DE102012200136A1 - Method for producing scalable compressed video stream in computer system, involves combining base output stream coded with second quality value with base output stream coded with third quality value for certain quality parameter - Google Patents

Abstract

The method involves providing a compressed input video stream (118) which is coded with a first value for certain quality parameter. The compressed input video stream is transcoded to base output stream and enhancement signal. The base output stream coded with a second quality value for certain quality parameter is combined with base output stream coded with third quality value for certain quality parameter, where the second value is lower quality than first value for certain quality parameter and third value is of high quality than second value for certain quality parameter. An independent claim is included for a device for producing scalable compressed video stream.

Description

background

For scalable encoding of video compression methods are used, which result in a compressed bit stream in which one or more subgroups of the entire bit stream can be decoded, with reduced quality such as reduced resolution, frame rate or bit rate. Scalable encoding methods are found in most video compression standards, including MPEG-1, MPEG-2, and MPEG-4. Examples of scalable video encoding include compression of an HD bit stream in which an SD subset can be decoded, or compression of a 60 Hz bit stream in which a 30 Hz subset can be decoded.

A particular application field for scalable video compression is the fact that many television service providers are planning to introduce video services at 1080p60 Hz over the next few years. This format is used by many of the consumer electronics high-end HD displays currently available. The fact that this format uses progressive-scan technology eliminates the need for de-interlacing on this display and the 1080-line format offers higher resolution than the 720p format.

The Joint Video Team (JVT) of the ISO / MPEG Group and the ITU-T have developed a standard design for SVC (Scalable Video Coding) based on H.264 / AVC. According to the draft, an SVC encoder outputs a lower-level base-layer stream than the original and at least one enhancement stream. Optionally, a receiver may only decode the base-layer stream or decode the base-layer stream in combination with one or more of the enhancement streams to reconstruct a higher-quality image sequence. The SVC design provides significant flexibility in scalable video encoding, and its compression tools are highly efficient. However, SVC technology is very complex, for both encoders and decoders. Therefore, it is necessary to develop a satisfactory mechanism that can cost-effectively implement an SVC codec.

Summary

Roughly speaking, instead of implementing SVC coding directly from the input uncompressed video stream, according to one aspect of the invention, the unencoded input video stream is first encoded according to a high quality compression standard such as 1080p60 AVC. The high quality compressed video stream is then transcoded into a scalable format, such as 1080p60 SVC. 1080p60 AVC codecs are currently available, and the complexity of implementing the transcoder is less than that of a native encoder, especially if the coding decisions of the 1080p input are for either re-encoding the base-layer output stream or of the enhancement layer output stream, or both. For certain applications, the transcoder may be advantageously implemented in a general-purpose computer. The method therefore enables cost-effective implementation of SVC coding.

Specific aspects of the present invention are described in the claims, the description and the drawings.

Brief description of the drawings

The invention will be described with respect to certain embodiments thereof, and reference is made to the drawings, wherein:

1A Figure 10 is an overall block diagram of an encoder incorporating features of the invention.

1B and 1C conventional receivers for decoding represent a scalable video stream.

2 a symbolic block diagram of an embodiment of the transcoder in 1A is.

3 a simplified block diagram of a computer system 310 which may be employed to implement software incorporating aspects of the present invention.

Detailed description

The following detailed description is provided to illustrate the present invention and not to limit its scope, which is defined by the claims. A variety of equivalent variants will be apparent to those skilled in the art from the present description.

Background information

The standard MPEG-4 / AVC is widely used to encode video. This standard encodes images both spatially and temporally. Each image is first divided into non-overlapping macroblocks, each macroblock comprising a 16x18 array of luminance samples and blocks of 8x8 chrominance Contains samples that are superimposed over it. A decision is made to encode the macroblock as an inter-macroblock, that is, to time and space encode the macroblock, or to encode the macroblock as an intra-macroblock, that is, to only spatially encode the macroblock , A macroblock is time coded by means of a process for compensating motion between images (inter-picture motion compensation operation). In such a process, a macroblock to be subjected to motion compensation compensation is identified and subtracted therefrom to generate a prediction error macroblock. The prediction macroblock is derived from another image, referred to as a reference image, or may be an interpolation of a plurality of prediction macroblocks, each resulting from different reference images. The prediction macroblock need not have exactly the same spatial coordinates (pixel row and column) as the macroblock from which it is subtracted, and may be spatially offset from it. A motion vector serves to identify the macroblock based on its spatial displacement and the reference image from which it originated. (If the prediction macroblock is an interpolation of multiple prediction macroblocks, a motion vector is determined for each prediction macroblock to be interpolated.)

