Re: [FFmpeg-devel] [PATCH] fftools/ffprobe: Avoid overflow when calculating DAR

[Anton Khirnov <anton@khirnov.net>]

Quoting Derek Buitenhuis (2024-05-03 18:36:23)
> Both the codecpar's width and height, and the SAR num and den are
> ints, which can overflow. Cast to int64_t, which is what av_reduce
> takes.
> 
> Without this, occasionally, display_aspect_ratio can be negative in
> ffprobe's -show_stream output.
> 
> Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
> ---
>  fftools/ffprobe.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fftools/ffprobe.c b/fftools/ffprobe.c
> index 0d4cd0b048..5b40dad527 100644
> --- a/fftools/ffprobe.c
> +++ b/fftools/ffprobe.c
> @@ -3324,8 +3324,8 @@ static int show_stream(WriterContext *w, AVFormatContext *fmt_ctx, int stream_id
>          if (sar.num) {
>              print_q("sample_aspect_ratio", sar, ':');
>              av_reduce(&dar.num, &dar.den,
> -                      par->width  * sar.num,
> -                      par->height * sar.den,
> +                      (int64_t) par->width  * sar.num,
> +                      (int64_t) par->height * sar.den,

Aren't we supposed to avoid assumptions that int is always strictly
smaller than 64bit?

-- 
Anton Khirnov
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