CN102104776A - Network television platform moving pictures experts group (MPEG) audio multi-phase synthesis filtering method - Google Patents
Network television platform moving pictures experts group (MPEG) audio multi-phase synthesis filtering method Download PDFInfo
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- CN102104776A CN102104776A CN2009101891163A CN200910189116A CN102104776A CN 102104776 A CN102104776 A CN 102104776A CN 2009101891163 A CN2009101891163 A CN 2009101891163A CN 200910189116 A CN200910189116 A CN 200910189116A CN 102104776 A CN102104776 A CN 102104776A
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- 230000015572 biosynthetic process Effects 0.000 title abstract 3
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Abstract
The invention relates to a network television platform moving pictures experts group (MPEG) audio multi-phase synthesis filtering method, which is used for converting frequency domain signals of network television platform MPEG audio into time domain signals for output. The method comprises the step of: performing discrete cosine transform on N floating points of an input sequence of the MPEG audio to obtain 2N values of an output sequence, wherein the step further comprises the following steps of: 1) acquiring discrete cosine transform (DCT)-II values of the N points; 2) obtaining DCT values of the N points by utilizing the periodicity and symmetry of a cosine function; and 3) outputting the DCT values of the N points as the 2N values of the output sequence. By the network television platform MPEG audio multi-phase synthesis filtering method, the frequency domain signals can be rapidly converted into the time domain signals for output; and compared with the conventional method, the invention has the advantages that: floating point multiplication operations are reduced, the decoding efficiency is high and the execution efficiency of an MPEG technology is remarkably improved.
Description
Technical field
The present invention relates to embedded platform Web TV and field of set-top, more particularly, relate to the heterogeneous synthetic filtering method of a kind of Web TV platform mpeg audio.
Background technology
In such as multimedia IT product such as Web TV, MP3 player or set-top box, the audio/video encoding/decoding technology be these products soul, good audio/video encoding/decoding technology can be brought more perfect audiovisual experience to the consumer with the cost of minimum.Wherein, be an encoding and decoding technique of present extensive use in audio area MPEG (Moving Pictures ExpertsGroup, dynamic image expert group) technology.The final step of mpeg audio decoding is heterogeneous synthetic filtering, its objective is frequency-region signal is converted into time-domain signal output.This step need be carried out a large amount of floating-point multiplications, comprises N floating number of the list entries of mpeg audio carried out the step of discrete cosine transform with 2N value obtaining output sequence.
Yet above-mentioned steps is the principles illustrated realization in conjunction with the heterogeneous synthetic filtering of ISO/IEC11172-3 at present, does not pass through any optimization, floating-point multiplication number of times height, and decoding efficiency is low.
Summary of the invention
The technical problem to be solved in the present invention is, at the above-mentioned operation times height of existing heterogeneous synthetic filtering method and the low defective of decoding efficiency provides a kind of Web TV platform mpeg audio heterogeneous synthetic filtering method.
The technical solution adopted for the present invention to solve the technical problems is: construct the heterogeneous synthetic filtering method of a kind of Web TV platform mpeg audio, with 2N the value that obtains output sequence frequency-region signal is converted into time-domain signal and exports thereby can be apace N floating number of the list entries of mpeg audio be carried out discrete cosine transform.
The invention provides the heterogeneous synthetic filtering method of a kind of Web TV platform mpeg audio, be used for the frequency-region signal of Web TV platform mpeg audio is converted to time-domain signal output, comprise N floating number of the list entries of mpeg audio carried out the step of discrete cosine transform with 2N value obtaining output sequence, wherein, above-mentioned steps further may further comprise the steps:
S1) obtain N the DCT-II value of putting;
S2) utilize the periodicity of cosine function and the DCT value that symmetry is obtained this N point;
S3) the DCT value of above-mentioned N point is exported as 2N value of output sequence.
In the heterogeneous synthetic filtering method of Web TV platform mpeg audio of the present invention, described step S1) further may further comprise the steps:
S11) obtain N/2 the DCT-II value of putting;
S12) by the DCT-II value of above-mentioned N/2 point obtain N put in the DCT-II value of even number corner;
S13) by the DCT-II value of above-mentioned N/2 point obtain N put in the DCT-II value of odd number corner.