Images can be classified as intra or I images, predictive or P images, and bidirectionally predictive or B images, respectively. An I-picture contains only intra macroblocks. A P-picture may contain inter-macroblocks, but only forward-looking predictions from a previous reference picture are allowed. A P-picture may also contain intra-macroblocks for which no adequate prediction could be determined. A B-picture may include intra-macroblocks, inter-macroblocks that have undergone forward motion compensation, inter-macroblocks that have undergone backward motion compensation, that is, are predicted from a following reference picture, and include enter macroblocks that are bidirectional Have been subjected to motion compensation, that is to say predicted on the basis of an interpolation of prediction macroblocks in respective preceding and following reference pictures. If the mode of the P or B pictures is the interlaced mode, each individual field macroblock can be separately subjected to motion compensation, or the two fields can be interleaved to form a frame macroblock, and the frame macroblock can be instantaneously Be subjected to motion compensation.

Spatial compression is performed on selected 8x8 luminance pixel blocks and selected 8x8 pixel chrominance blocks of selected prediction error macroblocks or selected intra macroblocks. Spatial compression includes the steps of transforming each block, quantizing each block, scanning each block into a sequence, run-level encoding the sequence, and encoding the variable-length sequence subjected to run-level coding. Optionally, prior to transformation, a macroblock of a frame may be formatted as a frame macroblock including blocks including alternating lines of samples from each of the two single fields of the frame, or formatted as a field macroblock in which samples of different fields are arranged in separate blocks of the macroblock. The quantization scale factor can be changed from macroblock to macroblock, and the weighting matrix can be changed from image to image. Macroblocks or coded blocks thereof may be skipped if they have coded zero (or near zero) data. Suitable codes are inserted into the formatted bitstream of the encoded video signal, such as non-contiguous macroblock address increments or encoded block patterns to indicate skipped macroblocks and blocks.

Additional formatting is applied to the variable length coding sequence to help identify the following elements within the encoded bitstream, i. H. individual sequences of images, groups of images of the sequence, images of a group of images, slices of images, macroblocks and blocks within macroblocks. Some of the listed layers are optional, such as the layer of the group of images and the slice layer, and may be omitted from the bitstream if desired. Various parameters and flags are inserted into the formatted bitstream, which are also each of those listed above Show decisions (as well as others not described above). A short list of some of these parameters and flags includes picture coding type (I, P, B), macroblock type (ie, forward prediction, backward prediction, bidirectional prediction, spatially encoded only), macroblock prediction type (field, Frame, etc.), quantization parameters, etc. A flag may be inserted in the coded video signal to indicate that a during a telecine process for converting movie images to NTSC video (using the known 3: 2 Zero-down procedure) repeated field in the coded video signal has been omitted.

When encoding the video signal to MPEG-4, the encoder must generate a bitstream which does not cause buffer overflow or overflow of a decoder which decodes the video signal. For this purpose, the encoder models the buffer of the decoder and in particular monitors the filling state of the buffer of the decoder. It is assumed that the decoder buffer fills bits of the bitstream at a particular rate, which is a function of the channel rate at a particular time. It is assumed that images are immediately removed at a certain time relative to the encoding as well as a presentation time of each image, see for example the U.S. Patent No. 6,091,776 Linzer, hereby incorporated by reference, in which various ways of modeling a decoder buffer by a coder are discussed in detail. Using such a model, the coder can adjust various coding parameters to control the number of bits produced for each coded picture, thus preventing overflow or idling of the decoder buffer. For example, the encoder may adjust the quantization parameters, promote selection of certain types of coding over others, add fill data to images, change the number of B and P images, change a threshold quality level that serves to determine whether Intra or inter coding of macroblocks, etc., and thus to increase or decrease the number of bits generated for each picture. In general, the encoder generates a target bit budget for each frame, which, among other parameters, is a function of the channel rate, the buffer size of the decoder (usually taken as a given constant), and the availability / occupancy of the decoder buffer immediately before and after removal of the special image for which a budget is generated. The encoder then adapts its encoding, trying to achieve the target budget for the image.

