JP2002165219A - Image-signal decoding device and decoding and encoding device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device which can perform satisfactory recoding operation, when a decoding image signal, which is edited in such a way that decoded image signals which are output from a plurality of image-signal decoding devices and on which each encoding parameter before a decoding operation is superposed are changed over, is re-encoded. SOLUTION: In an encoding-information generation circuit 52, information in a decoding-device discriminating signal memory 51 in which a value (decoder ID), indicating the discrimination of a decoding device itself is recorded in addition to image encoding parameters and macroblock encoding parameters. The information is formatted to a bit pattern to be stored in an encoding information memory 42. In an encoding-information superposing circuit 43, image information which is stored in an output frame memory 39 and encoding parameters as encoding information which is stored in the encoding information memory 42 are input, and encoding parameters are superposed on the LSB bit of the color difference signal of the image information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decoded picture signal obtained by decoding a coded picture signal which has been subjected to high-efficiency predictive coding, which corresponds to each macroblock at the time of coding the coded picture signal. The present invention relates to an image signal decoding device that superimposes and outputs each encoding parameter. The present invention is particularly applicable to a case where a decoded image signal edited by switching a decoded image signal on which each of the encoding parameters before decoding output from a plurality of image signal decoding devices is superimposed is re-encoded. It is an object of the present invention to provide an image signal decoding device capable of performing good re-encoding.

Further, the present invention provides good re-encoding when a decoded image signal edited by switching a plurality of decoded image signals on which the respective encoding parameters before decoding are superimposed is re-encoded. It is an object of the present invention to provide an image signal decoding / encoding device that enables the decoding.

[0003]

2. Description of the Related Art In recent years, digitalized image and audio signals are compressed by highly efficient predictive coding, and the compressed information is used to transmit information through transmission lines such as satellite waves, terrestrial waves, and telephone lines. Has been put to practical use. In such services, MPEG2, which is an international standard, is used as a high-efficiency predictive coding method for video and audio signals.
Is used. MPEG2 is an encoding method that compresses the information amount of an image signal using correlation between adjacent pixels of an image signal (correlation in a spatial direction) and correlation between frames or fields (correlation in a time direction).

[0004] Image encoding in the MPEG2 standard is processed by the following algorithm. First, temporally continuous image frames are sorted into a reference frame and a predicted frame. The reference frame can be restored using only the encoded data of the frame by using only the correlation in the spatial direction. The predicted frame is obtained by using both the temporal correlation and the spatial correlation from the reference frame,
Encoding efficiency can be further improved with respect to the reference frame. The prediction frame is restored from the decoded reference frame and the encoded data.

A specific encoding system used in MPEG2 image encoding will be described with reference to FIG. The I frame, which is a reference frame, exists periodically and serves as a reference for decoding processing. Further, the predicted frames include a P frame encoded by only prediction from a temporally previous reference frame and a B frame encoded by predictive encoding from two temporally preceding and succeeding reference frames. The P frame itself is a predicted frame and also serves as a reference frame for the subsequent B frame and P frame.

An I-frame image signal is a luminance signal which is
It is divided into processing units called macroblocks of pixels × vertical 16 pixels. The data of the divided macro block is
The image data is further divided into two-dimensional blocks in units of 8 × 8 pixels, and DCT (discrete cosine transform) processing, which is a type of orthogonal transform, is performed. Since the signal after the DCT conversion shows a value according to the frequency component of the two-dimensional block, the component concentrates on a low frequency in a general image. In addition, the information deterioration of the high frequency component has the property of being less visually noticeable than the information deterioration of the low frequency component.
Therefore, the amount of information is compressed by quantizing the low-frequency component finely and roughly the high-frequency component, and performing variable-length coding on the continuous length of the quantized coefficient component and the coefficient component having no coefficient component (coefficient 0). ing.

[0007] The image signal of the P frame is divided into macroblocks of 16x16 pixels, similarly to the I frame. In the P frame, a motion vector between the macro frame and a reference frame is calculated. The detection of a motion vector is generally obtained by block matching. The reference frame at the position where the horizontal and vertical positions of the macroblock are moved by the motion vector value and each pixel of the macroblock is set to 16
The sum of absolute difference values (or sum of squared differences) of each pixel divided into × 16 pixels is obtained, and the value of the motion vector having the minimum value is output as the detected motion vector.

