[FFmpeg-trac] #7183(undetermined:new): Concat very slow with dvd_subtitles
FFmpeg
trac at avcodec.org
Wed May 2 21:35:37 EEST 2018
#7183: Concat very slow with dvd_subtitles
-------------------------------------+-------------------------------------
Reporter: oerg866 | Type: defect
Status: new | Priority: normal
Component: | Version:
undetermined | unspecified
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
Summary of the bug:
FFMPEG will process concatenation of vob files with subtitles agonizingly
slowly (less than real time speed on my i9-7900x with stream copy!) and
the progress display is erratic.
How to reproduce:
{{{
ffmpeg f concat -safe 0 -i list.txt -vcodec copy -acodec pcm_s16be -scodec
copy mux.vob
}}}
list.txt contains several vob files with MPEG2 video, LPCM audio and
subtitles.
Separate concat with several files that have video, audio and subtitles
and then remuxing to a final output works infinitely faster, like so:
{{{
ffmpeg -f concat -safe 0 -i list.txt -vcodec copy -acodec pcm_s16be
mux1.vob
ffmpeg -f concat -safe 0 -i list.txt -vn -an -scodec copy mux2.vob
ffmpeg -i mux1.vob -i mux2.vob -map 0:v -map 0:a -map 1:s -vcodec copy
-acodec pcm_s16be -scodec copy mux.vob
}}}
HOWEVER, this breaks subtitle timing (they play about two seconds too
early. Also potential bug?)
Below is a sample of ffmpeg's console output with the buggy command.
{{{
C:\OUTPUT>ffmpeg -f concat -safe 0 -i list.txt -vcodec copy -acodec
pcm_s16be -scodec copy mux.vob
ffmpeg version N-86691-gc885356 Copyright (c) 2000-2017 the FFmpeg
developers
built with gcc 7.1.0 (GCC)
configuration: --enable-gpl --enable-version3 --enable-cuda --enable-
cuvid --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-nvenc
--enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r
--enable-gnutls --enable-iconv --enable-libass --enable-libbluray
--enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme
--enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame
--enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264
--enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsnappy
--enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame
--enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-
libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-
libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma
--enable-zlib
libavutil 55. 67.100 / 55. 67.100
libavcodec 57.100.103 / 57.100.103
libavformat 57. 75.100 / 57. 75.100
libavdevice 57. 7.100 / 57. 7.100
libavfilter 6. 94.100 / 6. 94.100
libswscale 4. 7.101 / 4. 7.101
libswresample 2. 8.100 / 2. 8.100
libpostproc 54. 6.100 / 54. 6.100
Guessed Channel Layout for Input Stream #0.1 : stereo
Input #0, concat, from 'list.txt':
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Video: mpeg2video (Main), yuv420p(tv, bottom first),
720x576 [SAR 16:15 DAR 4:3], 25 fps, 25 tbr, 90k tbn, 90k tbc
Stream #0:1: Audio: pcm_dvd, 48000 Hz, stereo, s16, 1536 kb/s
Stream #0:2: Subtitle: dvd_subtitle
File 'mux.vob' already exists. Overwrite ? [y/N] y
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (pcm_dvd (native) -> pcm_s16be (native))
Stream #0:2 -> #0:2 (copy)
Press [q] to stop, [?] for help
[svcd @ 0000000004928b60] VBV buffer size not set, using default size of
130KB
If you want the mpeg file to be compliant to some specification
Like DVD, VCD or others, make sure you set the correct buffer size
Output #0, svcd, to 'mux.vob':
Metadata:
encoder : Lavf57.75.100
Stream #0:0: Video: mpeg2video (Main), yuv420p(tv, bottom first),
720x576 [SAR 16:15 DAR 4:3], q=2-31, 25 fps, 25 tbr, 90k tbn, 90k tbc
Stream #0:1: Audio: pcm_s16be, 48000 Hz, stereo, s16, 1536 kb/s
Metadata:
encoder : Lavc57.100.103 pcm_s16be
Stream #0:2: Subtitle: dvd_subtitle
frame= 2003 fps=159 q=-1.0 size= 944kB time=00:01:20.04 bitrate=
96.6kbits/s speed=6.34x
}}}
--
Ticket URL: <https://trac.ffmpeg.org/ticket/7183>
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