overall architecture

1A Figure 4 is an overall block diagram of an encoder incorporating features of the invention. It can be seen that the uncoded bit sequence 112 in original quality an encoder 110 which turns it into a first compressed video stream 114 coded. The first compressed video stream 114 has sufficient information to reconstruct an uncoded image sequence having a first perceived quality that is usually (but not necessarily) substantially the same as that of the original input image sequence 112 , That is, the first compressed video stream 114 encodes the original image sequence with specific values for each of a plurality of "quality parameters". The term "quality parameter" as used herein includes, for example, resolution, refresh rate, scan type (progressive or interleaved), and bit rate. The term used herein also includes parameters, such as signal-to-noise ratio, that are dependent on others of the quality parameters. In the example in 1A is the first compressed video stream 114 specified to have an MPEG-4 / AVC format encoded with a resolution of 1920 × 1080 pixels in progressive scan mode and with a refresh rate of 60 Hz. encoder 110 capable of producing an uncoded 1080p60 image sequence to such a compressed video stream 114 to code are available.

The terms "video stream" and "output stream" as used herein are intended to include not only the image data itself, but all metadata necessary to restore the frames to a particular quality level. These streams are sometimes referred to herein as "bitstreams", but the units of the stream in various embodiments may be bits, bytes, fields, frames, or any other unit appropriate to the embodiment.

The first compressed video stream 114 becomes a transcoder 116 provided it into a scalable compressed video stream 118 transforms. The scalable compressed video stream 118 consists of a compressed base-layer video stream 120 and a compressed enhancement layer video stream 122 , Additional compressed enhancement layer video streams may be included in other embodiments. In the embodiment in FIG 1A has the compressed base-layer video stream 120 have enough information to reconstruct an uncoded image sequence that has a second but no better perceived quality. The second perceived quality is lower than the perceived quality of the first compressed video stream 114 , The compressed enhancement layer video stream 122 has enough information to combine with the compressed base-layer video stream 120 to reconstruct an uncoded image sequence having a perceived quality better than that of the compressed base-layer video stream 120 , Usually, it is essentially the same as the perceived quality of the compressed input video stream 114 However, this is not required in all embodiments.

That is, if the first compressed video stream 114 encoded with a first value for a particular one of the quality parameters (e.g., resolution) becomes the compressed base-layer video stream 120 is encoded with a second, but not better, value for the particular quality parameter, the second value being of lower quality than the first value. The compressed enhancement layer video stream 122 encoded in combination with the compressed base layer video stream 120 the image sequence having a third value for the determined quality parameter, the third value being of higher quality than the second value.

Typically, the third value corresponds to the first value, but in some embodiments may be between the first and second values.

In the example in 1A has the scalable compressed video stream 118 the format used in the publication ISO / IEC JTC 1 / SC 29 / WG 11 , "Study text (version 3) of ISO / IEC 14496-10: 2005 / FPDAM3 Scalable Video Coding (in integrated form with ISO / IEC 14996 10 ), April 2007, (hereinafter referred to as "SVC draft"), which is hereby incorporated by reference. The first compressed video stream 114 is encoded with a resolution of 1920 × 1080 pixels. The compressed base-layer video stream 120 is encoded with a resolution of 1280 × 720 pixels, that is with a lower quality than the first compressed video stream 114 , The compressed enhancement layer video stream 122 encodes in combination with the compressed base-layer video stream 120 the image sequence with the full input resolution of 1920 × 1080. In another embodiment, it is possible that the compressed enhancement layer video stream 122 in combination with the compressed base-layer video stream 120 the image sequence is encoded with an intermediate resolution, such as 1600x900 pixels. Such an embodiment may also include a second compressed enhancement layer video stream (not shown) in the scalable compressed video stream 118 contain. Additionally compressed enhancement layer video streams are also possible.