The difference between each pixel of the macroblock and each pixel of the two-dimensional block extracted by the motion vector is calculated. If an accurate motion vector is detected,
Since the information amount of the difference block is much smaller than the information amount of the original macro block, a quantization process that is rougher than that of the I frame can be performed. Actually, it selects whether to encode the differential block or the non-differential block (Intra block) (prediction mode determination), and performs the same DCT / variable-length encoding process on the selected block as the I frame And the amount of information is compressed.

The processing similar to that of the P frame is performed on the B frame. However, since the reference frames exist before and after, a motion vector is detected between each of the reference frames. B
In the frame, the choices of prediction are prediction from the previous reference frame (Forward prediction) and prediction from the rear reference frame (Backw
ard prediction) ・ Average value per pixel of two prediction blocks (Avera
ge prediction), there are 3 types, and 4 including Intra blocks
The prediction mode is determined from the type. Since the B frame can be predicted from the reference frame that is temporally preceding and succeeding, the prediction efficiency is further improved as compared with the P frame. Therefore, quantization is generally performed more coarsely than P frames. The selected block is subjected to the same encoding processing as the I and P frames.

[0010] Since the B frame is decoded, a prediction process is performed from a reference frame that is temporally later. Therefore, the reference frame is encoded prior to the B frame. Therefore, the input image signals are rearranged and encoded in the order shown in FIG. In the decoding process, the decoded images are reproduced in the order of the input image signals by performing reverse sorting and outputting.

A conventional general encoding apparatus and a conventional decoding apparatus for realizing MPEG2 image encoding will be described with reference to FIGS. 6 and 7, respectively.

In the encoding apparatus shown in FIG. 6, an input digital image signal is recorded in a frame memory (input image memory) 1, and a delay for rearranging the input digital image signal in the encoding order according to the encoding syntax. Is made. The digital signal output from the input image memory 1 is cut out by a two-dimensional block conversion circuit 2 into macroblocks.

In the reference frame, the DCT is performed on the macroblock data in units of 8 × 8 pixels by the orthogonal transformation circuit 4 and sent to the quantization circuit 4. The DCT coefficient quantized in the quantization circuit 4 is subjected to variable-length or fixed-length encoding by referring to an address corresponding to the coefficient in the encoding table 16 in the encoding circuit 5, Information (encoding parameter) indicating the location of the macroblock in the screen and the coded data
Are multiplexed and output as a bit stream.

On the other hand, the DCT coefficients quantized by the quantization circuit 4 are subjected to inverse quantization and inverse DCT processing in an inverse quantization circuit 7 and an inverse orthogonal transform circuit 8, and an encoded bit stream is decoded and deblocked. The data is stored in the reference image memory 11 via the circuit 9 and the adding circuit 10.

Subsequently, in the predicted frame, the motion vector between the macroblock data cut out from the input image memory 1 and the image stored in the reference image memory 11 is calculated by the motion vector detection circuit 12. Desired. Based on the output motion vector, the prediction block is converted by the motion compensation prediction circuit 13 into the reference image memory 11.
The motion compensation prediction circuit 13 selects a prediction mode, generates a difference signal from the input image block to be encoded by the subtractor 14, and sends the signal to the orthogonal transformation circuit 3.
The difference signal is subjected to the same processing as that of each block of the frame, the DCT coefficients are quantized, and output as a bit stream together with a motion vector and a prediction mode (encoding parameter).

As for the control of the code amount, the code amount of the output stream is compared with the target code amount in the code amount control circuit 15, and the quantization of the quantization circuit 4 is performed in order to approach the target code amount. Control (quantization scale). For the three types of frames having different amounts of information, the target code amount for each frame is calculated using the characteristics and appearance frequency of each frame type for the set encoding rate. Further, the target code amount is virtually simulated for the stream buffer of the decoding device, and is limited so that the buffer does not overflow or underflow. The quantization scale calculates the quantization scale value for the target code amount for each frame type and performs the quantization process by using the fact that the scale and the output code amount generally have an inversely proportional relationship. By changing the quantization scale in a direction approaching the target code amount for each block, the coded bit stream is suppressed within the target code amount.

In the decoding device shown in FIG. 7, an input bit stream is first stored in a stream buffer 31. The coded bit stream contains a virtually simulated buffer value, and the decoding process is performed after the buffer value is stored for the buffer value, so that the buffer is broken and the decoding process stops. I'm preventing. The bit stream is sent to the variable length decoding circuit 32.
Separates encoding parameters such as quantization scale, prediction mode, and motion vector, and decodes quantized DCT coefficients. The decoded DCT coefficient is subjected to inverse quantization and inverse DCT processing in an inverse quantization circuit 33 and an inverse orthogonal transform circuit 34 similar to those in the encoding circuit, and an Intra block or a difference block is decoded. Via the adder 36.

