[FFmpeg-devel] [PATCH/RFC] honor DAR aspect ratio in nuv files.

[Michael Niedermayer]

On Sun, Jun 08, 2008 at 08:50:05PM +0200, elupus wrote:
> 
> >> Anyway, here is a updated patch that behavies just like official myth
> >> player (and actually works). It considers a value of 1.0, which the old
> >> muxers wrote, a DAR of 4:3. 
> > [...]
> >> +        av_reduce(&vst->codec->sample_aspect_ratio.num,
> >> +                  &vst->codec->sample_aspect_ratio.den,
> >> +                  height * aspect,
> >> +                  width, 255);
> > 
> > this is wrong
> > converting height * aspect to an integer is nonsense
> > 
> > [...]
> 
> Right, missed that. This should be better, but i'm not sure what I should
> set the max num/den in av_reduce/av_d2q.
> 
> Joakim
Content-Description: Attached file: 0001-The-aspect-stored-in-nuv-files-is-not-PAR-it-s-DAR.patch
> From eeccd8442fb4fc93bed7a43986ce1e5d0b8b8d53 Mon Sep 17 00:00:00 2001
> From: elupus <elupus at ecce.se>
> Date: Sun, 8 Jun 2008 20:29:34 +0200
> Subject: [PATCH] The aspect stored in nuv files is not PAR, it's DAR. Old muxers encode a hardcoded value of 1.0, which we interpret as a DAR of 4:3.
> 
> ---
>  libavformat/nuv.c |   10 +++++++++-
>  1 files changed, 9 insertions(+), 1 deletions(-)
> 
> diff --git a/libavformat/nuv.c b/libavformat/nuv.c
> index 74393af..6cce6bd 100644
> --- a/libavformat/nuv.c
> +++ b/libavformat/nuv.c
> @@ -123,6 +123,7 @@ static int nuv_header(AVFormatContext *s, AVFormatParameters *ap) {
>      ByteIOContext *pb = s->pb;
>      char id_string[12], version_string[5];
>      double aspect, fps;
> +    AVRational dar;
>      int is_mythtv, width, height, v_packs, a_packs;
>      int stream_nr = 0;
>      AVStream *vst = NULL, *ast = NULL;
> @@ -137,6 +138,10 @@ static int nuv_header(AVFormatContext *s, AVFormatParameters *ap) {
>      get_byte(pb); // 'P' == progressive, 'I' == interlaced
>      url_fskip(pb, 3); // padding
>      aspect = av_int2dbl(get_le64(pb));
> +    if(aspect > 0.9999 && aspect < 1.0001)
> +        dar = (AVRational){4, 3};
> +    else
> +        dar = av_d2q(aspect, 10000);
>      fps = av_int2dbl(get_le64(pb));
>  
>      // number of packets per stream type, -1 means unknown, e.g. streaming
> @@ -156,7 +161,10 @@ static int nuv_header(AVFormatContext *s, AVFormatParameters *ap) {
>          vst->codec->width = width;
>          vst->codec->height = height;
>          vst->codec->bits_per_sample = 10;
> -        vst->codec->sample_aspect_ratio = av_d2q(aspect, 10000);
> +        av_reduce(&vst->codec->sample_aspect_ratio.num,
> +                  &vst->codec->sample_aspect_ratio.den,
> +                  height * dar.num,
> +                  width  * dar.den, 255);

if(aspect > 0.9999 && aspect < 1.0001)
    aspect= 4.0/3.0;
vst->codec->sample_aspect_ratio = av_d2q(aspect*width/height);



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

There will always be a question for which you do not know the correct awnser.
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