In the heterogeneous synthetic filtering method of Web TV platform mpeg audio of the present invention, described step S11) further may further comprise the steps:
S111) N/2 some DCT-II value is decomposed into N/4 point, obtains the DCT-II value of N/2 point;
S112) decomposable process repeating step S111) is 2 until N.
In the heterogeneous synthetic filtering method of Web TV platform mpeg audio of the present invention, described N is 32.
The present invention also provides a kind of Web TV platform mpeg audio heterogeneous synthetic filtering method, be used for the frequency-region signal of Web TV platform mpeg audio is converted to time-domain signal output, comprise 32 floating numbers of the list entries of mpeg audio are carried out the step of discrete cosine transform with 64 values obtaining output sequence, wherein, above-mentioned steps further may further comprise the steps:
S1) obtain the DCT-II value of 32 points;
S2) utilize the periodicity of cosine function and the DCT value that symmetry is obtained these 32 points;
S3) the DCT value of above-mentioned 32 points is exported as 64 values of output sequence.
In the heterogeneous synthetic filtering method of Web TV platform mpeg audio of the present invention, described step S1) further may further comprise the steps:
S11) obtain the DCT-II value of 16 points;
S12) obtain the DCT-II value of even number corner in 32 points by the DCT-II value of above-mentioned 16 points;
S13) obtain the DCT-II value of odd number corner in 32 points by the DCT-II value of above-mentioned 16 points.
In the heterogeneous synthetic filtering method of Web TV platform mpeg audio of the present invention, described step S11) further may further comprise the steps:
S111) the DCT-II value with 16 points is decomposed into 8 points, obtains the DCT-II value of 16 points;
S112) decomposable process repeating step S111) is until being decomposed into 2 points.
Implement the heterogeneous synthetic filtering method of Web TV platform mpeg audio of the present invention, have following beneficial effect: the present invention can be converted into frequency-region signal time-domain signal output apace, compare its floating-point multiplication number of times reduces with existing method, the decoding efficiency height has obviously improved the execution efficient of MPEG technology.
Description of drawings
The invention will be further described below in conjunction with drawings and Examples, in the accompanying drawing:
Fig. 1 is the flow chart of the heterogeneous synthetic filtering method of Web TV platform mpeg audio in the preferred embodiment of the present invention;
Fig. 2 is the particular flow sheet of the heterogeneous synthetic filtering method of Web TV platform mpeg audio in the preferred embodiment of the present invention.
Embodiment
In order to make purpose of the present invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with drawings and Examples.
The heterogeneous synthetic filtering method of Web TV platform mpeg audio provided by the invention is used for the frequency-region signal of Web TV platform mpeg audio is converted to time-domain signal output.This method comprises carries out the step of discrete cosine transform with 2N value of acquisition output sequence with N floating number of the list entries of mpeg audio.Wherein, N is a positive integer.In existing application, N is 32, and 32 floating numbers that are about to the list entries of mpeg audio are carried out discrete cosine transform to obtain 64 values of output sequence.
See also Fig. 1, be the flow chart of the heterogeneous synthetic filtering method of Web TV platform mpeg audio in the preferred embodiment of the present invention.As shown in Figure 1, in the method for the present invention N floating number of the list entries of mpeg audio being carried out discrete cosine transform further may further comprise the steps with the step of 2N value obtaining output sequence:
At first in step S1, obtain the DCT-II value of N point;
In step S2, utilize the periodicity of cosine function and DCT (Discrete Cosine Transform, the discrete cosine transform) value that symmetry is obtained this N point subsequently;
In step S3, N the DCT value of putting of above-mentioned acquisition exported as 2N value of output sequence at last.
See also Fig. 2, be the particular flow sheet of the heterogeneous synthetic filtering method of Web TV platform mpeg audio in the preferred embodiment of the present invention.Be that step S 1 further may further comprise the steps among Fig. 1:
At first in step S11, obtain the DCT-II value of N/2 point earlier;
In step S12, obtain the DCT-II value of even number corner in N the point by the DCT-II value of above-mentioned N/2 point subsequently;
In step S13, obtain the DCT-II value of odd number corner in N the point by the DCT-II value of above-mentioned N/2 point at last.
And above-mentioned steps S11 obtains the step of DCT-II value of N/2 point and further may further comprise the steps:
In step S111, N/2 some DCT-II value is decomposed into N/4 point, obtains the DCT-II value of N/2 point;
Again the DCT-II value of N/4 point is decomposed into N/8 point subsequently, so recursively goes on, constantly repeat this decomposable process, until being 2 until N.
