[FFmpeg-devel] [PATCH] QCELP decoder

Kenan Gillet kenan.gillet
Tue Nov 25 22:17:04 CET 2008


On Nov 22, 2008, at 2:22 PM, Michael Niedermayer wrote:

> On Fri, Nov 21, 2008 at 09:46:05AM -0800, Kenan Gillet wrote:
>>
>> On Nov 21, 2008, at 3:26 AM, Michael Niedermayer wrote:
>>
>>> On Thu, Nov 20, 2008 at 05:51:22PM -0800, Kenan Gillet wrote:
>>>> Hi,
>>>> On Nov 20, 2008, at 5:08 PM, Michael Niedermayer wrote:
>>>>
>>>>>>>
>>>>>>>
>>>>>>> [...]
>>>>>>>> +/**
>>>>>>>> + * Computes the Pa or Qa coefficients needed for LSP to LPC
>>>>>>>> conversion.
>>>>>>>> + * We only need to calculate the 6 first elements of the
>>>>>>>> polynomial.
>>>>>>>> + *
>>>>>>>> + * @param lspf line spectral pair frequencies
>>>>>>>> + * @param v_poly polynomial input/output as a vector
>>>>>>>> + *
>>>>>>>> + * TIA/EIA/IS-733 2.4.3.3.5-1/2
>>>>>>>> + */
>>>>>>>> +static void lsp2poly(const float *lspf,
>>>>>>>> +                     float *v_poly) {
>>>>>>>> +    float val, *v;
>>>>>>>> +    int   i;
>>>>>>>> +
>>>>>>>> +    // optimization to simplify calculation in loop
>>>>>>>> +    v_poly++;
>>>>>>>> +
>>>>>>>> +    for (i = 0; i < 10; i += 2) {
>>>>>>>> +        val = -2 * cos(M_PI * *lspf);
>>>>>>>> +        lspf += 2;
>>>>>>>> +        v = v_poly + FFMIN(4, i);
>>>>>>>> +
>>>>>>>> +        if (i < 4) {
>>>>>>>> +            v[2] = v[0];
>>>>>>>> +            v[1] = v[0] * val + v[-1];
>>>>>>>> +        }
>>>>>>>> +        for ( ; v > v_poly; v--)
>>>>>>>> +            v[0] = v[0]
>>>>>>>> +                 + v[-1] * val
>>>>>>>> +                 + v[-2];
>>>>>>>> +        v[0] += v[-1] * val;
>>>>>>>> +    }
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +/**
>>>>>>>> + * Reconstructs LPC coefficients from the line spectral pair
>>>>>>>> frequencies
>>>>>>>> + * and performs bandwidth expansion.
>>>>>>>> + *
>>>>>>>> + * @param lspf line spectral pair frequencies
>>>>>>>> + * @param lpc linear predictive coding coefficients
>>>>>>>> + *
>>>>>>>> + * @note: bandwith_expansion_coeff could be precalculated  
>>>>>>>> into a
>>>>>>>> table
>>>>>>>> + *        but it seems to be slower on x86
>>>>>>>> + *
>>>>>>>> + * TIA/EIA/IS-733 2.4.3.3.5
>>>>>>>> + */
>>>>>>>> +void qcelp_lspf2lpc(const float *lspf,
>>>>>>>> +                    float *lpc) {
>>>>>>>> +    float pa[6], qa[6];
>>>>>>>> +    int   i;
>>>>>>>> +    float bandwith_expansion_coeff = -
>>>>>>>> QCELP_BANDWITH_EXPANSION_COEFF;
>>>>>>>> +
>>>>>>>
>>>>>>>> +    pa[0] = 0.5;
>>>>>>>> +    pa[1] = 0.5;
>>>>>>>> +    lsp2poly(lspf, pa);
>>>>>>>> +
>>>>>>>> +    qa[0] = 0.5;
>>>>>>>> +    qa[1] = -0.5;
>>>>>>>> +    lsp2poly(lspf + 1, qa);
>>>>>>>
>>>>>>> it should be faster to deal with 0.5 + 0.5x / 0.5 - 0.5x after
>>>>>>> building
>>>>>>> the polynomials
>>>>>>
>>>>>> done
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> anyway, see ff_acelp_lsp2lpc
>>>>>>
>>>>>> done, it is globally ~10% faster.
>>>>>>
>>>>>> but it gives some significant difference in the WAV output.
>>>>>> I doule check, and it seems to come from the float rounding :(
>>>>>> here is the list of result of 'tiny_psnr old.wav new.wav'.
