CN101361277B - Method and apparatus for processing an audio signal - Google Patents
Method and apparatus for processing an audio signal Download PDFInfo
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- CN101361277B CN101361277B CN200780001528.9A CN200780001528A CN101361277B CN 101361277 B CN101361277 B CN 101361277B CN 200780001528 A CN200780001528 A CN 200780001528A CN 101361277 B CN101361277 B CN 101361277B
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Abstract
A method for processing an audio signal, comprising the steps of extracting an ancillary signal for generating the audio signal and an extension signal included in the ancillary signal from a received bit stream, checking a level of the bit stream, selectively decoding the extension signal according to the level of the bit stream, and generating the audio signal using the ancillary signal. Accordingly, in case of processing the audio signal by the present invention, it is able to reduce a corresponding load of operation to enable efficient processing and enhance a sound quality.
Description
Technical field
The present invention relates to the method and apparatus of audio signal.Although the present invention is applicable to the application of wide scope, it is specially adapted to handle residual signals.
Background technology
Generally speaking, audio signal comprises down-mix audio signal and auxiliary data signal.And auxiliary data signal can comprise spatial signal information and spread signal.In this case, " spread signal " be meant by down-mix audio signal is carried out channel expansion handle make when generating multi-channel signal signal can be near primary signal the required additional signal of reconstruct.For example, spread signal can comprise residual signals." residual signals " is meant and primary signal and the corresponding signal of difference between the signal of decoding.When multichannel audio was deciphered, residual signals can be used for following situation.For example, residual signals can be used for the compensation or the compensation of the particular channel in when decoding of artistic down-mix signal.And residual signals also can be used for this two kinds of compensation.So, can utilize residual signals that the reconstructed audio signal of input is become more signal near primary signal, to improve sound quality.
Summary of the invention
Technical problem
Yet if decoder is unconditionally decoded on spread signal, although can improve sound quality according to the type of decoder, complexity rises and computational load increases.
In addition, because the header information of audio signal generally is immutable, header information only is inserted into bit stream once.But only be inserted in the bit stream situation once at header information, if audio signal need be used for broadcasting or VOD from the decoding of random time point, then can not the decoded data frame information owing to there is not header information.
Technical scheme
Therefore, the present invention relates to a kind of method and apparatus of having eliminated the audio signal of the limitation of one or more because relevant technologies and the problem that shortcoming causes basically.
An object of the present invention is to provide a kind of method and apparatus that is used for audio signal, the treatment effeciency of the audio signal of mat improves by the decoding of skipping spread signal.
Another object of the present invention provides a kind of method and apparatus that is used for audio signal, and the decoding of the spread signal of mat utilizes the length information of this spread signal and skipped.
Another object of the present invention provides a kind of method and apparatus that is used for audio signal, and the audio signal that is used to broadcast of mat can be reproduced from random time point.
Another purpose of the present invention provides a kind of method and apparatus that is used for audio signal, and the audio signal of mat is handled according to class information.
According to an aspect of the present invention, provide a kind of method of audio signal, it may further comprise the steps: receive bit stream; From the bitstream extraction down-mix audio signal that is received, auxiliary signal and spread signal, described down-mix audio signal is handled generation by multi-channel audio signal being carried out multi-channel audio, described spread signal is included in the expansion area of described auxiliary signal, and described auxiliary signal comprises header extension district and frame expansion area; Obtain the length information of described spread signal respectively from described header extension district and described frame expansion area; Based on the length information that obtains from described header extension district, skip the decoding that is included in the described spread signal in the described header extension district; Based on the length information that obtains from described frame expansion area, skip the decoding that is included in the described spread signal in the described frame expansion area; And generate described multi-channel audio signal to described down-mix audio signal by using described auxiliary signal.
Preferably, the auxiliary signal that does not comprise described spread signal comprises the spatial parameter that is used to generate described multi-channel audio signal, and it is poor that described spatial parameter comprises the levels of channels of energy difference between the expression sound channel, the inter-channel coherence of expression inter-channel coherence and the sound channel predictive coefficient information of using when generating triple-track by two sound channels.
Preferably, described spread signal comprises residual signals.
Preferably, the length information to described spread signal distributes fixed bit.
Preferably, according to the length type information of described spread signal, can change the ground allocation bit to the length information of described spread signal.
Preferably, according to the length of described spread signal, to the length information of described spread signal allocation bit adaptively.