Below the heterogeneous synthetic filtering method of Web TV platform mpeg audio of the present invention is analyzed.
At first, in the heterogeneous synthetic filtering method of existing Web TV platform mpeg audio, be to realize 32 floating numbers of the list entries of mpeg audio are carried out discrete cosine transform with 64 values obtaining output sequence in conjunction with ISO/IEC11172-3.The algorithm that provides according to ISO/IEC 11172-3 ANNEX-A Figure3-A.3 (being designated hereinafter simply as standard), through 5 steps with list entries X[0..31] 32 floating numbers be transformed to 32 PCM sample values outputs.Below be 5 steps that provide in the standard:
①Shift?64?to?1024?FIFO
for?i＝64?to?1023
V[i]＝V[i-64]
②Calculate?64?values?V[i]by?matrixing
for?i＝0?to?63
for?k＝0?to?31
V[i]+＝C[i][k]*X[k]
C[i wherein] [k]=cos[(16+i) (2k+1) π/64]
③Building?a?512?values?vector?U
for?i＝0?to?7
for?j＝0?to?31
U[64*i+j]+＝V[128*i+j]
U[64*i+32+j]+＝V[128*i+96+j]
④Multiply?U?vector?by?D?window
for?j＝0?to?511
W[i]＝U[i]*D[i]
D[i wherein] see ISO/IEC 11172-3, Table 3-B.3.
⑤Calculating?32?Samples
for?i＝0?to?31
Si＝0
for?j＝0?to?15
Si+＝W[i+32*j]
//Output?PCM?Sample：PCMi＝Si*32768
In the algorithm that in standard, provides, the 2. the step be DCT (32 → 64) computing, with 32 value X[k of list entries] be transformed to 64 value V[i of output sequence], common 64*32=2648 the floating-point multiplication of direct computing.Method provided by the invention is carried out at execution efficient how to improve this step.Mainly be divided into following three phases.
Being decomposed into step S1, step S2 and step S3 in the phase I, is to utilize 32 DCT-II to replace DCT (32 → 64).
Because cosine function has periodically and symmetry, so DCT has periodically, at first obtain 32 values of output sequence by DCT (32 → 32), can directly obtain 64 output valves of DCT (32 → 64) by these 32 values, concrete grammar is as follows:
//in[32]，out[64]
for(i＝0；i＜16；i++)
out[i]＝in[i+16]；
out[16]＝0；
for(i＝17；i＜48；i++)
out[i]＝-in[48-i]；
for(i＝48；i＜64；i++)
out[i]＝-in[i-48]；
The DCT here (32 → 32) is 32 DCT-II types.
In second stage, above-mentioned steps S1 is obtained the DCT-II value of N point and further decompose, and utilization is decomposed into N/2 point DCT-II sum with N point DCT-II value and realizes.
With V[i] sequence is divided into even number item (V[2i]) and odd term (V[2i+1]).V[i] output sequence of the DCT-II that can be ordered by N/2 of the even number item of sequence directly obtains; An element in the DCT-IV output sequence can continuous element sum be represented with two in the DCT-II output sequence.Being V[i] odd term of sequence obtains indirectly by the output sequence of the DCT-II that N/2 is ordered.
In the phase III, continue N/2 point DCT-II is decomposed into two N/4 point DCT-II again, and above-mentioned derivation is recursively gone on, up to N=2.Thus, it is as follows to obtain the multiplication number of times of each point DCT-II:
N=2 1 time
N=4 2+2 * 1=4 time
N=8 4+2 * 4=12 time
N=16 8+2 * 12=32 time
N=32 16+2 * 32=80 time
This shows that the present invention can be converted into frequency-region signal time-domain signal output apace, compare its floating-point multiplication number of times with existing method and reduce that the decoding efficiency height has obviously improved the execution efficient of MPEG technology.
The present invention is described according to specific embodiment, but it will be understood by those skilled in the art that when not breaking away from the scope of the invention, can carry out various variations and be equal to replacement.In addition, for adapting to the specific occasion or the material of the technology of the present invention, can carry out many modifications and not break away from its protection range the present invention.Therefore, the present invention is not limited to specific embodiment disclosed herein, and comprises that all drop into the embodiment of claim protection range.
