encode-slice won't work if filetype is .mp4

[nnuel]

For me it works splendid for .mkv file, for which many kudo's. However, the .mp4 files leave me with 0 byte files.

[Zoxjib]

I'm not sure its an issue with .mp4 files. I have this issue now with .mkv files, while some other .mkv files seem to get processed by encode-slice without issues.

[Zoxjib]

When it happens with detached=no the error says 'Encode failed, check the log'. I can't find the log, it doesn't appear in the console/terminal. Is there another location for this specific log?

[Zoxjib]

@nnuel I was investigating the problem over the mpv irc channel and with occivink's help found that the issue was related to a subtitle track. by adding -sn to the codec command (-sn disables the encoding of subtitles) or just shutting the subtitle off during playback/encode, I was able to bypass the issue.

Apparently no logs are saved because the script uses a detached process, so the ffmpeg output log goes into nothingness. If you want to see the log, you can run mpv through cli, run the encode script (which will print out the ffmpeg command to the cli, without the log). then copy-paste the same ffmpeg command manually in the cli to see which errors appear.

[Zoxjib]

For future reference, the errors were along these lines:

[mp4 @ 000002e3cebbd240] Could not find tag for codec ass in stream #2, codec not currently supported in container

Automatic encoder selection failed for output stream #0:2. Default encoder for format mp4 (codec none) is probably disabled. Please choose an encoder manually.