Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/12—Systems in which the television signal is transmitted via one channel or a plurality of parallel channels, the bandwidth of each channel being less than the bandwidth of the television signal
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/115—Selection of the code volume for a coding unit prior to coding
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/124—Quantisation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
  • H04N19/146—Data rate or code amount at the encoder output
  • H04N19/152—Data rate or code amount at the encoder output by measuring the fullness of the transmission buffer
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
  • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
  • H04N19/172—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a picture, frame or field
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/40—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
  • H04N19/61—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding in combination with predictive coding
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
  • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
  • H04N21/236—Assembling of a multiplex stream, e.g. transport stream, by combining a video stream with other content or additional data, e.g. inserting a URL [Uniform Resource Locator] into a video stream, multiplexing software data into a video stream; Remultiplexing of multiplex streams; Insertion of stuffing bits into the multiplex stream, e.g. to obtain a constant bit-rate; Assembling of a packetised elementary stream
  • H04N21/2365—Multiplexing of several video streams
  • H04N21/23655—Statistical multiplexing, e.g. by controlling the encoder to alter its bitrate to optimize the bandwidth utilization
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards

Definitions

• Digital video signals coding method and corresponding coding or transcoding system Digital video signals coding method and corresponding coding or transcoding system.
• the present invention relates to a method for transmitting a constant bitrate digital video bitstream corresponding to n multiplexed variable bitrate coded video bitstreams, comprising the steps of :
• This invention is useful in the field of digital television transmission, for implementing a statistical multiplexer that allows to have an improved dynamic allocation of the bitrate in each channel.
• n digital video signals have to be transmitted through an identical number of channels having a predetermined global allocated bitrate.
• a coding apparatus of this type is described for instance in the document EP 0685971.
• This apparatus comprises a plurality of encoders, for coding the input video signals at variable rates, and a bit allocating stage, supplied with estimated information coming from the encoders and provided for sending back to the encoders, on the basis of said information, an indication of an allowed allocation of bits.
• Such a dynamic allocation allows to grant more bitrate on more complex sequences, which not only reduces the probability of getting strong artifacts and improves the bandwidth efficiency, but also makes sure that the quality perception will be the same in each channel (the video quality is evaluated for each parallel video signal and the bitrate is requested in correspondence with said evaluation).
• the quality perception does not take into account the audio information when digital audio signals accompany the video ones, which is often the case.
• the invention relates to a method such as described in the opening paragraph of the description and which is moreover characterized in that it also comprises the steps of :
• the invention relates to a constant bitrate digital video transmission system comprising n parallel video coding branches, the variable bitrate output signals of said branches being directed towards a constant bitrate transmission channel via a multiplexer and a bitrate allocation being defined for each encoding branch by means of a common controller that receives from each coding branch at least one respective video parameter created in association with each video bitstream, characterized in that it also comprises :
• Such a system may also be adapted to another type of environment, for controlling transcoders, when for instance a transport stream is processed and bitrate is re-allocated by having bitrate transcoding.
• - FigJ shows a television transmission system incorporating an embodiment of the invention
• - Fig.2 shows a similar system in another type of environment.
• a digital video signals coding system carrying out the method according to the invention is illustrated in FigJ. It comprises n parallel encoding channels, including variable bitrate video encoders 110a to 1 lOn. Each of these encoders receives a respective video signal to be encoded, said signal being in fact a bitstream of data that have been previously subdivided into blocks of pixels, DCT transformed and quantized. These n input video signals are referenced EN(1) to EN(n), and the n output signals of the encoders are referenced N(l) to N(n). These n output signals are coded bitstreams sent with a variable bitrate towards a multiplexer 20, the output of which is a single coded bitstream S with a fixed bitrate. Said bitrate is the limited bitrate allowed by the transmission channel, referenced 100.
• a rate controller 30 is then provided in order to receive from each encoder 110a to 1 lOn one or several specific parameters associated to each video signal processed by each respective encoder and to send back to said encoders specific signals for controlling the bitrate allocation of these encoders on the basis of these specific parameters and with the object of being in accordance with the bitrate allowed in the transmission channel.
• the requested bitrate corresponding to that evaluation is obtained by controlling the quantizer step size of each encoding channel.
• the audio signals that accompany the video signals and have also to be transmitted are also sent towards the rate controller 30 and participate in the allocation of the bitrate in each channel.
• the base band audio signal - referenced EA(1) to EA(n) - associated to each video signal is sent towards an associated analysis circuit 40a to 40n.
• the circuits 40a to 40n yield to the controller 30 a specific parameter which is intended to influence the bitrate allocation of the corresponding channel.
• the parameter is the acoustic level of the signals EA(1) to EA(n).
• the acoustic level of one or several signals EA(i) is higher, the corresponding bit allocations may be decreased, since an user brings less attention to a picture accompanied by a higher acoustic level and which moreover is often a picture changing quickly (on the contrary, a low acoustic level is often associated to pictures that are rather still).
• bitrate finally obtained at the output of the multiplexer 20 is the same as when the analysis circuits are not provided, but the distribution of the respective bit allocations given by the signals N(l) to N(n) is now different, each of said allocations being now weighted by one (or several) audio parameters(s).
• the system according to the invention has been described in the case the encoding channels comprise video encoders, but the invention is similarly implemented even with another type of environment, when the input signals EN(1) to EN(n) are, as shown in Fig.2, signals already coded sent to transcoders 210a to 210n (in place of encoders).
• the bitrate of each channel is re-allocated by having bitrate transcoding. This re-allocation is then, as in the first described implementation, influenced by the audio parameters measured in the analysis circuits 40a to 40n.
• the present coding method can be implemented either by means of wired electronic circuits or, alternatively, by means of a set of instructions stored in a computer-readable medium, said instructions replacing at least a part of the circuits of the system and being executable under the control of a computer or a digital processor in order to carry out the same functions as fulfilled in said replaced circuits.
• the invention then also relates to a computer-readable medium comprising a software module that includes computer-executable instructions for performing the steps, or some steps, of the hereinabove described method.

Landscapes

• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Compression Or Coding Systems Of Tv Signals (AREA)
• Compression, Expansion, Code Conversion, And Decoders (AREA)
• Television Systems (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (1)

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• 2000
  • 2000-05-04 WO PCT/EP2000/004213 patent/WO2000074388A1/en active IP Right Grant
  • 2000-05-04 KR KR1020017001102A patent/KR100721272B1/ko not_active IP Right Cessation
  • 2000-05-04 JP JP2001500560A patent/JP4508503B2/ja not_active Expired - Fee Related
  • 2000-05-04 CN CNB008010099A patent/CN1192633C/zh not_active Expired - Fee Related
  • 2000-05-04 EP EP00931173A patent/EP1101360A1/de not_active Withdrawn

Non-Patent Citations (1)

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