Claims (7)
1. heterogeneous synthetic filtering method of Web TV platform mpeg audio, be used for the frequency-region signal of Web TV platform mpeg audio is converted to time-domain signal output, comprise N floating number of the list entries of mpeg audio carried out the step of discrete cosine transform with 2N value obtaining output sequence, it is characterized in that above-mentioned steps further may further comprise the steps:
S1) obtain N the DCT-II value of putting;
S2) utilize the periodicity of cosine function and the DCT value that symmetry is obtained this N point;
S3) the DCT value of above-mentioned N point is exported as 2N value of output sequence.
2. the heterogeneous synthetic filtering method of Web TV platform mpeg audio according to claim 1 is characterized in that described step S1) further may further comprise the steps:
S11) obtain N/2 the DCT-II value of putting;
S12) by the DCT-II value of above-mentioned N/2 point obtain N put in the DCT-II value of even number corner;
S13) by the DCT-II value of above-mentioned N/2 point obtain N put in the DCT-II value of odd number corner.
3. the heterogeneous synthetic filtering method of Web TV platform mpeg audio according to claim 2 is characterized in that described step S11) further may further comprise the steps:
S111) N/2 some DCT-II value is decomposed into N/4 point, obtains the DCT-II value of N/2 point;
S112) decomposable process repeating step S111) is 2 until N.
4. according to any heterogeneous synthetic filtering method of described Web TV platform mpeg audio in the claim 1 to 3, it is characterized in that described N is 32.
5. heterogeneous synthetic filtering method of Web TV platform mpeg audio, be used for the frequency-region signal of Web TV platform mpeg audio is converted to time-domain signal output, comprise 32 floating numbers of the list entries of mpeg audio are carried out the step of discrete cosine transform with 64 values obtaining output sequence, it is characterized in that above-mentioned steps further may further comprise the steps:
S1) obtain the DCT-II value of 32 points;
S2) utilize the periodicity of cosine function and the DCT value that symmetry is obtained these 32 points;
S3) the DCT value of above-mentioned 32 points is exported as 64 values of output sequence.
6. the heterogeneous synthetic filtering method of Web TV platform mpeg audio according to claim 5 is characterized in that described step S1) further may further comprise the steps:
S11) obtain the DCT-II value of 16 points;
S12) obtain the DCT-II value of even number corner in 32 points by the DCT-II value of above-mentioned 16 points;
S13) obtain the DCT-II value of odd number corner in 32 points by the DCT-II value of above-mentioned 16 points.
7. the heterogeneous synthetic filtering method of Web TV platform mpeg audio according to claim 6 is characterized in that described step S11) further may further comprise the steps:
S111) the DCT-II value with 16 points is decomposed into 8 points, obtains the DCT-II value of 16 points;
S112) decomposable process repeating step S111) is until being decomposed into 2 points.
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| CN101025919A (en) * | 2006-02-22 | 2007-08-29 | 上海奇码数字信息有限公司 | Synthetic sub-band filtering method for audio decoding and synthetic sub-band filter |
| WO2009039451A2 (en) * | 2007-09-19 | 2009-03-26 | Qualcomm Incorporated | Efficient design of mdct / imdct filterbanks for speech and audio coding applications |
| WO2009076666A1 (en) * | 2007-12-13 | 2009-06-18 | Qualcomm Incorporated | Fast algorithms for computation of 5-point dct-ii, dct-iv, and dst-iv, and architectures |
| CN101546560A (en) * | 2008-03-28 | 2009-09-30 | 展讯通信（上海）有限公司 | Audio coding and decoding device and coding and decoding method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101025919A (en) * | 2006-02-22 | 2007-08-29 | 上海奇码数字信息有限公司 | Synthetic sub-band filtering method for audio decoding and synthetic sub-band filter |
| WO2009039451A2 (en) * | 2007-09-19 | 2009-03-26 | Qualcomm Incorporated | Efficient design of mdct / imdct filterbanks for speech and audio coding applications |
| WO2009076666A1 (en) * | 2007-12-13 | 2009-06-18 | Qualcomm Incorporated | Fast algorithms for computation of 5-point dct-ii, dct-iv, and dst-iv, and architectures |
| CN101546560A (en) * | 2008-03-28 | 2009-09-30 | 展讯通信（上海）有限公司 | Audio coding and decoding device and coding and decoding method |
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Application publication date: 20110622 |