed image would require excessive. Further, for example, as having a medium via Gao or lower available bandwidth data communication network to transmit still images, the transmission time will be very long or networks are likely to clog occur. If you want to send real-time digital video sequence as a series of images, the bandwidth requirements even more stringent for example, at a rate of 30 frames per second using the YUV color transfer a model representation includes a series of numbers and a sequence in QCIF format image need to use uncompressed 9Mb / s

(百万比特/秒)以上的带宽。 (Megabits / second) or more bandwidth. 由于需要很大的存储器容量、传输信道容量和硬件性能,因此,在被用于视频记录、传输和显示时,这种高数据速率通常是不切实际的。 Because it requires a large memory capacity, transmission channel capacity and hardware performance, and therefore, when used for video recording, transmission and display, such a high data rate is typically impractical. 如果要在ISDN(综合业务数字网)或PSTN If you want to ISDN (Integrated Services Digital Network) or PSTN

(公共交换电话网)这类固定线路上实时传送视频序列,那么可用数据传输带宽通常约为64k/s。 (Public Switched Telephone Network) such real-time transmission of video sequences on a fixed line, the available data transmission bandwidth is typically about 64k / s. 在移动可视电话中,至少有一部分传输是在无线电通信链路上进行的,那么可用带宽有可能会低到20kb/s。 In a mobile videophone, at least a part of the transmission is over a radio communications link, the available bandwidth is likely to be low 20kb / s. 这意味着必须显著减少用于表示视频数据的信息量,以便能在低带宽的通信网络上传输数字图像或视频序列。 This means must be significantly reduce the amount of information used to represent video data, in order to transmit digital images or video sequences on a low bandwidth communications network. 然而合乎需要的是,这种减少应该在不显著降低图像/视频序列质量的情况下实现。 However, it is desirable that this should not significantly reduce the case where the reduction in image / video sequence quality is achieved.

在过去数年中已经针对减少表示数字图像和视频序列所需数据量而进行了大量的研究工作,由此开发了多种不同方案和国际标准来对数字静止图像和数字视频进行压缩。 In the past few years has been to reduce the amount of data required for the representation of digital images and video sequences and done a lot of research work, which has developed a variety of different programs and international standards for digital compression of still images and digital video. 在现有的几乎所有静止图像和视频编码器中,所使用的基本的图像压缩方法都包含了基于块的变换编 In almost all conventional still image and a video encoder, the basic image compression methods used include a block-based transform coding

码。 code. 通常,变换编码是将来自一个包含像素值的图示的图像数据转换成一种包含一组系数值的形式,其中每一个系数值都是所论述变换的基函数的一个加权因数(乘数)。 Generally, transform coding is a transition from the icon image data of pixel values ​​includes a set of coefficient values ​​into a form comprising, wherein each coefficient value by a weighting factor is a function of converting the group (multiplier) discussed. 此外还可以显示,在典型的数字图像内部存在相当大程度的空间冗余。 May also be displayed in addition, there is a considerable degree of redundancy in the space inside a typical digital image. 事实上,这意味着图像内部任何像素值通常与其紧邻的其他像素值实际是相同的,也就是说,在像素 In fact, any pixel value which means that its internal images are usually close to the actual values ​​of other pixels is the same, that is to say, in pixels

值间存在很大程度上的相关。 Correlation between the extent of the value of existence. 此外进一步已知的是,在对图像执行某 Further further known that the image in the execution of a

些数学变换,例如二维离散余弦变换(DCT)的时候,这种空间冗余度将会显著降低,由此产生一个更为简洁的图像数据显示。 Some mathematical transforms, such as when a two-dimensional discrete cosine transform (DCT), which spatial redundancy will be significantly reduced, thereby producing a more compact display the image data. 在JPEG静止图像编码中使用的基于块的变换编码例如,在根据广泛使用的JPEG标准的基准模式所执行的静止图像 Used in the JPEG still image encoding block based transform coding, for example, performed in the still image according to the JPEG standard is widely used reference pattern

压缩中,所要编码的图像首先分成互不重叠的方形块阵列,其中举例来说,每一个块都包括一个8 x 8的图像像素阵列。 Compression, the image to be coded is first divided into a square array of non-overlapping blocks, wherein for example, each block including a pixel array of 8 x 8. 然后,就JPEG基 Then, based on the JPEG

准而言则是将二维离散余弦变换(DCT)独立应用于每一个图像块。 For quasi sucked dimensional discrete cosine transform (DCT) is applied independently to each image block. 这样做具有把来自像素值域的图像数据转换到空间频域并产生一组相应系数值的效果,其中每个系数值都是一个关于二维DCT基函数的加权因数。 This has to convert the image data from a pixel value domain to a spatial frequency domain results and generate a corresponding set of coefficient values, wherein each value is a weighting factor based on the two-dimensional DCT basis functions. 由此产生的系数值经过量化,然后使用熵编码而以一种无损方式对其进行编码,从而进一步减少供其显示所需要的数据量(也就是比特数)。 The resulting coefficient values ​​quantized, and entropy encoded in a lossless manner and it is encoded, for thereby further reducing the amount of data required for display (i.e. number of bits). 根据JPEG基准,熵编码器只使用了霍夫曼编码来产生一个压缩比特流,但在其他模式中也可以使用算术编码。 The JPEG standard, entropy encoder only uses Huffman coding to produce a compressed bit stream, the arithmetic coding may be used in other modes. 最终,用于描迷图像和编码参数(例如压缩类型、量化和编码表、图像大小等等)的数据被嵌入熵编码器产生的比特流中。 Finally, the fans used to describe the image, and coding parameters (e.g. compression type, quantization and encoding table, image size, etc.) data is embedded entropy encoder bitstream generated. 而由于JPEG标准包括四种备选编码模式并且只对可用的量化和编码表安插了少量约束条件,因而有必要执行上述操作,以便能在不同平台之间互换JPEG压缩比特流并且在毫无歧义的情况下重建图像。 Since the JPEG standard includes four alternate coding mode and only the available quantization coding table and a small number of placement constraints, it is necessary to perform the above operation, in order to JPEG compressed bit stream and interchange between different platforms without the reconstructed image in the case of ambiguity.

类似胶片上所记录的常规电影这样的数字视频序列包括一系列静止图像(通常称之为"帧,,),而运动错觉则是通过以通常为每秒15 到30帧这样的相对较快的速率相继显示所述帧而产生的。与任何静止图像一样,在一个数字视频序列内部,单独帧的像素值将会显示出相当大的空间冗余。因此,与单独的静止图像一样,数字视频序列的帧也可以由基于块的变换编码来进行处理。 Similar conventional movie film recorded on such a digital video sequence comprises a series of still images (often called "frame ,,), the illusion of motion is typically by 15 to 30 frames per second of such a relatively fast the successive display frame rate is generated. as with any still image in a digital video internal sequence, the pixel values ​​of individual frame will show considerable spatial redundancy. Thus, as a still image alone, a digital video the sequence of frames may be processed by the block-based transform coding.

同样,视频序列相邻帧的图像往往是相似的,因此,在某个视频帧与下一枧频帧之间,整体上的变化是非常小的。 Also, the video sequence adjacent frames tend to be similar, therefore, between a video frame and the next frame frequency soap, the change in the overall is very small. 这意味着在典型数字视频序列内部存在相当大的时间冗余。 This means that there is considerable redundancy in time inside a typical digital video sequence. 例如,在一个场景中可以包括诸如背景景物之类的某些静止元素,也可以包括某些运动区域,例如新闻广播员面部。 For example, in a scene may comprise some stationary elements, such as background scenery or the like, it may also include some motion region, e.g. newscaster face. 在序列的相邻帧中,背景可能保持不变,而场景中的唯一运动则由新闻广播员面部表情的变化产生。 In the sequence of adjacent frames, the background may remain the same, the only change in the scene movement by the newscaster facial expressions generated. 因此,在形成视频序列的压缩表示时,除了减少空间冗余的方法之外,也可以使用那 Thus, in the compressed representation of video sequence is formed, in addition to reducing spatial redundancy than the method, it may also be used

些减少序列中图《象数据时间冗余的技术,由此实现进一步的数据压缩。 These image data to reduce the temporal redundancy in the sequence of FIG technology ", thereby to achieve further data compression.

混合视频编码器/解码器 Hybrid video encoder / decoder

现有技术的视频编码系统使用了一种以运动补偿预测著称的技术来减少视频序列中的时间冗余。 The prior art video coding system using motion compensated prediction to a known technology to reduce the temporal redundancy in a video sequence. 就这种运动补偿技术而言,在数字视频序列中,某些(通常很多)帧的图像内容是从序列中的一个或多个其他帧"预测"的,其中所述其他帧即为通常所说的"参考帧"。 On such motion compensation, in a digital video sequence, certain (usually much) from the image content of the frame in the sequence of one or more other frame "prediction", wherein the other of the frames is the normal He said "reference frame." 图像内容的预测是通过使用"运动矢量"在将要编码的帧与一个或多个参考帧之间追踪一个图像中的对象或区域来实现的。 Prediction of image content is achieved by using "motion vectors" in a frame to be encoded with one or more reference frames between a tracking area or object in the image to achieve. 一般来说,在视频序列中, 一个或多个参考帧可以先于将要编码的帧或是跟随在所迷帧之后。 In general frame, in a video sequence, one or more reference frames may be encoded prior to or following the lost frame in the following. 然而,从本文的后续论述中可以明显看出,将运动补偿预测 However, from the subsequent discussion herein will be apparent, the motion compensated prediction

少两种类型的编码,这样做并不适当(或者可能)。 At least two types of coding, would not be appropriate (or possible).

使用运动补偿预测而被压缩的视频序列帧通常称为帧间编码或P 帧。 Motion compensated prediction is compressed video sequence frame is often called an inter-coded or P-frames. 光是运动补偿预测则很难提供足够清楚的视频帧图像内容表示, 因此通常有必要为各个帧内编码的帧提供一个所谓的"预测误差" Motion compensated prediction alone is difficult to provide a sufficiently clear image content represented by the video frames, it is often necessary to provide a so-called "prediction error" as the intra-coded frames for each

(PE)帧。 (PE) frame. 如本文稍后更为详细描述的那样,预测误差帧表示的是帧间编码帧的解码版本与编码帧图像内容之间的差别。 As later herein described in more detail below, the prediction error frame represents the difference between a decoded version of the inter-coded frame coded frame and the image content. 更具体地说,预测误差帧包含了表示将要编码的帧的像素值与基于所论述帧的预测 More specifically, the prediction error frame contains the pixel value to be encoded indicates a frame predicted on the basis of the frame as discussed

(帧间编码)版本而形成的对应重建像素值之间的差别。 Corresponding to the difference between the reconstructed pixel value (inter-coded) version is formed. 因此,预测误差帧具有与静止图像相似的特征,并且可以通过应用基于块的变换编码来减少表示该帧所需要的数据量(比特数)。 Thus, the prediction error frame has characteristics similar to a still image, and may be reduced by applying the transform coding block based on the amount of data required by the frame (number of bits).

没有使用运动补偿预测压缩的视频序列帧被称为帧内(帧内)编码或I帧。 No motion compensated prediction of a video sequence compressed frames are called intra (intraframe) coded or I-frames. 通常,帧内编码帧是借助了将基于块的变换编码应用于所要编码帧的像素值而产生的。 Typically, intra-coded frame by means of the transform coding the pixel value to be applied to block-based coded frames generated. 另外在可能的情况下,帧内编码帧的块是从同一帧以内的先前编码块中预测的。 In addition, where possible, blocks of intra-coded frame is predicted from previously coded blocks within the same frame. 这种技术即为通常所说的帧间预测,它具有进一步减少表示桢内-编码帧所需要的数据量的效果。 This technique is commonly referred to is the inter prediction, the frames having a further reduced represents - effect of amount of data required to encode the frame.

在将对图1加以参考,^图是常规混合视频编码器的示意图,'其中使用了帧内与帧间编码的组合来产生一个压缩(编码)视频比特流。 FIG 1 will be reference, ^ is a schematic representation of a conventional hybrid video encoder, 'which uses a combination of intra-frame and inter-frame coding to generate a (encoded) video bit stream compressed. 在图2中描述了相应的解码器并且稍后将在文中对其进行描述。 The corresponding decoder is described in FIG. 2 and which will be described later herein.

视频编码器300包括一个用于从相机或其他视频源(未显示)接 A video encoder 300 comprises a video from a camera or other source (not shown) connected

收数字视频信号的输入端301。 An input terminal receiving digital video signal 301. 它还可以包括一个调整为执行基于块的离散余弦变换(DCT)的变换单元304, 一个量化器306,一个反向量化器308, 一个调整成执行基于块的反离散预先变换(IDCT)的逆变换单元310,组合器312和316以及一个帧存储器320。 It may also include an adjustment for the implementation of 304, a quantizer 306, an inverse quantizer 308, an adjustment unit to perform the discrete cosine transform based on the transform block (DCT) based on an inverse discrete inverse pre-transform (IDCT) block conversion unit 310, a combiner 312 and 316, and a frame memory 320. 编码器还包括运动估计器330,运动场编码器(motion field encoder) 340以及运动补偿预测器350。 The encoder further comprises a motion estimator 330, a motion field coder (motion field encoder) 340 and a motion compensated predictor 350. 开关302和314则是通过控制管理器360在視频编码的帧内模式与视频编码的帧间模式之间切换编码器而以协同方式进行操作的。 Switch 302 and switch 314 is carried out by the encoder manager 360 controls the video encoder between the intra-mode and inter mode video encoding operation in a synergistic manner. 编码器300还包括视频复用编码器370,它从编码器300生成的各种类型信息中构成单独比特流335,以便进一步传输到远程接收终端,或者举例来说,它也可以将所述比特流保存在一个大容量存储介质中,例如计算机硬盘(没有显示)。 The encoder 300 further comprises a video multiplex coder 370 which forms a single bit-stream 335 from the encoder 300 various types of information generated, for further transmission to a remote receiving terminal, or for example, it may be the bits stream is stored in a large-capacity storage medium, such as a computer hard disk (not shown).

编码器300是如下运作的。 The encoder 300 is as follows works. 视频源提供给输入端301的各个未压缩视频帧都是以逐个宏块的方式接收和处理的,其中最好以光栅扫描顺序来对其进行处理。 Video source 301 to the input of each of uncompressed video frames, one by one in a macroblock are received and processed, preferably in raster scan order in which to process them. 在开始编码新的视频序列时,所述序列中的第一帧是作为一个帧内编码帧来编码的。 At the beginning of a new coded video sequence, the first frame of the sequence is coded as an intra-frame encoded. 接下来,除非满足下列条件之一,否则将通过对编码器进4亍编程来以帧间编码格式编码各帧:l)判定正被编码的当前帧与预测中使用的参考帧很不一样,并由此产生了过多预测误差信息;2)预先定义的帧内帧的重复间隔已经终止;或者3)从一个接收终端接收到一个反馈,该反馈表示的是一个要求以帧内编码格式来提供帧的请求。 Subsequently, unless one of the following conditions, otherwise it will be in inter-encoding format each frame by the encoder 4 into the right foot Programming: l) determining a reference frame used in the current frame being encoded and the prediction is very different, and thereby generating excessive prediction error information; 2) intra-frame repetition interval has expired predefined; or 3) from a receiving terminal to receive a feedback that indicates the intra-coded in a format requirements providing request frame.

条件1)的出现是通过监视组合器316的输出来检测的。 Condition 1) occurs is by monitoring the output of the combiner 316 is detected. 组合器316在正被编码帧的当前宏块与其在运动补偿预测部件350中产生的预测之间形成一个差值。 The combiner 316 forms a difference between the current macroblock and its prediction is generated in the motion compensation prediction section 350 in the frame being encoded. 如果关于这个差值的量度(例如像素值的绝对差值总和)超出一个预定门限,那么組合器316将经由控制线319 来向控制管理器360发出通知,并且控制管理器360将经由控制线313 来操作开关302和314,以便将编码器300切换到帧内编码模式。 If on this difference measure (e.g. the sum of absolute difference of pixel values) exceeds a predetermined threshold, the combiner 316 via the control line 319 to issue a control manager 360 to notify, and the control manager 360 via control line 313 and 314 to operate the switch 302 to switch the encoder 300 to the intra coding mode. 条件2 )的出现是借助于控制管理器360中的定时器或帧计数器而以如下方式进行监视,如果定时器终止或者帧计数器达到预定数量的帧,则控制管理器360经由控制线313操作开关302和314,以便将编码器切换到帧内编码模式。 Condition 2) occurs by means of the control manager 360 and a timer or frame counter is monitored in the following manner, if the timer expires, or the frame counter reaches a predetermined number of frames, the control manager 360 313 via control line operating switch 302 and 314, so that the encoder switching to the intra coding mode. 如果控制管理器360经由控制线321而从一个接收终端接收到一个表示接收终端需要对帧内编码帧进行刷新的反馈信号,则触发条件3)。 If the control manager 360 receives from a receiving terminal, via control line 321 represents a receiving terminal of feedback signals need to be refreshed for intra-coded frame, the trigger condition 3). 例如,如果先前发送的帧在其传送过程中因为千扰而受到严重破坏,进而不可能在接收机上对其进^f亍解码,则有可能出现这种情况。 For example, if a previously transmitted frame in its transmission process because thousand of interference severely damaged, and thus can not decode them into ^ f right foot at the receiver, there may happen. 在这种条件下,接收解码器发出一个要求以帧内编码格式来对下一帧进^f亍编码的请求,由此重新初始化所述编码序列。 In this condition, the receiving decoder issues a requirement in intra-coded format right foot forward request ^ f coding the next frame, thereby re-initialization of the coding sequence.

现在对帧内编码模式中的编码器300的操作进行描述。 Now the operation of the encoder 300 in the intra-coding mode will be described. 在帧内编码模式中,控制管理器360对开关302进行操作,以便从输入线318 接收视频输入。 In the intra coding mode, the control manager 360 operates switch 302 to receive video input from input line 318. 视频信号则是以逐个宏块的方式并经由输入线318而从输入端301接收的。 By way of the video signal macroblock by macroblock and received from an input terminal 301 via the input line 318. 在对其进行接收的时候,构成宏块的亮度和色度值块传递到DCT变换单元304,所述单元对每一个块值执行一个二维离散余弦变换,由此为各个块产生一个二维DCT系数阵列。 When receiving them, the luminance and chrominance values ​​constituting the macroblock is passed to DCT transformation unit 304, the unit is a two-dimensional discrete cosine transform for each block performing value, thereby generating a two-dimensional blocks for each array of DCT coefficients. 举例来说, 在前迷情况中,每一个宏块都包括4个8 x 8的亮度值块以及两个在空间上与之对应的8 x 8像素的色度值块,而DCT变换部件304则为每个块产生一个8 x 8的系数值阵列。 For example, the fans in the former case, each macroblock includes four blocks of 8 x 8 luminance values ​​and the 8 x 8 pixel blocks two chrominance values ​​of spatially corresponding thereto, and the DCT transform section 304 each block was generated for an 8 x 8 array of values ​​of the system.

关于各个块的DCT系数传递到量化器306,在所述量化器306中使用量化参数QP对其进行量化。 DCT coefficients with respect to each block is transmitted to a quantizer 306, quantization parameter QP used in the quantizer 306 quantizes them. 关于量化参数QP的选择是经由控制线315并由控制管理器360来控制的。 Choose how the quantization parameter QP is controlled via line 315 by the control manager 360 controlled. 由于经过量化的系数的数值精度低于DCT变化单元304初始生成的系数的数值精度,因此所述量化会引入一个信息损失。 Since the numerical precision after quantized DCT coefficients is less than the coefficient change unit 304 of the initial numerical precision generated, thus the quantization introduces a loss of information. 这样就提供了另外一种借以减少表示视频序列中各个图像所需数据量的机制。 This provides another thereby reducing the amount of data representing a video sequence mechanisms each desired image. 然而,与实质无损的DCT变换所不同, 通过量化引入的信息损失会导致图像质量的不可逆降级。 However, the essence of the different lossless DCT transform, introduced by quantifying the loss of information can lead to irreversible image quality degradation. 应用于DCT 系数的量化程度越高,图像质量的损失也就越大。 The higher the degree of quantization applied to the DCT coefficients, the greater the loss of image quality.

