Valgrind error in mpegps_read_header

[Міхаіл]

I noticed strange crashes working on my own code and attempted to run it under valgrind. The error reported by the tool is there even with the stock ffmpeg-executable -- without my code in the equation.

How to reproduce:

% valgrind ffmpeg -i robot.avi
ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with FreeBSD clang version 3.4.1 (tags/RELEASE_34/dot1-final 208032) 20140512
...
==52950== Conditional jump or move depends on uninitialised value(s)
==52950==    at 0x554F02F: mpegps_read_header (mpeg.c:148)
==52950==    by 0x55D43DA: avformat_open_input (utils.c:593)
==52950==    by 0x40F881: ??? (in /opt/bin/ffmpeg)
==52950==    by 0x40F10C: ??? (in /opt/bin/ffmpeg)
==52950==    by 0x40EE93: ??? (in /opt/bin/ffmpeg)
==52950==    by 0x41AC7B: ??? (in /opt/bin/ffmpeg)
==52950==    by 0x408F8E: ??? (in /opt/bin/ffmpeg)
==52950==    by 0x4020FFF: ???
==52950== 

The reported line mpeg.c:148 reads:

    if (!memcmp("IMKH", buffer, 4)) {

[Міхаіл]

The sample input (from php-ffmpeg test_media)

[Carl Eugen Hoyos]

I wasn't able to reproduce (and I wonder how memcmp() must be implemented for this issue to occur) but should be fixed in a5c1c7a8b3d13c86b453558628951c3f52054ab4