[FFmpeg-devel] [PATCH v2] avcodec/h2645_vui: Interpret a degenerate SAR as unspecified.

[Giovanni Mascellani]

Hi,

gentle ping about this patch I sent a few months ago, receiving no reply.

Thanks, Giovanni.


Il 31/07/24 11:45, Giovanni Mascellani ha scritto:
> The specification says that if either the numerator or the
> denominator is zero then the SAR is to be intended unspecified.
> Internally ffmpeg represents an unspecified SAR as 0/1, while
> fractions with a zero denominator are not handled properly;
> so we bridge the gap by replacing x/0 with 0/1.
> 
> Signed-off-by: Giovanni Mascellani <gmascellani at codeweavers.com>
> ---
>   libavcodec/h2645_vui.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/libavcodec/h2645_vui.c b/libavcodec/h2645_vui.c
> index e5c7bf46f9..c8df733399 100644
> --- a/libavcodec/h2645_vui.c
> +++ b/libavcodec/h2645_vui.c
> @@ -46,6 +46,8 @@ void ff_h2645_decode_common_vui_params(GetBitContext *gb, H2645VUI *vui, void *l
>           else if (vui->aspect_ratio_idc == EXTENDED_SAR) {
>               vui->sar.num = get_bits(gb, 16);
>               vui->sar.den = get_bits(gb, 16);
> +            if (vui->sar.den == 0)
> +                vui->sar = (AVRational){ 0, 1 };
>           } else
>               av_log(logctx, AV_LOG_WARNING,
>                      "Unknown SAR index: %u.\n", vui->aspect_ratio_idc);