如图1的线路325所示,对每一个块来说,其经过量化的DCT系数将从量化器306传递到视频复用编码器370。 As shown in FIG. 1 line 325, for each block, its quantized DCT coefficients 306 pass from the video multiplex coder 370 quantizer. 视频复用编码器370 使用一个Z字形扫描过程来对各个块的变换系数进行排序。 Video multiplex coder 370 using a Z-shaped scanning process to sort each block of transform coefficients. 这个操作是将经过量化的变换系数的二维阵列转换到一个一维阵列中。 This operation is converted into a one-dimensional array through the two-dimensional array of quantized transform coefficients. 如图3 所示的典型的Z字形扫描大致是以空间频率递增的顺序来对系数进行排序的。 Typical zigzag scanning as shown in FIG. 3 Z is substantially a spatial frequency increasing order of the coefficients are sorted. 此外,所述操作往往还根据系数值来对其进行排序,以使一维阵列中位置较早的系数更有可能比阵列中位置靠后的系数具有更大绝对值。 Furthermore, the operation tends to be further sorted based on the coefficient value, so the earlier one-dimensional array are more likely to have a coefficient of a position greater than the absolute value of the coefficient array in a position on. 这是因为在图像块内部,较低的空间频率往往具有较高的幅度。 This is because inside the image block, the lower spatial frequencies tend to have higher amplitude. 因此,在经过量化的变换系数的一维阵列中,末尾的那些值通常为零。 Thus, in a one-dimensional array of quantized transform coefficients, the value at the end of those usually zero.

DCT变换系数的游程-等级(run-level )编码 DCT transform coefficients in the run - level (run-level) encoded

通常,视频复用编码器370使用了名为等级(level )和游程(run)的两个值来表示一维阵列中经过量化的各个非零系数。 Typically, the video multiplex coder 370 using the called Level (Level) and run (run) of the two respective non-zero value to represent a one-dimensional array of quantized coefficients elapsed. 等级是经过量化的系数的值,而游程则是所论述系数之前的连续零值系数数目。 Level is the value after quantized coefficients, and run is the number of consecutive zero-valued coefficients preceding the coefficient discussed. 关于给定系数的游程和等级的值经过排序而使得等级的值是在相关的游程值之前。 A value for the run value and the level of the ordered coefficients given level is such that before the associated run value. 而与零相等的等级值则用于表示所述块中没有非零系数。 With the level value equal to zero is used to indicate no nonzero coefficients in the block.

这个大小为0的等级值称为E0B (块结束)符号。 This size is referred to as gradation value 0 E0B (end of block) symbol. 燏编码 Yu - coding

通过使用熵编码,在视频复用器370中进一步对游程和等级的值进行了编码。 By using entropy coding, and further the value of the run levels are coded in a video multiplexer 370. 所述熵编码是一个无损操作,它利用的是所编码数据集内部符号通常具有不同出现概率这一事实。 The entropy coding is a lossless operation, which uses the encoded data sets typically have different internal symbol occurrence probability of the fact. 这样一来,通过指派一个可变数字,可以用具有更少比特的码字来表示更有可能出现的符号, 而不是使用固定数量的比特来表示每个符号。 Thus, by assigning a variable number, can be used with fewer bits to represent a symbol of a codeword is more likely to occur, rather than using a fixed number of bits to represent each symbol. 因此,熵编码通常称为可变长度编码(VLC)。 Thus, commonly referred to as entropy coding variable length coding (VLC). 由于某些等级和游程比其他值更有可能出现, 因此可以有效使用熵编码技术来减少表示游程和等级的值所需要的比特数目。 Because some level and run values ​​are more likely than others, and therefore can be used effectively to reduce the entropy encoding technique run value represents the number of bits and the level needed. 在这里可以使用多种不同方法来实施熵编码。 Herein you can use many different ways to implement entropy coding. 例如,游程和等级参数的熵编码可以借助于定义所编码数据集中各个可能符号与相应可变长度码之间映射的查找表实施。 For example, entropy coding of the run and the level parameter may define the encoded data centralized lookup table mapping between the symbols corresponding to the various possible embodiment by means of a variable length code. 这种查找表通常是通过对训练资料进行统计分析而被定义的,其中所述训练资料与所编码符号包含相同符号并具有相似统计特性。 This lookup table is usually by statistical analysis of training data is defined, wherein the training symbols comprising the encoded data and the same reference numerals and have similar statistical properties. 此外还有一种名为算术编码的替换技术,它可用于将游程和等级值转换成可变长度码字。 There is also a technique called arithmetic coding Alternatively, it can be used to convert the run and level values ​​into variable length codewords. 例如,在对一组符号进行算术编码时,用于对转换系数块进行量化的游程与等级值是作为一个浮点型的十进制数来编码的。 For example, when a set of symbols arithmetic coding, block transform coefficients for quantization and run-level value as a floating point decimal encoded.

一旦使用了恰当方法来对游程和等级值进行熵编码,则视频复用编码器进一步将其与控制信息结合,此外还使用了一种适于所论述信息类型的可变长度编码方法来进行熵编码,从而形成编码图^f象信息335 的单独压缩比特流。 By using the appropriate approach to entropy encoding of the run and level values, then the video in combination with a further complex control information encoder, also uses a type of information suitable for variable length coding method performs entropy discussed coding, thereby forming the image information encoder 335 of FIG. ^ f individual compressed bitstream.

宏块的本地解码版本也是在编码器300中形成的。 Locally decoded version of the macroblock is also formed in the encoder 300. 这个操作是通过将量化器306输出的关于各个块的量化变换系数经由反向量化器308以及在逆变换单元310中应用一种反向DCT变换来完成的。 This operation is performed on each block by transform coefficients quantized accomplished via the inverse quantizer 308 and applying an inverse transform unit A 310 in the inverse DCT conversion output of the quantizer 306. 这样一来,重建的像素阵列是为所述宏块中的各个块构造的。 Thus, the pixel array is the reconstructed macroblock in each block configuration. 最终得到的图像数据输入到组合器312。 Finally obtained image data is input to combiner 312. 在帧内编码模式中对开关314进行设定, 以使经由开关314到达组合器312的输入为零。 Setting of the switch 314 in intra-coding mode, switch to null 314 via the input reaching combiner 312. 这样一来,组合器312 执行的操作等价于传递那些没有发生变化的解码图像数据。 In this way, the operation performed by combiner 312 is equivalent to passing the decoded image data that is not changed.

在接收到当前帧的宏块并对宏块执行了单元304、 306、 308、 310 和312中的前述编码和解码步骤的时候,在帧存储器32 0中构造帧内编码帧的解码版本。 Upon receiving the macroblock of the current frame and macro block 304 is executed, 306, 308, 310 and 312 and the decoding step, when coding, intra-coded frame structure 320 in the decoded version of the frame memory unit. 在对当前帧的最后一个宏块执^f亍了帧内编码和后续解码之后,帧存储器320将会包含一个完全解码的帧,在以帧间编码格式编码后续接收的视频帧的过程中,所述完全解码的帧可以用作一个预测参考帧。 After the last macroblock of the current frame is performed right foot ^ f the intra encoding and subsequent decoding, a frame memory 320 will contain a completely decoded frame, during a video frame subsequent to inter-encoding format received, said fully decoded frames may be used as a prediction reference frame.

现在对帧间编码模式中的编码器3 00的操作进行描述。 Now the operation of an inter coding modes of the encoder 300 will be described. 在帧间编码模式中,控制管理器360通过操作开关302来从线路317接收其输入,其中包含了组合器316的输出。 In inter coding mode, the control manager 360 through the operation of switch 302 to receive its input from line 317, which comprises the output of combiner 316. 组合器316以宏块方式从输入端301中接收视频输入信号。 The combiner 316 receives the video macroblock mode input signal from the input terminal 301. 在组合器316接收到构成宏块的亮度和色度值的块的时候,它会形成相应的预测误差信息块。 When the combiner 316 receives the blocks of luminance and chrominance values ​​of the macroblock, it forms corresponding blocks of prediction error information. 所述预测误差信息表示的是所论述的块与运动补偿预测单元350中产生的其预测值之间的差值。 The prediction error information represents the difference between the prediction value and the motion compensation prediction unit block 350 discussed generated. 更具体地说,关于宏块中各个块的预测误差信息包括所述值的二维阵列,其中每一个值表示的都是所编码亮度或色度信息块中一个像素值与依照下述过程而为所述块形成的运动补偿预测所获取的解码像素值之间的差值。 More specifically, the prediction error information for each block of the macroblock comprises a two-dimensional array on the value, wherein a pixel value according to the following processes are encoded luminance or chrominance information for each block a value represented by as the difference between the decoded pixel value motion compensated prediction block formed acquired. 因此,在每个宏块都包括8x8像素的亮度值块以及两个在空间上与之对应的8 x 8像素的色度值块的情况下,关于宏块的预测误差信息也包括四个8 x 8的亮度预测误差值块,以及两个在空间上与之对应的8 x 8的色度预测误差值块。 Thus, each macro block includes the case where the 8x8 block and the pixel values ​​of the luminance values ​​of chroma blocks 8 x 8 pixels of two spatially corresponding prediction error information for the macroblock also includes four 8 x 8 luminance blocks of prediction error values, and two chrominance blocks of prediction error values ​​corresponding spatially to 8 x 8.

关于宏块中各个块的预测误差信息被传递到DCT变换单元304,所述单元对每个预测值块执行一个二维离散余弦变换,以便为每一个块都产生一个DCT变换系数的二维阵列。 Each block in the macroblock of prediction error information is transmitted to the DCT unit 304, the unit performs a two-dimensional discrete cosine transformation to each block of predictive values ​​for each block to produce a two-dimensional array of DCT transform coefficients . 因此,在关于各个宏块的预测误差信息包含四个8 x 8的亮度预测误差值块以及两个在空间上与之对应的8 x 8的色度预测误差值块的情况下,DCT转换单元304为每个预测误差块产生一个8 x 8的变换系数值阵列。 Thus, in the case where the prediction error information about each macroblock comprising luminance blocks of prediction error values ​​of four 8 x 8 blocks and two chrominance prediction error values ​​in the corresponding space of 8 x 8, the DCT converting unit for each prediction error block 304 to generate a transform coefficient value of an array of 8 x 8. 关于各个预测误差块的变换系数则被传递到量化器306,其中使用一个量化参数QP并以一种与上文中结合帧内模式中的编码器操作所描述的方式相似的方式来对其进行量化。 Transform coefficients on the respective prediction error blocks were transferred to the quantizer 306, using a quantization parameter QP of one and in a similar manner as above in connection with intra-mode encoder operation described manner quantify . 同样,关于量化参数QP的选择是由控制管理器36Q通过控制线315来进行控制的。 Similarly, regarding the selection of the quantization parameter QP to 36Q is controlled by a control line 315 by the control manager.

经过量化的DCT系数表示的是宏块中各个块的预测误差信息,如图1中的线路325所示,这些系数从量化器306传递到视频复用器370。 Quantized DCT coefficients are represented by respective blocks of a macroblock of prediction error information, as shown in FIG. 1 line 325, the transmission coefficients from the quantizer 306 to the video multiplexer 370. 与帧内编码模式一样,视频复用编码器370使用了前述Z字形扫 As with the intra-coding mode, the video multiplex coder 370 using the Z-shaped sweep

描过程(参见图3)来对各个预测误差块的变换系数进行排序,然后则将每一个非零量化系数表示成一个等级和一个游程值。 Described procedure (see FIG. 3) to sort the transform coefficients each prediction error block, and then each non-zero quantized coefficients will be expressed as a level and a run value. 此外它还使用 In addition it also uses

了熵编码并以一种与上文结合帧内编码模式所描述的方式相似的方式来对游程和等级值进行压缩。 Entropy coding and the intraframe coding mode in a manner as described above in connection with a manner similar to compress the run and level values. 视频复用编码器370还经由线路326从运动场编码单元340中接收运动矢量信息,并且从控制管理器360中接收控制信息。 Video multiplex coder 370 also receives motion vector information from motion field coding unit 340 via line 326, and receive control information from control manager 360. 该编码器对运动矢量信息进行熵编码,并且形成一个单独的编码图像信息比特流335 ,所述比特流中包含了经过熵编码的运动矢量、预测误差和控制信息。 The encoder entropy encoding motion vector information, and forms a single bit-stream of coded image information 335, the bit stream through entropy encoding contains a motion vector, prediction error and control information.

经过量化的DCT系数表示的是宏块中各个块的预测误差信息,这些系数也是从量化器306传递到反向量化器308。 Quantized DCT coefficients are represented by respective blocks in the macroblock of prediction error information, the coefficients are passed from quantizer 306 to the inverse quantizer 308. 在这里对其进行反向量化并且将最终得到的反向量化DCT系数应用于反向DCT变换单元310,其中在所述单元中对其进行DCT变换,以便产生局部解码的预测误差值块。 Here subjected to the inverse quantization and the finally obtained inverse quantized DCT coefficients to inverse DCT transform unit 310, which are subjected to the DCT transform unit to produce locally decoded prediction error block values. 然后,经过局部解码的预测误差值块输入到组合器312中。 Then, after the local decoded prediction error values ​​inputted to the block combiner 312. 在帧间编码模式中将对开关314进行设置,以使组合器312还接收关于运动补偿单元350产生的宏块中各个块的预测像素值。 In inter coding mode, switch 314 will be provided, so that the combiner 312 also receives predicted pixel value of the macroblock on the motion compensation unit 350 generates the respective blocks. 组合器312 将预测误差值的每一个局部解码块与相应的预测像素值块相结合,以便产生重建图像块并将其存入帧存储器320。 The combination of 312 local decoded prediction for each block and the predicted block of pixel values ​​corresponding to the combination of error values ​​to produce reconstructed image blocks and stored in the frame memory 320.

由于视频信号的宏块是从视频源接收并且经过先前所述的单元304、 306、 308、 310和312中的编码和解码步骤,因此帧内编码帧的解码版本是在帧存储器320中构造的。 Since the macroblocks and the video signal is received through the previously described unit 304, 306, 308, 310 and 312 from the step of encoding and decoding a video source, the decoding version intra-coded frame is constructed in the frame memory 320 . 在对视频信号的最后一个宏块执行了帧内编码和后续解码之后,帧存储器320包含一个完全解码的帧,所述帧可以在用帧间编码格式解码后续接收的视频帧的过程中充当一个预测参考帧。 After performing intra-coding and subsequent decoding of the last macroblock of the video signal, the frame memory 320 contains a completely decoded frame, the frame may serve as a subsequent video frame during inter-coding decoding the received format prediction reference frame.

现在描述的是为当前帧的一个宏块产生预测。 It is now described to produce a predicted macroblock of the current frame. 任何一个以帧间编码格式编码的帧都需要一个用于运动补偿预测的参考帧。 Any inter-frame encoding format requires a reference frame for motion compensated prediction. 这意味着在对视频序列进行编码的过程中,无论将要编码的第一帧是序列中的第一个帧还是其他帧,都有必要采用帧间编码格式来对其进行编码。 This means that in the process of video sequences encoding, regardless of the first frame to be encoded in the sequence of the first frame or other frames have been necessary, an inter-frame encoding format to encode it. 而这转而意味着当控制管理器36将视频编码器300切换到帧间编码模式时,通过对先前形成的编码帧进行解码,由此形成的完整参考帧已经可以在编码器的帧存储器320中使用。 Which in turn means that when the switching manager 36 controls the video encoder 300 to the inter coding mode, by decoding the encoded frame previously formed, thereby forming a complete reference frame memory 320 in frame already encoder use. 通常,参考帧是通过对帧内编码帧或帧间编码帧进4于局部解码来形成的。 Typically, the reference frame is obtained by intra-coded frame or the inter-coded into the local decoding frame 4 formed.

在为当前帧的一个宏块生成预测的过程中,第一个步骤是由运动估计单元330执4亍的。 In the process for generating a predicted macroblock of the current frame, a first step is performed by the motion estimation unit 330 of the right foot 4. 运动估计单元330经由线路328来接收那些构成所编码的帧的亮度和色度值块。 Motion estimation unit 330 receives the blocks of luminance and chrominance values ​​for those frames constituting the encoded via line 328. 然后,它执行一个块匹配操作,以^f更识别参考帧中实质对应于当前宏块的一个区域。 It then performs a block matching operation in order to identify more ^ f the reference frame corresponding to a substantial area of ​​the current macroblock. 为了执行所述块匹配操作,运动现场估计单元经由线路327来访问帧存储器320中保存的参考帧数据。 In order to perform the block matching operation, motion estimation reference frame data field 327 to access unit stored in the frame memory 320 via the line. 更具体地说,运动估计单元330是通过对表示受检查宏块与候选最佳像素匹配区域间像素值差别的不同数值(例如绝对差值之和)进行计算来执行块匹配的,其中所述最佳像素匹配区域来源于帧存储器320中保存的参考帧。 More specifically, the motion estimation unit 330 performs block matching is performed by calculating different values ​​(e.g., sum of absolute differences) representing the difference between the optimum pixel value by checking the matching area candidate macroblock pixel, wherein the best match pixel region from the reference frame stored in the frame memory 320. 在参考帧的预定搜索范围以内,针对所有可能偏移上的偏移而计算了一个差值,并且运动估计单元330 确定了最小的计算差值。 Within a predetermined search range of the reference frame for all possible offsets offset calculating a difference value, and the motion estimation unit 330 determines the smallest calculated difference value. 当前帧的宏块与产生最小差值的参考帧的候选像素值块之间的偏移则定义了关于所讨论的宏块的运动矢量。 Macroblock of the current frame and the candidate offset between the blocks of pixel values ​​produced the smallest difference reference frame defines the motion vector about the macroblock in question.

一旦运动估计单元330为宏块产生了运动矢量,则其将运动矢量输出到运动场编码单元340。 Once the motion estimation unit 330 generates a macroblock motion vector, it outputs the motion vector to the motion field coding section 340. 所述运动场编码单元34(H吏用一个包含一组基函数和运动系数的运动模型来对从运动估计单元330接收的运动矢量进行近似估计。更具体地说,运动场编码单元340将运动矢量表示为一组运动系数值,其中在将这些值与基函数相乘的时候则形成了运动矢量的一个近似值。通常, 一个平移运动模型只具有两个运动系数并且在这里使用了基函数。 The motion field coding unit 34 (H officials be carried out using a motion model contains a set of basis functions and motion coefficients from the motion of the motion vector estimation unit 330 receives the approximated. More specifically, the motion field coding unit 340, the motion vector represents a set of motion coefficient values ​​which, when these values ​​are multiplied by the base function approximation is formed of a motion vector. typically, a translational motion model having only two motion coefficients and basis functions is used here.

运动系数从运动场编码单元340传递到运动补偿预测单元"0。运动补偿预测单元350还从帧存储器320中接收运动估计单元330识别的像素值的最佳匹配候选区域。通过使用运动场编码单元340产生的运动矢量的近似表示以及来自参考帧的像素最佳匹配候选区域的像素值,运动补偿预测块350为宏块中的每一个块都产生一个预测像素值的阵列。每一个预测像素值块都传递到组合器316,在所述组合器中则将对应于当前宏块的块中的实际(输入)像素值与预测像素值相减。 这样就得到了一组关于宏块的预测误差块。 Motion coefficients from the motion field coding unit 340 is transmitted to the motion compensation prediction unit "0. motion compensation prediction unit 350 also receives the motion estimation best matching candidate region of pixel values ​​identified unit 330 from the frame memory 320. The motion field is generated by using the coding unit 340 a pixel value motion vector and an approximate representation of the best matching candidate region of pixels from the reference frame, motion compensated prediction block 350 for each block of the macroblock are predicted to generate an array of pixel values. each block of predicted pixel values ​​are passed to the combiner 316, the combiner will block corresponding to the macroblock of the current actual (input) pixel value and the predicted pixel values ​​are subtracted. this resulted in a set of prediction error blocks for the macroblock is.

