[FFmpeg-user] Concat and extract image cause FFmpeg to hang in 3.3 and 3.4

[Moritz Barsnick]

On Tue, Jan 16, 2018 at 01:47:44 +0000, Jeff Wang wrote:
> ffmpeg -i topia.flac -i topia_png.flac -threads 0 -map_chapters -1 -f flac -filter_complex "[0:a:0][1:a:0]concat=n=2:v=0:a=1[cat_a]" -map "[cat_a]" -acodec flac -sample_fmt s16 -ac 2 -ar 44100 -sn -vn topia.flac+topia_png.flac.flac -map 1:1 -f image2 -vcodec copy -frames:v 1 extract.png

In addition to the command line, could you kindly also post the
complete, uncut console output of a working and a non-working attempt?
Even if you have no warning or error messages, the outputs contain
valuable information.

Furthermore, instead of (or in addition to) testing releases, please
also try latest git master, as that's where any recent bug fixes will
have been made. (If you're not building the binaries yourselves, third
parties do provide binaries for several platforms.)

Does removing "-threads 0" help?

> We're in the process of upgrading to 3.3 and this is prevent us from
> doing that.

Why are you updating to 3.3 and not 3.4.x? While I can understand why
you may want to stick to releases, why an older one?


Cheers,
Moritz

P.S.: With my artificially created input, I couldn't reproduce.