[FFmpeg-devel] [PATCH] QCELP decoder
Michael Niedermayer
michaelni
Sat Nov 22 23:22:27 CET 2008
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 ...
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Old school: Use the lowest level language in which you can solve the problem
conveniently.
New school: Use the highest level language in which the latest supercomputer
can solve the problem without the user falling asleep waiting.
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