>>>>>
>>>>> what happens with double instead of float?
>>>>
>>>> with keeping the signature of qcelp_lspf2lpc(float *, float *)
>>>> and changing all the calculation into double for
>>>> the code before and after optimization:
>>>
>>> hmm
>>>       old vs. new
>>> float    ~3  -5 stddev
>>> double   ~0.5-1 stddev
>>>
>>> it seems this code is rather sensitive to rounding
>>>
>>> how do the differences look for
>>>       float vs. double
>>> new
>>> old
>>>
>>> ?
>>
>> 101.mov: audio mismatchs from previous build
>>     stddev:    0.02 PSNR: 78.92 bytes:   250284/   250284
>>
>> V6_text.mov: audio mismatchs from previous build
>>     stddev:    0.50 PSNR: 54.00 bytes: 11371244/ 11371244
>>
>> blue_earth.mov: audio mismatchs from previous build
>>     stddev:    0.40 PSNR: 55.92 bytes: 19681324/ 19681324
>>
>> codeblue-interrupt01.mov: audio mismatchs from previous build
>>     stddev:    0.02 PSNR: 79.21 bytes:   276524/   276524
>>
>> codeblue-interrupt06.mov: audio mismatchs from previous build
>>     stddev:    0.31 PSNR: 58.03 bytes:   642924/   642924
>>
>> codeblue-plot08motor.mov: audio mismatchs from previous build
>>     stddev:    0.29 PSNR: 58.81 bytes:  1534764/  1534764
>>
>> h263.mov: audio mismatchs from previous build
>>     stddev:    0.46 PSNR: 54.85 bytes: 13511404/ 13511404
>>
>> h263.trashed.mov: audio mismatchs from previous build
>>     stddev:    0.46 PSNR: 54.85 bytes: 13511404/ 13511404
>>
>> installfect_export.mov: audio mismatchs from previous build
>>     stddev:    1.19 PSNR: 46.60 bytes: 10448044/ 10448044
>>
>> oldepisode.mov: audio mismatchs from previous build
>>     stddev:    1.09 PSNR: 47.35 bytes:  4588844/  4588844
>>
>> schlangenmannliten.mov: audio mismatchs from previous build
>>     stddev:    0.28 PSNR: 59.01 bytes:  8820844/  8820844
>>
>> surge-1-16-B-Qclp.mov: audio mismatchs from previous build
>>     stddev:    1.52 PSNR: 44.48 bytes:  1156524/  1156524
>>
>> 8fe3b9dcd6d7e6db3375521c5c1b_Video_041606_002.3g2: audio mismatchs
>> from previous build
>>     stddev:    0.02 PSNR: 78.98 bytes:   721004/   721004
>>
>> Test3gpp-mp4a.3g2: audio mismatchs from previous build
>>     stddev:    0.01 PSNR: 90.74 bytes:   219244/   219244
>>
>> c8wwz2m0.3g2: audio mismatchs from previous build
>>     stddev:    0.00 PSNR: 91.54 bytes:   241964/   241964
>>
>> qtaudio-qcelp-problem.3g2: audio mismatchs from previous build
>>     stddev:    0.02 PSNR: 80.33 bytes:   208044/   208044
>>
>> test.3g2: audio same as previous build
>>
>> tube.3g2: audio mismatchs from previous build
>>     stddev:    0.00 PSNR: 98.65 bytes:   113004/   113004
>>
>> zg3dx2d6.3g2: audio mismatchs from previous build
>>     stddev:    0.36 PSNR: 56.84 bytes:   486444/   486444
>>
>> vidoo_MP4_audio_Qcelp13k.k3g: audio mismatchs from previous build
>>     stddev:    0.41 PSNR: 55.68 bytes:   743724/   743724
>
> well, what i meant was a comparission between
> old float and old double and a second
> comparission between new float and new double
>
> you posted just one so i really dont know what these compare ...
>