Due to the flexibility of the scalable compressed video stream 118 offers, decoders can be created with different capabilities. 1B and 1c Figure 2 illustrates two conventional receivers for decoding such a stream. The decoder 124 in 1B Receives both the compressed base-layer video stream 120 as well as the compressed enhancement layer video stream 122 and combines the information in both and outputs an uncoded image sequence 126 which has essentially the same quality as the original uncoded image sequence 112 that is 1080p60. Standards and methods for combining the base and enhancement streams are set forth in the aforementioned SVC design. The decoder 128 in 12C receives only the compressed base-layer video stream 120 and gives an uncoded image sequence 130 a quality (720p60) lower than that of the original uncoded image sequence 112 , It is assumed that decoders in 1C less expensive than the one in 1B ,

2 is a symbolic block diagram of one embodiment of the transcoder 116 ( 1A ). It includes a decoder 210 containing the compressed input video stream 114 receives and a decoded version 212 outputs. The decoder 210 may be conventional and operates according to the principles described in the SVC design for AVC encoded compressed video streams listed above. The decoded video stream 212 has the same values for different quality parameters as those generated by the compressed input video stream 114 get supported. In 2 For example, it includes a 60 Hz sequence of images in progressive scan mode at a resolution of 1920 × 1080 pixels.

The decoded video stream 112 becomes a quality reducer 214 provided a version 216 reduced quality of the decoded version 212 of the compressed input video stream. The version 216 degraded quality has reduced quality in that for at least one quality parameter, the value of this parameter in the uncompressed video stream 216 is of lower quality than the value of this parameter in the decoded input compressed video stream 212 , In the embodiment in FIG 2 the quality parameter is the resolution, and its value in the uncompressed video stream 216 is 1280 × 720, that is, the quality is lower than its value in the decoded input compressed video stream 212 (1920 × 1080). The quality reduction facility 214 includes conventional vertical and horizontal 3: 2 decimation filters for down-converting each image. The quality reduction facility 214 can be implemented in hardware or on a general purpose computer. Decimation filters can be efficiently implemented on modern general-purpose CPUs using their built-in DSP instruction set, such as the SSE instructions in Intel X86 processors.

The quality-reduced version 216 the decoded version of the compressed input video stream then becomes a conventional AVC encoder 218 which encodes them according to the principles described in the SVC design for AVC encoded compressed video streams listed above. Its output is the compressed base-layer output current 120 ( 1A ). Preferably, AVC encoder is used 218 when creating the compressed input video stream 114 Re-set AVC coding decisions that are scaled as needed to account for the change in one or more quality parameter values. These coding decisions are made in the compressed input video stream 114 represented as encoding metadata. For example, as with the broken line 219 indicated, decoder 210 as part of its decoding process coder 218 as information, at least image types, macroblock modes, macroblock quantizer scaling factors, motion vectors, macroblock quantizer scaling factors, motion vectors, macroblock partitions, number of bits per frame, field or frame formats used for macroblocks and images and patterns of coded blocks and repeating field positions. In the embodiment in 2 in which the quality reduction includes reduction of the resolution, motion vectors, macroblock partitions, macroblock modes, and quantization parameters are parameterized by the intermediate scaling unit 221 scaled to 720p. By reusing coding decisions made in the compressed input video stream 114 AVC coding is greatly simplified because the overall complexity of acquiring statistics and selecting among numerous choices is avoided. Alternatively, a native AVC encoder for 720p60 can be used which operates completely independently and does not reuse previous coding decisions. The use of a native 720p60 encoder, although more expensive than an encoder that reuses coding decisions, has the advantage that they already exist and are available in large quantities. Of course, such a native 720p60 AVC encoder could be outside or in the transcoder.

The compressed base-layer output stream 120 becomes, as with renewed reference to 2 can be seen, even another conventional decoder 220 which recycles the stream in accordance with principles described in the SVC design for AVC encoded compressed video streams listed above. The exit 222 from decoder 220 is a decoded version of the compressed base-layer output stream 120 and forms the output of encoder 128 in 1C to. Thus, in the embodiment in FIG 2 the exit 222 from decoder 220 an uncompressed image sequence whose resolution is lower than that of the decoded compressed input video stream 212 whose mode, however, is like that of the stream 212 is the progressive scan mode and has the same refresh rate of 60 Hz as current 212 ,