According to another aspect of the present invention, a kind of device of audio signal is provided, it comprises: demultiplex unit, it receives bit stream, from the bitstream extraction down-mix audio signal that is received, auxiliary signal and spread signal, described down-mix audio signal is handled generation by multi-channel audio signal being carried out multi-channel audio, described spread signal is included in the expansion area of described auxiliary signal, and described auxiliary signal comprises header extension district and frame expansion area; The down-mix audio signal decoding unit of the described down-mix audio signal of decoding; The auxiliary signal decoding unit of the described auxiliary signal of decoding; The spread signal decoding unit; And channel expansion audio mixing unit, it generates described multi-channel audio signal by using described auxiliary signal to described down-mix audio signal, wherein said spread signal decoding unit comprises: the extension signal length reading unit, and it obtains the length information of described spread signal respectively from described header extension district and frame expansion area; And selectivity decoding unit, it is based on the length information that obtains from described header extension district, skip the decoding that is included in the described spread signal in the described header extension district, and, skip the decoding that is included in the described spread signal in the described frame expansion area based on the length information that obtains from described frame expansion area.
Beneficial effect
The present invention has following effect or advantage.
At first, in the situation of decoding, the present invention optionally decodes spread signal to realize more efficient decoding.In the situation that spread signal is decoded, the present invention can improve the sound quality of audio signal.In the situation of spread signal not being decoded, the present invention can reduce complexity.In addition, even spread signal is decoded, the present invention also can improve sound quality and reduce computational load equally by the predetermined low frequency part of only decoding.In addition, in the situation that audio signal is used for broadcasting etc., the present invention can be to have the mode that does not still have header information in the identification audio signal, from random time point audio signal.
The accompanying drawing summary
Be included in this to provide further understanding of the present invention, and in this application combined and constitute its a part of accompanying drawing embodiments of the present invention are shown, it can be used to explain principle of the present invention with specification.
In the accompanying drawing:
Fig. 1 is the block diagram of audio signal encoding apparatus according to an embodiment of the invention and audio signal decoder;
Fig. 2 is the schematic block diagram of spread signal decoding unit 90 according to an embodiment of the invention;
Fig. 3 and Fig. 4 are the figure that is used to explain the fixed bits assignment of extension signal length information according to an embodiment of the invention;
Fig. 5 and Fig. 6 are the figure that is used to explain the variable bit distribution of the extension signal length information that depends on length type according to an embodiment of the invention;
Fig. 7 and Fig. 8 are the figure that is used to explain the adaptive bits assignment of the extension signal length information that depends on the true length of spread signal according to one embodiment of present invention;
Fig. 9 is the figure that disposes the bit stream structure of audio signal according to one embodiment of present invention with down-mix audio signal, auxiliary signal and spread signal;
Figure 10 is the figure that disposes the bit stream structure of audio signal according to one embodiment of present invention with auxiliary signal that comprises spread signal and down-mix audio signal;
Figure 11 is the figure that founds the bit stream structure of audio signal according to one embodiment of present invention with the configuration of down-mix audio signal or auxiliary signal;
Figure 12 is the figure that disposes the broadcasting flow structure of audio signal according to one embodiment of present invention with down-mix audio signal and auxiliary signal;
Figure 13 is according to one embodiment of present invention in the situation that audio signal is used for broadcasting etc., and the identifying information that whether is included in the auxiliary signal of head uses the length information of spread signal to handle the flow chart of the method for spread signal as indicated; And
Figure 14 uses optionally the decode flow chart of method of spread signal of the length information of spread signal according to the rank of bit stream according to one embodiment of present invention.
Preferred forms of the present invention
Other features and advantages of the present invention will be set forth in the following description, and partly will be apparent from describe, and perhaps can know from the practice of the present invention.Purpose of the present invention and other advantage can be realized and obtained by the structure of specifically noting in printed instructions and claims and the accompanying drawing.
In order to realize these and other advantage and according to purpose of the present invention, as embody and broadly described, a kind of method of treatment in accordance with the present invention audio signal may further comprise the steps: extract the spread signal that is used for generating the auxiliary signal of audio signal and is included in this auxiliary signal from the bit stream that receives; Read the length information of this spread signal; Skip the decoding of spread signal or do not use decoded results based on this length information; And utilize auxiliary signal to generate audio signal.
In order further to realize these and other advantage and according to purpose of the present invention, a kind of method of audio signal may further comprise the steps: obtain the position of the auxiliary signal that indication is used for generating audio signal and be included in the synchronizing information of position of the spread signal of this auxiliary signal; Skip the decoding of spread signal or do not use decoded results based on this synchronizing information; And utilize this auxiliary signal to generate audio signal.
For further these and other advantage of realization and according to purpose of the present invention, a kind of device of audio signal comprises: signal extraction unit, and it extracts the spread signal that is used for generating the auxiliary signal of audio signal and is included in this auxiliary signal from the bit stream that receives; The extension signal length reading unit, it reads the length information of described spread signal; The selectivity decoding unit, it is skipped the decoding of spread signal or is not used decoded results based on this length information; And channel expansion audio mixing unit, it utilizes auxiliary signal to generate audio signal.
For further these and other advantage of realization and according to purpose of the present invention, a kind of device of audio signal comprises: the synchronizing information acquiring unit, and it obtains the position of the auxiliary signal that indication is used for generating audio signal and is included in the synchronizing information of position of the spread signal of this auxiliary signal; The selectivity decoding unit, it is skipped the decoding of spread signal or is not used decoded results based on this synchronizing information; And channel expansion audio mixing unit, it utilizes this auxiliary signal to generate audio signal.
