[FFmpeg-devel] [PATCH] Ensure sample_aspect_ratio.den is nonzero

[David Conrad]

Hi,

Currently no decoders check for validity of sample_aspect_ratio, specifically, whether sample_aspect_ratio.den is nonzero. This leads to an issue with theora files, which have 0/0 written a lot of the time, causing ffmpeg to calculate an aspect ratio of 4/1 after some math involving NaNs.

Since "unknown" is the only valid interpretation of a denominator of zero, this adds a check to both avcodec_open() and avcodec_decode_video2() to set {0,1} which is a safer value to give to user applications.

Alternatively, I could put the check in each codec that sets it directly from the bitstream, or clarify the API that a zero denominator is allowed and fix ffmpeg.

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