现在对图2所示的视频解码器400的操作进行描述。 Now the operation of the video decoder shown in FIG. 2, 400 will be described. 解码器400 包括一个从编码器300接收编码比特流并将其解复用成其组成部分的视频复用解码器470, 一个反向量化器410, 一个反向DCT变换器420, 一个运动补偿预测单元440, 一个帧存储器450, 一个组合器430, 一个控制管理器460以及一个输出端480。 It comprises a decoder 400 from the encoder 300 receives the encoded bit stream multiplexing and demultiplexing the video into its constituent parts by a decoder 470, an inverse quantizer 410, an inverse DCT transformer 420, a motion compensated prediction unit 440, a frame memory 450, a combiner 430, a control manager 460, and an output terminal 480.

控制管理器460对所解码的是帧内编码帧或帧间编码帧做出响 Control manager 460 of their decoded is intra-coded or inter-frame coded frame to make a ring

应,从而对解码器4 00的操作进行控制。 Should, thus operation of the decoder 400 is controlled. 帧内/帧间触发控制信号将导致解码器在解码模式中进行切换,其中举例来说,所述信号是在从编码器接收的各个压缩视频帧的报头部分所提供的图像类型信息中导出的。 Intra / inter control trigger signal will cause the decoder to switch decoding mode, wherein for example, the signal is received from an encoder in a respective compressed image type information in the header portion of the video frames provided by the derived . 帧内/帧间触发控制信号由视频复用解码器470从编码视频比特流中提取并且经由控制线422传递到控制管理器460。 Intra / inter control signal 470 is triggered by the video multiplex decoder extracts from the encoded video bit stream and transmitted to the control manager 460 via control line 422.

帧内编码帧的解码是以一个接一个的宏块为基础来执行的,其中实际上每一个宏块都是在一识别出接收视频比特流335中与之相关的编码信息的时候就被解码的。 Decoding the intra-coded frame is one after another performed macroblock basis, wherein a macroblock is virtually every identified in a received video bitstream 335 of encoded information related thereto is decoded when of. 视频复用解码器47G首先从涉及所论述宏块的可能控制信息中分离那些关于宏块中的块的编码信息。 Video multiplex decoder 47G discussed relates to the first control information may be separated from those blocks for the macroblock coded in the macroblock. 而关于帧内编码宏块中各个块的编码信息包括可变长度码字。 And each block coding information comprises variable length codewords on intra-coded macroblock. 这些码字表示的是用于块中非零量化DCT系数的熵编码的等级和游程值。 These codewords are represented by a block of non-zero quantized DCT coefficients entropy coding run values ​​and level. 视频复用解码器410使用一种可变长度解码方法来对可变长度码字进行解码, 由此恢复等级和游程值,其中所述方法与编码器300中使用的编码方法相对应。 Video multiplex decoder 410 uses for a variable length decoding method for decoding variable length code words, thereby restoring the level and run values, said encoding method using a method of the encoder 300 corresponding to. 然后,所述解码器为宏块中的各个块重建量化变换系数阵列并且将其传递到反向量化器410。 Then, the decoder is a macroblock reconstructed quantized transform coefficients for each block and passes it to an array of inverse quantizer 410. 此外还在视频解复用器中使用了一种恰当的可变长度解码方法来对涉及宏块的任何控制信息进行解码, 并且将其传递到控制管理器460。 Further still video demultiplexer using an appropriate variable length decoding method for decoding the control information relates to any of the macroblock, and passes it to control manager 460. 特别地,与应用于变换系数的量化等级相关的信息由视频复用解码器470从编码比特流中提取并且经由控制线424提供到控制管理器460。 In particular, to the transform coefficients associated with quantization level information 470 extracted from the video multiplex decoder from the encoded bit stream and provided to control manager 460 via control line 424. 控制管理器转而经由控制线415将这个信息传递到反向量化器420。 In turn, the control manager 415 via control line passes this information to the inverse quantizer 420. 反向量化器410根据控制信息来为宏块中的各个块反向量化那些量化过的DCT系数,并且将现在进行了反向量化的DCT系数提供给反向DCT变换器420。 Inverse quantizer 410 provides the control information for the respective blocks in the macroblock quantization inverse quantized DCT coefficients of those, and the now inverse quantized DCT coefficient a according to the inverse DCT transformer 420.

反向DCT变换器420对用于宏块中各个块的反向量化DCT系数执行反向DCT变换,以便形成一个包含重建像素值并经过解码的图像信息块。 Inverse DCT transformer 420 pairs for each block of quantized DCT coefficients inverse transform performing inverse DCT macroblock, after the image block to form a decoded reconstructed pixel values ​​and contains. 由于在帧内编码宏块的编码/解码中并未使用运动补偿预测,因此控制管理器460以一种防止在帧内编码宏块的解码中4吏用任何参考信息的方式来控制组合器430。 Since motion compensation is not used in the intra prediction coding / decoding macroblock, the control manager 460 in a decoding intra-coded macroblock 4 officials in any way to prevent the reference information 430 to control the composition . 关于宏块中各个块的重建像素值则传递到解码器的视频输出端480,其中举例来说,可以将所述值提供给一个显示设备(没有显示)。 On the reconstruction of the pixel values ​​in each block of the macroblock is passed to the video output of the decoder 480, wherein for example, the value may be provided to a display device (not shown). 此外,关于宏块的各个块的重建像素值还保存在帧存储器45 0中。 Further, on the reconstruction of the pixel values ​​of the respective blocks in the macroblock are also stored in the frame memory 450. 由于对帧内编码帧的后续宏块进行解码和保存, 因而在帧存储器450中逐渐汇聚出一个解码帧,并且由此可以将所述帧充当一个参考帧,以便在与后续接收的帧间编码帧的解码相关联的 Because of the subsequent macroblocks intra-coded frame is decoded and stored, which gradually converge a decoded frame in the frame memory 450, and thereby the frame can serve as a reference frame for receiving the subsequent inter-coded associated with the decoded frame

运动补偿预测中^f吏用。 ^ F motion compensated prediction with officials.

帧间编码帧也是以逐个宏块的方式来解码的,实际上,每一个帧间编码宏块都是在从接收比特流中识别到与之相关的编码信息的时候 Frames are inter-coded macroblocks one by one, to be decoded, in fact, each of inter-coded macroblocks are identified at the time of receiving the bit stream from the encoded information associated

就被解码的。 To be decoded. 视频复用解码器470从编码运动矢量信息和涉及所论述宏块的可能控制信息中分离出关于帧间编码宏块各个块的编码预测误差信息。 Video multiplex decoder 470 and the coded motion vector information may relate discussed macroblock control information separated from the information about the inter-coded macroblocks coded prediction error for each block. 如上所述,用于宏块中各个块的编码预测误差信息包括可变长度代码字,它表示的是用于所述预测误差块的非零量化变换系数熵编码的等级和游程值。 As described above, for each block encoded prediction error information comprises variable length codewords macro block, which is represented by a non-zero quantized transform coefficients of the prediction error entropy coding block level and run values. 视频复用解码器470使用一种可变长度解码方法来对可变长度码字进行解码,由此恢复等级和游程值,其中所述方法与编码器300中使用的编码方法相对应。 Video multiplex decoder 470 uses a variable length decoding method decodes the variable length codewords, thereby restoring the level and run values, said encoding method using a method of the encoder 300 corresponding to. 然后所述解码器重建一个关于宏块中各个块的量化变换系数阵列并且将其传递到反向量化器410。 The decoder then reconstructs an array of quantized transform coefficients on a macroblock for each block and passes them to inverse quantizer 410. 此外,在视频复用解码器中也使用了一种恰当的可变长度编码方法来对涉及帧间编码宏块的控制信息进行解码,并且所述信息则传递到控制管理器460。 Further, in the video multiplex decoder also be used with an appropriate variable length coding method decodes the control information relates to inter-coded macro block, and the information is passed to control manager 460. 与应用于预测误差块的变换系数的量化等级相关联的信息则是从编码比特流中提取的,并且所述信息是经由控制线424 提供到控制管理器460的。 Extracting the information is associated with the quantization level applied to the prediction error block transform coefficients from the encoded bit stream, and the information is provided to control manager 460 via control line 424. 控制管理器460转而经由控制线4"将这个信息传递到反向量化器420。反向量化器420根据控制信息来对这些表示宏块中各个块的量化DCT系数进行反向量化,并且将现在反向量化的DCT系数提供给反向量化器420。然后则在反向DCT变换器420 中对表示各个块的预测误差信息的反向量化DCT系数进行反变换,以便为宏块中的每一个块生成一个重新建立的预测误差值的阵列。 4 in turn control manager 460 "via the control line to pass this information to the inverse quantizer 420. The inverse quantizer 420 performs inverse quantization of the quantized DCT coefficients of each block of the macroblock according to the control information indicates, and now inverse quantized DCT coefficient to inverse quantizer 420. in the inverse DCT transformer and the 420 inverse quantized DCT coefficients representing the prediction error information for each block of inverse transform, for each macroblock a block generating an array of prediction error values ​​re-established.

涉及宏块的编码运动矢量信息由视频复用解码器47G从编码视频比特流335中提取并且是使用一种恰当的可变长度解码方法而被解码的。 Relates to encoding of motion vector information of the macroblock 47G extracted by the video multiplex decoder 335 from the encoded video bitstream and is used in an appropriate variable length decoding method is decoded. 由此得到的解码运动矢量经由数据线426传递到运动补偿预测单元44 0,其中所述单元使用了一个与编码器300中编码所述帧间编码宏块所用运动模型相同的运动模型来为宏块重建一个运动矢量。 Decoding motion vector data thus obtained is transferred via line 426 to the motion compensation prediction unit 440, wherein the movement unit uses the same motion model model encoding the inter-coded macroblock with an encoder 300 and to the macro a block motion vector is reconstructed. 重建的运动矢量与编码器的运动估计单元330最初确定的运动矢量相似。 The reconstructed motion vector and the motion estimation motion vector encoder unit 330 is similar to the initially determined. 解码器的运动补偿预测单元440则使用重建的运动矢量而在帧存储器450保存的预测参考帧中识别重建像素区域的位置。 Decoder motion compensation prediction unit 440 using the predicted motion vector is reconstructed reference frame stored in the frame memory 450 to identify the position of reconstructed pixel region. 例如,参考帧可以是一个先前解码的帧内编码帧,也可以是一个先前解码的帧间编码帧。 For example, the reference frame may be a previously decoded intra-coded frame, or may be a previously decoded inter-coded frame. 但不论出现哪种情况,重建运动矢量指示的像素区域都被用于形成一个所论述宏块的预测。 In either case however, the pixel region indicated by the motion vector reconstruction are used to form a prediction macroblock discussed. 更具体地说,运动补偿预测单元440通过 More specifically, the motion compensation prediction unit 440

从参考帧中识别的像素区域拷贝相应的像素值来形成一个关于宏块中各个块的像素值阵列。 Pixel values ​​of pixels corresponding to the identified region copied from the reference frame to form the array of pixel values ​​of the respective blocks in a macro block on. 而所述预测则是从参考帧中导出的像素值块, And said predicted block of pixel values ​​are derived from the reference frame,

它从运动补偿预测单元440传递到组合器430,在那里它与经过解码的预测误差信息相结合。 It passes from the motion compensation prediction unit 440 to the combiner 430 where it combined with the decoded prediction error information. 在实践中,每个预测块的像素值都被添加到反向DCT变换器420输出的相应重建预测误差值中。 In practice, the pixel values ​​of each predicted block are added to corresponding reconstructed prediction error values ​​output by inverse DCT transformer 420 in. 由此可以得到关于宏块中各个块的重建像素值阵列。 Thus each block can be reconstructed array of pixel values ​​on a macroblock. 重建的像素值则传递到解码器的视频输出端480并且保存在帧存储器450中。 Reconstructed pixel values ​​are passed to the video output of the decoder 480 and stored in the frame memory 450. 由于解码和保存了帧间编码帧的宏块,因此在帧存储器450中逐渐汇聚成一个解码帧,由此所述解码帧作为一个参考帧而在其他帧间编码帧的运动补偿预测中4吏用。 Because the decoding and saving the inter-coded frame's macro-block, thus gradually converging to a decoded frame in the frame memory 450, whereby the decoded frame as a reference frame and the motion compensated prediction interframe encoding the other frames 4 officials use.

H. 26L视频编码标准 H. 26L video coding standard

ITU-T建议H. 26L是国际电联开发的视频编码标准族中的最新标准。 ITU-T Recommendation H. 26L video coding standards developed by the ITU in the latest standards. 特别地,这个标准旨在以通常小于64kb/s的低比特率来进行视频编码,因此所述标准特别适合对经由那些需要优先考虑如何最佳使用 In particular, the low bit rate standard intended to generally less than 64kb / s to perform video coding standard and therefore particularly suitable for the priorities of how best to use those via

可用带宽的无线通信网或任何固定线路通信网所传送的数字视频进行编码。 Available bandwidth of a wireless communication network, or any fixed-line communication network digital video transmitted encoded. ITU-T H. 26L定义的视频编码系统是一个混合视频编码系统, 它是根据如上所述与图1和2所述的通用视频编码器300和解码器400 相结合的一般原则来运作的。 The video encoding system defined in ITU-T H. 26L video coding is a hybrid system which is based on the general principles described above in FIGS. 1 and 2 according to a generalized video encoder 300 and the decoder 400 to operate in combination. 特别地,依照H. 26L实现的视频编码系统使用的是将基于块的变换编码与运动补偿预测相结合,从而减少视频序列中的空间和时间冗余。 In particular, in accordance with the H. 26L video coding system is implemented using transform coding and motion compensated prediction block based on the combination, reducing spatial and temporal redundancy in a video sequence.

H. 26L建议的最新版本即为通常所说的Test Model 8 ( TML8 ), 在"H. 26L Test Model Long Term Number 8 ( TML-8 ) draft 0,, ( ITU-T 电信标准化部分,研究组16,视频编码专家小组)中对其进行了描述, 这个版本的建议规定了两种备选的熵编码模式。在第一种(缺省)模式中使用了所谓的通用可变长度编码(UVLC)方法来对所有语法元素进行编码。UVLC编码模式是一种查找表方法,其中在不考虑所论述信息类型的情况下用同一组可变长度码字来表示视频编码器产生的所有不同类型的信息。而在所谓的"高复杂度类(profile)"中指定使用的备选熵编码方法是一种以基于上下文的自适应二进制算术编码(CABAC)而著称的技术。这种方法是一种持续适应于编码信息统计性质的二进制算术编码形式,并且在现有技术中作为最有效的熵编码形式中的一种而闻名(参见H. Witten、 RM Neal与JG Clear H. 26L is the latest version of the proposed known as Test Model 8 (TML8), in the "H. 26L Test Model Long Term Number 8 (TML8) draft 0 ,, (ITU-T Telecommunication Standardization Sector, Study Group 16, the video coding experts group) they are described in this version of the proposal provides for two alternative entropy coding modes using a so-called universal variable length coding (UVLC in the first (default) mode ) approach to all the different types .UVLC coding mode is a coding table lookup method in which as discussed does not consider the case where variable length code words with the same type of information can be denoted by the video encoder generated for all syntax elements information in the so-called "high complexity class (Profile)" is specified using an alternative method of entropy coding is a kind of context-based adaptive binary arithmetic coding (CABAC) known in the art. this method is an continuously adapted to the form of binary arithmetic coding information encoded statistical properties and well known (see H. Witten as the most effective form of entropy coding in the prior art, RM Neal and JG Clear y在1987年6月发表于Commun. ACM第30巻第520 - 540页的"Arithmetic coding for data compression" —文)。 y Commun ACM published in Volume 30 of the first 520 in June 1987 -. "Arithmetic coding for data compression" 540 page - text).

由于UVLC熵编码使用了同一组可变长度码字来表示视频编码器生成的所有类型的信息,因此所述码字的统计性质通常并没有最佳匹配于将要编码的信息特征。 Since UVLC entropy coding using the same set of variable length codewords to represent all types of information generated by the video encoder, and therefore the statistical properties of the codeword is not usually the best match to the feature information to be encoded. 例如,用于表示为帧内编码图像块的量化DCT 系数的特定游程和等级值的出现频率很可能与涉及量化参数值的控制信息中的值的出现情况不同。 For example, for indicating the occurrence frequency of a specific level and run values ​​for the quantized DCT coefficients of intra-coded image blocks and appear likely to be different values ​​of the case where the control information relates to the value of the quantization parameter. 在H. 26L中引入了CABAC熵编码方法, 以便克服l)VLC熵编码方法所固有的次优特性。 CABAC entropy encoding method is introduced in H. 26L, to overcome the VLC l suboptimal properties inherent entropy coding methods). 如本文中先前所述,算术编码表示的是一个将要用单独的可变长度码(浮点数)来进行编码的符号群。 As previously described herein, it denotes arithmetic coding is to use a single variable length code (floating point) for encoding the symbol constellation. 与独立编码各个符号的熵编码方法相比,这种方法提供了特有的优点。 Compared with the method of entropy coding each symbol independently encoded, this method provides unique advantages. 具体地说,独立编码各个符号的熵编码方法至少需要使用一个比特来表示各个符号。 More specifically, each symbol of entropy coding methods need at least one independently coded bits to represent each symbol. 由于算术编码表示的是具有单个码字的符号群,因而有可能实现小于1比特/秒的数据压缩速率。 Because having a single symbol group code word represented by arithmetic coding, is therefore possible to achieve less than 1 bit / sec data compression rate. 因此,H. 26L 中提供的CABAC方法还有可能提高数据压缩。 Therefore, H. CABAC method provided in 26L also possible to improve the data compression. 此外,由于所述方法是一种自适应方法,因此它能够考虑到所编码信息的统计特征变化,由此确保即使所编码数据性质发生某种程度的变化,也能够保持数据压缩性能。 Further, since the method is an adaptive method, it is possible to take into account the statistical characteristics of the encoded change information, thereby ensuring some degree even change the nature of occurrence of the encoded data, data compression performance can be maintained.

基于上下文的算术编码 Context-based arithmetic coding

如上所述,CABAC算术编码是一种熵编码方法,它能适应于所编码信息的变化统计。 As mentioned above, CABAC entropy coding arithmetic coding is a method that can adapt to changing statistics encoded. 这样一来,与假设固定统计特性的熵编码技术相比, 所述方法能够提供改善的压缩效率。 Thus, compared with the assumed statistical properties of the fixed entropy encoding technique, the method capable of providing an improved compression efficiency. 图4描述的是一种示范性的基于上下文的二进制算术编码器700。 Exemplary is a context-based binary arithmetic encoder 700 depicted in FIG. 4. CABAC是一种二进制算术编码方法, 因此,所要编码的具有非二进制序列的数据符号首先在二进制映射单元710中转换成二进制值("二进制化")。 CABAC is a binary arithmetic coding method, therefore, to be non-coded data symbols having a binary sequence is first converted into a binary value ( "binarization") binary mapping unit 710. 所述二进制化处理包括将所要编码的符号映射到一个二进制序列(bin),其中每一个二进制序列都具有一个相应的二进制序列编号并且可以赋予一个值O或1。 The binarization processing comprises mapping the symbols to be encoded into a sequence of binary (bin), wherein each binary sequence having a respective binary sequence numbers and may be assigned a value of O or 1. 以下在表1中给出了这种映射的一个实例。 The following gives an example of such a mapping in Table 1. 但是原则上也可以设想使用其它二进制化方案。 However, in principle it is also conceivable to use other binary scheme.