Should be understood that above general description and the following detailed description are exemplary and explanat, and aim to provide the of the present invention further explanation to as claimed in claim.
Embodiments of the present invention
Below will be in detail with reference to better embodiment of the present invention, its concrete exemplary plot is shown in the drawings.
Fig. 1 be audio signal encoding apparatus according to an embodiment of the invention and audio signal decoder block diagram.
With reference to figure 1, code device comprises down-mix unit 10, down-mix audio signal coding unit 20, auxiliary signal coding unit 30, spread signal coding unit 40 and multiplexed unit 50.
At multiple source audio signal X1, X2 ... Xn is imported in the situation of down-mix unit 10, and down-mix unit 10 generates down-mix audio signal by this multi-source signal being carried out the multi-channel audio processing.Down-mix audio signal comprises monophonic signal, stereophonic signal and multiple source audio signal." source " comprises sound channel, and is described to sound channel for convenience's sake.In specification of the present invention, explanation is carried out with reference to monophony or stereo downmix signal.Yet, the invention is not restricted to monophony or stereo downmix signal.Code device can be optionally and the artistic down-mix signal that provides from the outside directly is provided.In the multi-channel audio process, can generate auxiliary signal by multi-channel audio signal, and also can generate spread signal corresponding to additional information.In this case, auxiliary signal can comprise spatial signal information and spread signal.The down-mix audio signal that is generated, auxiliary signal and spread signal by down-mix audio signal coding unit 20, auxiliary signal coding unit 30 and spread signal coding unit 40 codings, are sent to multiplexed unit 50 respectively then.
In the present invention, " spatial information " is meant that code device will be by carrying out multi-channel audio essential, information necessary that is decoding device when down-mix audio signal being carried out channel expansion audio mixing generation multi-channel signal also of institute when handling the down-mix audio signal generated and being transferred to decoding device to multi-channel signal.Spatial information comprises spatial parameter.Spatial parameter comprises CLD (levels of channels is poor), the ICC (inter-channel coherence) that indicates correlation between the sound channel, the CPC (sound channel predictive coefficient) that uses etc. of energy difference between the indication sound channel when generating triple-track by two sound channels.And " spread signal " is meant and carrying out making when the channel expansion audio mixing generates multi-channel signal signal reconstruct to get more near the necessary additional information of primary signal by decoding device to down-mix audio signal.For example, additional information comprises residual signals, artistic downmix residual signal, artistic tree extension signal etc.In this case, residual signals indication is corresponding to the signal of the difference between primary signal and the encoded signal.In the following description, suppose that residual signals comprises general residual signals or is used for the artistic downmix residual signal that artistic down-mix signal compensates.
In the present invention, down-mix audio signal coding unit 20 or down-mix audio signal decoding unit 70 are meant that coding or decoding do not comprise the codec of the audio signal of auxiliary signal.In the present invention, down-mix audio signal is considered as do not comprise an example of the audio signal of auxiliary signal.And down-mix audio signal coding unit 20 or down-mix audio signal decoding unit 70 can comprise MP3, AC-3, DTS or AAC.If to the encoding/decoding audio signal function, then down-mix audio signal coding unit 20 or down-mix audio signal decoding unit 70 can comprise the codec of following exploitation and the codec of having developed in the past.
Multiplexed unit 50 can generate bit stream by multiplexed down-mix audio signal, auxiliary signal and spread signal, then the bit stream that is generated is transferred to decoding device.In this case, down-mix audio signal and auxiliary signal both can be transferred to decoding device with bitstream format.Perhaps, auxiliary signal and down-mix audio signal can be transferred to decoding device with the individual bit stream format respectively.To in Fig. 9 to 11, explain the details of bit stream.
Decoded rather than decoded from beginning from the beginning of random time point as the bit stream that is used to broadcast because of audio signal, so can not use in the situation of header information of previous transmission, just can use another header information that is inserted in the audio signal to come decoded audio signal.Lose during transmitting audio signal in the situation of header information, decoding should be from the random time point of received signal.So header information can be inserted into audio signal at least once.If header information only exists once in the front portion of audio signal,, can not carry out decoding owing to lack header information then for situation at random time point received audio signal.In this case, can introduce header information according to predetermined format (for example, the time interval, space interval etc.).Can insert the identifying information that whether has header information in the indication bit stream.And audio signal can optionally comprise head according to identifying information.For example, auxiliary signal can optionally be introduced head according to header identification information.To in Fig. 9 to 12, explain the details of bit stream structure.
Decoding device comprises demultiplex unit 60, down-mix audio signal decoding unit 70, auxiliary signal decoding unit 80, spread signal decoding unit 90 and channel expansion audio mixing unit 100.
