[FFmpeg-devel] [PATCH 2/3] avcodec/mpegvideo_enc: Limit bitrate tolerance to the representable

[Michael Niedermayer]

On Wed, Jun 02, 2021 at 05:48:53PM +0200, Michael Niedermayer wrote:
> On Sun, May 30, 2021 at 03:20:06PM -0300, James Almer wrote:
> > On 5/30/2021 3:02 PM, Michael Niedermayer wrote:
> > > Fixes: error: 1.66789e+11 is outside the range of representable values of type 'int'
> > > Fixes: Ticket8201
> > > 
> > > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > > ---
> > >   libavcodec/mpegvideo_enc.c | 6 +++++-
> > >   1 file changed, 5 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/libavcodec/mpegvideo_enc.c b/libavcodec/mpegvideo_enc.c
> > > index c01488f483..13618394a5 100644
> > > --- a/libavcodec/mpegvideo_enc.c
> > > +++ b/libavcodec/mpegvideo_enc.c
> > > @@ -455,9 +455,13 @@ av_cold int ff_mpv_encode_init(AVCodecContext *avctx)
> > >       if (!s->fixed_qscale &&
> > >           avctx->bit_rate * av_q2d(avctx->time_base) >
> > >               avctx->bit_rate_tolerance) {
> > > +        double nbt = avctx->bit_rate * av_q2d(avctx->time_base) * 5;
> > >           av_log(avctx, AV_LOG_WARNING,
> > >                  "bitrate tolerance %d too small for bitrate %"PRId64", overriding\n", avctx->bit_rate_tolerance, avctx->bit_rate);
> > > -        avctx->bit_rate_tolerance = 5 * avctx->bit_rate * av_q2d(avctx->time_base);
> > > +        if (nbt <= INT_MAX) {
> > > +            avctx->bit_rate_tolerance = nbt;
> > > +        } else
> > > +            avctx->bit_rate_tolerance = INT_MAX;
> > 
> > Maybe bit_rate_tolerance can be made an int64_t? We have done that with all
> > bitrate fields in AVCodecContext and similar structs.
> > We're still in the open ABI period, so it can be done right now.
> 
> for master i agree but this patch is for fixing this bug and backporting.
> It is strictly speaking undefined behavior, We cannot backport a 64bit API
> update.
> We can after applying this immedeatly replace it by a 64bit solution
> which is more correct.
> Sadly i have more of these to fix so i suspect i will be working on more
> of these before i would get to changing this to 64bit so if you want it
> dont hesitate to push a matching change after this

will apply the patch


[...]
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