[FFmpeg-devel] [PATCH][RFC] Fix field order for interlaced AVDJ and AVRN in ntsc mode

Michael Niedermayer michaelni at gmx.at
Sun May 12 18:29:56 CEST 2013


On Sun, May 12, 2013 at 02:15:52PM +0200, Piotr Bandurski wrote:
> Hi,
> 
> Attached patch fixes decoding of interlaced AVDJ and AVRn in ntsc mode (ticket #1656).
> 
> The only problem is that I get 
> 
> [mjpeg @ 01b4c620] mjpeg: error, decode_app parser read over the end
> 
> so how many bytes should I subtract?
> 
> AVDJ samples:
> 
> http://www1.datafilehost.com/d/e11fadc3
> 
> Regards

> diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
> index b439547..41df345 100644
> --- a/libavcodec/mjpegdec.c
> +++ b/libavcodec/mjpegdec.c
> @@ -1374,9 +1374,15 @@ static int mjpeg_decode_app(MJpegDecodeContext *s)
>              4bytes      field_size
>              4bytes      field_size_less_padding
>          */
> +        int mode; /* 1 - ntsc, 2 - pal */
>              s->buggy_avid = 1;
>          i = get_bits(&s->gb, 8); len--;
>          av_log(s->avctx, AV_LOG_DEBUG, "polarity %d\n", i);
> +        skip_bits(&s->gb, 200);
> +        mode = get_bits(&s->gb, 8);
> +        if (mode == 1)
> +            s->interlace_polarity = 1;

> +        len -= 26;

this needs a check on len being big enough

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

It is what and why we do it that matters, not just one of them.
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