Classifications

• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
  • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
  • G10L19/008—Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S3/00—Systems employing more than two channels, e.g. quadraphonic

Definitions

• the present invention relates to an encoding method and apparatus and a decoding method and apparatus, and more particularly, to an encoding method and apparatus and a decoding method and apparatus in which a multi-channel audio signal is encoded or decoded so that all or part of information included in a header can be retransmitted.
• a multi-channel audio signal is downmixed into a mono or stereo signal and the mono or stereo signal is encoded, instead of encoding each channel of the multi-channel audio signal.
• a multi-channel audio signal is encoded together with spatial information indicating spatial cues.
• FIG. 1 is a diagram for illustrating a bitstream of a multi-channel audio signal generated using a typical method of encoding a multi-channel audio signal.
• a bitstream of a multi-channel audio signal is divided into one or more frames (i.e., frames 1 through 3), and is thus transmitted or decoded in units of the frames.
• a header is placed ahead of frame 1.
• the header includes Spatial Audio Coding (SAC) configuration information, and each of frames 1 through 3 includes spatial information of a corresponding frame.
• SAC configuration information comprises information that can be commonly applied to frames 1 through 3, i.e., sampling frequency information, frame length information, and tree configuration information specifying a downmix combination of a multi-channel signal .
• the present invention provides an encoding method and apparatus in which information that is selected from a header can be retransmitted as additional configuration information.
• the present invention also provides a decoding method and apparatus in which a bitstream including additional configuration information that is selected from a header can be decoded.
• an encoding method includes encoding spatial information that is calculated based on a multi-channel audio signal and a downmix signal, generating additional configuration information based on information that is selected from the encoded spatial information, encoding the downmix signal, generating a bitstream by combining the encoded downmix signal with the encoded spatial information, and inserting the additional configuration information into the bitstream.
• an encoding apparatus includes a downmix unit which generates a down- mix signal based on a multi-channel audio signal, a core encoder which encodes the down-mix signal, a spatial information generation unit which calculates spatial information of the multi-channel audio signal, a parameter encoder which encodes the spatial information, and a bitstream generation unit which generates a bitstream by combining the encoded spatial information and the encoded down-mix signal and inserts additional configuration information that is selected from the encoded spatial information into the bitstream.
• the decoding method includes demultiplexing an encoded down-mix signal and additional information from a current frame of an input bitstream, determining whether additional configuration information has been retransmitted based on the additional information, and generating a multi-channel audio signal corresponding to the current frame based on the additional configuration information if the additional configuration information is determined to have been retransmitted.
• the decoding apparatus includes a demultiplexer which demultiplexes an encoded down-mix signal and additional information from a current frame of an input bitstream, a core decoder which generates a down-mix signal by decoding the encoded down-mix signal, a parameter decoder which determines whether additional con- figuration information has been retransmitted based on the additional information, and generates spatial information by encoding the additional configuration information if the additional configuration information is determined to have been retransmitted, and a multi-channel synthesization unit which generates a multi-channel audio signal based on the spatial information and the down-mix signal.
• a computer- readable recording medium having recorded thereon a program for executing an encoding method, the encoding method including encoding spatial information that is calculated based on a multi-channel audio signal and a downmix signal; generating additional configuration information based on information that is selected from the encoded spatial information; and encoding the downmix signal, generating a bitstream by combining the encoded downmix signal with the encoded spatial information, and inserting the additional configuration information into the bitstream.
• a computer- readable recording medium having recorded thereon a program for executing a decoding method, the decoding method including demultiplexing an encoded down- mix signal and additional information from a current frame of an input bitstream; determining whether additional configuration information has been retransmitted based on the additional information; and generating a multi-channel audio signal corresponding to the current frame based on the additional configuration information if the additional configuration information is determined to have been retransmitted.
• FIG. 1 is a diagram for illustrating a bitstream of a typical multi-channel audio signal
• FIG. 2 is a block diagram of a system for encoding/decoding a multi-channel audio signal to which encoding and decoding methods according to an embodiment of the present invention are applied;
• FIGS. 3 and 4 present syntax of spatial information used in the present invention
• FIGS. 5 and 6 are flowcharts illustrating a decoding method according to an embodiment of the present invention.
• FIG. 7 is a flowchart illustrating a decoding method according to another embodiment of the present invention. Best Mode for Carrying Out the Invention
• Methods and apparatuses for encoding and decoding a multi-channel audio signal according to the present invention can be applied to the processing of a multi-channel audio signal.
• the present invention is not restricted thereto.
• the present invention can also be applied to the processing of a signal other than a multi-channel audio signal.
• FIG. 2 is a block diagram of a system for encoding/decoding a multi-channel audio signal to which encoding and decoding methods according to an embodiment of the present invention are applied.
• an encoding apparatus 100 includes a downmix unit 110, a spatial information generation unit 120, a core encoder 130, a parameter encoder 135, and a bitstream generation unit 140.
