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Bug 774936 - media-libs/libvpx segfaults ffmpeg during encoding when compiled with -ftree-vectorize
Summary: media-libs/libvpx segfaults ffmpeg during encoding when compiled with -ftree-...
Status: RESOLVED FIXED
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: AMD64 Linux
: Normal normal (vote)
Assignee: Gentoo Media-video project
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2021-03-09 00:07 UTC by ppdplayer
Modified: 2021-04-30 02:20 UTC (History)
3 users (show)

See Also:
Package list:
Runtime testing required: ---

Attachments
emerge --info gcc ffmpeg libvpx (emergeinfo,9.57 KB, text/plain)
2021-03-09 02:17 UTC, ppdplayer 		Details
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Description ppdplayer 2021-03-09 00:07:05 UTC 
This flag should be filtered out. It crashes in function "vpx_convolve_copy_sse2". Note that libvpx is also generally unstable with this compiler flag. I've used this in the past and it has experienced random segfaults.

Reproducible: Always
Comment 1 Ionen Wolkens gentoo-dev 2021-03-09 02:01:23 UTC 
Personally can't reproduce with -march=skylake -O2 -ftree-vectorize for neither vp8 nor vp9 encodes (gcc-10.2.0-r5, libvpx-1.9.0 and ffmpeg-4.3.2), so it may also be something -march-specific or something I haven't tried.

More information may be needed, what ffmpeg command? emerge --info? libvpx/ffmpeg versions? Is this reported upstream?
Comment 2 ppdplayer 2021-03-09 02:16:31 UTC 
Using -march=znver2, same packages. Command was "ffmpeg -i file.mkv out.webm"

This is not reported upstream.
Comment 3 ppdplayer 2021-03-09 02:17:04 UTC 
Created attachment 690114 [details]
emerge --info gcc ffmpeg libvpx
Comment 4 ppdplayer 2021-03-09 03:52:11 UTC 
I should also note this happened on znver1, so maybe it is -march specific.
Comment 5 ppdplayer 2021-04-30 01:43:02 UTC 
This seems to be (somehow) fixed by gcc-11.