In the case of a prediction block, the prediction mode decoded by the motion compensation prediction circuit 37 and the motion vector value
The addition with the prediction block cut out from the reference image memory 38 is performed by the adder 36, and the image signal of the macroblock is restored. In the case of an I or P frame, the restored macroblock data is written to the reference image memory 38. In the case of a B frame, the output frame memory 39
And output as an image signal. The image data of the I and P frames written in the reference image memory 38 is added to the output frame memory 39 at the output timing in accordance with the timing of FIG.

In such a system for distributing information using image coding, there is a need to decode a stream that has been once coded and perform the coding process again. One is a case where information is transmitted from a place where information is collected and recorded to a place where information is distributed. The transmission path may be a wired / wireless communication line or a recording medium, but if the transmission path and the transmission path of the distribution system have different bandwidths, it is necessary to change the bit rate of the bit stream. In addition, there is a case where a recorded image signal is edited and processed. In a case where a plurality of image signals are connected or a character telop or the like is inserted into the image signals, it is difficult to realize the stream without decoding the stream.

In such an apparatus (transcoder) for performing re-encoding processing, an image signal (decoded baseband signal) transmitted by the transcoder is reduced in order to reduce encoding deterioration at the time of re-encoding. A method of superimposing and transmitting frame coding information such as a frame type at the time of coding and a macroblock coding parameter is considered above.

In MPEG2 encoding, the quality of an image signal generally deteriorates in the order of an I frame, a P frame, and a B frame. Since the I frame is a reference frame, it is quantized more finely than other frames, and there is no reference from other images, so that the I frame is not affected by reference frame deterioration. As the P frame and the B frame become, they are roughly quantized and are easily affected by reference frame degradation. When a frame that was a B frame when re-encoding was encoded as an I frame, an image with large deterioration was used as a reference frame,
The predicted frame is affected by the deterioration, and the image quality at the time of re-encoding becomes large. By referring to the encoding parameters and matching the frame type at the time of re-encoding, the above-mentioned degradation factor is reduced. In addition, by using the macroblock coding parameter in the coding parameter, the processing amount for detecting the motion vector can be reduced, and the information amount of the macroblock can be obtained based on the quantization scale and the number of coding bits. And good code amount control can be expected during bit rate conversion.

The encoding parameters for re-encoding need to be transmitted from the decoding processing means to the re-encoding processing means in temporal and spatial correspondence with the video signal.

As a transmission method for realizing this, there is SMPTE 319M which defines a rule of superimposing an MPEG-2 video encoding parameter on a standard television quality 4: 2: 2 digital component video signal and transmitting the signal. Also, the SMPTE 351M proposal is currently under discussion to determine the provisions for superimposing and transmitting MPEG-2 video coding parameters on high-definition television quality 4: 2: 2 digital component video signals.

A specific method of superimposing the coding parameters will be described with reference to SMPTE 319M as an example. The baseband signal includes a luminance signal (Y) and two color difference signals (Cb, Cr).
The data is transmitted at a sampling ratio of 2: 2, and each pixel value is composed of 10 bits (1024 levels). MPEG
In two-image encoding, the information amount of a decoded image is composed of 8 bits (256 levels), so that
The bit becomes a transmission unnecessary area. The coding parameter is superimposed on this area. In the example of SMPTE 319M Table 3, the least significant bit of Cb and Cr in the transmission unnecessary area is set as the superimposition area.

As an example of a coding parameter to be superimposed specifically, a coding parameter standardized by SMPTE 319M (SM
PTE 319M See Figure 1). For each 16 × 16 pixel area constituting each macroblock, it is a macroblock coding parameter, which is coding information for each macroblock, and a part of frame coding information (coding information for each image). Write picture coding parameters. (The macroblock coding parameter and the picture coding parameter are collectively referred to as a coding parameter here.) When the LSBs of Cb and Cr are combined, there are 256 bits, and 256 bits exist.
The bits indicate the information of SMPTE 319M Figure 1. 8 × 8 with motion vector value, prediction mode, quantization scale, effective DCT coefficient as macroblock coding parameters
Additional information such as a block pattern (coded_block_pattern) and the number of bits required when each additional information and DCT coefficient are encoded are recorded as information.

