[MPlayer-dev-eng] aspect ratio: container vs vd_ffmpeg

[Michael Niedermayer]

Hi

On Tuesday 06 May 2003 14:09, Moritz Bunkus wrote:
> Hi.
>
> While implementing aspect ratio support for the Matroska demuxer I
> noticed that vd_ffmpeg.c overrides sh_v->aspect with whatever is stored
> in the MPEG4 stream - even if there is NO special AR stored:
>
> [ffmpeg] aspect_ratio: 0.000000
>
> This way aspect ratio settings from the container will never be taken
> into account. Wouldn't it be better only to override sh_v->aspect if the
> aspect ratio stored in the MPEG4 stream is != 0.0 ? Someone (Rich? I
> think I remember you working on that code) obviously already thought
> about it but uncommented that if:
>
> //    if(ctx->last_aspect>=0.01 && ctx->last_aspect<100)
>           sh->aspect = ctx->last_aspect;
>
> (in libmpcodecs/vd_ffmpeg.c, line 349)
>
> If I remove those comments then at least the container AR is taken into
> account correctly, but I don't have any test files which have AR info
> stored in the MPEG4 stream, so I cannot test those.
btw, note that mpeg4 doesnt contain a "unknown" aspect ratio value so u cant 
distinguish 1:1 pixel aspect (square pixels) from undefinied (IIRC most use 
1:1 pixel aspect if its unknown ...) 

-- 
Michael
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