[FFmpeg-devel] [PATCH] avformat/movenc: Explicitly address potential division by zero.

[Lucas Cooper]

Just pinging in case this got lost somewhere.

On 21 April 2017 at 00:01, Lucas Cooper <bobobo at google.com> wrote:

> Does this need any more work or explanation?
>
> On 19 Apr. 2017 7:32 am, "Lucas Cooper" <bobobo at google.com> wrote:
>
>> Michael's right. The problem is that NaN is casted to an int, resulting
>> in rate having undefined value. Not sure how I neglected to add that part.
>>
>> On 19 Apr. 2017 2:32 am, "Michael Niedermayer" <michael at niedermayer.cc>
>> wrote:
>>
>>> On Wed, Apr 19, 2017 at 12:49:38AM +0200, Hendrik Leppkes wrote:
>>> > On Wed, Apr 19, 2017 at 12:34 AM, Lucas Cooper
>>> > <bobobo-at-google.com at ffmpeg.org> wrote:
>>> > > find_fps attempts to infer framerate from AVCodec's timebase. When
>>> this
>>> > > results in a frame rate that isn't explicitly marked as supported in
>>> > > av_timecode_check_frame_rate, find_fps returns the AVStream's
>>> > > avg_frame_rate, which, per avformat.h, _may_ be set (or not).
>>> > >
>>> > > mov_get_mpeg2_xdcam_codec_tag, mov_get_h264_codec_tag and
>>> > > find_compressor attempt to call av_q2d on the return value of
>>> find_fps,
>>> > > which in the above case, may result in division by zero.
>>> >
>>> > Floating point division by zero is not an error (as av_q2d performs),
>>> > and in these cases the wrong return value is likely harmless.
>>> >
>>> > What is the actual error you are trying to fix?
>>>
>>> from looking at the code, i guess its the cast to int of a non finite
>>> double
>>>
>>> [...]
>>>
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