Subtitles not merged in the Matroska (.mkv) container: "invalid data found when post processing"

[ethicnology]

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Checklist

• I'm reporting a bug unrelated to a specific site
• I've verified that I'm running yt-dlp version 2022.11.11 (update instructions) or later (specify commit)
• I've checked that all provided URLs are playable in a browser with the same IP and same login details
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar issues including closed ones. DO NOT post duplicates
• I've read the guidelines for opening an issue

Provide a description that is worded well enough to be understood

For the given URL, I want to download the source video/audio with all the subtitles available and merge all this contents in a mkv container.

To achieve this I tried the following command:

yt-dlp --embed-subs --sub-langs all --convert-subs srt --merge mkv "https://www.arte.tv/fr/videos/077330-001-A/50-nuances-de-grecs/"

#5833 (comment)

Provide verbose output that clearly demonstrates the problem

• Run your yt-dlp command with -vU flag added (yt-dlp -vU <your command line>)
• Copy the WHOLE output (starting with [debug] Command-line config) and insert it below

Complete Verbose Output

[debug] Command-line config: ['-vU', '--embed-subs', '--sub-langs', 'all', '--convert-subs', 'srt', '--merge', 'mkv', 'https://www.arte.tv/fr/videos/077330-001-A/50-nuances-de-grecs/']
[debug] Encodings: locale UTF-8, fs utf-8, pref UTF-8, out utf-8, error utf-8, screen utf-8
[debug] yt-dlp version 2022.11.11 [8b64402] (linux_exe)
[debug] Python 3.10.6 (CPython x86_64 64bit) - Linux-5.19.0-26-generic-x86_64-with-glibc2.36 (OpenSSL 3.0.7 1 Nov 2022, glibc 2.36)
[debug] exe versions: ffmpeg 5.1.1 (setts), ffprobe 5.1.1
[debug] Optional libraries: Cryptodome-3.15.0, brotli-1.0.9, certifi-2022.09.24, mutagen-1.46.0, sqlite3-2.6.0, websockets-10.4
[debug] Proxy map: {}
[debug] Loaded 1723 extractors
[debug] Fetching release info: https://api.github.com/repos/yt-dlp/yt-dlp/releases/latest
Latest version: 2022.11.11, Current version: 2022.11.11
yt-dlp is up to date (2022.11.11)
[debug] [ArteTV] Extracting URL: https://www.arte.tv/fr/videos/077330-001-A/50-nuances-de-grecs/
[ArteTV] 077330-001-A: Downloading JSON metadata
[ArteTV] 077330-001-A: Downloading m3u8 information
[ArteTV] 077330-001-A: Downloading m3u8 information
[ArteTV] 077330-001-A: Downloading m3u8 information
[debug] Formats sorted by: hasvid, ie_pref, lang, quality, res, fps, hdr:12(7), vcodec:vp9.2(10), channels, acodec, filesize, fs_approx, tbr, vbr, abr, asr, proto, vext, aext, hasaud, source, id
[info] 077330-001-A: Downloading subtitles: fr, de
[debug] Default format spec: bestvideo*+bestaudio/best
[info] 077330-001-A: Downloading 1 format(s): VOF-2320+VOF-program_audio_0-VOF
[info] Writing video subtitles to: Moi, mioches et méchant [077330-001-A].fr.vtt
[debug] Invoking hlsnative downloader on "https://arte-cmafhls.akamaized.net/am/cmaf/077000/077300/077330-001-A/201214144624/medias/077330-001-A_st_VF-MAL.m3u8"
[hlsnative] Downloading m3u8 manifest
[hlsnative] Total fragments: 1
[download] Destination: Moi, mioches et méchant [077330-001-A].fr.vtt
[download] 100% of    7.91KiB in 00:00:00 at 33.82KiB/s
[info] Writing video subtitles to: Moi, mioches et méchant [077330-001-A].de.vtt
[debug] Invoking hlsnative downloader on "https://arte-cmafhls.akamaized.net/am/cmaf/077000/077300/077330-001-A/201214144624/medias/077330-001-A_st_VA-ALL.m3u8"
[hlsnative] Downloading m3u8 manifest
[hlsnative] Total fragments: 1
[download] Destination: Moi, mioches et méchant [077330-001-A].de.vtt
[download] 100% of    1.16KiB in 00:00:00 at 4.37KiB/s
[SubtitlesConvertor] Converting subtitles
[debug] ffmpeg command line: ffmpeg -y -loglevel repeat+info -i 'file:Moi, mioches et méchant [077330-001-A].fr.vtt' -f srt -movflags +faststart 'file:Moi, mioches et méchant [077330-001-A].fr.srt'
[debug] ffmpeg command line: ffmpeg -y -loglevel repeat+info -i 'file:Moi, mioches et méchant [077330-001-A].de.vtt' -f srt -movflags +faststart 'file:Moi, mioches et méchant [077330-001-A].de.srt'
Deleting original file Moi, mioches et méchant [077330-001-A].de.vtt (pass -k to keep)
Deleting original file Moi, mioches et méchant [077330-001-A].fr.vtt (pass -k to keep)
[download] Moi, mioches et méchant [077330-001-A].mkv has already been downloaded
[EmbedSubtitle] Embedding subtitles in "Moi, mioches et méchant [077330-001-A].mkv"
[debug] ffmpeg command line: ffmpeg -y -loglevel repeat+info -i 'file:Moi, mioches et méchant [077330-001-A].mkv' -i 'file:Moi, mioches et méchant [077330-001-A].fr.srt' -i 'file:Moi, mioches et méchant [077330-001-A].de.srt' -map 0 -dn -ignore_unknown -c copy -map -0:s -map 1:0 -metadata:s:s:0 language=fra -map 2:0 -metadata:s:s:1 language=deu -movflags +faststart 'file:Moi, mioches et méchant [077330-001-A].temp.mkv'
[debug] ffmpeg version 5.1.1-1ubuntu1 Copyright (c) 2000-2022 the FFmpeg developers
  built with gcc 12 (Ubuntu 12.2.0-1ubuntu1)
  configuration: --prefix=/usr --extra-version=1ubuntu1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libglslang --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librist --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --disable-sndio --enable-pocketsphinx --enable-librsvg --enable-libmfx --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-libplacebo --enable-shared
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
Input #0, matroska,webm, from 'file:Moi, mioches et méchant [077330-001-A].mkv':
  Metadata:
    COMPATIBLE_BRANDS: iso6mp41
    MAJOR_BRAND     : iso5
    MINOR_VERSION   : 512
    ENCODER         : Lavf59.27.100
  Duration: 00:03:00.48, start: 0.000000, bitrate: 2324 kb/s
  Stream #0:0(eng): Video: h264 (Main), yuv420p(progressive), 1280x720 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 1k tbn (default)
    Metadata:
      HANDLER_NAME    : Mainconcept MP4 Video Media Handler
      VENDOR_ID       : [0][0][0][0]
      DURATION        : 00:03:00.480000000
  Stream #0:1(fra): Audio: aac (LC), 44100 Hz, stereo, fltp (default)
    Metadata:
      HANDLER_NAME    : Mainconcept MP4 Sound Media Handler
      VENDOR_ID       : [0][0][0][0]
      DURATION        : 00:03:00.349000000
file:Moi, mioches et méchant [077330-001-A].fr.srt: Invalid data found when processing input