In the picture_element_information area, frame coding information as shown in SMPTE 319M Table 4 is divided for each macroblock (this division is a picture coding parameter). Written. This area has 32 bits for each macroblock. If picture_element_information of all macroblocks is collected over the entire frame, frame coding information copied a plurality of times can be restored.

FIG. 8 shows an example of such a transcoder for transmitting the coding parameters from the decoding device to the coding device. In this example, a synthesizing device is inserted between a decoding device and an encoding device, and an image obtained by editing a decoded baseband signal is re-encoded by the encoding device. The configuration diagrams of the decoding device and the encoding device shown in FIG. 8 will be described with reference to FIGS. 9 and 10, respectively. 6 and 7
The same reference numerals are given to the same parts as those of the encoding apparatus and the decoding apparatus, respectively, and the description of the parts is omitted.

The variable length decoding circuit 32 of the decoding device shown in FIG.
Calculates the frame coding information and the macroblock coding parameter at the time of decoding, and the number of bits of the macroblock to be coded, and inputs them to the coded information generation circuit 41. In the coding information generation circuit 41, the picture coding parameter and the macroblock coding parameter, which are coding parameters, are formatted into a bit pattern as shown in SMPTE 319M Figure 1 and stored in the coding information memory 42.

The coded information superimposing circuit 43 receives the image information stored in the output frame buffer 39 and the coding parameters stored in the coded information memory 42, and inputs the LSB bits of the color difference signal of the image information. Is superimposed with the encoding parameter. The coded information memory 42 stores I, P,
A plurality of frames are provided so as to correspond to the output rearrangement of the B frames, and the encoded information superimposing circuit 43 changes the order of the encoding parameters to be extracted depending on the frame type.

In the coding apparatus shown in FIG. 10, a coding information separating circuit 21 extracts coding parameters from an image signal in an input image memory. The extracted coding parameters are stored in the coding information memory 22. The encoding syntax control circuit 24 detects the frame type from the extracted encoding parameters and performs control to rearrange the input images in the encoding order. If the coding parameters of the frame cannot be extracted, a non-detection signal is sent from the coding information separation circuit 21 and the coding syntax is formed in the coding device in the same manner as in the conventional normal coding processing. Then, an encoding process is performed (a normal encoding process similar to the process for an image signal on which an encoding parameter is not superimposed is performed). The macroblock information generation circuit 23 reads the coding parameters stored in the coding information memory 22 in a different order according to the coding syntax, and extracts the coding parameters for each macroblock.

The extracted coding parameters are transmitted to the motion compensation prediction circuit 13 and the code amount control circuit 15. The motion compensation prediction circuit 13 uses the motion vector and the prediction mode that are present in the coding parameters, and uses the reference image memory 11
, A difference signal from the input image block to be encoded is generated, and sent to the orthogonal transformation circuit 3. If the coding parameter in the frame or the coding parameter for each macroblock cannot be extracted, a non-detection signal is sent from the coding information separation circuit 21 to the motion compensation prediction circuit 13 and the conventional coding Motion vector detection and prediction mode selection processing are performed in the same manner as the processing.

In the code amount control circuit 15, the quantization scale and the required number of bits at the time of coding for each macroblock are input as coding parameters, and the set code amount at the coding bit rate which is the current control target is obtained. By performing the comparison process, an appropriate quantization scale is determined, and the encoding process is performed.

[0033]

When an encoded image signal is decoded once and then edited, there is a case where a baseband decoded signal output from a plurality of decoding devices is switched and edited. As a transcoding device that performs this editing process, for example, as shown in FIG. 8, a device in which an image switch is inserted between a plurality of decoding devices and one encoding device can be considered. Switching processing is performed on the decoded baseband signal (image signal) by an image switch according to the switching timing, and the baseband signal that has been subjected to the switching processing is input to an encoding device and re-encoded. In this case, there is a problem in that it is not possible to recognize that the continuity of the coded information in frame units at the switching timing is cut off, and erroneous coded information is used at the time of re-coding. If the switching timing occurs in a frame, the macroblock coding parameter becomes an output of a different decoding device depending on a portion within one screen (one image unit), that is, becomes a coding parameter of a different stream. If used incorrectly at the time of conversion, inconsistency occurs in macroblock coding parameters such as a motion vector and a prediction mode, causing a problem of deteriorating image quality. Further, even if it is possible to recognize that the encoding parameter has been destroyed, re-encoding is performed free, and a good transcoding function cannot be realized.

