Bug#967941: nautilus: fails to generate thumbnails for h264 encoded video files

[Simon McVittie]

Control: reassign 967941 libopenblas0-pthread 0.3.10+ds-2
Control: affects 967941 + nautilus totem

On Thu, 22 Oct 2020 at 21:31:41 +0200, Thorsten Ehlers wrote:
> So I dug a little bit deeper into this bug

Please include some context in replies to bugs: package maintainers will
usually see your messages out of context.

For the libopenblas0-pthread maintainers: the original bug report is that
h.264 video files were not thumbnailed successfully by GNOME's Nautilus
file manager. The actual thumbnailing is delegated to
totem-video-thumbnailer, from the totem package.

I can reproduce this with the sample videos from the original bug report
after installing libopenblas0-pthread. After removing libopenblas0-pthread,
the alternative switches to /usr/lib/x86_64-linux-gnu/atlas/libblas.so.3
and the thumbnailer works again.

Steps to reproduce:

$ sudo apt install totem libopenblas0-pthread youtube-dl
$ youtube-dl https://www.youtube.com/watch?v=LTvFsTbyILg
$ youtube-dl https://www.youtube.com/watch?v=l7GX_XII2K0
$ totem-video-thumbnailer -v Yosemite\ Nature\ Drone\ Video-LTvFsTbyILg.webm tmp.png
(succeeds)
$ totem-video-thumbnailer -v Beautiful\ Nature\ 1080p.-l7GX_XII2K0.mkv tmp.png

Output:

TotemVideoThumbnailer-Message: 22:02:21.412: Initialised libraries, about to create video widget
TotemVideoThumbnailer-Message: 22:02:21.436: setting URI file:///home/smcv/tmp/Beautiful%20Nature%201080p.-l7GX_XII2K0.mkv
TotemVideoThumbnailer-Message: 22:02:21.437: Video widget created
TotemVideoThumbnailer-Message: 22:02:21.437: About to open video file
TotemVideoThumbnailer-Message: 22:02:21.713: Checking whether file has cover
TotemVideoThumbnailer-Message: 22:02:21.713: Opened video file: 'Beautiful Nature 1080p.-l7GX_XII2K0.mkv'
TotemVideoThumbnailer-Message: 22:02:21.713: About to seek to 0.333333
TotemVideoThumbnailer-Message: 22:02:21.757: About to get frame for iter 0

(totem-video-thumbnailer:98347): GStreamer-WARNING **: 22:02:21.758: failed to create thread: Error creating thread: Resource temporarily unavailable

(totem-video-thumbnailer:98347): GLib-ERROR **: 22:02:21.763: ../../../glib/gmem.c:112: failed to allocate 3145167 bytes
[1]    98347 trace trap (core dumped)  totem-video-thumbnailer -v Beautiful\ Nature\ 1080p.-l7GX_XII2K0.mkv tmp.png

> and in my case it turned out
> the real problem is libopenblas0-pthread version 0.3.10+ds-2 and -3.
> 
> This package is a dependency of libopenblas0 which is a dependency of Octave and others.
> 
> Creating a thumbnail with totem-video-thumbnailer fails for flv and mkv videos like that one mentioned by the OP:
> 
> (totem-video-thumbnailer:37500): GStreamer-WARNING **: 21:23:41.129: failed to create thread: Error creating thread: Die Ressource ist zur Zeit nicht verfügbar
> 
> (totem-video-thumbnailer:37500): GLib-ERROR **: 21:23:41.131: ../../../glib/gmem.c:112: failed to allocate 3145167 bytes
> Trace/Breakpoint ausgelöst
> 
> Installing libopenblas0-pthread_0.3.10+ds-1 or adding the -l option in /usr/share/thumbnailers/totem.thumbnailer works
> around this bug.

The -l option is documented to disable the time limit for thumbnail
generation (the default is that totem-video-thumbnailer gives up after
30 seconds). This is implemented as a watchdog thread.

Perhaps the watchdog thread and whatever threads are used by
libopenblas0-pthread, together, are enough to exceed a memory limit?
totem seems to set its RLIMIT_DATA to 512M plus the size of the file.

    smcv