[FFmpeg-devel] [PATCH] QCELP decoder

[Michael Niedermayer]

On Thu, Oct 30, 2008 at 03:18:45PM -0700, Kenan Gillet wrote:
> 
> On Oct 30, 2008, at 6:16 AM, Michael Niedermayer wrote:
> 
> > On Tue, Oct 28, 2008 at 04:47:02PM -0700, Kenan Gillet wrote:
[...]
> 
> [...]
> >> +static void interpolate_lspf(float *interpolated_lspf,
> >> +                             const float curr_weight,
> >> +                             const float *curr_lspf,
> >> +                             const float *prev_lspf) {
> >> +    int   i;
> >> +
> >> +    for (i = 0; i < 10; i++)
> >> +        interpolated_lspf[i] = (1.0 - curr_weight) * prev_lspf[i]
> >> +                             +        curr_weight  * curr_lspf[i];
> >> +}
> >
> > iam ok with the code but the names have to be changed
> > both fixed point (ff_acelp_weighted_vector_sum) and this should have
> > similar names
> > now imho *celp and lsp dont belong in the names as the code is not  
> > specific
> > for that.
> 
> what about makin and using  a more generic
> ff_weighted_vector_sumf(
>          float* out,
>          const float *in_a,
>          const float *in_b,
>          float weight_coeff_a,
>          float weight_coeff_b,
>          int length);

fine

[...]

> and I am not sure if bigger is better or lower is faster ;)

lower is faster ...


[...]
> 
> 
> >> +}
> >> +
> >> +/*
> >> + * Determine the framerate from the frame size and/or the first  
> >> byte of the frame.
> >> + *
> >> + * @return 0 on success, negative error number otherwise.
> >> + */
> >> +static int determine_framerate(AVCodecContext *avctx,
> >> +                               QCELPContext *q,
> >> +                               const int buf_size,
> >> +                               uint8_t **buf) {
> >> +    int claimed_rate = -1;
> >> +
> >> +    switch (buf_size) {
> >> +    case 35: claimed_rate = RATE_FULL;
> >> +    case 34: q->framerate = RATE_FULL;
> >> +             break;
> >> +
> >> +    case 17: claimed_rate = RATE_HALF;
> >> +    case 16: q->framerate = RATE_HALF;
> >> +             break;
> >> +
> >> +    case  8: claimed_rate = RATE_QUARTER;
> >> +    case  7: q->framerate = RATE_QUARTER;
> >> +             break;
> >> +
> >> +    case  4: claimed_rate = RATE_OCTAVE;
> >> +    case  3: q->framerate = RATE_OCTAVE;
> >> +             break;
> >> +
> >> +    case  1: claimed_rate = SILENCE;
> >> +    case  0: q->framerate = SILENCE;
> >> +             break;
> >> +
> >> +    default:
> >> +        return -1;
> >> +    }
> >> +
> >> +    if (claimed_rate >= 0) {
> >> +        q->framerate = *(*buf)++;
> >> +
> >> +        if (claimed_rate != q->framerate)
> >> +            av_log(avctx, AV_LOG_WARNING, "Claimed framerate and  
> >> buffer size mismatch.\n");
> >> +    } else
> >> +        av_log(avctx, AV_LOG_WARNING,
> >> +               "Framerate byte is missing, guessing the framerate  
> >> from packet size.\n");
> >> +
> >
> > putting a switch for 34,16,7,3,0 in a seperate function the  
> > following could
> > be used:
> >
> > q->framerate= foo(buf_size);
> > if(q->framerate < 0){
> >    q->framerate = *(*buf)++;
> >
> >    if (foo(buf_size+1) != q->framerate)
> >        av_log(avctx, AV_LOG_WARNING, "Claimed framerate and buffer  
> > size mismatch.\n");
> > }else{
> >
> > ...
> >
> 
> done, use 35, 17,8, 4 and 1 because it is much more probable that the  
> buffer contains a framerate byte.
> Actually, I have never seen any files where the framerate byte is  
> missing; I just kept this check because
> it was in the SOC code.

> Should I remove it ? or keep it ?

hmmmmm
do what you prefer ...


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

When the tyrant has disposed of foreign enemies by conquest or treaty, and
there is nothing more to fear from them, then he is always stirring up
some war or other, in order that the people may require a leader. -- Plato
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