[FFmpeg-trac] #6947(undetermined:new): Unwanted visual formatting added when embedding subtitles
FFmpeg
trac at avcodec.org
Fri Jan 5 14:59:39 EET 2018
#6947: Unwanted visual formatting added when embedding subtitles
-------------------------------------+-------------------------------------
Reporter: forthrin | Type: defect
Status: new | Priority: normal
Component: | Version:
undetermined | unspecified
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
When playing an MP4 file with embedded subtitles in VLC, the subtitles are
shown as specified by the user in VLC's subtitle preferences, but *not*
"Font colour" and "Opacity".
After discussing this with the VLC team, it may seem like FFmpeg secretly
applies font colour and opacity when embedding the subtitles.
{{{
$ cat a.srt
1
00:00:00,000 --> 00:10:00,000
The quick brown fox jumps
over the lazy dog.
$ ffmpeg -i a.mp4 -i a.srt -vcodec copy -scodec mov_text b.mp4
}}}
{{{
$ ffmpeg -i b.mp4 b.srt
$ cat b.srt
1
00:00:00,000 --> 00:09:56,459
<font face="Serif" size="18">The quick brown fox jumps
over the lazy dog.</font>
}}}
According to this, FFmpeg applies "Font face" and "Font size", but not
"Font colour" and "Opacity". Strange...
Anyway, unless the tx3g/mov_text format *requires* visual formatting, it
seems most correct that a plain text subtitle is embedded *as-is*, eg.
without any applied formatting, leaving all formatting to the video
player.
Please give insight how the subtitle embedding works, and how to embed
subtitles without visual formatting.
ffmpeg 3.4.1 (macOS/Homebrew)
--
Ticket URL: <https://trac.ffmpeg.org/ticket/6947>
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