Demultiplex unit 60 receives bit streams, isolates encoded down-mix audio signal, encoded auxiliary signal and encoded spread signal then from the bit stream that is received.70 pairs of encoded down-mix audio signal of down-mix audio signal decoding unit are decoded.And 80 pairs of encoded auxiliary signals of auxiliary signal decoding unit are decoded.
Simultaneously, spread signal can be included in the auxiliary signal.The spread signal of need decoding expeditiously is so that generate multi-channel audio signal expeditiously.So, the spread signal decoding unit 90 encoded spread signal of can optionally decoding.Particularly, encoded spread signal can be decoded, and the decoding of perhaps encoded spread signal can be skipped.Sometimes, if the decoding processing of spread signal is skipped, then encoded signal can be got more near primary signal by reconstruct, and decoding efficiency is improved.
For example, if the rank of decoding device (level) is lower than bit stream, the decoding device spread signal that can not decode and be received then.So the decoding of spread signal can be skipped.Even because of the bit stream that is superior to of decoding device, the decoding of spread signal is available, the decoding of spread signal also can be skipped by another information of obtaining from audio signal.In this case, for example, this another information can comprise the information of the decoding that indicates whether to carry out spread signal.This will explain with reference to Figure 14 in the back in detail.
For example, in order to omit the decoding of spread signal, can from bit stream, read the length information of spread signal, and can utilize this length information to skip the decoding of spread signal.Perhaps, the decoding that can utilize the synchronizing information of position of indication spread signal to skip spread signal.This will explain with reference to figure 2 in the back in detail.
Can define the length information of spread signal by variety of way.For example, can distribute fixed bit, perhaps can distribute variable bit according to the predetermined length information type, perhaps adaptability ground distributes the bit of the length that is suitable for true spread signal when reading the length of spread signal.In Fig. 3 and Fig. 4, explain the details of fixed bits assignment.In Fig. 5 and Fig. 6, explain the details of variable bit.And in Fig. 7 and Fig. 8, explain the details of adaptive bits assignment.
The length information of spread signal can be positioned at ancillary data area.In this case, existence of ancillary data area indication reconstitutes down-mix audio signal in the zone of the required additional information of primary signal.For example, can be with spatial signal information or spread signal a example as auxiliary data.So the length information of spread signal can be arranged in the expansion area of auxiliary signal or auxiliary signal.
Particularly, the length information of spread signal is arranged in the header extension district of auxiliary signal, the frame data expansion area of auxiliary signal or two districts in header extension district and frame data expansion area of auxiliary signal.This will explain with reference to figure 9 to 11 after a while in detail.
Fig. 2 is the schematic block diagram of spread signal decoding unit 90 according to an embodiment of the invention.
With reference to figure 2, spread signal decoding unit 90 comprises extension signal type information acquisition unit 91, extension signal length reading unit 92 and selectivity decoding unit 93.And selectivity decoding unit 93 comprises that rank decoding unit 94, spread signal information acquisition unit 95 and spread signal information skips unit 96.Spread signal decoding unit 90 is exported the spread signal through decoding then from the bit stream of demultiplex unit 60 reception spread signals.Sometimes, spread signal decoding unit 90 may not exported spread signal, maybe can be by to spread signal bit stream zero padding output spread signal intactly.For the situation of not exporting spread signal, can use the method for the decoding of skipping spread signal.Extension signal type acquiring unit 91 obtains the information of the type of indication spread signal from bit stream.For example, the information of the type of indication spread signal can comprise residual signals, artistic downmix residual signal, artistic tree extension signal etc.In the present invention, residual signals is the generic term that general residual signals and being used to compensates the artistic downmix residual signal of artistic down-mix signal.Residual signals can be used for compensating artistic down-mix signal or the compensation of the particular channel in when decoding in the multi-channel audio signal.Randomly, also can use this two kinds of situations.If the type of spread signal is determined that by extension signal type information then extension signal length reading unit 92 reads the length of the spread signal of being determined by the type information of spread signal.No matter whether carry out spread signal decoding this all can realize.In case read the length of spread signal, selectivity decoding unit 93 is just optionally decoded to spread signal.This can be determined by rank determining unit 94.Particularly, rank determining unit 94 selects whether to carry out the decoding of spread signal by the rank of bit stream is compared with the rank of decoding device.For example, if the rank of decoding device is equal to or higher than the rank of bit stream, then decoding device obtains information about spread signal via spread signal information acquisition unit 95, and this information of decoding then is with the output spread signal.The spread signal of being exported is transferred to channel expansion audio mixing unit 100, so that use when reconstruct primary signal or generation audio signal.Yet,, can skip the decoding that spread signal is skipped in unit 96 via spread signal if the rank of decoding device is lower than the rank of bit stream.In this case, can skip the decoding of spread signal based on the length information that reads by extension signal length reading unit 92.Therefore, in using the situation of spread signal, can realize more reconstruct, to improve sound quality near primary signal.If necessary, can reduce the operand of decoding device by the decoding of omitting spread signal.