• a decoding apparatus 200 includes a demultiplexer 210, a core decoder 220, a parameter decoder 230, and a multi-channel synthesization unit 240.
• the downmix unit 110 generates a downmix signal by downmixing a multi-channel audio signals comprising n channels into a mono or stereo signal.
• the encoding apparatus 100 may use an artistic downmix signal that is processed externally, instead of generating a downmix signal.
• the spatial information generation unit 120 calculates spatial information regarding a multi-channel audio signal.
• the core encoder 130 encodes the downmix signal generated by the downmix unit 110.
• the parameter encoder 135 encodes the spatial information obtained by the spatial information generation unit 120.
• the bitstream generation unit 140 generates a bitstream by combining the encoded downmix signal and the encoded spatial information.
• the bitstream generation unit 140 may insert additional configuration information, if necessary, into the bitstream.
• the additional configuration information corresponds to all or part of spatial information or other information included in the header of the bitstream. In short, spatial information and additional configuration information can be included in a bitstream generated by the bitstream generation unit 140.
• the demultiplexer 210 receives a bitstream input to the decoding apparatus 200, and demultiplexes an encoded downmix signal and encoded additional information from the received bitstream.
• the core decoder 220 generates a downmix signal by decoding the encoded downmix signal.
• the parameter decoder 230 generates spatial information by decoding the encoded additional information. If the encoded additional information comprises additional configuration information, the parameter decoder 230 may generate spatial information based on the additional configuration information.
• the multi-channel synthesization unit 240 generates a multi-channel audio signal based on the spatial information generated by the multi-channel synthesization unit 240 and the downmix signal generated by the core decoder 220.
• FIGS. 3 and 4 present syntax of spatial information used in the present invention.
• SpatialSpecificConfigO indicates spatial information included in a header.
• SpatialFrame() indicates frame information which is information corresponding to each frame.
• SpatialSpecificConfigO corresponds to SAC configuration information, and particularly, spatial information that can be commonly applied to a number of frames.
• SpatialSpecificConfigO comprises bsSamplingFrequency which indicates sampling frequency, bsFrameLength which indicates frame length, and bsTreeConfic which indicates information specifying a downmix combination of a multi-channel signal.
• SpatialFrameO comprises spatial information of each frame such as Framinginfo() which indicates time slot information in connection with the number of parameter sets.
• a multi-channel audio signal is encoded so that SpatialSpecficConfig (), which corresponds to all or part of SAC configuration information, can be inserted into either a certain frame or each frame of the bitstream as additional configuration information.
• SAC configuration information can be inserted not only into a header of a bitstream but also into either a certain frame or each frame of the bitstream.
• a multi-channel audio signal can be encoded in the following manner.
• a retransmission flag e.g., bsResendSptialSpecificConficFrame
• SpatialFrameO a retransmission flag indicating whether the additional configuration information has been retransmitted
• the retransmission flag bsResendSptialSpecificConficFrame is set in SpatialFrameO, it may be determined, during the decoding of a bitstream, that additional configuration information corresponding to SpatialSpecifigConfigO is inserted into the bitstream.
• a retransmission flag bsResendSpatialSpecificConfigHeader may be set in
• SpatialSpecifigConfigO which is included into a header of a bitstream. If the re- transmission flag bsResendSpatialSpecificConfigHeader is set, it may be determined again whether a retransmission flag bsResendSpatialSpecificConficFrame in Spa- tialFrameO is set, and additional configuration information may be received again according to the result of the determination. If the retransmission flag bsResendSpatial- SpecificConfigHeader is not set, it means that a bitstream does not comprise any additional configuration information, and thus, the bitstream can be readily decoded without the need to reexamine the retransmission flag bsResendSpatialSpecific- ConficFrame.
• Additional configuration information may be comprised of SpatialSpecificConfigO or may be comprised of a parameter set SpatialSpecificConfigParam that is selected from SpatialSpecificConfigO.
• a retransmission flag bsResendSpatialSpeci- ficConficParamFrame may be inserted into SpatialFrame(). If the retransmission flag bsResendSpatialSpecificConficParamFrame is set, it may be determined that the parameter set SpatialSpecificConfigParam has been retransmitted.
• a retransmission flag bsResendSpatialSpecificConfigParamHeader may be included in SpatialSpecifigConfigO.
• the retransmission flag bsResendSpatialSpecificConfig- ParamHeader may be reexamined, and additional configuration information may be received again according to the results of the reexamination.
• the retransmission flag bsResendSpatialSpecificConfigParamHeader it may be determined that a bitstream does not comprise additional configuration information.
• the parameter set SpatialSpecificConfigParam which corresponds to part of spatial information included in a header of a bitstream, may include at least one of a plurality of pieces of information included in SpatialSpecficConfig().
• a retransmission flag bsResendTreeConfigFrame may be inserted into SpatialFrame(). For example, if the retransmission flag bsResendTreeConfigFrame is set, it is determined that bsTreeConfig has been retransmitted. As described above, a retransmission flag bsRe- sendTreeConfigHeader may be inserted into SpatialSpecifigConfigHeader. If the retransmission flag bsResendTreeConfigHeader is set, the retransmission flag bsResendTreeConfigFrame can be reexamined.
