[FFmpeg-devel] [PATCH]Force gif aspect ratio multiplication to 64bit

[Michael Niedermayer]

On Thu, Apr 03, 2014 at 09:14:00AM +0200, Carl Eugen Hoyos wrote:
> Hi!
> 
> Sorry if I misunderstand but I believe the attached patch is simpler than 
> using av_mul_q() to avoid an integer overflow calculating gif aspect ratio.
> 
> Please comment, Carl Eugen

LGTM


>  gif.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 40524f0f32562662aa8e4446336de11d3e71490c  patchgifaspect64.diff
> diff --git a/libavformat/gif.c b/libavformat/gif.c
> index 68320c6..874bbde 100644
> --- a/libavformat/gif.c
> +++ b/libavformat/gif.c
> @@ -36,7 +36,7 @@ static int gif_image_write_header(AVFormatContext *s, int width, int height,
>      int i, aspect = 0;
>  
>      if (sar.num > 0 && sar.den > 0) {
> -        aspect = sar.num * 64 / sar.den - 15;

> +        aspect = sar.num * 64ULL / sar.den - 15;
>          if (aspect < 0 || aspect > 255)

thats not sufficient, aspect is just an int and this might not fit
in it also the <0 check needs int64 not uint64


[...]

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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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