在CABAC方法中,每一个二进制序列都指派给一个所谓的"上下文,,(基于上下文的算术编码由此得名)。 一个上下文可以视为是集中在一起并具有相似统计特征的二进制序列。换句话说,在这里假设对指派给上下文的每一个二进制序列来说,其包含数值1或0的概率 In the CABAC method, each of the binary sequences assigned to a so-called ",, context (context-based arithmetic coding, hence the name). A context can be viewed as together and have similar statistical characteristics binary sequence. Transducers words, here assumed that a binary sequence for each assigned to a context, the probability value of 1 or 0 comprising

与属于所迷上下文的其他二进制序列相似。 Similar to other fans binary sequence belonging to the context. 这样一来,用于在算术編码器中产生码字的概率估计是为每一个上下文而不是将要编码的每个 Thus, the probability of a codeword in the arithmetic encoder is used to estimate for each context not to be coded for each

<table>table see original document page 20</column></row> <table>表1 <Table> table see original document page 20 </ column> </ row> <table> TABLE 1

可能的二进制序列定义的。 Possible binary sequence defined. 每个上下文都是依照一个"上下文模型" 定义的,并且所述上下文是基于将要编码的数据符号(由此为二进制 Each context is in accordance with a "context model" is defined, and the context is based on data symbols to be coded (thus binary

序列)的统计特征信息而被预先建立的。 Sequence) the statistical characteristics of the information to be pre-established. 通常,如果将o的出现概率 In general, if the probability of occurrence o

与1的出现概率之间的差值增至最大,则会提高二进制算术编码器所能实现的数据压缩比率。 And the difference between the probability of occurrence of an increased maximum data binary arithmetic coder can achieve compression ratios will be increased. 同样,基于上下文的算术编码性能还取决于上下文模型的选择。 Similarly, context-based arithmetic coding performance also depends on the selected context model. 通常,这意味着应该选择那些能使指派给每个上 Typically, this means that you should choose those that can be assigned to each of the

下文的二进制序列的0和1的出现概率间的差值达到最大的上下文模型。 The difference between the binary sequence 0 below the occurrence probability and a maximum context model.

在图4所述的示范性的基于上下文的算术编码器中, 一旦在二进制映射单元710 二进制化所要编码的符号,则在上下文指派单元中将其指派给一个相应的上下文。 In the context of FIG arithmetic coder according to an exemplary 4-based, once the mapping unit 710 binarizes the binary symbol to be encoded, the context will be assigned a unit which is assigned to the respective context. 然后则将指派给相应二进制序列(也就是1或0)的值传递到算术编码器730。 It will then be assigned to the corresponding binary sequence (i.e. 1 or 0) is the value passed to the arithmetic coder 730. 随后,算术编码器730的编码引擎750使用一个指派了二进制序列的上下文的概率估计来对二进制序列的数值进行编码。 Subsequently, the coding engine 730 arithmetic coder 750 using a context probability assigned a binary sequence estimation value of a binary sequence is coded. 在这里,作为算术编码器实现的数据压缩比的性能依赖于概率估计的精度。 Here, as the arithmetic coder data compression ratio performance achieved depends on the accuracy of the estimated probability. 从原则上讲,所述估计可以是固定或自适应的。 In principle, the estimate may be fixed or adaptive. 如果使用固定概率估计,则关于上下文的概率估计将被指派给预定值并且在编码处理中保持不变。 If a fixed probability estimate, the estimate on the context probability will be assigned to a predetermined value and remains unchanged in the encoding process. 固定概率估计通常是通过对与所要编码的实际资料具有相似统计特征的训练资料进行分析而被预先得到的。 Fixed probability estimate is usually carried out by analyzing training data with similar statistical characteristics of the actual data to be encoded and is obtained in advance. 如果使用了自适应概率估计,则使用固定值来为各个上下 If using adaptive probability estimation, a fixed value is used for each vertical

文初始化概率估计,并且才艮据那些至此为止经过编码的数据(二进制序列)的实际统计特征而在整个编码处理中更新所述概率。 Probability estimation initialization message, and only those so far, according to Gen after the actual statistical characteristics of the encoded data (binary sequence) of updating the probabilities in the entire coding process. 执行自适应编码估计通常会更好,因为它们可以适应所要编码的资料。 Perform adaptive coding estimation is usually better, because they can adapt to the information to be encoded.

图4所示的示范性的基于上下文的算术编码器使用了自适应概率估计并且包括一个对经过更新的概率估计进行计算的概率估计单元740。 Probabilistic context-based adaptive arithmetic coder used and comprises a probability estimation elapsed probability update estimates calculated as shown in FIG. 4 exemplary estimation unit 740. 每一个上下文的概率估计则是通过记录指派给各个上下文的各个二进制序列中1和0的出现次数来更新的。 Each context probability estimate is updated by recording the number of occurrences assigned to each respective context in the binary sequence 0 and 1. 例如,对指派给任意上下文k的二进制序列来说,如果为其指派了m次值0并且为其指派了n 次值l,那么,对上下文k中的l来说,其概率估计是n/(n(m+l)), 对于0来说,其概率估计则是(m+l)/(n(m+l))。 For example, a binary sequence assigned to the k arbitrary context, if assigns the m-th value 0 and assigns the value l n times, then, in the context l k, its probability estimate is n / (n (m + l)), for 0, the probability is estimated (m + l) / (n (m + l)).

图5描述的是与结合图4所描述的编码器相对应的基于上下文的算术解码器800。 FIG 4 is a connection with the encoder described corresponding context-based arithmetic decoder 800 described in FIG. 5. 在输入端810,基于上下文的算术解码器接收一个表示经过算术编码的数据符号的比特流。 At the input terminal 810, a context based arithmetic decoder receiving a bit stream of data symbols represented through arithmetic coding. 一开始,根据先前接收的解码符号,在上下文指派单元850中计算一个上下文并且更新二进制序列值的概率估计。 Beginning, according to a previously received symbol is decoded, in the context of assigning a context calculation unit 850 and the probability of a binary sequence value updating estimates. 在这里,上下文指派单元850执行的上下文指派与概率估计单元830执行的关于概率估计的计算都是使用与编码器相同的方法来完成的。 In this context, the context assignment unit 850 performs assignment of probability estimate is calculated with respect to the probability estimation unit 830 are performed by the encoder using the same method to complete. 然后,接收到的比特馈送到算术编码器820的算术编码引擎840中,在那里使用计算得到的上下文以及二进制序列值的当前概率估计来将其转换成解码的二进制序列值。 Then, the received bit is fed to the arithmetic coder arithmetic coding engine 840 820, a binary sequence using context and the value calculated by the current probability estimate where to convert a binary value to a decoded sequence. 在二进制序列-数值映射单元860中,经过解码的二进制序列映射到游程和等级的值。 In binary sequence - Numerical mapping unit 860, after the decoded binary sequence mapped to a value of run and level.

在H. 26L中使用的CABAC方法 Used in the method of H. 26L CABAC

现在将对ITU-T建议H. 26L中选定用于高复杂度类的CABAC算术编码方法的细节进行详细描述。 Will now ITU-T recommendation H. 26L for details of the selected high complexity of CABAC-based arithmetic coding method will be described in detail. 根据H. 26L TML 8,游程和等级值的上下文依赖于所编码的块类型以及二进制化的等级或游程值的二进制序列数目。 8 depending on the context, the run and level values ​​H. 26L TML depends on the block type and binary coded number or sequence of binary levels of run value. 不同的块类型是依照对系数值进行排序的扫描方式(单/ 双)、成分类型(亮度/色度,AC/DC)或是编码模式(帧间/帧内)来定义的。 Different block types are sorted in accordance with the scan pattern based on the value (single / dual), component type (luminance / chrominance, AC / DC) or a coding mode (intra / inter) defined. 然而,对指定类型来说,上下文只依赖于二进制序列数目。 However, for the specified type, context dependent only on the number of binary sequences. 更具体地i兌,依照H. 26L TML 8,在这里为等级编码定义了四个上下文。 More specifically against i, in accordance with the H. 26L TML 8, where the definition of the context for the four level code. 第一个上下文用于第一个二进制序列,第二个上下文用于第二个二进制序列,第三个上下文用于那些表示等级幅度的剩余二进制序列。 A context for the first binary sequence a first, a second binary sequence for the second context, the context for the third binary sequence that represents a level of the remaining amplitude. 剩余上下文则用于等级的符号。 The context for the symbols remaining level. 此外还使用了相似的方法来将游程值指派给上下文。 In addition, using similar methods to assign to the context-run value. 对游程来说,存在三个上下文,第一个上下文用 Is to run, there are three contexts, a first context

于第一个二进制序列,第二个上下文用于第二个二进制序列,第三个上下文则用于所有剩余的二进制序列。 The first binary sequence in a second binary sequence context for the second, third context is used for all remaining binary sequence. 由于游程值始终等于或大于零,因此对附加上下文而言,没有必要为其表示符号信息。 Since the run value is always greater than or equal to zero, so the additional context, there is no need for information representation symbols. 这样一来, 对一个给定类型的块来说,针对变换系数的二进制序列(等级和游程 Thus, for a given type of block, the transform coefficients for a binary sequence (the level and run

编码)所进行的将二进制序列指派给上下文的处理可以如下概括: 6/ur,ZH ( 1 ) Coding) for binary sequences assigned to the context of the process may be summarized as follows: 6 / ur, ZH (1)

其中6//?_/7r是二进制序列数目,C0/7^,t是上下文编号。 Wherein 6 //? _ / 7r is a binary number sequence, C0 / 7 ^, t is the context number. 根据H. 26L TML 8, MAX —BIN —VAL的值设定为3,但是原则上也可以使用不同的MAX —BIN —VAL来作为替换。 The value H. 26L TML 8, MAX -BIN -VAL is set to three, but can in principle also use different MAX -BIN -VAL as replacement.

游程-等级对是如下编码的:首先根据块/系数类型来对游程和等级进行分类,其中所述类型包括:扫描模式、系数类型(DC/AC)以及编码模式(帧间/帧内或16x16帧内)。 Run - level pair is encoded as follows: First, to classify the blocks according to the run and level / type of coefficient, wherein the type comprising: a scanning mode, type coefficients (DC / AC) and the coding mode (inter / intra or 16x16 intra). 然后通过将等级和游程映射到一个二进制序列来对其进行二进制化,并且根据每一个二进制序列的编号来将其指派给一个上下文。 And then run-level mapping to a binary sequence to be binarized, and to assign it to each of a context number according to a binary sequence.

图6a ~ 6d通过参考示范性的4 x 4量化DCT系数阵列而对这个处理进行了详细描述。 FIG. 6a ~ 6d and this process is described in detail by the 4 x 4 array of quantized DCT coefficients exemplary reference. 此外它还描述了用于追踪量化DCT系数的游程和等级值的统计特性的方法,从而论证了CABAC方法的自适应特征。 In addition, it describes a method for tracking the statistical properties of the run and level values ​​of the quantized DCT coefficients, adaptive feature thus demonstrates the method of CABAC. 在这里,首先对经过量化的DCT系数值的二维阵列进行Z字形扫描,以便产生一个图6a所示的值的一维阵列。 Here, after the first DCT coefficient values ​​of a two-dimensional array of quantized Z-zag scan, in order to produce a one-dimensional array of values ​​shown in a FIG. 6a. 然后将一维阵列中的非零系数值作为游程和等级值对来加以表示。 The non-zero coefficient values ​​and one-dimensional array as the value of run and level to be represented. 如先前所述,每一个等级值都表示一个非零的量化DCT系数值,而相关的游程则对应于所论述系数之前的零值系数的数目。 As previously described, each class value indicates a non-zero quantized DCT coefficient values, and the associated run value corresponding to the number of zero coefficients before the coefficients discussed. 在图6b中给出了来源于示范性的量化DCT系数阵列的游程-等级对。 It gives the quantized DCT coefficients derived from the exemplary array of the run in Figure 6b - level pair. 在各个对中,等级值处于游程值之前并且将等于零的等级值用作一个块结束符号,以便指示所述块中没有非零系数值。 In each pair, the level value precedes the zero run value and the level value is used as a block end symbol, to indicate that the block is not a non-zero coefficient values.

接着,每一个游程和等级值都转换成一个二进制值。 Subsequently, each of the run and level values ​​are converted into a binary value. 根据H. 26L TML 8,用于转换量化DCT变换系数值的游程和等级的二进制化方案与上文中图1所示方案相同。 Binarization scheme converts quantized DCT transform coefficient values ​​of run and level with the embodiment shown in FIG. 1 described above the same as the H. 26L TML 8, is used. 图6c显示的是将表l给出的二进制化方案应用于示范性阵列中的游程和等级值的结果。 Figure 6c shows the results given in Table l binarization scheme is applied to level values ​​and run an exemplary array. 此外,图6c还显示了依 Furthermore, Figure 6c also shows by

照H. 26L而将二进制序列指派给上下文。 According to H. 26L and the binary sequence is assigned to the context. 如上所述,其中仅仅使用了三个上下文来描述游程和等级值的大小。 As described above, wherein only used to describe the context of the three sizes of the run and level values. 第一个上下文对应于二进制序列l,第二个上下文对应于二进制序列2,而第三个上下文则包括了所有剩余的二进制序列。 The first binary sequence corresponding to the L context, the second context corresponding to the binary sequence of 2, and the third context includes all the remaining binary sequence. 在图6c中,上下文是通过粗体横线来描绘的。 In Figure 6c, the context is portrayed by a horizontal line in bold. 通过检查图6c可以看出,大多数等级值都映射到指派给上下文3的二进制序列,而大多数游程值则映射到指派给上下文1的二进制序列。 As can be seen by examining FIG. 6C, most level values ​​are mapped to a binary sequence 3 is assigned to the context, and most run value is mapped to a binary sequence assigned to the context 1.

每一个经过指派的上下文的概率估计是在编码了二进制序列之后才更新的。 After each assignment context probability estimate it is that after encoding the binary sequence was updated. 而游程和等级的概率估计则是独立更新的。 The probability run and grade estimate is a separate update. 如先前所述, 给定上下文的概率估计表示的是指派给所论述的上下文的二进制序列的统计特征。 As previously described, the probability estimates given context indicates the context of the statistical feature assigned to a binary sequence discussed. 更具体地说,所述概率估计描述的是指派给上下文的二进制序列中包含0或1的概率。 More specifically, the probability estimates assigned to describe the probability of a binary sequence context contains 0 or 1. 图6d以一种示范方式描述了为游程和等级更新概率估计的方法。 FIG. 6d in one exemplary embodiment describes a method for the estimation of the probability of a run and a level update. 该图中描述的是在二进制化那些代表图6a 所示的4 x 4量化DCT系数块的游程和等级,并且将其指派给上下文, 进而在算术编码器中编码的前后,在指派到指定游程或等级的上下文的二进制序列中包含0或1的概率。 The figure is binarized those described on behalf of Figure 6a shown in FIG. 4 x 4 quantized DCT coefficient blocks the run and level, and assign it to the context, and thus before and after encoded in the arithmetic coder, in an assignment to the specified run context level or probability of a binary sequence containing 0 or 1. 图6d采用了表格形式,其中记录了在指派给各个上下文的二进制序列中的1和0的出现情况。 FIG. 6d using a table form, which is recorded in the case of occurrence of 0 and 1 is assigned to a binary sequence in the respective context. 因此, 一个指定上下文的概率估计是如下给出的: Accordingly, a probability that the specified context is estimated as given below:

0的概率=0的数目/ ( 0的数目+ 1的数目) 0 = 0 the probability of the number / (0 + the number of the number 1)

1的概率=1的数目/ ( 0的数目+ 1的数目) 1 = probability number 1 / (number 0 + 1 number)

在这个图中,假设图6a所示的量化DCT系数的4 x 4块是最早处理的块。 In this figure, the block is 4 x 4 block of quantized DCT coefficients of the first process shown in FIG assumed 6a. 这意味着在表中没有记录1和0的先前出现情况。 This means that no records appear in Table 1 and 0 in the previous case. 为了克服这个问题,在这里假设在处理所述块之前,每一个上下文都具有相等的包含1或0的概率。 To overcome this problem, the process is assumed here that prior to the block, each having a context equal probability of containing 0 or 1. 而这种假设是通过在记录0和1的出现情况的列中输入相同的值来表示的。 This assumption is input by the same value 0 and the recording occurs in the case of a column represented. 在图6d中,l被用于初始化概率估计。 In Figure 6d, l is used to initialize the probability estimate. 作为选择,也可以使用一个来源于训练数据分析的概率估计来为各个上下文初始化概率估计。 Alternatively, you can use a probabilistic analysis of estimates derived from the training data to estimate the probability for each context initialization. 然后则在二进制化关于量化DCT变换系数的游程和等级值并将其指派给上下文的时候对各个上下文的二进制序列中出现的1和0的数目进行计数,由此更新概率估计。 In regard to the binarized and then run and level values ​​quantized DCT transform coefficients and the time that the number assigned to the context of a binary sequence 1 and 0 appearing in various contexts is counted, thereby updating the probability estimation. 图6d的右手列显示了在处理过图6a所示的4 x 4量化DCT块之后的情况。 FIG. 6d right-hand column shows what happens after processing of FIG. 4 x 4 quantized DCT blocks shown 6a.

尽管与UVLC熵编码方法相比,在ITU-T建议H. 26L TML 8的高复杂度类中采用的CABAC算术编码方法在数据压缩方面提供了改进, 但是就编码效率来说,所述方法仍不是最佳的。 Although compared with UVLC entropy coding method, CABAC in ITU-T recommendation H. 26L TML arithmetic coding method of high complexity class 8 employed provides improved data compression respect, it is the coding efficiency, the method is still It is not optimal. 因此,本发明的一个 Accordingly, the present invention is a

目的是提供一种能够进一步提高编码效率的基于上下文的算术编码方法和系统。 Object is to provide a further improved arithmetic coding method and system for context-based coding efficiency.

发明内容 SUMMARY

本发明基于这样一种认识,那就是在使用基于上下文的算术编码来对指定数据符号进行编码的时候,通过使用那些对指派了其他数据符号的上下文加以考虑的上下文模型,可以在编码效率方面得到提 The present invention is based on the recognition that when in use to encode a context based arithmetic encoding of the specified data symbols, can be obtained in terms of coding efficiency by using a context model to be considered as those assigned to the context of the other data symbols mention

高。 high. 特别地,通过参考H. 26L TML 8的高复杂度类中使用的CABAC方法,本发明的发明人已经确定,在游程与关联于DCT变换系数的等级之间存在某些联系。 In particular, by using the reference H. 26L TML high complexity of the CABAC method of class 8, the present inventors have determined that some connection exists between the level of DCT transform coefficients in the run is associated. 此外发明人还确定了可以使用这些关系来构造改进的上下文模型,其中所述模型能在将CABAC方法应用于游程和等级值的时候使之以经过提高的编码效率来运作。 In addition the inventors also determined relationship may be used to construct these improved context model, wherein the model can make the CABAC method is applied at the time of the run and level values ​​in order to improve coding efficiency through operation. 特别地,发明人已经确定,连续等级值将会显示出极大相似性。 In particular, the inventors have determined that the continuous level value will show great similarities. 更具体地说,在指定的变换系数块内部,所编码系数的等级实质上通常具有类似于先前编码系数等级的幅度。 More specifically, in the interior of the specified block of transform coefficients, the level of encoded coefficients typically have substantially similar to the previously encoded coefficient amplitude level. 此外发明人还确定了等级与游程值之间的一个反比关系。 Further the inventors have also identified an inverse relationship between the level and run values. 特别地,越大的等级值越有可能在较小的游程值之前。 In particular, the larger the value of the level before the more likely a smaller run value. 反过来一样是成立的,也就是说,较小的等级值很可能是在较大的游程之后。 In turn, the same is true, that is, the smaller level value is likely to be after a large run. 因此,本发明提出为DCT变化系数的编码创建新的上下文模型,其中所述模型顾及了等级与游程值之间的这些关系。 Accordingly, the present invention proposes to create a new context model is encoded DCT coefficient of variation, wherein the model takes into account the relationship between these levels and the run value.

在为了执行基于上下文的编码器而设计的第一个上下文模型中, 对指派给一个二进制化的系数等级值的二进制序列来说,其上下文依赖于先前编码的系数等级。 In order to perform a first context model based on the context of the encoder design, the assigned binary sequence for a binary value of the coefficient levels, its context dependent on the level of the previously encoded coefficient. 在为了执行基于上下文的解码器而设计的第二个上下文模型中,对指派给二进制化的系数等级值的二进制序列 In the second context model to perform a context-based decoder design, the assigned binary sequence for the binary value of the coefficient levels

来说,其上下文依赖于先前解码的系数等级。 , Its context dependent on a previously decoded coefficient levels. 在为了实施基于上下文的解码器或是基于上下文的算术解码器而设计的第三个上下文模型中,对指派给二进制化的系数游程值的二进制序列来说,其上下文依 In the context of a decoder embodiment for the third context model or context-based arithmetic decoder designed based on the sequence of binary coefficients assigned to the binarized run value, its context by

赖于先前解码的系数等级值。 It depends on the level of the coefficient values ​​previously decoded.

