[FFmpeg-devel] [PATCH] ac3dec_fixed: always use the USE_FIXED=1 variant of the AC3DecodeContext

[Christophe Gisquet]

Hi,

2015-03-13 22:28 GMT+01:00 Andreas Cadhalpun <andreas.cadhalpun at googlemail.com>:
> -int ff_eac3_parse_header(AC3DecodeContext *s);
> +static int ff_eac3_parse_header(AC3DecodeContext *s);

It's somewhat cosmetics, but if these functions become static, they
would better drop the ff_ prefix.

> -            float accum = 0.0f;
> +            INTFLOAT accum = 0.0f;
[...]
>              for (i = 0; i < bandsize; i++) {
> -                float coeff = s->transform_coeffs[ch][bin++];
> +                INTFLOAT coeff = s->transform_coeffs[ch][bin++];
>                  accum += coeff * coeff;
[...]
> -            float nscale = s->spx_noise_blend[ch][bnd] * rms_energy[bnd] * (1.0f / INT32_MIN);
> -            float sscale = s->spx_signal_blend[ch][bnd];
> +            INTFLOAT nscale = s->spx_noise_blend[ch][bnd] * rms_energy[bnd] * (1.0f / INT32_MIN);
> +            INTFLOAT sscale = s->spx_signal_blend[ch][bnd];
>              for (i = 0; i < s->spx_band_sizes[bnd]; i++) {
> -                float noise  = nscale * (int32_t)av_lfg_get(&s->dith_state);
> +                INTFLOAT noise  = nscale * (int32_t)av_lfg_get(&s->dith_state);

Does that work at all? I mean, if it's fixedpoint, I would have
expected some renormalization, various things to avoid overflows,
potential warnings because of casts, etc.

And is the output on eac3 samples, eg here:
http://samples.mplayerhq.hu/A-codecs/AC3/eac3/
(particularly the spx ones)
anything listenable?

Maybe the extensions should simply be declared as unsupported by the fp version?

-- 
Christophe