As an example of the method for skipping the decoding of omitting spread signal in the unit 96 in spread signal information, in the situation of the length information that uses spread signal, the bit of spread signal or byte length information can be inserted in the data.And decoding can be proceeded by skipping with the bit field of the as many spread signal of value that obtains from length information.To explain the method for the length information that limits spread signal with reference to figure 3 to 8.
As another example of the method for the decoding of omitting spread signal, the decoding that can skip spread signal based on the synchronizing information of the position of indication spread signal.For example, can insert synchronization character at the point that spread signal finishes with predetermined bit.Decoding device continues the bit field of search residual signals, up to the synchronization character that finds spread signal.In case find synchronization character, the decoding device process that just stops search is proceeded decoding then.Particularly, can skip the decoding of spread signal up to the synchronization character that finds spread signal.As another example, in the situation of the decoding of carrying out spread signal, can after being done syntactic analysis, spread signal decode according to the method for selecting of decoding.When carrying out the decoding of spread signal, the synchronization character of spread signal can be read but may be unavailable.
Fig. 3 and Fig. 4 are the figure that is used to according to one embodiment of present invention to explain about the fixed bits assignment of the length information of spread signal.
The length information of spread signal can be defined by bit or byte unit.If length information is determined by byte units, is represented that then spread signal has been assigned with byte.Fig. 3 illustrates in the simplest mode and defines method about the length information of spread signal.And, the schematically illustrated method shown in Figure 3 of Fig. 4.Defined the syntactic constituents of the length information that is used to indicate spread signal, and predetermined bit has been distributed to syntactic constituents.For example, " bsResidualSignalLength " is defined as syntactic constituents, and distributes 16 bits as fixed bit.Yet this method may consume quite a large amount of bits.So the method shown in Fig. 5, Fig. 6, Fig. 7 and Fig. 8 is explained as follows.
Fig. 5 and Fig. 6 are used to explain depend on that length type distributes the figure of bit of the length information of spread signal changeably according to one embodiment of present invention.
Fig. 5 is depicted as and defines the method that has how many bits will be used for " bsResidualSignalLength " and define a syntactic constituents more, with further minimizing bit consumption.And the schematically illustrated method shown in Figure 5 of Fig. 6.For example, " bsResidualSignalLengthtype " is newly defined as length type.If the value of " bsResidualSignalLengthtype " is 0, then give " bsResidualSignalLength " with 4 Bit Allocation in Discrete.If the value of " bsResidualSignalLengthtype " is 1, then give " bsResidualSignalLength " with 8 Bit Allocation in Discrete.If the value of " bsResidualSignalLengthtype " is 2, then give " bsResidualSignalLength " with 12 Bit Allocation in Discrete.If the value of " bsResidualSignalLengthtype " is 3, then give " bsResidualSignalLength " with 16 Bit Allocation in Discrete.In this case, the bit that is distributed is exemplary.So, can distribute the bit different with the bit of above definition.In order to reduce bit consumption more, provide the method shown in Fig. 7 and Fig. 8 than above method.
Fig. 7 and Fig. 8 are the figure of bit that is used to explain the length information that distributes spread signal adaptively of the true length that depends on spread signal according to one embodiment of present invention.
If the input spread signal, the length information value that then can read spread signal is up to the initial value of determining.If length information value equals predetermined value, then can additionally read the value of determining up in addition.If length information value equals another predetermined value, then can additionally read the value of determining in addition up to another.In this case, if length information value is not this another predetermined value, then Dui Ying value is in statu quo exported as length information value.Therefore, according to the True Data length adaptability read the length information of spread signal, can farthest reduce bit consumption thus.Example shown in explained later Fig. 7 and Fig. 8.
In Fig. 7, with the example of residual signals as spread signal.If the input residual signals, then the residual signal length of 4 bits is read.If length information value (bsResidualSignalLength) is 2
4-l (=15) then reads the value of 8 bits as bsResidualSignalLengthl again.If length information value (bsResidualSignalLength) is (2
4-l)+(2
8-l) (=15+255), then read the value of 12 bits again as bsResidualSignalLength2.In an identical manner, if length information value (bsResidualSignalLength) is (2
4-l)+(2
8-l)+(2
12-1) (=15+255+4095), then read the value of 16 bits again as bsResidualSignalLength3.
Another example of the adaptive bits assignment of the length information of the schematically illustrated spread signal of Fig. 8.