发明人还进一步确定,在与不同图像块相关联的变换系数值之间存在某种相似性。 The inventors have further determined that there is some similarity between the transform coefficient values ​​associated with a different image blocks. 这些相似性在相互靠近的图像块间会变得更大,并且在相互紧邻的图像块之间往往最强。 These similarities between image blocks close to each other becomes larger, and most often between image blocks next to each other. 更具体地说,用于表示特定图像块的非零变换系数值的数量Nc往往与接近或邻接所论述图像块中的非零变换系数值的数目是相同的。 More specifically, for indicating the number Nc of non-zero transform coefficient values ​​of a specific image block is often close to or abutting with the number of nonzero transform coefficient values ​​discussed in the image block are the same. 因此,本发明还引入了这样一个概 Accordingly, the present invention also introduces such an overview

念,那就是为变换编码的图像块提供一个非零变换系数数目的指示并且使用熵编码来对这个值进行编码。 Read, that is to provide a number of non-zero transform coefficients for the image block indicated transform coding and entropy coding to encode this value. 此外,如果将基于上下文的算术 Further, if the context-based arithmetic

编码用于对Nc值进行编码,那么发明人已经确定,较为有利的是通过对指派给用于至少一个其他变换编码图像块的上下文加以考虑而将块的Nc值指派给一个上下文。 Encoding for encoding Nc value, the inventors have determined that it is advantageous to at least one other context transform encoded image block is assigned to be taken into account by the Nc value for the block assigned to a context. 这样一来,在相互靠近的图4象块之间,Nc Thus, between the block of FIG. 4 as close to each other, Nc of

建议H. 26L Tm1 8,并没有^图像块中非零变换系一数的数目进行编码。 Recommendation H. 26L Tm1 8, the number of lines and a number of ^ no image block is coded nonzero transform. 作为替换并且如先前所示,在这里提供了一个块结束(EOB)指示。 Alternatively and as shown previously, there is provided in the end of a block (the EOB) indication. E0B 指示表示已经对相应于非零系数的最后一个游程-等级对进行了编码。 E0B corresponding indication indicates a non-zero coefficient has last run - Level of encoded. 发明人确定,与当前在H.26L TML 8中所用的提供E0B指示的方法相比,这里提出的方法将会导致编码效率上的提高,其中在本发明 The inventors have determined, as compared with current methods provide E0B indicated in H.26L TML 8 used, the method presented here will lead to improvement in the encoding efficiency, in the present invention, wherein

中提供了一个块中非零系数数目的明确指示,并且使用了基于上下文的算术编码来对其进行编码。 It provides the number of nonzero coefficients in a block explicitly indicated, and uses them to a context based arithmetic coding coding.

尽管本发明背后的动机及其基本概念是在视频编码/解码中给出的,尤其是就h. 26l tml 8给出的,但是应该理解,本发明也可以适用于其他视频编码系统和静止图像编码。 Although the motivation and the basic concept behind the present invention is given in a video encoding / decoding, in particular with regard h. 26l tml 8 is given, it should be understood that the present invention may be applied to other still image and video coding systems coding. 从原则上讲,本发明可以应用于任何一个使用了基于块的变换编码与基于上下文的算术编码的图像编码系统。 In principle, the present invention is applicable to any use of a block-based transform coding and image coding system context-based arithmetic coding.

根据本发明的第一个方面,提供了一种图像编码方法,其中将图像分成具有多个像素的多个块,每一个像素具有一个像素值,并且对所述像素值块执行一个变换编码操作,以便产生相应的变换系数值块。 According to a first aspect of the present invention, there is provided an image encoding method, wherein the image is divided into a plurality of blocks having a plurality of pixels, each pixel having a pixel value, and performing a transform encoding operation on the block of pixel values to produce a corresponding block of transform coefficient values. 在一个给定扫描顺序中扫描所述变换系数值块,以便产生一个经过扫描的系数值阵列,并且使用多个数字对来表示经过扫描的阵列中的系数值,所述数字对具有一个第一数字和一个第二数字。 In a scan order the scanning transform coefficient values ​​for a given block, through the array of values ​​to produce a scan line, and a plurality of numbers to represent the coefficient values ​​through the array in the scan, the pair having a first digital number and a second number. 将第一数字和第二数字指派给表示所述数字对的多个上下文中的一个。 The first and second digital numbers assigned to represent one of a plurality of context in the digital. 根据本 According to the

发明的第一个方面, 一个数字对的第一值是基于另一个数字对中的第一数字而被指派给一个上下文的。 The first aspect of the invention, a first digital value is based on another of the first digit pair is assigned to a digital context.

优选地,基于一个数字对中的第一数字而将另一个数字对中的第一数字指派给一个上下文的步骤顾及指派了其他数字对中的第一数字的上下文。 Preferably, the first based on a number and the other numbers in digit pair is assigned to a first step of a digital Contextual assigned the first number in the context of the other figures.

较为有利的是,数字对中的第一数字表示的是一个非零系数值。 It is advantageous that the number of the first digital representation is a non-zero coefficient value. 优选地,数字对的第一数字与非零系数值的大小是相等的。 Preferably, the size of the first digital value and the number of the nonzero coefficient are equal. 优选地,数字对中的第二数字表示的是在非零系数值之前的多个连续零系数值。 Preferably, the number of the second digital representation is a plurality of non-zero coefficient values ​​before consecutive zero coefficient values.

优选地,所述上下文是一个基于上下文的算术编码器的上下文。 Preferably, said context is a context-based arithmetic coder context. 更为优选的是,所述上下文是基于上下文的二进制运算编码器的上下文。 More preferably, said context is a context based on the context of the binary arithmetic encoder.

较为有利的是,第一和第二数字映射到一组二进制序列,其中每一个二进制序列都具有一个相关联的二进制序列编号,并且每一个二 It is advantageous that the first and second set of numbers is mapped to a binary sequence, wherein each binary sequence having a binary sequence number associated with each of the two and a

进制序列都能采用第一值或第二值中的一个。 Ary sequence can adopt a first value or a second value.

优选地,每个第一和第二数字都映射到所述一组二进制序列中的一个,而将数字映射到所述一组二进制序列中给定的一个则是通过将二进制序列的值指派给第一值来指示的。 Preferably, each of the first and second numbers are mapped to one of a set of binary sequences, and the digital map to a set of binary sequences is given a value assigned by the binary sequences a first indicated value.

优选地,第一值是1并且第二值是0。 Preferably, the first value is 1 and the second value is 0.

优选地,每一组二进制序列都被指派给一个上下文。 Preferably, each set of binary sequences is assigned to a context.

非常有利的是,在对指派了其他数字对中第一数字的上下文加以考虑的情况下,基于另一个数字对中的第一数字而将一个数字对中的第一数字指派给一个上下文的步骤是通过检查所述其他数字对的第一数字所映射的二进制序列的二进制序列编号来执行的。 Very advantageously, in the case where the other numbers assigned to be considered in the context of the first number, based on the another digital and digital to a first digit pair is assigned to a first step of a digital context binary sequence is a binary sequence by the first ID number of said additional checking of the digital map to be executed.

较为有利的是,所述方法还包括保持一个用于描述各个上下文的统计特性的概率估计。 It is advantageous that the method further comprises maintaining a probabilistic description of the statistical properties of the respective context estimation.

优选地,对各个上下文来说,所述概率估计表示的是具有指派给上下文的预定值的数字的统计似然性。 Preferably, for each context, the probability estimates are expressed with a digital value assigned to a predetermined statistical likelihood context.

优选地,对各个上下文来说,所述概率估计是通过记录指派给所论述上下文的二进制序列中的笫一值和第二值的出现情况来保持的。 Preferably, for each context, the probability estimates assigned to the recording occurs by a value Zi binary sequences discussed in the context of the case and a second value to hold.

根据本发明的第二个方面,提供了一种图像编码方法,其中将图像分成具有多个像素的多个块,每一个像素都具有一个像素值,并且对所述像素值块执行一个变换编码操作,以便产生相应的变换系数值块。 According to a second aspect of the present invention, there is provided an image encoding method, wherein the image is divided into a plurality of blocks having a plurality of pixels, each pixel having a pixel value, and performing a transform coding of the pixel values ​​of the block operation to produce corresponding transformed block of coefficient values. 在一种给定扫描顺序中扫描变换系数值块,以便产生一个经过扫描的系数值阵列,并且使用多个数字对来表示经过扫描的阵列中的系数值,其中所述数字对具有一个第一数字和一个第二数字。 In one transform coefficient scan order of blocks of values ​​for a given scan to generate an array of values ​​through the scan lines, and a plurality of numbers to represent the coefficient values ​​through the array in the scan, wherein said pair having a first digital number and a second number. 将第一数字和第二数字指派给表示所述数字对的多个上下文中的一个。 The first and second digital numbers assigned to represent one of a plurality of context in the digital. 根据本发明的第二个方面,数字对的第二数字是基于数字对中的第一数字而 According to a second aspect of the present invention, the second digital number is based on a first number of the number of

被指派给一个上下文的。 It is assigned to a context.

优选地,基于一个数字对中的第一数字而将另一个数字对中的第一数字指派给一个上下文的步骤对指派了其他数字对中第一数字的上下文加以考虑。 Preferably, a number based on the first number and the other numbers in the first digital steps are assigned to a context of the other figures to be assigned in consideration of the first context number.

较为有利的是,数字对中的笫一数字表示的是一个非零系数值。 It is advantageous that the number of Zi is a digital representation of a non-zero coefficient value. 优选地,数字对的第一数字与非零系数值的大小是相等的。 Preferably, the size of the first digital value and the number of the nonzero coefficient are equal.

优选地,数字对中的第二数字表示的是在非零系数值之前的多个连续零系数值。 Preferably, the number of the second digital representation is a plurality of non-zero coefficient values ​​before consecutive zero coefficient values.

优选地,所述上下文是一个基于上下文的算术编码器的上下文。 Preferably, said context is a context-based arithmetic coder context. 更为优选的是,所述上下文是基于上下文的二进制运算编码器的上下文。 More preferably, said context is a context based on the context of the binary arithmetic encoder.

较为有利的是,第一和第二数字映射到一组二进制序列,其中每一个二进制序列都具有一个相关联的二进制序列编号,并且每一个二进制序列都能采用第一值或第二值中的一个。 It is advantageous that the first and second set of numbers is mapped to a binary sequence, wherein each binary sequence having a binary sequence number associated with each of a binary sequence and can adopt a first or second value in One.

优选地,每个第一和第二数字都映射到所述一组二进制序列中的一个,而将数字映射到所述一组二进制序列中给定的一个则是通过将二进制序列的值指派给第一值来指示的。 Preferably, each of the first and second numbers are mapped to one of a set of binary sequences, and the digital map to a set of binary sequences is given a value assigned by the binary sequences a first indicated value.

优选地,第一值是1并且第二值是o。 Preferably, the first value is 1 and the second value is o.

优选地,每一组二进制序列都被指派给一个上下文。 Preferably, each set of binary sequences is assigned to a context.

非常有利的是,在对指派了其中一个数字对的第二数字的上下文加以考虑的情况下,基于数字对中第一数字而将数字对中第二数字指派给一个上下文的步骤是通过检查第二数字所映射的二进制序列的二进制序列编号来执行的。 It is very advantageous, in the case be considered in which the assignment of a second number of digital context, based on the numbers and the numbers of the first digit in the second digit is assigned to the step of a context by examining the first SEQ ID NO binary second digital binary sequences mapped performed.

较为有利的是,所述方法还包括保持一个用于描述各个上下文的统计特性的概率估计。 It is advantageous that the method further comprises maintaining a probabilistic description of the statistical properties of the respective context estimation.

优选地,对各个上下文来说,所述概率估计表示的是具有指派给上下文的预定值的数字的统计似然性。 Preferably, for each context, the probability estimates are expressed with a digital value assigned to a predetermined statistical likelihood context.

优选地,对各个上下文来说,所述概率估计是通过记录指派给所论述上下文的二进制序列中的第一值和第二值的出现情况来保持的。 Preferably, for each context, the probability estimates assigned by recording a first value appears as discussed in the context of a binary sequence and a second value to keep the case.

优选地,根据本发明第一和第二方面的方法全都适用于变换系数值块。 Preferably, the first and second aspects of the present invention is applicable to all blocks of transform coefficient values.

根据本发明的第三个方面,提供了一种编码器,包括用于将图像分为具有多个像素的多个块的装置,其中每一个像素都具有一个像素值,此外还包括用于对《象素值块执行一个变换编码操作,以便产生一个相应的变换系数值块的装置。 According to a third aspect of the present invention, there is provided an encoder comprising means for dividing an image into a plurality of blocks having a plurality of pixels, each pixel having a pixel value, further including means for "performing a pixel value of the block transform coding operation to generate a corresponding value of the block transform-based device. 所述编码器还包括用于以一个给定扫描顺序来扫描变换系数值块,以便产生经过扫描的系数值阵列的装置,用于表示多个数字对所代表的经过扫描的阵列中的系数值的装置,所述数字对具有一个第一数字和一个第二数字,以及用于将第一数字和第二数字指派给表示数字对的多个上下文之一的装置。 Said encoder further comprises means for a given scan order to scan the transform coefficient values ​​of blocks in order to produce a device of the system scans the array of values ​​for coefficient values ​​representing the scanned array of a plurality of digital represented in means, having a pair of said first digital number and a second number, and the first and second digital numbers for the digital means for assigning one of a plurality of contexts to FIG. 根据本 According to the

发明的第三个方面,所述编码器包括用于根据另一个数字对的第一数字而将数字对的第一数字指派给一个上下文的装置。 A third aspect of the invention, the encoder comprises a first digital number by the first pair and another digital to digital assigned to a device context.

根据本发明的第四个方面,提供了一种编码器,包括用于将图像分成具有多个像素的多个块的装置,其中每一个像素都具有一个像素值,此外还包括对像素值块执行一个变换编码操作,以便产生相应的变换系数值块的装置。 According to a fourth aspect of the present invention, there is provided an encoder comprising means for dividing the image into a plurality of blocks having a plurality of pixels, each pixel having a pixel value and further comprising a block of pixel values ​​of perform a transform coding operation to generate a corresponding value of the block transform-based device. 所述编码器还包括用于以一个给定扫描顺序扫描变换系数值块,以便产生经过扫描的系数值阵列的装置,用于表示多个数字对所代表的经过扫描的阵列中的系数值的装置,其中所述数字对具有一个第一数字和一个第二数字,以及用于将第一数字和第二数字指派给表示数字对的多个上下文之一的装置。 Said encoder further comprises means for a given scan order the scanning block transform coefficient values, the coefficient values ​​in order to produce a means of scanning the array, the array used to represent the coefficient values ​​of the plurality of digital scanned represented in the apparatus, wherein said pair having a first digital number and a second number, and the first and second digital numbers for the digital means for assigning one of a plurality of contexts to FIG. 根据本发明的第四个方面,所述编码器包括用于根据数字对中的第一数字而将数字对的第二数字指派给一个上下文的装置。 According to a fourth aspect of the present invention, the encoder comprises a second digital number of the first number and the number of devices assigned to a context.

根据本发明的第五个方面,提供了一种图像编码方法,其中将图像分成具有多个像素的多个块,每一个像素都具有一个像素值,并且对像素值块执行一个变换编码操作,以便产生相应的变换系数值块。 According to a fifth aspect of the present invention, there is provided an image encoding method, wherein the image is divided into a plurality of blocks having a plurality of pixels, each pixel having a pixel value, and performing a transform coding operation on the block of pixel values, to produce a corresponding block of transform coefficient values.

根据本发明的第五个方面,所述方法包括如下步骤:提供一个表示变换系数值块中非零系数值数目的数字,以及将这个数字指派给一个表示所述数字的上下文。 According to a fifth aspect of the present invention, the method comprising the steps of: providing a block of transform coefficient values ​​represented nonzero coefficient value of the digital number, and this number will be assigned to a number representative of the context.

非常有利的是,将表示变换系数值块中非零变换系数值数目的数字指派给一个上下文的步骤对指派了另一个数字的上下文加以考虑, 其中所述另一个数字表示的是另一个变换系数块中的非零系数值数目。 Very advantageously, the transform coefficient values ​​representing a block of non-zero transform coefficient value of the digital number of steps assigned to a consideration of context of context assigned another number, wherein the digital representation is another other transform coefficients the number of nonzero coefficient value in the block.

非常有利的是,变换值块是在给定扫描顺序中扫描的,由此产生了一个经过扫描的系数值阵列,并且在所述经过扫描的阵列中,系数值是由多个数字对来表示的,其中所述数字对具有一个第一数字和一个第二数字。 Very advantageously, the conversion value in a given block is scanned in a scan order, thereby generating an array of values ​​of the scanned lines, and scanning through the array, the coefficient values ​​are represented by a pair of said plurality of digital wherein said pair having a first digital number and a second number.

较为有利的是,数字对中的第一数字表示的是一个非零系数值。 It is advantageous that the number of the first digital representation is a non-zero coefficient value. 优选地,数字对的第一数字与非零系数值的大小是相等的。 Preferably, the size of the first digital value and the number of the nonzero coefficient are equal. 更为优选的是,数字对的第一数字与非零系数值减1的大小是相等的。 More preferably, the first non-zero digit number and coefficient values ​​of reduced size is equal to 1.

优选地,数字对中的第二数字表示的是在非零系数值之前的多个连续零系数值。 Preferably, the number of the second digital representation is a plurality of non-zero coefficient values ​​before consecutive zero coefficient values.

优选地,在这里没有提供一个指示处于经过扫描的系数值阵列中的最后一个非零系数值的块结束指示。 Preferably, there is no indication in a block after the last non-zero coefficient value of a value array scanning lines end instruction.

优选地,根据本发明第一、第二和第五方面的方法每一个都适用于变换系数值块。 Preferably, according to the first, second and fifth aspect of the present invention are applicable to each of the block transform coefficient values.

根据本发明的第六个方面,提供了一种编码器,其中包括用于将图像分成具有多个像素的多个块的装置,其中每一个像素都具有一个像素值,此外还包括用于对像素值块执行一个变换编码操作,以便产生相应的变换系数值块的装置。 According to a sixth aspect of the present invention, there is provided an encoder, which includes means for dividing the image into a plurality of blocks having a plurality of pixels, each pixel having a pixel value, further including means for performing a pixel value of the block transform coding operation to generate a corresponding value of the block transform-based device. 所述编码器包括提供一个用于指示变换系数值块中非零系数值数目的数字的装置,以及用于将所述数字指派给一个表示所述数字的上下文的装置。 Said encoder comprises providing a digital value for the number of transform coefficient values ​​indicating means nonzero coefficient in the block, and means for assigning a digital context means the digital representation.

非常有利的是,所述编码器还包括用于在对指派了另一个数字的上下文加以考虑的情况下指派所述指示变换系数值块中非零变换系数值数目的数字的装置,其中所述另一个数字指示的是另一个变换系数块中非零变换系数的数目。 Very advantageously, said encoder further comprises means for assigning the transform coefficient values ​​indicating the number of digital devices nonzero transform coefficient values ​​in the block is considered to be a case where another number assigned context, wherein said another number indicates the number of the other transform coefficients in the block of non-zero transform coefficients.