ERROR: Postprocessing: file:Moi, mioches et méchant [077330-001-A].fr.srt: Invalid data found when processing input
Traceback (most recent call last):
  File "yt_dlp/YoutubeDL.py", line 3276, in process_info
  File "yt_dlp/YoutubeDL.py", line 3453, in post_process
  File "yt_dlp/YoutubeDL.py", line 3435, in run_all_pps
  File "yt_dlp/YoutubeDL.py", line 3414, in run_pp
  File "yt_dlp/postprocessor/common.py", line 24, in run
  File "yt_dlp/postprocessor/common.py", line 129, in wrapper
  File "yt_dlp/postprocessor/ffmpeg.py", line 654, in run
  File "yt_dlp/postprocessor/ffmpeg.py", line 323, in run_ffmpeg_multiple_files
  File "yt_dlp/postprocessor/ffmpeg.py", line 361, in real_run_ffmpeg
yt_dlp.postprocessor.ffmpeg.FFmpegPostProcessorError: file:Moi, mioches et méchant [077330-001-A].fr.srt: Invalid data found when processing

[pukkandan]

Ah, so that's what your issue was. This looks like #4127. Try our custom ffmpeg builds where this is fixed - https://github.com/yt-dlp/FFmpeg-Builds

[ethicnology]

@pukkandan It seems to work with your custom FFmpeg, thank you I can kill my own script.

Why the first subtitle track is enabled by default ?
Is there a way to unset all subtitles tracks by default?
Do you have any idea if your patches will be implemented in official FFmpeg program ?

Actual subtitles merging command:

 ffmpeg -y -loglevel repeat+info -i 'file:Moi, mioches et méchant [077330-001-A].mkv' -i 'file:Moi, mioches et méchant [077330-001-A].fr.srt' -i 'file:Moi, mioches et méchant [077330-001-A].de.srt' -map 0 -dn -ignore_unknown -c copy -map -0:s -map 1:0 -metadata:s:s:0 language=fra -map 2:0 -metadata:s:s:1 language=deu -movflags +faststart 'file:Moi, mioches et méchant [077330-001-A].temp.mkv'

[pukkandan]

Why the first subtitle track is enabled by default ?
Is there a way to unset all subtitles tracks by default?

See #3709 (comment)

Do you have any idea if your patches will be implemented in official FFmpeg program ?

No idea. You can track the issue at https://trac.ffmpeg.org/ticket/8684

[ethicnology]

For posterity

Download source with all available subtitles converted to SubRip (.srt) without any default tracks merged into Matroska container (.mkv)

yt-dlp -vU --embed-subs --sub-langs all --convert-subs srt --ppa "EmbedSubtitle:-disposition:s:0 0" --merge mkv "URL"