According to the present invention, when a decoded image signal edited by switching between decoded image signals output from a plurality of image signal decoding apparatuses and superimposed with respective encoding parameters before decoding is re-encoded, It is an object of the present invention to provide an image signal decoding device capable of performing good re-encoding and an image signal decoding / encoding device.

[0035]

Accordingly, in order to solve the above-mentioned problems, the present invention provides the following apparatus. (1) Superimposing each encoding parameter corresponding to each macroblock at the time of encoding the encoded image signal on a decoded image signal obtained by decoding an encoded image signal which has been subjected to high efficiency prediction encoding. An image signal decoding device for outputting, wherein each of the coding parameters is a macroblock coding parameter that is coding information for each macroblock, and a picture coding parameter that is a part of coding information for each image. In the image signal decoding device that includes the image signal decoding device, an identification signal of the image signal decoding device is added to each of the encoding parameters, and a superimposing unit that superimposes the encoding parameter added with the identification signal on the decoded image signal is provided. Characteristic image signal decoding device. (2) Superimposing each encoding parameter corresponding to each macroblock at the time of encoding the encoded image signal on a decoded image signal obtained by decoding an encoded image signal which has been subjected to high efficiency prediction encoding. A plurality of image signal decoding processing units to output,
A plurality of image signal decoding processing units, each of which includes a macroblock coding parameter which is coding information for each macroblock and a picture coding parameter which is a part of coding information for each image; When,
An image signal switching unit that switches and outputs the decoded image signals respectively supplied from the plurality of image signal decoding processing units, and, for the decoded image signal output from the image signal switching unit, from the decoded image signal An image signal decoding / encoding device having an image signal encoding / processing unit for performing high-efficiency predictive encoding based on each of the separated encoding parameters, wherein each of the image signal decoding units includes Adding an identification signal to each of the encoding parameters,
Superimposing means for superimposing the encoding parameter to which the identification signal has been added on the decoded image signal is provided, and the image signal encoding processing unit includes an encoding unit for each of the encoding parameters separated from the decoded image signal corresponding to one image unit. From, detecting means for detecting the identification signal of the image signal decoding device that has performed decoding to the decoded image signal, for each identical identification signal with respect to the detected identification signal, each for which the identification signal was detected It is determined whether or not the encoding information of one image unit is obtained by combining the picture encoding parameters extracted from the encoding parameters, and if the encoding information of the one image unit is obtained, the detection is performed. It is determined whether or not the identification signals are all the same, and if the detected identification signals are not the same, the coding information of one image unit is detected from the obtained coding parameters. It is determined whether there is only one type of identification signal, and based on the determination result, it is determined whether the obtained encoded information of one image unit is valid or invalid at the time of encoding. First determining means for determining whether the macroblock coding parameter in each of the separated coding parameters is valid or invalid at the time of coding, based on the detected identification signal. Determining means, the image signal coding processing unit uses the macroblock coding parameters and the picture coding parameters for the macroblock coding parameters and the picture coding parameters determined to be valid for coding, For the macroblock coding parameters and picture coding parameters determined to be Generates information corresponding to the data and picture encoding parameter used for encoding, the image signal decoding and coding apparatus characterized by.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Each part of an embodiment of the present invention will be described by taking as an example a transcoding device (schematic configuration is the same as that shown in FIG. 8) capable of switching and editing using the embodiment of the present invention. FIG. 1 shows a configuration diagram of an image signal decoding apparatus according to one embodiment. The same reference numerals are given to the same parts as those shown in FIG. 9 which is a conventional example, and the detailed description of those parts will be omitted.

The variable length decoding circuit 32 calculates a picture coding parameter, a macroblock coding parameter, and the number of coding bits of a macroblock at the time of decoding in the same manner as in the conventional example, and inputs it to the coding information generation circuit 52. I do. In the encoding information generation circuit 52, in addition to the picture encoding parameter and the macroblock encoding parameter, information of the decoding device identification signal memory 51 in which a value (Decoder ID) indicating the identification of the decoding device itself is recorded. Then, it is formatted into a bit pattern and stored in the encoded information memory 42.

The coding parameters (the macroblock coding parameters, which are coding information for each macroblock, and the picture coding parameters, which are part of the frame coding information (coding information for each image), are combined here. As an example of a specific format of the encoding parameter), the one shown in the above-described SMPTE 319M Figure 1 is used. About 4 bits (for example, the 0th bit in the vertical direction and the 6th to 9th bits in the horizontal direction) are used as a Decoder ID addition area.

