I just built the most recent ffmpeg from git (cloned today Jan 23rd) and
when I stream copy an mpeg2 file (see example output below) in some cases
I'm getting a LOT of buffer underflow errors and in all cases (so far) I'm
getting a couple warnings:
[vob @ 0x1dde980] VBV buffer size not set, using default size of 130KB
[vob @ 0x1dde980] Timestamps are unset in a packet for stream 0.
If I use ffmpeg 2.8.5 (output also below), I don't get any buffer
underflow errors or either of the warning messages.
I believe the change that caused the buffer underflow errors and the "VBV
buffer size" warning is in libavformat/mpegenc.c at this point:
https://github.com/FFmpeg/FFmpeg/blob/8bcadaacc2b8dc3c5d6569835a5ca20e62d3efca/libavformat/mpegenc.c
and the change that caused the "Timestamps are unset" warning is in
libavformat/mux.c at this point:
https://github.com/FFmpeg/FFmpeg/blob/8de1ee9f725aa3c550f425bd3120bcd95d5b2ea8/libavformat/mux.c
-------------------------------------------------------------------------------
$ ffmpeg-dev -i clip.mpg -codec copy -f vob clip-copy-dev.mpg
ffmpeg version N-78014-gce855bf Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 4.9.2 (GCC) 20150212 (Red Hat 4.9.2-6)
configuration: --prefix=/usr/local/ffmpeg-master-20160122 --enable-gpl
--enable-version3 --enable-nonfree --disable-static --enable-shared
--disable-debug --enable-libass --enable-libfdk-aac --enable-libfreetype
--enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis
--enable-libvpx --enable-libx264 --enable-libx265 --enable-x11grab
--disable-ffplay --disable-ffserver
libavutil 55. 14.100 / 55. 14.100
libavcodec 57. 22.100 / 57. 22.100
libavformat 57. 22.100 / 57. 22.100
libavdevice 57. 0.100 / 57. 0.100
libavfilter 6. 27.100 / 6. 27.100
libswscale 4. 0.100 / 4. 0.100
libswresample 2. 0.101 / 2. 0.101
libpostproc 54. 0.100 / 54. 0.100
Input #0, mpeg, from 'clip.mpg':
Duration: 00:05:00.01, start: 0.536378, bitrate: 12570 kb/s
Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p(tv), 1920x1080 [SAR
1:1 DAR 16:9], max. 30000 kb/s, 23.98 fps, 23.98 tbr, 90k tbn, 47.95 tbc
Stream #0:1[0x80]: Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
Stream #0:2[0x81]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
[vob @ 0x1a37aa0] 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, vob, to 'clip-copy-dev.mpg':
Metadata:
encoder : Lavf57.22.100
Stream #0:0: Video: mpeg2video, yuv420p, 1920x1080 [SAR 1:1 DAR 16:9],
q=2-31, max. 30000 kb/s, 23.98 fps, 23.98 tbr, 90k tbn, 23.98 tbc
Stream #0:1: Audio: ac3, 48000 Hz, 5.1(side), 448 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[vob @ 0x1a37aa0] Timestamps are unset in a packet for stream 0. This is
deprecated and will stop working in the future. Fix your code to set the
timestamps properly
[vob @ 0x1a37aa0] buffer underflow st=0 bufi=235395 size=237308
[vob @ 0x1a37aa0] packet too large, ignoring buffer limits to mux it
[vob @ 0x1a37aa0] buffer underflow st=0 bufi=235395 size=237308
... [many buffer underflow messages]
[vob @ 0x1a37aa0] buffer underflow st=0 bufi=318458 size=319139
[vob @ 0x1a37aa0] packet too large, ignoring buffer limits to mux it
[vob @ 0x1a37aa0] buffer underflow st=0 bufi=318458 size=319139
frame= 7193 fps=4921 q=-1.0 Lsize= 453204kB time=00:05:00.00
bitrate=12375.5kbits/s speed= 205x
video:431243kB audio:16406kB subtitle:0kB other streams:0kB global
headers:0kB muxing overhead: 1.240936%
$ ffmpeg -i clip.mpg -codec copy -f vob clip-copy-2.8.5.mpg
ffmpeg version 2.8.5 Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 4.9.2 (GCC) 20150212 (Red Hat 4.9.2-6)
configuration: --enable-gpl --enable-version3 --enable-nonfree
--disable-static --enable-shared --disable-debug --enable-libass
--enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264
--enable-libx265 --enable-x11grab --disable-ffplay --disable-ffserver
libavutil 54. 31.100 / 54. 31.100
libavcodec 56. 60.100 / 56. 60.100
libavformat 56. 40.101 / 56. 40.101
libavdevice 56. 4.100 / 56. 4.100
libavfilter 5. 40.101 / 5. 40.101
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 2.101 / 1. 2.101
libpostproc 53. 3.100 / 53. 3.100
Input #0, mpeg, from 'clip.mpg':
Duration: 00:05:00.01, start: 0.536378, bitrate: 12570 kb/s
Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p(tv), 1920x1080 [SAR
1:1 DAR 16:9], max. 30000 kb/s, 23.98 fps, 23.98 tbr, 90k tbn, 47.95 tbc
Stream #0:1[0x80]: Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
Stream #0:2[0x81]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
Output #0, vob, to 'clip-copy-2.8.5.mpg':
Metadata:
encoder : Lavf56.40.101
Stream #0:0: Video: mpeg2video, yuv420p, 1920x1080 [SAR 1:1 DAR 16:9],
q=2-31, max. 30000 kb/s, 23.98 fps, 23.98 tbr, 90k tbn, 23.98 tbc
Stream #0:1: Audio: ac3, 48000 Hz, 5.1(side), 448 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame= 7193 fps=4595 q=-1.0 Lsize= 453204kB time=00:05:00.00
bitrate=12375.5kbits/s
video:431243kB audio:16406kB subtitle:0kB other streams:0kB global
headers:0kB muxing overhead: 1.240936%
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