In Fig. 8, if the input spread signal then preferentially reads 4 bits.If by reading value that length information obtains less than 4 bits, then Dui Ying value becomes length information.Yet, if, read 8 bits in addition again by reading value that length information obtains greater than 4 bits.If the value that reads in addition is less than 8 bits, total read length information value corresponding to 12 (=4+8).Yet, if the value that reads in addition greater than 8 bits, reads 16 bits more in addition.This will be explained as follows in detail.At first, if the input length information then reads 4 bits.The scope of real length information value is 0~14.If length information value becomes 2
4-l (=15) then reads spread signal in addition once more.In this case, can additionally read spread signal up to 2
8-2 (=254).Yet, if length information value is corresponding to less than 2
4The value of-l (=15), value 0~(2 of then reading
4-2) in statu quo export (=14).In case length information value becomes (2
4-l)+(2
8-l), then read spread signal in addition once more.In this case, can additionally read spread signal up to (2
16-1).Yet, if length information value is corresponding to less than 2
16-1 value, value 0~(2 of then reading
16-1) in statu quo export (=14).In this case, as mentioned above, the bit of distribution is the example that is used to explain.So also can distribute other bit different with the bit of above-mentioned definition.
The length information of spread signal can be the length information of extension signal header or the length information of spread signal frame data simultaneously.So the length information of spread signal can be arranged in header area and/or region frame data.To explain the bit stream structure that is used for this with reference to figure 9 to 12.
Fig. 9 and Figure 10 illustrate embodiments of the invention, wherein show the bit stream structure with down-mix audio signal, auxiliary signal and spread signal configuration audio signal.
Audio signal comprises down-mix audio signal and auxiliary signal.As an example of auxiliary signal, can lift spatial signal information is example.Down-mix audio signal and auxiliary signal are the unit transmission separately with the frame.Auxiliary signal can comprise header information and data message, perhaps can only comprise data message.Therefore, in the file/general flow structure of an audio signal of configuration, header information is followed by data message preceding.For example, in the situation of the file/general flow structure that disposes audio signal with down-mix audio signal and auxiliary signal, downmix signal header and ancillary signal header can be used as header information and are present in the front portion.And the configurable frame of down-mix audio signal data and auxiliary signal data is as the data message after the front portion.In this case, by the expansion area of definition auxiliary data, can locate spread signal.Spread signal can be included in the auxiliary signal maybe can be used as independent signal.Fig. 9 illustrates the situation that spread signal is used as independent signal, and Figure 10 illustrates the situation that spread signal is arranged in the expansion area of auxiliary signal.So in having the situation of spread signal, in file/general flow structure, the head of spread signal can be used as header information and is present in the front portion, downmix header and spatial information head are too.Forwardly,, can also comprise extension signal data as data message, and down-mix audio signal data and auxiliary signal data, be used to dispose a frame.Because spread signal can optionally be decoded,, or be present in after the auxiliary signal serially so it can be positioned at the decline of frame.The length information of explaining among Fig. 3 to 8 can be present in the header area of spread signal and/or in the data field of spread signal.In this case, be present in the length information of the length information indication extension signal header in the header area (extension signal header), and be present in the length information of the length information indication extension signal data in the data field (extension signal data).Therefore, read the length information that is present in each district from bit stream, and decoding device can be skipped the decoding of spread signal based on length information.
Figure 11 is the figure that disposes the bit stream structure of independent audio signal according to one embodiment of present invention with down-mix audio signal or auxiliary signal.
Audio signal comprises down-mix audio signal and auxiliary signal.Can adopt the example of spatial signal information as auxiliary signal.Down-mix audio signal and auxiliary signal can be transmitted as independent signal respectively.In this case, down-mix audio signal has such structure: as the downmix signal header (downmix signal header of header information
) be positioned at the front portion, and (the down-mix audio signal data are 1., 2., 3. as the down-mix audio signal data of data message
) after downmix signal header.Equally, auxiliary signal has such structure: as the ancillary signal header (ancillary signal header of header information
) be positioned at the front portion, and (the auxiliary signal data are 1., 2. as the auxiliary signal data of data message
) after ancillary signal header.Because spread signal can be included in the auxiliary signal, so the structure of a kind of spread signal after auxiliary signal can be provided.So, extension signal header
In ancillary signal header
Afterwards, extension signal data 1. the auxiliary signal data 1. after.Equally, extension signal data 2. the auxiliary signal data 2. after.In this case, the length information of spread signal can be included in extension signal header
, extension signal data 1. and/or extension signal data 2. ... and
In each among.
Simultaneously, different with file/general flow structure, because be can not use the situation of previous transmission header information, can use another header information that is included in the audio signal to decode from random time point decoded audio signal rather than from beginning to decode.Audio signal that is used for broadcasting etc. in use or the situation of having lost header information during transmitting audio signal, decoding should be from any moment of received signal.So, can indicate whether to exist the identifying information of head to improve decoding efficiency by definition.Explain the flow structure that is used to broadcast below with reference to Figure 12.
Figure 12 is the figure that disposes the broadcasting flow structure of audio signal according to one embodiment of present invention with down-mix audio signal and auxiliary signal.