The decoded compressed base-layer output stream 212 is combined with the decoded compressed input video stream 212 an enhancement layer calculation device 224 provided. Enhancement layer calculator 224 encodes the enhancement layer output stream 122 according to the above SVC design. Information from the compressed output stream 120 and the decompressed output stream 222 can, as specified in this design, with efficient compression of the video stream 212 be used. As a decoded version of the compressed base-layer output stream 120 instead of the version 216 of the compressed base layer output stream before encoding is the enhancement layer output stream 122 , compared to the base-layer current as it is actually received by the receiver and not compared to an idealized version 216 that is actually not sent, more specifically. However, it is clear that in another embodiment the version 216 of the compressed base layer output stream prior to encoding the enhancement layer calculator 224 instead of the decoded version 222 of the compressed base layer output stream can be provided.

Likewise, the version of the input video stream is that of the Enhancement Layer Calculator 224 in 2 is provided, the decoded version 212 and not the compressed version 114 itself. It is obvious that in another embodiment it is the compressed version 114 that is the Enhancement Layer Calculator 224 provided.

The enhancement layer calculation device 224 generates a coded representation of the 1080p input signal 212 , First, the first signal 222 up-converted to 1080p format. The compressed enhancement layer output stream 122 is then calculated using the inter-layer compression tools in the SVC design document above and using the up-converted signal as the predictor of the decoded compressed input video stream 212 calculated. Usually, the up-converted signal 222 a very good predictor of the signal 212 especially for video that does not have a large amount of high spatial frequency information. The inter-layer compression tools in the SVC design document listed above compress the enhancement layer stream for this video data very efficiently. For video material where the up-converted signal 222 not a good predictor of the signal 212 instead, non-scalable AVC standard compression tools may be used instead of portions of the enhancement layer output stream 122 to create.

In a simple embodiment where the base layer coder 218 Using only the original (scaled) 1080p AVC encoding decisions, the output stream becomes 122 the SVC enhancement layer also comes exclusively from the original compressed one Input video stream 114 coded, as with the broken line 226 in 2 is indicated. The encoding tools described in the SVC design above are used. That is, motion vectors, block partitioning, and residual of inter-coded 1080p SVC macroblocks are directly extracted from the compressed input video stream using the SVC inter-layer inter-coding mode 114 predicted.

In one embodiment, the AVC encoder 218 is independent and the coding decisions from the compressed input video stream 114 not reused, it is still possible the coding decisions of the base layer stream 120 or the input stream 114 encoding the enhancement layer output current 122 to use again.

In a more complicated embodiment, the transcoder also evaluates other possible encoding modes. For example, suppose the video signal being encoded is a multiburst signal. In an I-picture, the top row of macroblocks can be encoded using inter-layer intra-prediction. In this signal, the high spatial frequency information in the multi-burst is not present in the 720p base layer and must be encoded in the enhancement layer. However, for all macroblock rows below the top row, AVC intra-vertical prediction works very effectively. Other embodiments will be apparent to the reader.

The output bit rate is in the transcoder 116 controlled. In one embodiment, the original AVC encoder becomes 110 ( 1A ) is controlled to operate at 90% of the bit rate used for the combined currents 120 and 122 the base layer and the SVC enhancement layer is to be expected. The coding section of the calculation device 224 the enhancement layer then uses quantizer values from the base-layer stream 120 again and the resulting bitrate of the enhancement layer output stream 122 should approach the remaining 10% of the combined bitrate budget.

In another embodiment, the original AVC encoder operates 110 ( 1A ) at a very high bitrate. This will cause the transcoder 115 provided a higher quality input, the rate control information from the compressed input video stream 114 but can not be reused. In this case, the transcoder works 116 with its own rate control and uses, for example, conventional buffer emulation feedback techniques. An advantage of this more complicated embodiment is that the transcoder 116 can use shared optimized base layer / enhancement layer rate control, where bits are assigned to the base layer to improve the video quality of both the base layer and the enhancement layer. Many other embodiments for bit rate control are presented to the user.

implementation

In one embodiment, each of the in 1A and 2 appearing functional blocks implemented in hardware. in another embodiment, at least the transcoding device 116 implemented in software on a multipurpose computer. A multi-purpose computer is an excellent platform for this purpose. The input and output video streams 114 . 120 and 122 are transported via the IP / Ethernet interface. The requirements of motion estimation processing typically limit the quality that is possible in computer-based video encoding, the transcoder 116 in 2 however, does not need to make extensive motion estimates. The computer also contains plenty of memory for the transcoder 116 is sufficient to store 720p images, 720p motion vectors and mode decisions, as well as the 1080p AVC motion vectors and mode decisions.

