[FFmpeg-devel] [PATCH]VDPAU support for MPEG-4 ASP

[Reimar Döffinger]

On Sat, Sep 05, 2009 at 01:08:46AM +0200, Carl Eugen Hoyos wrote:
> Attached patch adds support for decoding MPEG-4 ASP on Nvidia's latest 
> VDPAU hardware.

This brings again up the same question: why do we have an extra codec
for these formats when the acceleration could just be selected via
pixfmt?

> +// greatest common divisor
> +static int gcd(int u, int v)

av_gcd.

> +        int d = gcd(s->pp_time, s->pb_time);
> +        render->info.mpeg4.trd[0] = s->pp_time / d;
> +        render->info.mpeg4.trb[0] = s->pb_time / d;

av_reduce?

> +        render->info.mpeg4.trd[1] = (s->time - s->pb_time + s->pp_time
> +                                       + (s->pb_time >> 1))/s->pb_time
> +               - (s->time - s->pb_time + (s->pb_time >> 1))/s->pb_time;
> +        render->info.mpeg4.trb[1] = (s->time + (s->pb_time >> 1))/s->pb_time
> +                     - (s->time - s->pb_time + (s->pb_time >> 1))/s->pb_time;

Is it really necessary to round and divide twice?
At least this needs an explaining comment.

> +    render->info.mpeg4.vop_coding_type                   = s->pict_type - FF_I_TYPE;

Hm, not sure if that doesn't assume a bit too much.