根据本发明的第七个方面,提供了一种计算机程序,其中包括用于将图像分成具有多个像素值的多个块的代码,其中每一个像素值都具有一个像素值,此外还包括用于对像素值块执行一个变换编码操作,以便产生相应的变换系数值块的代码。 According to a seventh aspect of the present invention, there is provided a computer program, wherein the code comprises means for dividing the image into a plurality of blocks having a plurality of pixel values, where each pixel value having a pixel value, also comprises to perform a transform coding operation on the block of pixel values ​​to produce a corresponding value of the code block transform coefficients. 所述计算机程序还包括用于以给定扫描顺序扫描变换系数值块,以便产生经过扫描的系数值阵列的代码,用于使用多个数字来表示经过扫描的阵列中的系数值的代码,其中所述数字对具有一个第一数字和一个第二数字,以及用于将第一数字和第二数字指派给表示数字对的多个上下文之一的代码。 The computer program further comprises means for scanning in a given scan order a block transform coefficient values ​​to produce a value-based array scanning the code, using a plurality of digital codes to represent the coefficient values ​​of the array scanned through, wherein the number having a first number and a second number, and the first and second digital numbers are used to assign the digital code representing one of a plurality of contexts. 根据本发明的第七个方面,所述计算机程序还包括用于根据另一个数字对中的第一数字而将其中一个数字对的第一数字指派给一个上下文的代码。 According to a seventh aspect of the present invention, the computer program further comprises a first digital to another according to the figures and in which the first digit of a number assigned to a context code.

较为有利的是,数字对中的第一数字表示的是一个非零系数值。 It is advantageous that the number of the first digital representation is a non-zero coefficient value.

优选地,数字对的第一数字与非零系数值的大小是相等的。 Preferably, the size of the first digital value and the number of the nonzero coefficient are equal. 优选地,数字对中的第二数字表示的是在非零系数值之前的多个连续零系数值。 Preferably, the number of the second digital representation is a plurality of non-zero coefficient values ​​before consecutive zero coefficient values.

根据本发明的笫八个方面,提供了一种计算机程序,其中包括用于将图像分成具有多个像素值的多个块的代码,其中每一个像素值都具有一个像素值,此外还包括用于对像素值块执行一个变换编码操作,以便产生相应的变换系数值块的代码。 According Zi eight aspect of the invention, there is provided a computer program, wherein the code comprises means for dividing the image into a plurality of blocks having a plurality of pixel values, where each pixel value having a pixel value, also comprises to perform a transform coding operation on the block of pixel values ​​to produce a corresponding value of the code block transform coefficients. 所述计算机程序还包括用于以给定扫描顺序来扫描变换系数值块,以便产生经过扫描的系数值阵列的代码,用于使用多个数字来表示经过扫描的阵列中的系数值的代码,其中所述数字对具有一个第一数字和一个第二数字,以及用于将第一数字和第二数字指派给表示所述数字对的多个上下文之一的代码。 The computer program further comprises means for a given scan order to scan the block transform coefficient values ​​to produce a code value array of the scanning system, using a plurality of numbers to represent the coefficient values ​​through the array in the scan code, wherein said pair having a first digital number and a second number, and a first and a second digital code representing the number assigned to one of a plurality of digital contexts. 根据本发明的第八个方面,所述计算机程序还包括用于根据数字对中第一数字来把所述数字对的第二数字指派给一个上下文的代码。 According to an eighth aspect of the invention, the computer program further comprises a second pair of a first digital number to the number assigned to the pair of digital code in accordance with a context. 较为有利的是,数字对中的第一数字表示一个非零系数值。 Advantageous is a digital representation of the first non-zero coefficient value numbers. 优选地,数字对的第一数字与非零系数值的大小是相等的。 Preferably, the size of the first digital value and the number of the nonzero coefficient are equal. 优选地,数字对中的第二数字表示的是非零系数值之前的多个连续零系数值。 Preferably, the number of the second digital representation is a plurality of non-zero coefficient value zero before the continuous coefficient value.

根据本发明的笫九个方面,提供了一种计算机程序,其中包括用于将图像分成具有多个像素值的多个块的代码,其中每一个像素值都具有一个像素值,此外还包括用于对像素值块执行一个变换编码操作,以便产生相应的变换系数值块的代码。 The nine aspect of the present invention, Zi, there is provided a computer program, wherein the code comprises means for dividing the image into a plurality of blocks having a plurality of pixel values, where each pixel value having a pixel value, also comprises to perform a transform coding operation on the block of pixel values ​​to produce a corresponding value of the code block transform coefficients. 根据本发明的第九个方面, 所述计算机程序还包括用于提供表示变换系数值块中非零系数值数目的数字的代码,此外还包括用于将这个数字指派给一个表示所述数字的上下文的代码。 According to a ninth aspect of the invention, the computer program further includes providing a block transform coefficient values ​​represent the number of nonzero coefficient value of the digital code, this further including means for assigning a digital number representing the context code.

非常有利的是,所述计算机程序还包括用于在对指派了另一个数字的上下文加以考虑的情况下,将指示变换系数值块中非零变换系数值数目的数字指派一个上下文的代码,其中所述另一个数字指示的是另一个变换系数块中的非零系数值的数目。 Very advantageously, the computer program further comprises a case to be considered in the context of another figure assigned, block transform coefficient values ​​indicating the number of nonzero transform coefficient values ​​context assigned a digital code, wherein the another number indicates the number of non-zero transform coefficient values ​​of the other coefficients in the block.

根据本发明的第十个方面,提供了一种依照本发明第七、第八和第九方面的计算机程序。 According to a tenth aspect of the present invention, there is provided a computer program in accordance with the seventh, eighth and ninth aspects of the present invention.

根据本发明的第十一个方面,提供了一种基于上下文的算术编码方法,其中数据符号阵列是用一个码字来表示的。 According to an eleventh aspect of the present invention, there is provided a context-based arithmetic coding method, wherein the array of data symbols is represented by a code word. 所述阵列中的数据 The data array

符号是包含了一个第一数字和一个第二数字的数字对。 Symbol comprising a first and a second digital digit number pair. 所述数字对中的第一数字指派给一个从表示第一数字的多个上下文中选出的上下文,数字对中的第二数字则指派给一个从表示第二数字的多个上下文中选出的上下文。 The numbers of the first number is assigned to a plurality of contexts from the context represents a first selected number, of the second digital numbers are assigned to a plurality of contexts from a second number represents a selected context. 根据本发明的笫十一个方面,数字对的第一数字是基于数字对中另一个数字对的第一数字而被指派给上下文的。 The Zi eleven aspect of the invention, a first digital number is based on a first number of digital numbers are another pair is assigned to the context.

根据本发明的第十二个方面,提供了一种基于上下文的算术解码方法,其中数据符号阵列是从一个表示阵列的码字中解码的。 According to a twelfth aspect of the present invention, there is provided a context-based arithmetic decoding method, wherein the array of data symbols are decoded from a codeword represented array. 所述阵列中的数据符号是包含了一个第一数字和一个第二数字的数字对。 Data symbols in the array comprising a first number and a second digital number pair. 所述数字对的第一数字指派给一个从代表第一数字的多个上下文中选出的上下文,而数字对的第二数字则指派给一个从代表第二数字的多个上下文中选出的上下文。 The numbers assigned to the first digit pair selected from a plurality of context representing the first context number, the second digit number is assigned to a context selected from a plurality of numbers representing a second context. 根据本发明的第十二个方面,数字对的第一数字是基于数字对中的另一个数字对的第一数字而被指派给上下文的。 According to a twelfth aspect of the present invention, a first digital number is based on a first number of the another digital numbers to be assigned to the context.

根据本发明的第十三个方面,提供了一种基于上下文的算术编码方法,其中数据符号阵列是用一个码字来表示的。 According to a thirteenth aspect of the present invention, there is provided a context-based arithmetic coding method, wherein the array of data symbols with one codeword is represented. 所述阵列中的数据符号是包括一个第一数字和一个第二数字的数字对。 Data symbols in the array comprising a first digital number and a second number pair. 所述数字对的第一数字指派给一个从表示第一数字的多个上下文中选出的一个上下文,所述数字对的第二数字则指派给一个从表示第二数字的多个上下文中选出的上下文。 The first digit number assigned to a pair represents a context from the context of the first plurality of selected digits, the second digit is assigned to the digital to represent a plurality of contexts from a second selected number out of context. 根据本发明的第十三个方面,数字对的笫二数字是基于数字对中的第一数字而被指派给一个上下文的。 According to a thirteenth aspect of the present invention, the number of Zi two figures are based on a first digital number is assigned to a context.

根据本发明的第十四个方面,提供了一种基于上下文的算术解码方法,其中数据符号阵列是从一个表示阵列的码字中解码的。 According to a fourteenth aspect of the present invention, there is provided a context-based arithmetic decoding method, wherein the array of data symbols are decoded from a codeword represented array. 所述阵列中的数据符号是包括一个第一数字和一个第二数字的数字对。 Data symbols in the array comprising a first digital number and a second number pair. 所述数字对的第一数字指派给一个从表示第一数字的多个上下文中选出的上下文,所述数字对的第二数字则指派给一个从表示第二数字的多个上下文中选出的上下文。 The first digit number assigned to one pair of the plurality of contexts from the context represents a first selected number, said second digital numbers is assigned to one of the context of the second plurality represents a number selected from context. 根据本发明的第十四个方面,数字对的第二数字是基于数字对中的第一个数字而被指派给一个上下文的。 According to a fourteenth aspect of the present invention, a second pair of digital numbers are based on the numbers and the first number is assigned to a context.

根据本发明的第十五个方面,提供了一种基于上下文的算术编码方法,其中数据符号阵列是用一个码字来表示的,此外还提供了表示阵列中非零数据符号数目的数字并且将其指派给一个表示所述数字的上下文。 According to a fifteenth aspect of the present invention, there is provided a context-based arithmetic coding method, wherein the array of data symbols with one codeword is represented, in addition to providing a number of non-zero data symbols in the array represents and the numbers which is assigned to a number representative of the context.

根据本发明的第十六个方面,提供了一种基于上下文的算术编码器,其中包括用于使用码字来表示一个数据符号阵列的装置。 According to a sixteenth aspect of the present invention, there is provided a context-based arithmetic coder, which comprises a device using a codeword to represent a data symbol array. 所述阵列中的数据符号是包括第一数字和第二数字的数字对,所述编码器还包括用于将数字对的第一数字指派给一个从代表第一数字的多个上下文中选出的一个上下文的装置,以及将数字对的第二数字指派给一个从代表第二数字的多个上下文中选出的上下文的装置。 The array of data symbols comprising a first digital number and a second number of the encoder further comprises a first digital to digital assigned to a context selected from a plurality of numbers representing the first context means selected from a plurality of second digital representative of the context of a device context, and the second digital numbers assigned to the pairs. 根据本发明的第十六个方面,所述编码器包括根据所述数字对中一个数字对的第一数字而将另一个数字对的第一数字指派给一个上下文的装置。 According to a sixteenth aspect of the present invention, the first digital encoder comprising a first number of said digital in a number and the other pair of numbers assigned to a device context.

根据本发明的第十七个方面,提供了一种基于上下文的算术解码器,其中包括用于从表示数据符号阵列的码字中解码出数据符号阵列的装置。 According to a seventeenth aspect of the present invention, there is provided a context-based arithmetic decoder, which comprises means for decoding the data symbols from the array of data representing the codeword symbol array. 所述阵列中的数据符号是包括第一数字和第二数字的数字 Data symbols in the array comprising a first number and a second digital number

对,所述解码器还包括:用于将数字对的第一数字指派给从代表第一数字的多个上下文中选出的一个上下文的装置,以及将数字对的第二数字指派给一个从代表第二数字的多个上下文中选出的上下文的装置。 To said decoder further comprises: a first digit of the digital device selected from a plurality of contexts representative of a first number assigned to a context, and a second pair of digital numbers assigned from a a plurality of device context in the context of representing a second selected number. 根据本发明的第十七个方面,所述解码器包括根据所述数字对中 According to a seventeenth aspect of the present invention, said decoder comprising a pair of said digital

一个数字对的第一数字而将另一个数字对的第一数字指派给一个上下文的装置。 The first digit of a digit pair and the other numbers assigned to the first digital device to a context.

根据本发明的笫十八个方面,提供了一种基于上下文的算术编码器,其中包括使用码字来表示一个数据符号阵列的装置。 The Zi eighteen aspect of the invention, there is provided a context-based arithmetic coder, which comprises using a codeword to represent a data symbol array means. 所述阵列中的数据符号是包括第一数字和第二数字的数字对,所述编码器还包括用于将数字对的第一数字指派给从代表第一数字的多个上下文中选出的一个上下文的装置,以及将数字对的第二数字指派给一个从代表第二数字的多个上下文中选出的上下文的装置。 The array of data symbols comprising a first digital number and a second number of the first digit number assigned to a selected pair of said encoder further comprises a plurality of contexts from a first number representative of the a device context, and the context of a device selected from the plurality of second digital representative of the context of the second digital numbers assigned to the pairs. 根据本发明的第十八个方面,所述编码器包括用于根据数字对中第一数字而将数字对的第二 According to an eighteenth aspect of the present invention, the encoder comprises a first digital to digital and digital to second

数字指派给一个上下文的装置。 Number assigned to a device context.

根据本发明的第十九个方面,提供了一种基于上下文的算术解码器,其中包括用于从表示数据符号阵列的码字中解码出所述阵列的装置。 According to a nineteenth aspect of the present invention, there is provided a context-based arithmetic decoder, which comprises means for decoding code words from said array of data symbols represented in the array. 所述阵列中的数据符号是包括第一数字和第二数字的数字对,所述解码器还包括用于将数字对的第一数字指派给一个从代表第一数字的多个上下文中选出的上下文的装置,以及将数字对的第二数字指派给一个从代表第二数字的多个上下文中选出的上下文的装置。 The array of data symbols comprising a first digital number and a second number of said decoder further comprises means for digital assigned to the first digit pair is selected from a plurality of numbers representing the first context context means selected from a plurality of contexts representative of the second digital device context, and the second digital numbers assigned to the pairs. 根据本发明的第十九个方面,所述解码器包括用于根据数字对中第一数字而将数字对的第二数字指派给一个上下文的装置。 According to a nineteenth aspect of the present invention, the decoder comprises a means for assigning a context number according to a second pair of a first digital number and the digital right. 根据本发明的第二十个方面,提供了一种基于上下文的编码器, 其中包括使用一个码字来表示一个数据符号阵列的装置,此外还包括提供一个表示阵列中非零数据符号数目的数字的装置,以及将所述数字指派给一个表示所述数字的上下文的装置。 According to a twentieth aspect of the invention, there is provided a context-based encoder, which comprises using a codeword to represent a data symbol array device, also comprising providing a number of non-zero data symbols in the array represents a number It means, and said means for assigning a digital number representative of the context.

通过结合图7a到12来阅读本说明书,本发明将会变得清楚。 12 to FIG. 7a by binding to reading this specification, the present invention will become apparent. 附图说明 BRIEF DESCRIPTION

图1是一个对使用了基于块的变换编码以及运动补偿预测的示范性视频编码器结构进行描述的框图。 1 is a block diagram will be described using the transform-based encoding a video encoder and an exemplary configuration of the motion-compensated prediction block.

图2是与图1编码器相对应的示范性视频解码器的框图。 FIG 2 is a block diagram of an exemplary video decoder to the encoder of FIG. 1 corresponds.

图3是一个显示示范性的Z字形扫描的图示。 FIG 3 is illustrates an exemplary display of a Z-shaped scanning.

图4是显示现有技术中基于上下文的算术编码方案的编码器的框图。 FIG 4 is a block diagram showing the prior art based on the coding context arithmetic coding scheme.

图5是显示现有技术中基于上下文的算术编码方案的解码器的框图。 FIG 5 is a block diagram of a prior art decoder-based context-based arithmetic encoding scheme.

图6a是显示以Z字形方式扫描的量化DCT系数值的示范性二维阵列的图示。 Figure 6a is a graph showing an exemplary two-dimensional array of quantized DCT coefficients is scanned in zigzag Z values.

图6b是一个显示那些由图6a的阵列导出的等级和游程值的表格。 Figure 6b is a table displaying run value and rank those derived from the array of Figure 6a.

图6c是显示表1的二进制化方案应用于图6b的等级和游程的值所导致的二进制化的等级和游程值的表格。 Figure 6c is a table showing binarized run value and the level of the binary value applied to the scheme of Table 1 and Figure 6b levels caused by the run.

图6d是一个显示了用以从游程和等级中更新概率估计的方法的表格。 Figure 6d is a method to display the updated probability estimates from the run and the level of form.

图7a是一个显示了根据等级值而将上下文指派给二进制序列的方法的表格。 Figure 7a is a table showing a value according to the level assigning method of the context of the binary sequence.

图7b是一个显示了根据本发明第一实施例而将上下文指派给等级值的方法的表格。 Figure 7b is a shows a first embodiment of the present invention and the method of assigning a context to the table level value.

图8a是一个显示了基于游程值而将上下文指派给二进制序列的方法的表格。 8a is a table showing a method based on the run values ​​and the context assigned to a binary sequence.

图8b是一个显示了根据本发明第二实施例而将上下文指派给游程值的方法的表格。 8b is a shows a second embodiment of the present invention and the context is assigned to a run value table of the method.

图9是一个描述了依照本发明的基于上下文的算术编码方案的编 FIG. 9 is a scheme described in the context arithmetic coding-based codec in accordance with the present invention.

图io是一个依照本发明的解码器的框图。 FIG io is a block diagram of a decoder in accordance with the present invention. 图ll是一个描述了根据本发明优选实施例的图像编码方法的流程图。 Fig ll is a flowchart describing image encoding method according to a preferred embodiment of the present invention.

图12是一个描述了根据本发明另一个实施例的图像编码方法的流程图。 FIG 12 is a flowchart describing a video encoding method according to another embodiment of the present invention.

具体实施方式 detailed description

现在将对本发明的实施例进行详细论述。 Embodiments of the invention will now be discussed in detail. 如上所述,本发明提供了多种相关机制,通过该机制可以对基于上下文的算术编码器的编码效率(数据压缩)加以改进。 As described above, the present invention provides a variety of mechanisms, can be improved coding efficiency (data compression) context-based arithmetic coder through this mechanism. 这种改进是通过使用那些对指派了其他数据符号的上下文加以考虑的上下文模型来实现的。 This improvement is achieved by using a context model to be considered as those assigned to the context of other data symbols.

在下文笫1.1节详细描述了本发明的笫一实施例,该实施例涉及一种基于上下文的二进制算术编码器,所述编码器适于在例如ITU-T 建议H. 26L定义的图^f象编码系统中使用。 In 1.1 Zi Zi described in detail below an embodiment of the present invention, embodiments relate to a context-based binary arithmetic coder this embodiment, the encoder is adapted to e.g. ITU-T Recommendation H. 26L ^ f defined in FIG. encoding as used in the system. 在这个实施例中,通过对图像像素的变换编码块的量化编码系数进行游程-等级编码而产生的等级值是在考虑到了归属同一个块的另一个变换系数等级的情况下指派给上下文的。 In this embodiment, the quantized coding coefficient transform coding block image pixels are run - rank value level encoding is generated in consideration of the case where another transformation coefficient attributable to the same block level assigned to the context.

在第1.2节详细描述了本发明的第二实施例,该实施例也涉及一种用于图像编码系统的基于上下文的二进制算术编码器,其中所述系统可以是例如ITU-T建议H. 26L中定义的图像编码系统。 Section 1.2 describes in detail a second embodiment of the present invention, this embodiment also relates to a context-based binary arithmetic coder, wherein the system may be, for example, ITU-T Recommendation H. 26L encoding system for an image the image encoding system defined. 在第二实施例中,通过对图像像素的变换编码块的量化的DCT变换系数进行游程-等级编码而产生的游程值是在考虑到了游程值所属的游程-等级对的等级值的情况下指派给上下文的。 In the second embodiment, by the quantized DCT transform coefficients of transform coding block image pixels are run - run value level encoding is generated in consideration of the run value belongs to the run - assigning the case rank value level pairs to context.

在第1.3节描述了本发明第三实施例,该实施例同样涉及一种用于图像编码系统的基于上下文的算术编码器,其中所述系统可以是例如ITU-T建议H. 26L中定义的图^f象编码系统。 Section 1.3 describes the third embodiment of the present invention, this embodiment also relates to an image encoding system for embodiment context based arithmetic coding, wherein the system may be, for example, ITU-T Recommendation H. 26L defined ^ f image coding system of FIG. 才艮据第三实施例,变换编码图像块的非零变换系数的数目Nc被确定,并且在考虑到指派给用于至少一个其他变换编码图像块的Nc值的上下文的情况下,将其指派给一个上下文。 According to the third embodiment Gen only, the number of nonzero transform coefficients Nc transform coding image block is determined, and in consideration of a context is assigned to at least one other value Nc transform coding image block case, which is assigned give a context.