3 is a simplified block diagram of a computer system 310 , which can be used to implement software that includes aspects of the present invention. Even though 1A and 2 Representing individual components to perform certain operations is obvious that in one software embodiment, each component of the computer system 310 causes to work in the prescribed way. The individual components may be contained in separate software modules in the computer system, or they may be grouped into a single module, or may be in a combination of both, and the flow through the modules may be sequential or pipelined.

computer system 310 usually contains a processor subsystem 314 Using a number of peripheral devices via bus subsystem 312 communicated. To these peripheral devices may be a storage subsystem 324 that is a memory subsystem 326 and a file storage subsystem 328 includes, user interfaces, input devices 322 , User Interface Output Devices 320 and a network interface subsystem 316 belong. The input and output devices allow user interaction with the computer system 310 , Network interface subsystem 316 forms an interface to external networks and closes an interface to communication network 318 and is via communication network 318 coupled with corresponding interface devices in other computer systems. Communication network 318 can include many interconnected computer systems and communication links. These communication links may be cable links, optical links, radio links, or any other mechanism for transmitting information. Although in one embodiment communication network 318 the internet is, can communication network 318 in other embodiments, be any suitable computer network.

The physical hardware components of network interfaces are sometimes referred to as Network Interface Cards (NICs), although they may not be in the form of cards, and they may take the form of, for example, integrated circuits (ICs) and connectors attached directly to them motherboard, or may be in the form of macrocells fabricated on a single IC chip with other components of the computer system.

To the user interface input devices 322 can a keyboard, pointing devices, such as. A mouse, trackball, touchpad or graphics tablet, a scanner, a touch screen integrated into the display, audio input devices such as voice recognition systems, microphones, and other types of input devices. In general, the term "input devices" as used herein is intended to encompass all possible types of devices and ways of entering information into computer systems 310 and computer network 318 lock in.

To user interface output devices 320 may include a display subsystem, a printer, a fax machine or non-visual display devices such as audio output devices. The display subsystem may include a cathode ray tube (CRT), a flat panel display device such as a liquid crystal display (LCD) device, a projection device, or other mechanism for generating a visible image. The display subsystem may also provide non-visual display, such as via audio output devices. In general, the term "output device" as used herein is intended to encompass all possible types of devices and ways of outputting information from the computer system 310 to the user or to another device or computer system.

Storage subsystem 324 stores the basic programming and data structures that enable the functionality of certain embodiments of the present invention. For example, the various modules that implement the functionality of certain embodiments of the invention may be stored in a storage subsystem 324 get saved. These software modules are generally implemented by processor subsystem 314 executed.

Storage subsystem 926 generally contains a number of memories that have a random access memory (RAM) 930 for storing commands and data during program execution and a read-only memory (ROM) 932 Include in which fixed commands are stored. File storage subsystem 928 allows permanent storage of program and data files, and may include a hard disk drive, a floppy disk drive along with removable media, a CD-ROM drive, an optical drive, or removable media cartridges. The databases and modules that implement the functionality of certain embodiments of the invention may be provided on a computer-readable medium, such as one or more CD-ROMs, and file storage subsystems 928 get saved. The host memory 926 includes, among other things, computer commands that, when passing through the processor subsystem 914 to cause the computer system to function as described herein. When it is said that processes and software run in or on "the host" or "the computer", they will be in the processor subsystem 914 in response to computer instructions and data in the host memory subsystem 926 executed, which contains any local or remote memory for such commands and data.

Bus subsystem 312 forms a mechanism through which the various components and subsystems of computer system 310 communicate as intended with each other. Although bus subsystem 312 schematically illustrated as a single bus, alternative embodiments of the bus subsystem may utilize multiple buses.