sorry for the delay,

old float vs old double:

101.mov: audio mismatchs from previous build
     stddev:    2.10 PSNR: 41.65 bytes:   250284/   250284

V6_text.mov: audio mismatchs from previous build
     stddev:    2.54 PSNR: 40.00 bytes: 11371244/ 11371244

blue_earth.mov: audio mismatchs from previous build
     stddev:    1.86 PSNR: 42.73 bytes: 19681324/ 19681324

codeblue-interrupt01.mov: audio mismatchs from previous build
     stddev:    2.52 PSNR: 40.08 bytes:   276524/   276524

codeblue-interrupt06.mov: audio mismatchs from previous build
     stddev:    1.88 PSNR: 42.61 bytes:   642924/   642924

codeblue-plot08motor.mov: audio mismatchs from previous build
     stddev:    2.05 PSNR: 41.88 bytes:  1534764/  1534764

h263.mov: audio mismatchs from previous build
     stddev:    2.00 PSNR: 42.07 bytes: 13511404/ 13511404

h263.trashed.mov: audio mismatchs from previous build
     stddev:    2.00 PSNR: 42.07 bytes: 13511404/ 13511404

installfect_export.mov: audio mismatchs from previous build
     stddev:    3.80 PSNR: 36.51 bytes: 10448044/ 10448044

oldepisode.mov: audio mismatchs from previous build
     stddev:    5.06 PSNR: 34.02 bytes:  4588844/  4588844

schlangenmannliten.mov: audio mismatchs from previous build
     stddev:    1.60 PSNR: 44.00 bytes:  8820844/  8820844

surge-1-16-B-Qclp.mov: audio mismatchs from previous build
     stddev:    3.79 PSNR: 36.53 bytes:  1156524/  1156524

8fe3b9dcd6d7e6db3375521c5c1b_Video_041606_002.3g2: audio mismatchs  
from previous build
     stddev:    2.55 PSNR: 39.98 bytes:   721004/   721004

Test3gpp-mp4a.3g2: audio mismatchs from previous build
     stddev:    0.77 PSNR: 50.38 bytes:   219244/   219244

c8wwz2m0.3g2: audio mismatchs from previous build
     stddev:    0.51 PSNR: 53.81 bytes:   241964/   241964

qtaudio-qcelp-problem.3g2: audio mismatchs from previous build
     stddev:    1.94 PSNR: 42.36 bytes:   208044/   208044

test.3g2: audio same as previous build

tube.3g2: audio mismatchs from previous build
     stddev:    0.01 PSNR: 84.50 bytes:   113004/   113004

zg3dx2d6.3g2: audio mismatchs from previous build
     stddev:    2.28 PSNR: 40.94 bytes:   486444/   486444

vidoo_MP4_audio_Qcelp13k.k3g: audio mismatchs from previous build
     stddev:    1.18 PSNR: 46.64 bytes:   743724/   743724





new float vs new double:

101.mov: audio mismatchs from previous build
     stddev:    3.10 PSNR: 38.28 bytes:   250284/   250284

V6_text.mov: audio mismatchs from previous build
     stddev:    4.26 PSNR: 35.52 bytes: 11371244/ 11371244

blue_earth.mov: audio mismatchs from previous build
     stddev:    3.16 PSNR: 38.11 bytes: 19681324/ 19681324

codeblue-interrupt01.mov: audio mismatchs from previous build
     stddev:    4.36 PSNR: 35.31 bytes:   276524/   276524

codeblue-interrupt06.mov: audio mismatchs from previous build
     stddev:    3.36 PSNR: 37.57 bytes:   642924/   642924

codeblue-plot08motor.mov: audio mismatchs from previous build
     stddev:    3.12 PSNR: 38.23 bytes:  1534764/  1534764

h263.mov: audio mismatchs from previous build
     stddev:    3.39 PSNR: 37.50 bytes: 13511404/ 13511404

h263.trashed.mov: audio mismatchs from previous build
     stddev:    3.39 PSNR: 37.50 bytes: 13511404/ 13511404

installfect_export.mov: audio mismatchs from previous build
     stddev:    5.43 PSNR: 33.42 bytes: 10448044/ 10448044

oldepisode.mov: audio mismatchs from previous build
     stddev:    7.25 PSNR: 30.91 bytes:  4588844/  4588844

schlangenmannliten.mov: audio mismatchs from previous build
     stddev:    2.38 PSNR: 40.56 bytes:  8820844/  8820844

surge-1-16-B-Qclp.mov: audio mismatchs from previous build
     stddev:    5.76 PSNR: 32.90 bytes:  1156524/  1156524

8fe3b9dcd6d7e6db3375521c5c1b_Video_041606_002.3g2: audio mismatchs  
from previous build
     stddev:    3.40 PSNR: 37.49 bytes:   721004/   721004

Test3gpp-mp4a.3g2: audio mismatchs from previous build
     stddev:    1.44 PSNR: 44.94 bytes:   219244/   219244

c8wwz2m0.3g2: audio mismatchs from previous build
     stddev:    0.73 PSNR: 50.81 bytes:   241964/   241964

qtaudio-qcelp-problem.3g2: audio mismatchs from previous build
     stddev:    2.02 PSNR: 42.01 bytes:   208044/   208044

test.3g2: audio same as previous build

tube.3g2: audio mismatchs from previous build
     stddev:    0.01 PSNR: 84.67 bytes:   113004/   113004

zg3dx2d6.3g2: audio mismatchs from previous build
     stddev:    2.31 PSNR: 40.82 bytes:   486444/   486444

vidoo_MP4_audio_Qcelp13k.k3g: audio mismatchs from previous build
     stddev:    1.14 PSNR: 46.92 bytes:   743724/   743724










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