本发明的优选实施例组合了上述这三个实施例的功能。 Preferred embodiments of the present invention combines the functions of the above-described three embodiments.

如本文先前所述,ITU-T建议H. 26L TML 8的高复杂度类使用了 As previously described herein, ITU-T recommendation H. highly complex class uses 26L TML 8

一种以CABAC著称的基于上下文的算术编码形式。 Kind of CABAC known form of context-based arithmetic coding. 在一个根据H. 26L 实施的视频编码器中,CABAC方法被用于对由编码器产生的各种不同类型的信息进行编码,其中包括图像像素变换编码块所产生的变换系数(帧内编码模式)或是预测误差(帧间编码模式)。 In a video encoder according to embodiments of the H. 26L, the CABAC method is used for various types of information generated by the encoder for encoding, which includes transform coefficients (intra-coded coding block transform mode image pixel generated ) or prediction error (inter-coding mode). 通过对图像像素块进行变换编码产生的变换系数的二维阵列根据一种特定的扫描模式来扫描从而产生一维阵列。 A two-dimensional array of transform coefficients by transform coding pixel block image generated in accordance with a particular scan mode to scan to produce a one-dimensional array. 这两种扫描模式是在H. 26L中定义的。 Both are defined in the scanning mode of H. 26L. 第一种模式称为"单扫描模式",另一种模式则称为"双扫描模式"。 The first mode is called "single-scanning mode", another mode is known as "dual scan mode." 不管使用哪一种扫描模式,扫描变换系数都会将系数值的二维阵列转换成一个以预定方式来对系数进行排序的一维阵列。 Regardless of which use scanning mode, scanning a two-dimensional array of transform coefficients are converted into a coefficient value to a one-dimensional array of coefficients ordered in a predetermined manner. 在所述一维阵列 In the one-dimensional array

中,有序的变换系数值被转换成游程和等级值。 , The orderly transformation coefficient value is converted into run and level values. 在经过排序的一维阵列中,最后一个条目是一个依照H. 26L TML 8的块结束符号,该条目采取的是一个与零相等的等级值的形式。 In the ordered one-dimensional array, the last entry is a block end symbol in accordance with the H. 26L TML 8, which entry is to take a form of a level value equal to zero. 由此表明:在有序阵列中, 最后一个非零系数值已经转换成一个游程-等级对。 This indicates: in an ordered array, the last non-zero coefficient values ​​have been converted into a run - level pair.

游程和等级值是通过将其映射到一系列二进制序列而被转换成二进制数字的(二进制化),其中可以为每一个二进制数字都可被赋予值0或1 (参见表l)。 Run and level values ​​are to be converted into binary numbers by the sequence mapped to a series of binary (binarized), which may be assigned the value can for each binary digit of 0 or 1 (see Table l). 然后,经过二进制化的游程和等级值指派给上下文,也就是一个为游程和等级定义的单独的上下文集合。 Then, after the binarization level and run values ​​are assigned to a context, i.e. a set of separate context of run and level definition. 根据H. 26L TML8,对一个给定的块类型来说,为等级定义的上下文集合只依赖于指派了等级的二进制序列的编号。 According to H. 26L TML8, for a given block types, the context is set depends only on the level defined by a binary sequence number assigned level. 更具体地说,根据H. 26L TML 8而为等级编码定义了四个上下文。 More specifically, according to H. 26L TML 8 and defines four levels of context code. 第一个上下文用于第一个二进制序列,第二个上下文是用于第二个二进制序列,第三个上下文用于剩下的表示等级幅度的二进制序列。 A context for the first binary sequence a first, second context is a second binary sequence for the third context for the rest of the binary sequence represents the amplitude level. 剩余上下文则用于等级的符号。 The context for the symbols remaining level. 就游程来说,存在三个上下文,其中第一个上下文用于第一个二进制序列, 第二个上下文用于第二二进制序列,笫三个上下文则用于剩余的所有二进制序列。 Will run, the existence of three contexts, a first context in which a binary sequence for the first, second context for a second binary sequence, Zi all three contexts for the remaining binary sequence. 由于游程值总是等于或大于零,因此不需要使用一个附加上下文来表示符号信息。 Since the run values ​​always equal to or greater than zero, there is no need to use a symbol to represent the additional context information.

1. 1用于等级的上下文模型 1.1 level of context model for

根据本发明的第一实施例,在将一个二进制化的等级值指派给一个上下文时,除了考虑等级自身映射到的二进制序列之外,还要考虑到先前游程-等级对中的等级值。 According to a first embodiment of the present invention, when a level of the binary values ​​are assigned to a context, in addition to considering level binary sequence is mapped to itself, we should also take into account previous run - Ratings value pair. 在这个方面,术语"先前游程-等级对"意味着所述游程-等级对与有序系数值的一维阵列中的先前系数相对应。 In this regard, the term "previous run - level of" means that the run - level value of the one dimensional array system previously ordered coefficients, respectively. 以下的伪代码给出了一个用于将上下文指派给游程_等级 The following pseudo-code for a given context _ level assigned to the run

对的等级值的示范性过程,其中考虑到了等级本身映射到的二进制序 Exemplary process for the level values, taking into account the level of the binary sequence is mapped to itself

列以及先前游程_等级对中的等级值: Columns and previously run _ Ratings values ​​of:

<formula>formula see original document page 36</formula> <Formula> formula see original document page 36 </ formula>

few-(7^./? —,U^T^X+/7reK— /e^s/ 在表达式(2)中,/7reK_7eKe/是先前游程-等级对的等级值的大小。在每个块的开端,/?re^/ere/都会^皮初始化为零。在双扫描模式中,在每个扫描开端初始化/?rer/ere/,即每块两次。参数MAX —BIN —LEVEL提供了一种用于对由等级值映射到的二进制序列编号影响上下文指派的方式加以控制的手段。更具体地说,以一种与依照H.26L TML 8进行的当前上下文指派相似的方式,MAX—BIN —LEVEL有效定义了一个所有大于或等于MAX—BIN —LEVEL的二进制序列编号被指派到的上下文。以一种相似的方式,参数MAX — LEVEL提供了一种对先前游程-等级对中的等级值影响上下文指派的方式加以控制的手段。 图7a和图7b描述了才艮据本发明第一实施例并通过应用表达式(2 )的伪代码而将上下文指派给等级值的方法,其中MAX_BIN —LEVEL - 3并且MAX —LEVEL = 5。原则上可 few- (7 ^ / -.?, U ^ T ^ X + / 7reK- / e ^ s / in Expression 2) (, / 7reK_7eKe / run previously - the size of the level of level values ​​in each block. beginning, /? re ^ / ere / transdermal ^ are initialized to zero. in the dual scan mode, each scan start initialization /? rer / ere /, i.e. twice each parameter MAX -BIN -LEVEL provided a means to control the way the influence is mapped by a binary level SEQ ID value assigned to a context. more specifically, in a current context in accordance with the assignment H.26L TML 8 performed in a similar manner, MAX - BIN -LEVEL effectively defines a context all greater than or equal to MAX-BIN -LEVEL binary sequence number is assigned in a similar manner, the parameter MAX -. lEVEL is provided a previous run - Ratings pairs means controlled way influence the value of the assigned context. 7a and 7b described before, according to a first embodiment of the present invention Gen embodiment and by applying the expression (2) while the pseudo code assigned to the context of the method of level values, wherein MAX_BIN -LEVEL - 3 and MAX -LEVEL = 5. principle be 使用MAX_BIN_LEVEL与MAX—LEVEL的任何组合来定义一组适于所要编码的等级值统计特征的上下文。 1.2用于游程的上下文模型 Any combination of the MAX-LEVEL MAX_BIN_LEVEL to define a set of context to be adapted to the statistical characteristic of the level value encoding. 1.2 for the context model run

根据本发明的第二实施例,在这里使用了一种与第1.1节所描述的方法相类似的方法来将游程值指派给上下文。 According to a second embodiment of the present invention, a method is used here and as described in section 1.1 method similar to the run value assigned to the context. 更具体地说,在将一个二进制化的游程值指派给一个上下文的时候,除了考虑游程本身映射到的二进制序列之外,还要对游程值归属的游程_等级对的等级加以考虑。 More specifically, when assigned to a context of a binary value of a run, in addition to considering itself a binary sequence is mapped to run outside, but also on the level to be considered a home run value of run level pairs _. 下文中的伪代码给出了一个用于将上下文指派给游程-等级对中的游程值的示范性过程,在这个过程中顾及了游程本身映射到的二进制序列以及所述游程值所归属的游程-等级对的等级值: The following pseudo-code is given for assigning a context to run - level exemplary process for the run value, taking into account the run itself is mapped to a binary sequence and the run value belongs to run in the process - grade level value pairs:

<formula>formula see original document page 36</formula><formula>formula see original document page 37</formula> ( 3 ) <Formula> formula see original document page 36 </ formula> <formula> formula see original document page 37 </ formula> (3)

在表达式(3)中,/eKe/是游程-等级对中的等级值的大小。 In Expression (3), / eKe / are run - the size of the gradation value of the level. 参数MAX —BIN —RUN提供了一个对游程值映射到的二进制序列编号影响上下文指派的方式加以控制的手段。 Providing the parameter MAX -BIN -RUN binary sequence is mapped to a number of impact of the control means to be run value of the context assignment manner. 更具体地说,以一种与依照H. 26L TML 8进行的当前上下文指派相类似的方式,MAX —BIN-RUN有效定义了一个指派了大于或等于MAX_BIN_RUN的所有二进制序列编号的上下文。 More specifically, in a current context in accordance with the H. 26L TML 8 assignments performed in a similar manner, MAX -BIN-RUN effectively defines all binary context assigned a sequence number greater than or equal to the MAX_BIN_RUN. 以一种相似的方式,参数MAX —RUNL提供了一种对游程-等级对中的等级值影响上下文指派的方式进行控制的手段。 In a similar manner, the parameter MAX -RUNL is provided a run - by value means the level of impact on the level of control of context assignments. 图8a和图8b描述了依照本发明第二实施例并通过应用表达式(3)的伪代码而将上下文指派给等级值的方法,其中MAX —BIN —RUN = 3并且MAX —RUNL = 4。 8a and 8b describe a method according to a second embodiment of the present invention and by applying the expression (3) while the pseudo code assigned to the context level values, wherein MAX -BIN -RUN = 3 and MAX -RUNL = 4. 原则上可以4吏用MAX —BIN-RUN与MAX_RUNL的任何组合来定义一组适于所要编码的游程值统计特征的上下文。 4 may be defined in the context of a set of official statistical characteristics of run value is adapted to be encoded with a -BIN-RUN MAX and any combination MAX_RUNL principle. 1.3用于非零系数数目的上下文 1.3 context for the number of nonzero coefficients

特别地,本发明的第三实施例尤其涉及到将变换系数值的有序阵列转换成游程和等级值的方法,以及用信号通知那些与量化变化系数值的阵列相对应的游程-等级对数目的方法。 In particular, the third embodiment of the present invention is particularly directed to a method of converting an ordered array of transform coefficient values ​​into a run and level values, and a notification that the array of quantized variation coefficient value signal corresponding to a run - level the number of Methods. 更具体地说,在对一个图像像素块或是预测误差值进行变换编码,从而形成一个变换系数值的二维阵列并且对每一个系数值进行量化之后,阵列中的非零量化系数值数目将被确定。 More specifically, after the image of a pixel block prediction error values ​​or transform coding, thereby forming a two-dimensional array of transform coefficient values ​​and for each quantized coefficient value, the number of non-zero quantized coefficient values ​​in the array will be It is determined. 一个称为Nc的值将被指派给所述数字并被用于明确地用信号通知阵列中非零系数值的数目。 A value called Nc will be assigned to the digital system and to clear the number of non-zero values ​​signaled array. 因此,依照本发明的这个实施例,在这里不再需要一个诸如与零相等的等级值这样的E0B符号。 Thus, according to this embodiment of the present invention, here it is no longer needed as a symbol such E0B the level value equal to zero.

经过量化的变换系数进一步根据预定扫描顺序而被扫描,以便产生一个有序的一维阵列。 After further quantized transform coefficients is scanned according to a predetermined scanning order, to produce an ordered one-dimensional array. 可替换地,也可以在对量化系数值进行排序之后再确定Nc。 Alternatively, Nc may then determine, after sorting the quantized coefficient values. 然后,有序阵列中的每一个非零量化系数都转换成游程-等级对。 Then, each non-zero quantized coefficients ordered array is converted to a run - level pair. 根据本发明的这个实施例,游程-等级对的等级值表示的是经过量化的系数减1得到的值的大小,游程值则与所论述系数之前的连续零值量化系数的数目相对应。 According to this embodiment of the present invention, the run - level value level of representation is the result of quantized coefficients reduced size, the run value obtained in a continuous zero-valued quantized coefficients before discussed coefficients corresponding to the number. 由于不再将与零相等的等级值用作块结束指示符,因此为所述等级值赋予了量化系数减1所得到的 Since no longer equal to zero level value as the block end indicator, thus giving a quantized coefficient value of the level minus 1, obtained

值的大小。 Value size. 由此可以节省用于表示等级信息所需要的数据量(例如比特数目)。 Whereby the amount of data can be saved to the desired level information (e.g., number of bits).

然后,与Nc值一样,在这里使用了熵编码来对等级和游程值进行编码。 Then, the value of Nc, as used herein the entropy coding to encode the run value and the level. 在使用了诸如在H. 26L TML 8中实现的CABAC :J支术之类的基于上下文的算术编码方法的情况下,如上所述,可以根据本发明的第一和/或第二实施例来对游程和等级值进行编码。 In using such a CABAC implemented in H. 26L TML 8 in: J branching operation or the like based on the case where the context arithmetic coding method, described above, may be based on the first and / or second embodiment of the present invention. on the run and level values ​​are encoded. 可替换地,也可以将任 Alternatively, any one may be

何其他适当的上下文模型用于游程和等级值。 Any other suitable context models for the run and level values. 此外还可以为Nc定义一个单独的上下文模型。 Further Nc can also define a separate context model. 根据本发明的这个实施例,首先将表示给定块中非零量化变换系数数目的Nc值映射到一系列的二进制序列来对对其进行二进制化,其中每一个二进制序列都具有一个相应的二进制序列编号。 According to this embodiment of the present invention, the first block represents a given number of non-zero quantized transform coefficients Nc values ​​are mapped to a binary sequence to a series of binarizing thereof, wherein each binary sequence has a corresponding binary sequence number. 然后则基于Nc所映射到的二进制序列编号以及指派了一个Nc 值的至少一个其他图像块或宏块的Nc来确定用于所述Nc的上下文。 Nc at least one other block or macroblock of an image based on Nc and then mapped to a binary sequence number Nc and assigning a value to determine the context for the Nc. 以下的伪代码给出了用于将一个上下文指派给一个Nc值的示范性过程,在这个过程中考虑到了Nc本身映射到的二进制序列以及先前的Nc 值: The following pseudo-code shows an exemplary process for Nc value assigned to a context, taking into account the Nc binary sequence is mapped to itself and the previous value Nc in the process:

<formula>formula see original document page 38</formula> <Formula> formula see original document page 38 </ formula>

在表达式(4)中,/7/er—y7c即为先前的Nc值。 In the expression (4), / 7 / er-y7c Nc is the previous value.

在从编码器将经过编码的给定量化变换系数块的等级和游程值发送到一个解码器的时候,经过熵编码的Nc值是在对游程和等级值进行编码之前发送的。 Via the encoder transmits to the decoder when a given quantization level and a run value conversion coefficient block encoded through entropy encoding Nc is transmitted prior to the run and level values ​​from the encoding. 在解码器上对所述Nc值进行解码,其后则跟随着与所论述块的量化变换系数值相对应的游程-等级对。 Decoding the Nc value at the decoder, it is subsequently followed with a run corresponding quantized transform coefficient values ​​discussed block - level pairs. 当对等级值进行解码时,为了补偿在编码器中所作的相应减法,将会把数值+1加到各个等级大小中。 When decoding a rank value, in order to compensate the respective subtraction done in the encoder will be the value +1 is added to each grade in size.

为了展示使用图像编码方法而在编码效率上的改进,根据本发明,平均比特率差值是通过使用关于QP=28、 24、 20、 16的结果来计算的。 To demonstrate the use of the picture coding method and the coding efficiency improvement, according to the present invention, the average difference in bit rate by using the result on QP = 28, 24, 20, 16 is calculated. 表2显示了与TML 8相比较的百分比形式的比特率减少,其中 Table 2 shows the bit rate of 8 TML percentage reduction compared, wherein

MAX —LEVEL = 5并且MAX —RUN = 4。 MAX -LEVEL = 5 and MAX -RUN = 4. 所有帧都是在CABAC模式中作为I 帧来编码的。 All frames are in the mode as CABAC encoded I-frame. 如表2所示,比特率的减少范围是从0. 95到4. 74%。 As shown in Table 2, to reduce the bit rate range is from 0.95 to 4.74%. 当QP值很小的时候,所述改进将会更为显著。 When the value is small when the QP, the improvement will be more significant.

在表2中,出现在表格第一行的名称是在Gisle Bjontegaard的"Recommended Simulation Conditions for H. 26L" ( VCG-M75, ITU-T Video Coding Experts Group, Austin, Texas, USA, 2-4 April, 2001 )中使用的画面。 In Table 2, the table name appears in the first row of Gisle Bjontegaard in "Recommended Simulation Conditions for H. 26L" (VCG-M75, ITU-T Video Coding Experts Group, Austin, Texas, USA, 2-4 April , 2001) used in the screens.

<table>table see original document page 39</column></row> <table>表2 <Table> table see original document page 39 </ column> </ row> <table> Table 2

现在参考图9,根据本发明,发送端的编码器10包括一个用于保存先前等级和游程的单元16。 Referring now to Figure 9, according to the present invention, the transmitting side comprises an encoder unit 10 for holding a previous level of 16 and a run. 如图9所示,用于给定块的游程-等级对102被提供到映射单元12,所述映射单元12将所述对映射到一系列的二进制序列,每一个二进制序列都具有值0或1。 9, for a given block of the run - level of 102 is provided to mapping unit 12, the mapping unit 12 maps a series of the binary sequence, each sequence having a binary value of 0 or 1. 在表示游程-等级对的序列中,二进制序列的位置称为二进制序列编号。 In the run represented - on a sequence level, the position of the binary sequence is called binary SEQ ID NO. 二进制序列编号由信号104表示。 The binary signal 104 is represented by SEQ ID NO. 基于信号104和单元16提供的先前编码的等级值108,指派单元14将一个上下文指派给一个二进制序列编号。 Based on a previous level value encoded signal 104 and 108 of unit 16, unit 14 is assigned a context ID assigned to a binary sequence. 信号106 表示的上下文被提供到一个自适应算术编码器20。 Context 106 indicates a signal is supplied to the adaptive arithmetic coder 20. 而1的出现概率与0的出现概率则是通过一个概率估计单元22来估计的。 The probability of occurrence and probability of occurrence of 1 is 0 to unit 22 by an estimated probability estimates. 基于所述概率估计120,算术编码单元24对二进制序列进行编码。 120, the arithmetic coding unit 24 encodes binary sequence based on the probability estimation. 反馈信号124则从编码器24提供到概率估计模块22,从而更新概率估计。 Feedback signal 124 from the encoder 24 is supplied to a probability estimation module 22, thereby updating the probability estimation. 经过编码的信息转变成一个比特流122。 After the encoded information is converted into a bit stream 122. 以便传递到一个解码器或者保存在一个存储设备中以供稍后使用。 For delivery to a decoder or stored in a storage device for later use.

