#9409: Embedding some mp4 subtitles causes ffmpeg to hang -------------------------------------+------------------------------------- Reporter: Frank | Owner: (none) Type: defect | Status: new Priority: normal | Component: | undetermined Version: git-master | Resolution: Keywords: subtitles | Blocked By: Blocking: | Reproduced by developer: 0 Analyzed by developer: 0 | -------------------------------------+------------------------------------- Description changed by Frank: Old description:

I've run into a bug when trying to embed some subtitles into an MP4 file, ffmpeg hangs indefinitely with 100% cpu usage on one thread. When this happens the output file stops growing and what is usually a few seconds job simply does not finish even if left for hours.

This only started happening recently with some videos downloaded from youtube-dl. I've tested this and it seems to be an issue with the latest version of every 4.x branch - 4.0.6, 4.1.6, 4.2.4, 4.3.2, and the latest git build. ffmpeg completes if I try this with the latest 3.4.8 branch, but the subtitles are broken and do not appear when selected.

Since I'm not sure where the problem is in the subtitle I can't cut out the problem part here for an example. I will attach one of the subtitle files that causes the issue and include the youtube-dl command that will download the smallest video.

youtube-dl command: {{{ youtube-dl.exe -v -f 160+249 --merge-output-format mp4 --sub-lang bn --write-auto-sub --embed-subs 0UlUbeaBCTg }}}

ffmpeg command being run by youtube-dl: {{{ ffmpeg -y -loglevel "repeat+info" -i "file:Making Flavored Rum _ Easy and Cheap! - Part 1-0UlUbeaBCTg.mp4" -i "file:Making Flavored Rum _ Easy and Cheap! - Part 1-0UlUbeaBCTg.bn.vtt" -map 0 -c copy -map "-0:s" -map "-0:d" "-c:s" mov_text -map "1:0" "-metadata:s:s:0" "language=ben" "file:Making Flavored Rum _ Easy and Cheap! - Part 1-0UlUbeaBCTg.temp.mp4" }}}

New description: I've run into a bug when trying to embed some subtitles into an MP4 file, ffmpeg hangs indefinitely with 100% cpu usage on one thread. When this happens the output file stops growing and what is usually a few seconds job simply does not finish even if left for hours. This only started happening recently with some videos downloaded from youtube-dl, including some that worked before with no changes in my ffmpeg version, so I think youtube must've change the way they write their subs. Additionally I've tested this and it seems to be an issue with the latest version of every 4.x branch - 4.0.6, 4.1.6, 4.2.4, 4.3.2, and the latest git build. ffmpeg does complete without errors if I try this with the latest 3.4.8 branch, but the subtitles are broken and do not appear when selected during playback. Since I'm not sure where the problem is in the subtitle I can't cut out the problem part of the video and attach it for an example since it's too big. I will attach one of the subtitle files that causes the issue and include the youtube-dl command that will download the smallest version of the video. youtube-dl command: {{{ youtube-dl.exe -v -f 160+249 --merge-output-format mp4 --sub-lang bn --write-auto-sub --embed-subs 0UlUbeaBCTg }}} ffmpeg command being run by youtube-dl: {{{ ffmpeg -y -loglevel "repeat+info" -i "file:Making Flavored Rum _ Easy and Cheap! - Part 1-0UlUbeaBCTg.mp4" -i "file:Making Flavored Rum _ Easy and Cheap! - Part 1-0UlUbeaBCTg.bn.vtt" -map 0 -c copy -map "-0:s" -map "-0:d" "-c:s" mov_text -map "1:0" "-metadata:s:s:0" "language=ben" "file:Making Flavored Rum _ Easy and Cheap! - Part 1-0UlUbeaBCTg.temp.mp4" }}} -- -- Ticket URL: <https://trac.ffmpeg.org/ticket/9409#comment:1> FFmpeg <https://ffmpeg.org> FFmpeg issue tracker

#9409: Embedding some mp4 subtitles causes ffmpeg to hang -------------------------------------+------------------------------------- Reporter: Frank | Owner: (none) Type: defect | Status: open Priority: important | Component: avcodec Version: git-master | Resolution: Keywords: subtitles | Blocked By: regression | Blocking: | Reproduced by developer: 1 Analyzed by developer: 0 | -------------------------------------+------------------------------------- Changes (by mkver): * keywords: subtitles => subtitles regression -- Ticket URL: <https://trac.ffmpeg.org/ticket/9409#comment:3> FFmpeg <https://ffmpeg.org> FFmpeg issue tracker