The Decoder ID can be set from outside,
When transcoding, it differs between multiple decoding devices.
By setting the ID, an identifiable signal can be obtained.

The coding information superimposition circuit 43 receives the image information stored in the output frame memory 39 and the coding parameters, which are the coding information stored in the coding information memory 42, as in the prior art. The coding parameter is superimposed on the LSB bit of the color difference signal of the image information.

Next, FIG. 2 shows a configuration diagram of an image signal encoding apparatus according to an embodiment, which will be described. The same reference numerals are given to the same parts as those shown in FIG. 10 which is a conventional example, and the detailed description of those parts will be omitted.

The macroblock information generation circuit 70 has a function shown in the conventional example and a Decoder in the encoding parameter.
The ID is extracted and stored in the Decoder ID memory 71.

When the macroblock information for one frame (one image unit) is stored, it can be recognized whether or not the frame is constituted by the output from the single decoding device.
In the frame information determination circuit 73, the Decoder ID detected from each macroblock of one frame and the frame coding information (the predetermined number of picture coding parameters, (It becomes encoded information), the validity / invalidity of the frame encoded information is determined and the frame information is acquired. If the encoding parameters can be extracted from all the macroblocks and the Decoder ID values for each macroblock in the Decoder ID memory 71 are all the same, it is determined that the output is a single decoding device. Also, it is compared with the Decoder ID of one frame before, and when the Decoder ID is different, it is determined that the switching point of the image signal is a frame unit.

A specific algorithm for acquiring frame information will be described with reference to FIG. First, for each identical Decoder ID detected from each macroblock for one frame,
Frame encoding information obtained by combining picture encoding parameters extracted from each encoding parameter for which the Decoder ID is detected is stored (step S).
1).

If no frame encoding information is obtained for any of the Decoder IDs (step S2), the frame type used is a frame type managed in advance in the encoding device (step S3). If there is a Decoder ID from which the frame encoding information could be extracted (step S
2) Encoding parameters can be extracted from all macroblocks, and the Deco for each macroblock
It is checked whether all der IDs are the same (this is set as condition 1) (step S4). When the condition 1 is satisfied, the extracted frame coding information is selected as a use candidate (step S5).

If condition 1 is not satisfied (step S
4) It is checked whether there are a plurality of Decoder IDs from which the frame coding information can be extracted (step S6), and in the case of one, the extracted frame coding information is selected as a use candidate (step S5). In the case of a plurality of frames, the frame encoding information corresponding to the same ID as the Decoder ID detected one frame before is preferentially selected as a use candidate (step S7, step S5).

If the frame encoding information selected as a use candidate corresponds to the same Decoder ID as the Decoder ID corresponding to the frame encoding information selected one frame before (step S8), the selection is made. The frame type in the encoded frame encoding information and other additional information in the encoded frame information are used as they are for re-encoding (step S9).

If the IDs are not the same (step S8), or if it is detected one frame earlier in step S7
If there is no frame encoding information corresponding to the same ID as the Decoder ID, the frame type of the selected frame encoding information is checked (step S11). In the case of No in step S7, selection from the plurality of pieces of frame encoding information is simply performed by selecting the first frame encoding information corresponding to the Decoder ID (that is, the first acquiring Deco ID).
The frame encoding information obtained from each encoding parameter in which the same Decoder ID as the der ID is detected may be used (step S10).

In step S11, the frame type is
In the case of an I-frame, complete encoding is performed within the frame, so that additional information is useful even for a frame having an independent Decoder ID. Therefore, the frame type in the frame coded information selected in step S10 and other additional information in the frame coded information are directly used for re-encoding.

If the frame type is a P frame (step S12), it is determined that the input has been switched (because it is determined in step S7 that the previous frame has a different Decorcer ID), and the frame type is changed to an I frame. Then, the additional information in the selected frame encoding information is discarded as being unusable (step S13).

In the case of a B frame, in order to limit the number of consecutive B frames, only when the previous frame is an I frame or a P frame (step S14),
The frame type is set to the B frame as it is (step S15). Otherwise, the frame type is set to I-frame, and in any case, the selected additional information in the frame coded information is discarded (step S13).

Next, the encoding syntax control circuit 24 controls the input images to be rearranged in the order of encoding based on the selected frame type, and converts the input image into frame encoding information determined to be valid by the frame information determination circuit 73. On the other hand, control is performed on a frame basis using the value. Also,
Like the reference image memory 11, the Decoder ID memory 71 stores and controls the Decoder ID of an image serving as a reference frame.