The type of computer system 310 itself may vary and include a personal computer, a portable computer, a workstation, a computer terminal, a network computer, a television, a mainframe, or any other data processing system or user device. As computers and networks are constantly changing, the description is of computer system 310 , this in 3 is shown, only as a specific example to illustrate embodiments of the present invention. There are many other configurations of computer system 310 possible, which has fewer or more components than that in 3 have shown computer system.

By "addressing" a particular signal, stream, or sequence of images to a previous signal, stream, or sequence of images, the text refers to if the previous signal, the previous stream, or the previous sequence of images is the particular signal, the particular stream or influenced the particular image sequence. If there is an intermediate processing element, intermediate step, or period, the particular signal, stream, or sequence of images may still be "responsive" to the previous signal, stream, or sequence of images. When the intermediate processing element or step combines more than one signal, stream or image sequence, the signal output of the processing element or step is considered to be "responsive" to each of the signal, stream or image sequence inputs. If the particular signal, stream, or sequence of images is the same as the previous signal, the previous stream, or the previous image sequence, this is only a special case where the particular signal, stream, or stream is determined Still, the picture sequence is considered "responsive" to the previous signal, the previous stream, or the previous picture sequence. "Dependence" of a particular signal, current, or sequence of images from another signal, stream, or sequence of images is similarly defined.

Although the present invention is disclosed with reference to the preferred embodiments and examples as described in detail above, it should be understood that these examples are illustrative only and not limiting. The reader opens up numerous variants. For example, although the methods described herein are described in terms of systems that are based on MPEG video coding standards, it will be appreciated that many of them can be applied to other video compression protocols as well.

In some of the described embodiments, reference is made to computer-aided processing. Accordingly, the invention may include, in methods for generating the scalable composite video stream, systems that include logic and resources for performing these methods, systems that utilize computer-implemented implementations of such methods, media that include logic or software for performing those methods, or streams that Logic or software to perform these methods include executed. It is intended that modifications and combinations readily apparent to those skilled in the art, which modifications and combinations are part of the spirit of the invention and the scope of the following claims.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 6091776 [0016]

Cited non-patent literature

• ISO / IEC JTC 1 / SC 29 / WG 11 [0022]
• ISO / IEC 14496-10: 2005 / FPDAM3 [0022]
• ISO / IEC 14996 10 [0022]

Claims (25)

