[FFmpeg-devel] [PATCH] Common ACELP code & G.729 [3/7] - vectors operations

[Michael Niedermayer]

On Thu, May 22, 2008 at 10:27:13PM +0700, Vladimir Voroshilov wrote:
> 2008/5/22, Michael Niedermayer <michaelni at gmx.at>:
> > On Thu, May 22, 2008 at 05:50:28PM +0700, Vladimir Voroshilov wrote:
> 
> [...]
> 
> >  > >> +void ff_acelp_fc_enchance_harmonics(
> >  > >> +        int16_t* fc_v,
> >  > >> +        int pitch_delay,
> >  > >> +        int16_t gain_pitch,
> >  > >> +        int length)
> >  > >> +{
> >  > >> +    int i;
> >  > >> +
> >  > >> +    for(i=pitch_delay; i<length;i++)
> >  > >> +        fc_v[i] += (fc_v[i - pitch_delay] * gain_pitch) >> 14;
> >  > >> +}
> >  > >> +
> >  > >> +void ff_acelp_build_excitation(
> >  > >> +        int16_t* exc,
> >  > >> +        const int16_t *ac_v,
> >  > >> +        const int16_t *fc_v,
> >  > >> +        int16_t gp,
> >  > >> +        int16_t gc,
> >  > >> +        int subframe_size)
> >  > >> +{
> >  > >> +    int i;
> >  > >> +
> >  > >> +    // Clipping required here; breaks OVERFLOW test.
> >  > >> +    for(i=0; i<subframe_size; i++)
> >  > >> +        exc[i] = av_clip_int16((ac_v[i] * gp + fc_v[i] * gc + 0x2000) >> 14);
> >  > >> +}
> >  > >
> >  > > duplicate, these 2 functions do the same, that is a wheighted sum of 2
> >  > > vectors.
> >  > >
> >  >
> >  > agree.
> >  > As i see
> >  >
> >  > ff_acelp_fc_enchance_harmonics(fc_v, pitch_delay, gain_pitch, length)
> >  >
> >  > is equal to
> >  >
> >  > ff_acelp_build_excitation(fc_v+pitch_delay, fc_v+pitch_delay,
> >  > fc,1<<14, gain_pitch, length-pitch_delay);
> >  >
> >  > but what should i do with rounding ?
> >  >
> >  > what about adding additional parameter (const summand) to
> >  > ff_acelp_build_excitation
> >  > I.e. something like:
> >  >
> >  > void ff_acelp_build_excitation(
> >  >         int16_t* exc,
> >  >         const int16_t *ac_v,
> >  >         const int16_t *fc_v,
> >  >         int16_t gp,
> >  >         int16_t gc,
> >  >         int16_t summand,
> >  >         int subframe_size)
> >  > {
> >  >     int i;
> >  >
> >  >     // Clipping required here; breaks OVERFLOW test.
> >  >     for(i=0; i<subframe_size; i++)
> >  >         exc[i] = av_clip_int16((ac_v[i] * gp + fc_v[i] * gc + summand) >> 14);
> >  > }
> >  >
> >  > What about renaming ff_acelp_build_excitation like ff_acelp_weighted_vector_sum
> >  > (and subframe_size -> length, ac_v -> vect_a, fc_v -> vect_b, gc ->
> >  > weight_coeff_a, gp -> weight_coeff_b)?
> >
> >
> > ok
> >
> >
> >
> >  >
> >  > P.S. "summand" don't look like the best name too.
> >
> >
> > maybe offset or rounder are better?
> >
> 
> here is the patch.
> I have also added "shift" parameter.
> This will simplify reusing from g729 postfilter (since it
> uses vectors with different fixed-point base).
[...]
> +void ff_acelp_fc_pulse_per_track(

id call it ff_acelp_decode_fixed_codebook_vector())


> +        int16_t* fc_v,
> +        const uint8_t *tab1,
> +        const uint8_t *tab2,

> +        int fc_index,

pulses_indices seems to fit better with pulses_signs
also i think it should be pulse_signs / indices not pulses

except these patch ok

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No snowflake in an avalanche ever feels responsible. -- Voltaire
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