In the situation of broadcasting stream, if header information only exists once in the front portion of audio signal, then put at any time in the situation of received audio signal, can not carry out decoding owing to lack header information.So, header information can be inserted audio signal at least once.In this case, can introduce header information according to predetermined format (for example, the time interval, space interval etc.).Particularly, header information can be inserted in each frame, periodically insert in each frame with fixed intervals, or to insert in each frame to the compartment aperiodicity at random.Perhaps, can insert header information once according to Fixed Time Interval (for example, 2 seconds).
The broadcasting flow structure of an audio signal of configuration has such structure: header information is inserted into once between data message at least.For example, in the situation of the broadcasting flow structure that disposes an audio signal, down-mix audio signal is preceding, and auxiliary signal is after this down-mix audio signal.The synchronizing information that is used to distinguish down-mix audio signal and auxiliary signal can be positioned at the front portion of auxiliary signal.And, can locate the identifying information whether (locate) indication exists about the header information of auxiliary signal.For example, if header identification information is 0, the then next frame that reads only has Frame and does not have header information.If header identification information is 1, the then next frame that reads has header information and Frame.This is applicable to auxiliary signal or spread signal.These header informations can be identical with the header information that has been transmitted at first maybe can be variable.In the variable situation of header information, new header information is decoded, so and after new header information the transmission data message according to through the decoding new header information decode.In header identification information was 0 situation, the frame of transmission only had Frame and does not have header information.In this case, for process frames of data, can use the header information of previous transmission.For example, if header identification information is 1 in Figure 12, then can exist ancillary signal header 1. with extension signal header 1..Yet if because header identification information is set to 0, the frame of next input does not have header information, can use the extension signal header information 1. of previous transmission to handle extension signal data 3..
Figure 13 is according to one embodiment of present invention in the situation that audio signal is used for broadcasting etc., and the identifying information that whether is included in the auxiliary signal of head handles based on the length information of spread signal the flow chart of the method for spread signal as indicated.
With reference to Figure 13, from the bit stream that is received, extract the spread signal (1301) that is used for generating the auxiliary signal of audio signal and is included in this auxiliary signal.Spread signal can be included in the auxiliary signal.Whether extraction indication head is included in the identifying information (1303) in the auxiliary signal.For example, if header identification information is 1, then its indication ancillary signal header is included in the auxiliary signal.If header identification information is 0, then its indication ancillary signal header is not included in the auxiliary signal.In spread signal was included in situation in the auxiliary signal, if header identification information is 1, then its indication extension signal header was included in the spread signal.If header identification information is 0, then its indication extension signal header is not included in the spread signal.Judge according to header identification information whether head is included in (1305) in the auxiliary signal.If head is included in the auxiliary signal, then extract length information (1307) from the head.And, the decoding (1309) that can skip spread signal based on length information.In this case, head acts in that each auxiliary signal and/or each spread signal are being brought into play in obtaining explaining.For example, header information can comprise the number, tree configuration information, quantitative mode information, ICC (level difference between sound channel), parameter smoothing information, the gain information that prevents to cut out (clip-prevention), the QMF (quadrature mirror filter) that is associated with information of information about residual signals, the synchronizing information about the position of the information of the length of residual signals, indication residual signals, sample frequency, frame length, parameter band etc.In addition, if according to header identification information, head is not included in the auxiliary signal, then can skip the decoding (1311) of spread signal based on the length information about head of previous extraction.
Figure 14 is according to one embodiment of present invention based on optionally the decode flow chart of method of spread signal of the length information of spread signal.
Profile (profile) means that the algorithmic technique key element in the decode procedure is standardized.Particularly, profile is the necessary one group of technology essential factor of decoding bit stream, and corresponding to a class substandard.Rank (level) limits the scope of the technology essential factor of stipulating in the profile of being supported.Particularly, rank acts on bringing into play aspect the complexity of ability that limits decoding device and bit stream.In the present invention, class information can comprise profile and other definition of level.The coding/decoding method of spread signal can change according to the class information of bit stream and the class information of decoding device.For example, even in the audio signal of transmission, have spread signal,, can carry out or can not carry out the decoding of spread signal as the decision level result of information.In addition, although carry out decoding, can only use predetermined low frequency part.In addition, in the decoding of spread signal, can skip the nearly length information of spread signal, so that do not carry out the decoding of spread signal.Perhaps, although spread signal is read fully, can not carry out decoding.In addition, read a part of spread signal, only reading section is decoded, and can not the remainder of spread signal be carried out.Perhaps, spread signal can be read fully, a part of spread signal of decoding, and all the other spread signals of not decoding.