A method of generating a scalable compressed video stream, comprising the steps of: Providing a compressed input video stream encoded with a first value for a particular quality parameter; and Transcoding the compressed input video stream to a base output stream and an enhancement signal, wherein the base output stream is coded with a second value for the determined quality parameter and the second value is of lower quality than the first value for the determined quality parameter, and the enhancement signal combined with the base output stream is encoded with a third value for the determined quality parameter, the third value being of higher quality than the second plant for the determined quality parameter. The method of claim 1, wherein the third value for the determined quality parameter is the same as the first value for the determined quality parameter. The method of claim 1, wherein the determined parameter comprises at least one of the group of criteria consisting of resolution, frame rate, signal-to-noise ratio, and bit rate. The method of claim 1, wherein the determined quality parameter comprises resolution. The method of claim 1, wherein the step of transcoding comprises the step of: Calculating the enhancement signal in response to both the input compressed video stream and the base output stream. The method of claim 5, wherein the step of calculating the enhancement signal comprises the steps of: Decoding the compressed input video stream to a decoded version of the compressed input video stream; and Calculating the enhancement signal in dependence on the decoded version of the compressed input video stream. The method of claim 5, wherein the step of calculating the enhancement signal comprises the steps of: Decoding the base output current to a decoded version of the base output current; and Calculating the enhancement signal in dependence on the decoded version of the base output current. A method of generating a scalable compressed video stream, comprising the steps of: Providing a compressed input video stream encoded with a first value for a particular quality parameter; Decoding the compressed input video stream to a decoded version of the compressed input video stream; Creating a reduced quality version of the decoded version of the compressed input video stream, wherein the reduced quality version has a second value for the determined quality parameter and the second value is of lower quality than the first value for the determined quality parameter; Encoding the reduced-quality version of the decoded version of the compressed input video stream to produce a base output stream; Calculating an enhancement signal in response to the input compressed video stream and the base output stream; and Outputting the base output current and the enhancement signal. The method of claim 8, wherein the enhancement signal combined with the base output stream has a value for the determined quality parameter that is the same as the first value for the determined quality parameter. The method of claim 8, wherein the step of encoding the version of the decoded version of the reduced quality compressed input video stream to generate a base output stream comprises the step of encoding the reduced quality version in response to encoding metadata that is encoded in the compressed input video stream. The method of claim 8, wherein the step of encoding the reduced-quality version of the decoded version of the compressed input video stream to generate a base output stream comprises the step of encoding the reduced-quality version in response to encoding metadata stored in the Base output current are present. The method of claim 8, wherein the step of calculating the enhancement signal comprises the steps of: Decoding the base output current to a decoded version of the base output current; and Calculating the enhancement signal in dependence on the decoded version of the compressed input video stream and the decoded version of the base output stream. A method of generating a scalable compressed video stream, comprising the steps of: providing a compressed input video stream encoded at a first resolution; and transcoding the compressed input video stream to a base output stream and an enhancement signal, wherein the base output stream is encoded at a second resolution that is lower than the first resolution, and the enhancement signal is combined with the base output stream can, so that results in a picture sequence that has the first resolution. Apparatus for generating a scalable compressed video stream for use with a compressed input video stream encoded with a first value for a particular quality parameter, the apparatus comprising a transcoder which transcodes the compressed input video stream to a base output stream and an enhancement signal, wherein the base output stream is coded with a second value for the determined quality parameter and the second value is of lower quality than the first value for the determined quality parameter, and the enhancement signal, when combined with the base output stream, is encoded with a third value for the determined quality parameter, the third value being of higher quality than the second value for the determined quality parameter. The apparatus of claim 14, wherein the third value for the determined quality parameter is the same as the first value for the determined quality parameter. The apparatus of claim 14, wherein the determined parameter comprises at least one of the group of criteria consisting of resolution, frame rate, signal-to-noise ratio, and bit rate. The apparatus of claim 14, wherein the transcoding means comprises means for calculating the enhancement signal in response to both the input video compressed signal and the base output current. The apparatus of claim 17, wherein the transcoding device comprises: means for decoding the compressed input video stream to a decoded version of the compressed input video stream; and means for calculating the enhancement signal in response to the decoded version of the compressed input video stream. The apparatus of claim 17, wherein the transcoding device comprises: means for decoding the base output current to a decoded version of the base output current; and means for calculating the enhancement signal in dependence on the decoded version of the base output stream. Apparatus for generating a scalable compressed video stream for use with a compressed input video stream encoded with a first value for a particular quality parameter, the apparatus comprising: decoding means coupled to receive the compressed input video stream, the decoding means outputting a decoded version of the compressed input video stream; a degraded means for creating a reduced quality version of the decoded version of the input compressed video stream, the reduced quality version having a second value for the determined quality parameter and the second value being of lower quality than the first value for the determined quality parameter; coding means for encoding the reduced-quality version of the decoded version of the compressed input video stream to produce a base output stream; and an enhancement layer calculation means for calculating an enhancement signal in response to both the input compressed video stream and the base output stream, wherein the device outputs both the base output current and the enhancement signal. The apparatus of claim 20, wherein the enhancement signal combined with the base output current has a value for the determined quality parameter that is the same as the first value for the determined quality parameter. The apparatus of claim 20, wherein the encoding means comprises means for encoding the reduced-quality version in response to encoding metadata contained in the input compressed video stream. The apparatus of claim 20, wherein the encoding means comprises means for encoding the reduced-quality version in response to encoding metadata present in the base output stream. The device of claim 20, wherein the enhancement layer calculation means comprises: means for decoding the base output current to a decoded version of the base output current; and means for calculating the enhancement signal in dependence on both the decoded version of the compressed input video stream and the decoded version of the base output stream. Apparatus for generating a scalable compressed video stream for use with a compressed input video stream encoded at a first resolution, the apparatus comprising transcoding means for summing the compressed input video stream to both a base output stream and an enhancement Signal is transcoded, and the transcoding device has a functional mode in which the base output current is coded with a second resolution which is lower than the first resolution, and in which the enhancement signal combined with the base output current, encoded with the first resolution.

Images