The significance detection circuit 72 receives the Decoder ID from the Decoder ID memory 71 and the macroblock coding parameters from the coded information memory 22, and performs macroblock coding separated from the input image signal. Determine whether the parameter can be used. The probabilistic success detection circuit 72 reads the Decoder ID detected from the encoding target macroblock, and if the prediction mode in the macroblock encoding parameter of the encoding target macroblock is not an Intra block, the macroblock code The motion vector value is read from the conversion parameter, and the address value of the Decoder ID of the macroblock in which the predicted reference image data exists is calculated.

When the motion vector value is X pixels in the horizontal direction, Y pixels in the vertical direction, and the point at the head position of the macroblock is H in the horizontal direction and V in the vertical direction, there are four types of address values in which the necessary Decoder ID exists. The macro block position is (1) horizontal (H + X) / 16, vertical (V + Y) / 16, (2) horizontal (H + X + 15) / 16, vertical (V + Y) / 16, (3) horizontal (H + X) / 16, Vertical (V + Y + 15) / 16 (4) Horizontal (H + X + 15) / 16, vertical (V + Y + 15) /
It becomes 16. Decoder ID read from these address values
If the Decoder IDs of the own macroblock match, the macroblock coding parameter is determined to be significant. However, when the prediction mode of the macroblock coding parameter is forward prediction, the forward reference picture De
In the case of backward prediction, only the coder ID may be determined by referring to only the Decoder ID of the backward reference image.

Further, from the encoding syntax control circuit 24, the Decoder ID recognized for each frame is input to the significance / invalidity detection circuit 72 together with the frame type. If the input Decoder ID is different from the Decoder ID of the own macroblock, it is assumed that the macroblock coding parameter is invalid.

Referring to the output signal of the significance detection circuit 72, the frame information obtained by the frame information determination circuit 73, and the non-detection signal of the coded information for each macro block by the coded information separation circuit 21, the macro block The encoding process is performed for each. In other words, when the significance detection circuit 72 determines that it is significant, the coding is performed based on the separated macroblock coding parameters corresponding to the coding target macroblock and the frame information acquired by the frame information determination circuit 73. Encode the target macroblock. When the probable and incompletion detecting circuit 72 determines that the information is ineffective, and when a non-detection signal is output from the coded information separating circuit 21, information corresponding to a macroblock coding parameter is newly generated, and the information and The encoding target macroblock is encoded based on the frame information acquired by the frame information determining circuit 73.

As described above, according to the apparatus of this embodiment, a plurality of coded image signals are decoded once, the decoded plurality of image signals are switched to perform editing, and then the coded image signals are re-edited. When performing the decoding process, the encoding parameters at the time of encoding before decoding are retained on the image signal output by the decoding device, and an identification signal that can identify each decoding device is added to the encoding parameter for each macroblock. And write it. Therefore, by detecting the identification signal at the time of re-encoding, switching of the decoded image signal in frame units (switching of the decoding device in frame units) can be determined, and switching of the decoding device in the frame can be recognized. Can be.

In the state where the identification signal is continuous, the frame information (information obtained from the frame coded information separated and extracted from the decoded image signal) is completely retained. Since the encoding process can be performed, the position of the I-frame at the time of re-encoding can be matched with the position of the I-frame of the stream that has been encoded before, and image degradation at the time of re-encoding can be reduced. further,
By controlling the re-encoding process based on the detected combination of the identification signals, it is possible to prevent a change that may cause a problem in the encoding syntax or a disturbance in the code amount control at the switching point.

Also, by using the detected identification signal, it is managed whether or not the macroblock coding parameter of the macroblock to be coded is in agreement with the control at the time of re-encoding. It is possible to easily recognize whether or not an unmatched area exists in the prediction block of the image, and it is possible to prevent re-encoding processing using an incorrect encoding parameter. As a result, it becomes possible to appropriately use coding parameters effective for re-encoding, thereby realizing a good transcoding function.

[0060]

As described above, when the image signal decoding apparatus of the present invention is used, a plurality of decoded image signals decoded by the image signal decoding apparatus (decoded image signals on which respective encoding parameters before decoding are superimposed). In the case where the edited decoded image signal is re-encoded by switching over, good re-encoding can be performed.

