[FFmpeg-devel] [PATCH 1/2] avformat/mov: Use av_rescale when calculating bit rate

[Michael Niedermayer]

On Wed, Oct 20, 2021 at 03:03:53PM +0100, Derek Buitenhuis wrote:
> It is less susceptible to overflows.
> 
> Signed-off-by: Derek Buitenhuis <derek.buitenhuis at gmail.com>
> ---
>  libavformat/mov.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 57c67e3aac..431f430368 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -7989,12 +7989,14 @@ static int mov_read_header(AVFormatContext *s)
>              AVStream *st = s->streams[i];
>              MOVStreamContext *sc = st->priv_data;
>              if (st->duration > 0) {
> -                if (sc->data_size > INT64_MAX / sc->time_scale / 8) {
> +                /* Akin to sc->data_size * 8 * sc->time_scale / st->duration but accounting for overflows. */
> +                st->codecpar->bit_rate = av_rescale(sc->data_size, sc->time_scale * 8, st->duration);

Does something ensure time_scale * 8 fits in int ? if not this needs a cast to *int64_t

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Republics decline into democracies and democracies degenerate into
despotisms. -- Aristotle
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