• bsTreeConfig it is possible to retransmit bsTreeConfig periodically or whenever necessary.
• a multi-channel audio signal with five channels comprises a portion whose quality is maintained even after the multi-channel audio signal is downmixed mono and a portion that must be compressed as stereo.
• the multi-channel audio signal must be encoded as stereo in order to maintain the quality of the multi-channel audio signal.
• only portions of the multi-channel audio signal that need to be compressed as stereo can be selectively encoded as stereo.
• the mode of encoding can be changed according to the type of signals during the encoding of signals as mono signals, thus obtaining signals with better quality than in the prior art at a given bitrate.
• bsTreeConfig can be divided into three bits, i.e., bsTreeExt, bsTreeCh, and bsTreeCfg, and bsTreeExt, bsTreeCh, and bsTreeCfg can be used, instead of retransmitting bsTreeConfig.
• FIGS. 5 and 6 are flowcharts illustrating a decoding method according to an embodiment of the present invention.
• operation S400 a header of an input bitstream is received.
• operation S405 it is determined whether a retransmission flag (bsResendSpatialSpecificConfigHeader) in the header is set. If it is determined in operation S405 that the retransmission flag
• a multi-channel audio signal is generated based on a downmix signal according to the additional configuration information.
• an encoded downmix signal and frame information are demultiplexed from the current frame, spatial information is generated based on the additional configuration information and the frame information, and a multi-channel audio signal is generated based on the spatial information and the encoded downmix signal. If the additional configuration information is part of the spatial information included in the header, other information that is needed to generate spatial information may be obtained from spatial information that is extracted from the header .
• operation S435 if it is determined in operation S415 that the retransmission flag (bsResendSpatialSpecificConficFrame) in the current frame is not set, a multi-channel audio signal is generated based on the configuration information included in the header. Operations S400 through S425, S435, and S440 through S450 are repeatedly performed until the end of the input bitstream is encountered .
• FIG. 7 is a flowchart illustrating a decoding method according to another embodiment of the present invention.
• a retransmission flag is included, not in a header but in a frame.
• operation S500 a frame of an input bitstream is received.
• operation S505 it is determined whether a retransmission flag in the frame is set.
• operation S510 if it is determined in operation S505 that the retransmission flag in the frame is set, additional configuration information is extracted (from the frame?).
• a multi-channel audio signal is generated based on the additional configuration information.
• spatial information is generated based on the additional configuration information and frame information, and then, a multi-channel audio signal is generated based on the spatial information and a downmix signal.
• operation S525 if it is determined in operation S505 that the retransmission flag in the frame is not set, spatial information is generated based on the frame information and configuration information that is extracted from a header of the input bitstream, and a multi-channel audio signal is generated based on the spatial information and the downmix signal.
• additional configuration information is inserted into a certain frame of a bitstream, thereby enabling the generation of a multichannel audio signal even when the header of the bitstream is not received as in a streaming service .
• the present invention can be realized as computer-readable code written on a computer-readable recording medium.
• the computer-readable recording medium may be any type of recording device in which data is stored in a computer-readable manner. Examples of the computer-readable recording medium include a ROM, a RAM, a CD- ROM, a magnetic tape, a floppy disc, an optical data storage, and a carrier wave (e.g., data transmission through the Internet).
• the computer-readable recording medium can be distributed over a plurality of computer systems connected to a network so that computer-readable code is written thereto and executed therefrom in a decentralized manner. Functional programs, code, and code segments needed for realizing the present invention can be easily construed by one of ordinary skill in the art.
• a multi-channel audio signal is encoded so that all or part of information included in a header can also be included in a predetermined frame.
• the present invention can be applied to streaming services.
• a multi-channel audio signal is encoded or decoded so that configuration can vary from one frame to another. Thus, it is possible to generate an optimum bitstream according to the circumstances.
• spatial information can be selectively transmitted only to a few frames.
• the present invention can be applied to the encoding/decoding of a multi-channel audio signal and can enable retransmission of all or part of information included in a header.
• the present invention is used to an encoding method and apparatus and a decoding method and apparatus in which a multi-channel audio signal is encoded or decoded so that all or part of information included in a header can be retransmitted.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Signal Processing (AREA)
• Acoustics & Sound (AREA)
• Audiology, Speech & Language Pathology (AREA)
• Health & Medical Sciences (AREA)
• Computational Linguistics (AREA)
• Human Computer Interaction (AREA)
• Mathematical Physics (AREA)
• Multimedia (AREA)
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• Compression, Expansion, Code Conversion, And Decoders (AREA)
• Stereophonic System (AREA)
• Time-Division Multiplex Systems (AREA)

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• 2006
  • 2006-10-20 EP EP06799359A patent/EP1946310A4/en not_active Ceased
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