Further, according to the image signal decoding / encoding apparatus of the present invention, the decoding edited by switching a plurality of decoded image signals (decoded image signals on which respective encoding parameters before decoding are superimposed). When re-encoding an image signal, good re-encoding can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image signal decoding device according to an embodiment.

FIG. 2 is a configuration diagram of an image signal encoding device according to an embodiment.

FIG. 3 is a diagram illustrating an encoding system used in MPEG2 image encoding.

FIG. 4 is a diagram showing the timing of rearranging the encoding order during MPEG2 encoding.

FIG. 5 is a diagram illustrating a relationship between a stream arrival order at the time of decoding and an output order of a decoded image.

FIG. 6 is a configuration diagram of an MPEG2 image encoding device.

FIG. 7 is a configuration diagram of an MPEG2 image decoding device.

FIG. 8 is a configuration diagram of a transcoding device that enables switching editing.

FIG. 9 shows a conventional MPEG having a transcoding function.
FIG. 35 is a configuration diagram of a two-image decoding device.

FIG. 10 shows a conventional MP having a transcoding function.
FIG. 2 is a configuration diagram of an EG2 image encoding device.

FIG. 11 is a diagram showing a frame information acquisition algorithm in one embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Encoding information separation circuit 22 Encoding information memory 24 Encoding syntax control circuit 51 Decoding device identification signal memory 52 Encoding information generation circuit 70 Macroblock information generation circuit 71 Decoder ID memory 72 Significant ineffectiveness detection circuit 73 Frame information judgment circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C059 KK01 KK36 MA00 MA05 MA23 ME01 NN01 PP05 PP06 PP07 RB12 RC00 RC11 SS01 SS06 TA71 TC00 TC01 TD11 UA05

Claims (2)

[Claims] An encoded image signal obtained by decoding an encoded image signal which has been subjected to high-efficiency predictive encoding is superimposed with encoding parameters corresponding to macroblocks at the time of encoding the encoded image signal. An image signal decoding device that outputs the macroblock encoding parameters, wherein each of the encoding parameters is a macroblock encoding parameter that is encoding information for each macroblock, and a picture encoding parameter that is part of encoding information for each image. Wherein the image signal decoding apparatus further comprises: superimposing means for adding an identification signal of the image signal decoding apparatus to each of the encoding parameters, and superimposing the encoding parameter to which the identification signal is added on the decoded image signal. An image signal decoding device characterized by the above-mentioned. 2. A decoding method for decoding a coded image signal which has been subjected to high-efficiency predictive coding, superimposing respective coding parameters corresponding to respective macroblocks at the time of coding the coded image signal. A plurality of image signal decoding processing units, wherein each of the coding parameters is a macroblock coding parameter that is coding information for each macroblock, and a picture that is a part of coding information for each image. A plurality of image signal decoding processing units that include an encoding parameter, an image signal switching unit that switches and outputs the decoded image signals respectively supplied from the plurality of image signal decoding processing units, An image signal encoding process for performing high-efficiency predictive encoding on the output decoded image signal based on the respective encoding parameters separated from the decoded image signal An image signal decoding / encoding device having: a coding parameter obtained by adding an identification signal of the image signal decoding processing unit to each of the coding parameters to each of the image signal decoding processing units; Superimposing means for superimposing on the decoded image signal, the image signal encoding processing section decodes the decoded image signal from the respective encoding parameters separated from the decoded image signal corresponding to one image unit. Detecting means for detecting the identification signal of the image signal decoding device that has performed, for each identification signal identical to the detected identification signal,
It is determined whether or not the coding information of one image unit is obtained by combining the picture coding parameters extracted from the respective coding parameters for which the identification signal is detected, and the coding information of one image unit is obtained. If it is determined whether the detected identification signals are all the same or not, if the detected identification signals are not the same, from each encoding parameter obtained the encoding information of one image unit It is determined whether the detected identification signal is of one type or not, and based on the determination result, whether the obtained encoded information of one image unit is valid or invalid at the time of encoding, respectively. First determining means for determining whether the macroblock coding parameter in each of the separated coding parameters is valid at the time of coding based on the detected identification signal. And a second judging means for judging whether or not the macroblock coding parameter and the picture coding parameter determined to be valid are the macroblock coding parameter and the picture coding parameter. Using the encoding parameters for encoding, regarding the macroblock encoding parameters and picture encoding parameters determined to be invalid, information corresponding to the macroblock encoding parameters and picture encoding parameters is generated and used for encoding. An image signal decoding / encoding device characterized by the above-mentioned.