For example, with reference to Figure 14, from the bit stream that is received, extract the spread signal (1410) that is used for generating the auxiliary signal of audio signal and is included in this auxiliary signal.And, can extract information about spread signal.The extension data type information that can comprise in this case, the data type of indicating spread signal about the information of spread signal.For example, extension data type information comprises residual error decoding data, artistic down-mix residual error decoding data, artistic tree growth data etc.So, judge the type of spread signal, and can read the length information (1420) of spread signal from the expansion area of audio signal.Subsequently, the rank of decision bit stream.This can judge with reference to following information.For example, if the type of spread signal is the residual error decoding data, then the class information of bit stream can comprise the bandwidth of output channels number, sample rate, residual signals etc.So, if the class information of above explanation is transfused to, then they with compare about the class information of decoding device to judge that whether spread signal is with decoded (1430).In this case, the rank of decoding device can preestablish.Generally speaking, the rank of decoding device should be equal to or greater than audio signal.This be because, decoding device should intactly decode the transmission audio signal.Yet in the situation that decoding device is limited (for example, in the situation of rank less than audio signal of decoding device), decoding is possible sometimes.Yet corresponding quality may deterioration.For example, if the rank of decoding device is lower than audio signal, then decoding device can not decoded audio signal.Yet in some cases, audio signal can be based on the rank of decoding device and is decoded.
Be lower than in other situation of level of bit stream the decoding (1440) that can skip spread signal based on the length information of spread signal in the rank of judging decoding device.On the other hand, be equal to or higher than in other situation of level of bit stream, can carry out the decoding (1460) of spread signal in the rank of decoding device.Yet although the decoding of spread signal is performed, decoding also can only be carried out (1450) on the predetermined low frequency part of spread signal.For example, have such situation: because decoding device is low power decoder, if spread signal by complete decoding, efficient will demote, perhaps, owing to the decoding device whole extend information of can not decoding, can use the predetermined low frequency part of spread signal.And only when the rank of the rank of bit stream or decoding device satisfied specified requirements, this was possible.
Industrial applicibility
Therefore, the various environment of Code And Decode signal may ubiquities, and can have the whole bag of tricks according to various environmental condition processing signals.In the present invention, as an example, this can not limit the scope of the invention with the method for audio signal.In this case, signal comprises audio signal and/or vision signal.Can make various modifications and variations and not break away from the spirit or scope of the present invention the present invention although described with reference to preferred embodiment of the present invention and illustrated that the present invention, those skilled in that art are appreciated that.Therefore, the present invention is intended to contain the interior all such modifications of the present invention and the variation of scope of appended claims and equivalent technique scheme thereof.
Claims (7)
1. the method for an audio signal, it may further comprise the steps:
Receive bit stream;
From the bitstream extraction down-mix audio signal that is received, auxiliary signal and spread signal, described down-mix audio signal is handled generation by multi-channel audio signal being carried out multi-channel audio, described spread signal is included in the expansion area of described auxiliary signal, and described auxiliary signal comprises header extension district and frame expansion area;
Obtain the length information of described spread signal respectively from described header extension district and described frame expansion area;
Based on the length information that obtains from described header extension district, skip the decoding that is included in the described spread signal in the described header extension district;
Based on the length information that obtains from described frame expansion area, skip the decoding that is included in the described spread signal in the described frame expansion area; And
Generate described multi-channel audio signal by using described auxiliary signal to described down-mix audio signal.
2. the method for audio signal as claimed in claim 1, it is characterized in that, the auxiliary signal that does not comprise described spread signal comprises the spatial parameter that is used to generate described multi-channel audio signal, and it is poor that described spatial parameter comprises the levels of channels of energy difference between the expression sound channel, the inter-channel coherence of expression inter-channel coherence and the sound channel predictive coefficient information of using when generating triple-track by two sound channels.
3. the method for audio signal as claimed in claim 1 is characterized in that, described spread signal comprises residual signals.
4. the method for audio signal as claimed in claim 1 is characterized in that, to the length information distribution fixed bit of described spread signal.
5. the method for audio signal as claimed in claim 1 is characterized in that, according to the length type information of described spread signal, can change the ground allocation bit to the length information of described spread signal.
6. the method for audio signal as claimed in claim 1 is characterized in that, according to the length of described spread signal, to the length information of described spread signal allocation bit adaptively.
7. the device of an audio signal, it comprises:
Demultiplex unit, it receives bit stream, from the bitstream extraction down-mix audio signal that is received, auxiliary signal and spread signal, described down-mix audio signal is handled generation by multi-channel audio signal being carried out multi-channel audio, described spread signal is included in the expansion area of described auxiliary signal, and described auxiliary signal comprises header extension district and frame expansion area;
The down-mix audio signal decoding unit of the described down-mix audio signal of decoding;
The auxiliary signal decoding unit of the described auxiliary signal of decoding;
The spread signal decoding unit; And
Channel expansion audio mixing unit, it generates described multi-channel audio signal by using described auxiliary signal to described down-mix audio signal,
Wherein said spread signal decoding unit comprises:
The extension signal length reading unit, it obtains the length information of described spread signal respectively from described header extension district and frame expansion area; And
The selectivity decoding unit, it is based on the length information that obtains from described header extension district, skip the decoding that is included in the described spread signal in the described header extension district, and, skip the decoding that is included in the described spread signal in the described frame expansion area based on the length information that obtains from described frame expansion area.
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