VTT subtitles are muxed instead of SRT although --convert-subs srt is used

[Razor-13]

Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2017.04.03. If it's not read this FAQ entry and update. Issues with outdated version will be rejected.

• I've verified and I assure that I'm running youtube-dl 2017.04.03

Before submitting an issue make sure you have:

• At least skimmed through README and most notably FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)

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If the purpose of this issue is a bug report, site support request or you are not completely sure provide the full verbose output as follows:

Add -v flag to your command line you run youtube-dl with, copy the whole output and insert it here. It should look similar to one below (replace it with your log inserted between triple ```):

youtube-dl -v -k --convert-subs srt --all-subs --embed-subs --embed-thumbnail --fixup warn -f best -o "%(title)s %(upload_date)s best.%(ext)s" https://www.youtube.com/watch?v=e_3dUgLXesk
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', '-k', '--convert-subs', 'srt', '--all-subs', '--embed-subs', '--embed-thumbnail', '--fixup', 'warn', '-f', 'best', '-o', '%(title)s %(upload_date)s best.%(ext)s', 'https://www.youtube.com/watch?v=e_3dUgLXesk']
[debug] Encodings: locale cp1253, fs mbcs, out cp737, pref cp1253
[debug] youtube-dl version 2017.04.03
[debug] Python version 3.4.4 - Windows-7-6.1.7601-SP1
[debug] exe versions: ffmpeg N-85091-g23ae3cc, ffprobe N-85091-g23ae3cc
[debug] Proxy map: {}
[youtube] e_3dUgLXesk: Downloading webpage
[youtube] e_3dUgLXesk: Downloading video info webpage
[youtube] e_3dUgLXesk: Extracting video information
[youtube] {22} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {43} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {18} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {36} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {17} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {137} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {248} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {136} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {247} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {135} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {244} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {134} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {243} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {133} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {242} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {160} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {278} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {140} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {171} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {249} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {250} signature length 42.40, html5 player en_US-vflRjgXJi
[youtube] {251} signature length 42.40, html5 player en_US-vflRjgXJi
[info] Writing video subtitles to: MLG STRANGER DANGER 20140831 best.ko.vtt
[info] Writing video subtitles to: MLG STRANGER DANGER 20140831 best.ja.vtt
[info] Writing video subtitles to: MLG STRANGER DANGER 20140831 best.ar.vtt
[youtube] e_3dUgLXesk: Downloading thumbnail ...
[youtube] e_3dUgLXesk: Writing thumbnail to: MLG STRANGER DANGER 20140831 best.jpg
[debug] Invoking downloader on
[download] Destination: MLG STRANGER DANGER 20140831 best.mp4
[download] 100% of 35.30MiB in 00:47                   
[ffmpeg] Converting subtitles
[debug] ffmpeg command line: ffmpeg -y -i 'file:MLG STRANGER DANGER 20140831 best.ko.vtt' -f srt 'file:MLG STRANGER DANGER 20140831 best.ko.srt'
[debug] ffmpeg command line: ffmpeg -y -i 'file:MLG STRANGER DANGER 20140831 best.ja.vtt' -f srt 'file:MLG STRANGER DANGER 20140831 best.ja.srt'
[debug] ffmpeg command line: ffmpeg -y -i 'file:MLG STRANGER DANGER 20140831 best.ar.vtt' -f srt 'file:MLG STRANGER DANGER 20140831 best.ar.srt'
[ffmpeg] Embedding subtitles in 'MLG STRANGER DANGER 20140831 best.mp4'
[debug] ffmpeg command line: ffmpeg -y -i 'file:MLG STRANGER DANGER 20140831 best.mp4' -i 'file:MLG STRANGER DANGER 20140831 best.ko.srt' -i 'file:MLG STRANGER DANGER 20140831 best.ja.srt' -i 'file:MLG STRANGER DANGER 20140831 best.ar.srt' -map 0 -c copy -map -0:s -c:s mov_text -map 1:0 -metadata:s:s:0 language=kor -map 2:0 -metadata:s:s:1 language=jpn -map 3:0 -metadata:s:s:2 language=ara 'file:MLG STRANGER DANGER 20140831 best.temp.mp4'
[atomicparsley] Adding thumbnail to "MLG STRANGER DANGER 20140831 best.mp4"
[debug] AtomicParsley command line: AtomicParsley 'MLG STRANGER DANGER 20140831 best.mp4' --artwork 'MLG STRANGER DANGER 20140831 best.jpg' -o 'MLG STRANGER DANGER 20140831 best.temp.mp4'

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The end file includes tx3g subtitles, not the converted srt ones.

[dstftw]

This is expected.

[Razor-13]

How it is expected? I use the covert to srt option, shouldn't it mux the srt subtitles?

[dstftw]

Neither srt nor vtt subtitles is supported by mp4. It's technically impossible to embed them into mp4.

[Razor-13]

Didn't know that. Can I force it to mux into mkv?