优选地,编码器10还包括一个能在将游程-等级对提供给算术编 Preferably, the encoder 10 can further comprise a run in the - to the arithmetic coding on the Level

码器20之前将块中非零系数数目Nc提供给算术编码器20的单元18, 因此还对Nc进行编码并且将其包含在比特流122中。 Before the block decoder 20 the number Nc of non-zero coefficients to the arithmetic encoder unit 1820, and thus also of Nc and encoding in a bit stream comprising 122. 所述Nc则是由信号110来表示的。 The Nc is represented by the signal 110. 在使用Nc的情况下,没有必要向解码器发送一个块结束(EOB)符号。 In the case where Nc is not necessary to send an end of block (the EOB) symbols to the decoder. 在现有技术中,大小为0的等级值将被用于EOB 符号。 In the prior art, the size of a class value 0 will be used EOB symbol. 更具体地说,Nc是在变换和量化之后才被发现的并且是使用熵编码来对其进行编码的。 More specifically, Nc is only found after transformation and quantization and entropy coding is used to encode them. 需要指出的是,在非零系数数目已知的情况下,不再有必要使用0等级值来用信号通知块结束。 It is noted that, in the case where the number of nonzero coefficients is known, is no longer necessary to use a 0 level values ​​signaled to end block. 因此,通过将量化系数值减l,可以对等级值进行修改。 Thus, by reducing the quantization coefficient value L, can be modified level values.

如图IO所示,在接收端使用解码器50来接收编码器IO提供的比特流122。 It is shown, at the receiving end using a decoder to receive the encoder 50 provides a bit stream in FIG IO IO 122. 接收到的比特流表示的是经过算术编码的数据符号,它是由参考数字202来表示的。 The received bit stream indicates the arithmetically encoded data symbols, which is denoted by reference numeral 202 in. 一开始,根据先前解码的符号,在上下文指派单元66中计算一个上下文,并且在概率估计单元62中更新二进制序列值的概率估计。 Beginning, previously decoded symbols, in the context of assigning a context calculation unit 66, and the estimated binary sequence probability update unit 62 estimates the value of the probability. 更新概率估计所依据的先前解码符号由参考数字205示。 Updating the probability estimation is based on previously decoded symbol shown by reference numeral 205. 上下文指派块66中执行的上下文指派以及概率估计块62执行的概率估计计算与编码器10中执行的相类似。 And the probability of context assignments assigned context probability estimation block 62 calculates estimation performed in the encoder 10 performs a phase 66 performed in a similar block. 然后,接收到的比特202 被馈送到算术编码器60的算术解码引擎64,在那里使用计算得到的上下文以及二进制序列值204的当前概率估计来将其转换成经过解码的二进制序列值206。 Then, the received bit 202 is fed to an arithmetic encoder 60 arithmetically decoding engine 64, and the context of a binary sequence where the calculated values ​​of the current probability estimate 204 to convert it to a binary decoded sequence 206 values. 在块68中,经过解码的二进制序列208被映射到游程和等级值。 In block 68, the decoded binary sequence 208 is mapped to the run and level values. 如果在编码器1G中对块中非零系数数目Nc进行编码并且在接收到的比特流202中提供了所述数目,则将信号214提供给二进制序列-数值映射模块68,由此通过将等级值加1来恢复经过量化的系数。 If the block is encoded in the number of nonzero coefficients in the encoder. 1G Nc and the number provided in the received bit stream 202, a signal is supplied to the binary sequence 214 - value mapping module 68, whereby the level by adding a value to restore the quantized coefficients.

图11是描述根据本发明优选实施例的图像编码方法的流程图。 FIG 11 is a flowchart illustrating an image encoding method according to a preferred embodiment of the present invention. 如图所示,方法500始于编码器接收一个图像的步骤510。 As shown, method 500 begins with the encoder receiving an image of step 510. 在步骤52 0, 将接收到的图像分成多个块。 In step 520, the received image into a plurality of blocks. 在步骤5 30对每一个块进行扫描,并且在步骤540获取块中经过量化的系数的等级和游程。 In step 530 to scan each block, and the acquisition block 540 through the quantized coefficients in the run and level step. 与现有技术的编码方案相比,在步骤550,本发明还在上下文的指派过程中使用了先前等级。 Compared with the prior art coding schemes used in the previous level assignment process step 550, in the context of the present invention also. 特别地,如第1.1节所述,将上下文指派到代表量化系数等级值的二进制序列的处理对先前编码的等级值加以考虑。 In particular, as in Section 1.1, the context assigned to process binary sequence representing the quantized coefficients to consider level values ​​previously coded level value. 同样,如1.2 节所述,将上下文指派到代表量化系数游程值的二进制序列的处理也考虑到了等级值。 Also, as the 1.2, assigned to the context processing binary sequence representing the quantized coefficients run value also takes into account the level value. 已指派的上下文传送到一个算术编码器,以便在步骤560中进行编码。 It is assigned a context transfer to the arithmetic encoder, for encoding in step 560. 另外,如第1.3节所述,Nc或非零量化系数的数目是在步骤530中扫描了所述块的过程之中或是之后才得到确定的, 并且在将Nc与上下文提供到一个解码器之前在步骤560中对Nc进行编码。 Further, as the number Nc of non-zero quantized coefficients, or section 1.3 is scanned only been ascertained in the process of or after the block in step 530, and Nc in the context provided to a decoder before encoding Nc in step 560.

可替换地,如图11所示,在指派上下文时并未考虑到先前编码的等级或游程,在这种情况下,通过将指示Nc的信号传递到接收端,可以改进所述图像编码方法。 Alternatively, as shown in FIG. 11, a context not considered when assigning the previously encoded level or run, in this case, by transmitting a signal indicating Nc to the receiving end, the image encoding method can be improved. 如图12所示,Nc是在步骤542中获取和提供的,而不是为了在步骤550中指派上下文而在步骤540中获取先前编码的等级和游程。 As shown, in step 12 it is to obtain Nc of 542 and provided, instead of assigning context to step 550 acquired previously coded level and run in step 540. 为了在步骤560中执行编码,Nc是在步骤550中指派上下文之前发送到算术编码器的。 In order to perform the encoding step 560, Nc is transmitted at step 550 prior to assigning a context to the arithmetic coder. 借助于发送Nc,在这里不再有必要将EOB符号发送到解码器。 By means of a transmission Nc, here it is no longer necessary to send EOB symbols to the decoder.

尽管在这里针对本发明的优选实施例而对其进行了描述,但是本领域技术人员将会理解,在不脱离本发明范围的情况下,可以对其进行形式和细节方面的前述和多种其他改变、省略和背离。 Although the preferred embodiments herein for the present invention and they are described, it will be understood by those skilled in the art, without departing from the scope of the present invention may be made in form and detail of the foregoing and various other changes, omissions and away.

Claims (28)

1.一种图像编码方法,其中图像被分成多个具有多个像素的块,每一个像素都具有一个像素值,并且变换编码操作对像素值的块执行从而产生一个相应的变换系数值块,所述变换系数值块是以一种给定的扫描顺序扫描的,从而产生一个经过扫描的系数值阵列,其中扫描的阵列中的系数值是由多个游程-等级数字对表示的,所述游程-等级数字对具有第一数字和第二数字,所述第一数字和第二数字被指派到表示游程-等级数字对的多个上下文之一, 其特征在于:游程-等级数字对的第二数字根据该游程-等级数字对的第一数字而被指派给一个上下文。 1. An image encoding method, wherein an image is divided into a plurality of blocks having a plurality of pixels, each pixel having a pixel value, and transform coding operations performed on the block of pixel values ​​to produce a corresponding block of transform coefficient values, the transform coefficient values ​​of a given block is based on sequential scanning of the scanning, through the array of values ​​to produce a scan line, wherein the coefficient values ​​in the array are scanned by a plurality of run - level digital representation of the run - having a first level digital number and a second number, said first and second digital numbers assigned to represent the run - one of a plurality of digital levels of context, characterized in that: the run - the first level of the digital according to the run number two - the first pair and digital numerical scale is assigned to a context.
2. 根据权利要求l的方法,其特征在于:所述多个上下文是基于上下文的算术编码器的上下文。 2. The method of claim l, wherein: said plurality of context-context is context-based arithmetic coder.
3. 根据权利要求l的方法,其特征在于:所述多个上下文是基于上下文的二进制算术编码器的上下文。 3. A method according to claim l, wherein: said plurality of context-context is context-based binary arithmetic coder.
4. 根据权利要求3的方法,其特征在于:所述游程-等级数字对的第一数字被映射到一组二进制序列,其中所述二进制序列中的每一个都具有一个相关的二进制序列编号,并且每一个都能取第一值或第二值之一。 4. A method according to claim 3, wherein: the run - a first number of digital levels are mapped to a set of binary sequences, wherein each of said binary sequences has an associated binary sequence number, and each of which can take a first value or second value.
5. 根据权利要求3的方法,其特征在于:所述游程-等级数字对的第二数字被映射到一组二进制序列,其中所述一组二进制序列中的每一个都具有一个相关的二进制序列编号,并且都能取第一值或第二值之一。 5. The method according to claim 3, wherein: the run - a second digital level number pairs are mapped to a set of binary sequences, wherein each of a set of binary sequences has an associated binary sequence number, and can take a first value or second value.
6. 根据权利要求4或5的方法,其特征在于:将数字映射到所述一组二进制序列中给定的一个是通过将二进制序列的值指派给第一值来指示的。 6. The method according to claim 4 or claim 5, wherein: the digital map to a set of binary sequences is given by the value of a binary sequence value assigned to a first instruction.
7. 根据权利要求4或5的方法,其特征在于:第一值是l且第二值是0' 7. The method according to claim 4 or claim 5, wherein: l is the first value and the second value is 0 '
8. 根据权利要求5的方法,其特征在于:根据游程-等级数字对中的第一数字而将游程-等级数字对中的第二数字指派给一个上下文的处理考虑到了游程-等级数字对的笫二数字映射到的二进制序列编号。 8. The method according to claim 5, characterized in that: according to the run - rank number of the first number and the run - grade number for the second number is assigned to a context of the processing takes into account the run - level number pairs Zi two binary numbers mapped to the sequence number.
9. 根据权利要求l的方法,其特征在于: 所述第一数字指示非零系数值,以及所述第二数字指示在所述非零系数值之前的连续零系数值的数目。 9. l The method according to claim, wherein: the first number indicates the non-zero coefficient value, and the second number indicates the number of consecutive zero coefficient values ​​before the non-zero coefficient values.
10. —种编码器,包括用于将图像分成多个具有多个像素的块的装置,其中每一个像素都具有一个像素值,此外还包括用于对像素块执行变换编码操作以便产生一个相应的变换系数值块的装置;用于以给定扫描顺序扫描变换系数值块以便产生一个扫描的系数值阵列的装置;用于使用多个游程-等级数字对来表示所述扫描的阵列中的系数值的装置,所述游程-等级数字对具有第一数字和第二数字的;以及用于将第一和第二数字指派给表示所述游程-等级数字对的多个上下文之一的装置,其特征在于:所述编码器包括用于根据游程-等级数字对的第一数字而将该游程-等级数字对的第二数字指派给一个上下文的装置。 10. - kind of encoder comprising means for dividing the image into a plurality of blocks having a plurality of pixels, each pixel having a pixel value, further including means for performing block transform coding of the pixels in order to generate a corresponding operation It means the value of the transform coefficient block; block means value to produce a scanned array of coefficient values ​​in a given scan scan order of transform coefficients; means for using a plurality of run - grade number represented by said scanning array in means coefficient values ​​of the run - having a first level digital number and a second number; and means for assigning the first and second digital to represent the run - level means to one of a plurality of digital contexts characterized in that: said encoder comprises means for run - and run the level of the first digital number pairs - a second number of numerical rating assigned to a device context.
11. 根据权利要求10的编码器,其特征在于:所述多个上下文是基于上下文的算术编码器的上下文。 The encoder according to claim 10, wherein: said plurality of context-context is context-based arithmetic coder.
12. 根据权利要求10的编码器,其特征在于:所述多个上下文是基于上下文的二进制算术编码器的上下文。 The encoder according to claim 10, wherein: said plurality of context is a context-based binary arithmetic coder context.
13. 根据权利要求12的编码器,其特征在于:它还包括用于将所述游程-等级数字对的第一数字映射到一组二进制序列的装置,其中所述二进制序列中的每一个都具有一个相关联的二进制序列编号并且能够取笫一值或第二值之一。 13. The encoder according to claim 12, characterized in that: further comprising means for the run - a first digital device to a digital level set is mapped to a binary sequence, wherein each of said binary sequence are associated with a binary serial number and can take the value or second value Zi.
14. 根据权利要求12的编码器,其特征在于:它还包括用于将所述游程-等级数字对的第二数字映射到一组二进制序列的装置,其中所述二进制序列中的每一个都具有一个相关联的二进制序列编号并且能够取第一值或第二值之一。 14. The encoder according to claim 12, characterized in that: further comprising means for the run - a second digital to digital level means a group mapped to a binary sequence, wherein each of said binary sequence are associated with a binary serial number and can take a first value or second value.
15. 根据权利要求13或14的编码器,其特征在于:它还包括用于通过将所述二进制序列指派给第一值从而将一个数字映射到所述一组二进制序列中指定的一个二进制序列的装置。 15. The encoder as claimed in claim 13 or 14, characterized in that: it further comprises a binary sequence by the value assigned to the first so as to a number of said binary sequence is mapped to a set of binary sequences specified apparatus.
16. 根据权利要求13或14的编码器,其特征在于:第一值是l并且第二值是0。 16. The encoder of claim 13 or 14, wherein: l is the first value and the second value is 0.
17. 根据权利要求14的编码器,其特征在于:所述用于根据游程-等级数字对中的第一数字而将该游程-等级数字对中的第二数字指派给一个上下文的装置对该游程-等级数字对中的第二数字所映射到的二进制序列编号加以考虑。 17. The encoder of claim 14, wherein: according to the run - means the level of the second digital number assigned to a context - number of levels and the number of the first run run - the level of the second digital numbers are mapped to a binary sequence number to be considered.
18. 根据权利要求10的编码器,其特征在于: 所述第一数字指示非零系数值,以及所述第二数字指示在所述非零系数值之前的连续零系数值的数目。 18. The encoder of claim 10, wherein: the first number indicates the non-zero coefficient value, and the second number indicates the number of consecutive zero coefficient values ​​before the non-zero coefficient values.
19. 一种基于上下文的算术编码方法,包括下列步骤: 用码字表示数据符号阵列,所述阵列中的数据符号是包含了第一数字和第二数字的游程-等级数字对,游程-等级数字对中的第一数字被指派给从代表第一数字的多个上下文中选出的上下文,游程-等级数字对中的第二数字则被指派给从代表第二数字的多个上下文中选出的上下文,其特征在于:游程-等级数字对的第二数字是基于该游程-等级数字对的第一数字而被指派给一个上下文的. 19. A context-based arithmetic coding method, comprising the steps of: a codeword represented by the data symbols array, said array comprising a first number and second numbers of a run - level number pairs, run - Level the first digit pair number is assigned to the context selected from a plurality of the first number representative of the context in the run - the level of the second digital numbers were assigned to multiple contexts of the second digital select from among the representatives out of context, characterized by: the run - a second digital level is based on the number of run - a first pair of digital numerical rating is assigned to a context.
20. —种基于上下文的算术解码方法,包括下列步骤: 从表示数据符号阵列的码字中解码数据符号阵列,所述阵列中的数据符号是包含了第一数字和第二数字的游程-等级数字对,游程-等级数字对的第一数字被指派给从代表第一数字的多个上下文中选出的上下文,而游程-等级数字对的第二数字则指派给从代表第二数字的多个上下文中选出的上下文,其特征在于:游程-等级数字对的第二数字是基于该游程-等级数字对中的第一数字而被指派给上下文的。 20. - kind of context-based arithmetic decoding method, comprising the steps of: data representing the symbol from the code word data symbols array decodes the data symbol array, said array comprising a first number and second numbers of a run - Level to digital, the run - a first digit of the grade number is assigned to a context selected from a plurality of the first number representative of the context in the run - a second digital to digital level is assigned to the plurality representing a second number contexts selected context, which is characterized in that: the run - a second digital level is based on the number of the run - in a first level of the digital numbers are assigned to the context.
21. 根据权利要求20的方法,其特征在于:所述多个上下文是基于上下文的二进制算术编码器的上下文。 21. The method according to claim 20, wherein: said plurality of contexts context is context-based binary arithmetic coder.
22. 根据权利要求21的方法,其特征在于:所述游程-等级数字对的第一数字被映射到一组二进制序列,所述二进制序列中的每一个都具有一个相关的二进制序列编号,并且每一个都能够取第一值或第二值中的一个。 22. The method according to claim 21, wherein: the run - a first number of digital level is mapped into a set of binary sequences, each of said binary sequences has an associated binary sequence number, and each capable of taking a first value or a second value.
23. 根据权利要求21的方法,其特征在于:所述游程-等级数字对的第二数字被映射到一组二进制序列,所述一组二进制序列中的每一个都具有一个相关的二进制序列编号,并且能够取第一值或第二值中的一个。 23. The method according to claim 21, wherein: the run - a second digital level number pairs are mapped to a set of binary sequences, each of said set of binary sequences has an associated binary sequence number and is capable of taking a first value or a second value.
24. —种基于上下文的算术编码器,包括使用码字来表示数据符号阵列的装置,所述阵列中的数据符号是包括第一数字和第二数字的游程-等级数字对;用于将游程-等级数字对的第一数字指派给从代表第一数字的多个上下文中选出的上下文的装置;以及用于将游程-等级数字对的第二数字指派给从代表第二数字的多个上下文中选出的上下文的装置,其特征在于:所述编码器还包括用于根据游程-等级数字对中的第一数字而将该游程-等级数字对中的第二数字指派给一个上下文的装置。 24. - kind of context-based arithmetic encoder comprising using a codeword to represent a data symbol means, said array of data symbols in the array comprising a first number and a second number run - level number pairs; for run - context means selected from a plurality of contexts representative of a first number of a first digital numerical rating assigned to; and run for - a second level of digital numbers assigned to the plurality of the second number from the representative context context selected device, wherein: said encoder further comprises means for run - and the run level of the first digital number - the level of the second digital number assigned to a context device.
25. —种基于上下文的算术解码器,包括用于从表示数据符号阵列的码字中解码出所述阵列的装置,其中所述阵列中的数据符号是包括第一数字和第二数字的游程-等级数字对;用于将游程-等级数字对的第一数字指派给从代表第一数字的多个上下文中选出的上下文的装置;以及将游程-等级数字对的第二数字指派给从代表第二数字的多个上下文中选出的上下文的装置,其特征在于:所述解码器包括用于根据游程-等级数字对中的第一数字而将该游程-等级数字对中的第二数字指派给一个上下文的装置。 25. - kind of context-based arithmetic decoder for decoding the codeword includes data representing a symbol array in the array device, wherein the data symbols in the array comprising a first number and a second number run - level of digital; for run - a first digital numerical rating of context means selected from a plurality of contexts representative of the number assigned to the first; and run - a second digital level assigned to the numbers of context context plurality means representing a second selected number, characterized in that: said decoder comprises means for run - and the run level of the first digital numbers - in a second level of the digital number assigned to a device context.
26. 根据权利要求25的解码器,其特征在于:所述多个上下文是基于上下文的二进制算术编码器的上下文。 26. The decoder of claim 25, wherein: said plurality of contexts context is context-based binary arithmetic coder.
27. 根据权利要求26的解码器,其特征在于:所述游程-等级数字对的笫一数字被映射到一组二进制序列,所述二进制序列中的每一个都具有一个相关的二进制序列编号,并且每一个都能够取第一值或笫二值中的一个。 27. The decoder of claim 26, wherein: said run - Zi a numerical scale of number pairs are mapped to a set of binary sequences, each of said binary sequences has an associated binary sequence number, and each is capable of assuming a first binary value or the sleeping mat.
28. 根据权利要求26的解码器,其特征在于:所述游程-等级数字对的第二数字被映射到一组二进制序列,所述一组二进制序列中的每一个都具有一个相关的二进制序列编号,并且能够取第一值或第二值中的一个。 28. The decoder of claim 26, wherein: the run - a second digital level number pairs are mapped to a set of binary sequences, each of said set of binary sequences has an associated binary sequence number, and is capable of taking a first value or a second value.
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