[FFmpeg-user] Some inputs make MP4 output sync incompatible with other applications

[Francois Visagie]

> -----Original Message-----
> From: ffmpeg-user-bounces at ffmpeg.org [mailto:ffmpeg-user-
> bounces at ffmpeg.org] On Behalf Of Carl Eugen Hoyos
> Sent: 23 August 2013 15:34
> To: ffmpeg-user at ffmpeg.org
> Subject: Re: [FFmpeg-user] Some inputs make MP4 output sync
> incompatible with other applications
> 
> Why do you think "-async 1" is deprecated? 

>From http://www.ffmpeg.org/ffmpeg-all.html:

'-async samples_per_second'
    ...
    This option has been deprecated. Use the aresample audio filter instead.

> > Out of sync for other applications:
> >
> > ffmpeg -i VTS_01_1.cut.VOB -filter:a
> > aformat=channel_layouts=stereo -c:a libvo_aacenc -c:v libx264 -preset
> > ultrafast -b:v 1000000 zzz.mp4
> >
> > In sync for other applications:
> >
> > ffmpeg -i VTS_01_1.cut.VOB -filter:a
> > aformat=channel_layouts=stereo -c:a libvo_aacenc -c:v libx264 -preset
> > ultrafast -b:v 1000000 zzz.mpg
> 
> (Difficult to see a difference.)

There's a very clear difference in output.

> There have been reports that libvo_aacenc produces worse results than the
> native encoder and should not be used.

By native do you mean the "experimental aac" codec below (from the Zeranoe
builds)? I.e. using it requires '-strict -2'?

C:\Users\fvisagie\Videos\My DVDs\MainMovie\Roxette Live in Sydney -
1991\VIDEO_TS\TESTSYNCCUT>ffmpeg -i VTS_01_1.cut.VOB -filter:a
aformat=channel_layouts=stere
o -c:a aac -c:v libx264 -preset ultrafast -b:v 1000000 zzz.mp4
ffmpeg version N-55159-gf118b41 Copyright (c) 2000-2013 the FFmpeg
developers
  built on Aug  1 2013 18:01:57 with gcc 4.7.3 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads
--enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r
--enable-gnutls --enab
le-iconv --enable-libass --enable-libbluray --enable-libcaca
--enable-libfreetype --enable-libgsm --enable-libilbc --enable-libmodplug
--enable-libmp3lame --ena
ble-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
--enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr
--enable-libsp
eex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc
--enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264
--enable-libxavs --
enable-libxvid --enable-zlib
  libavutil      52. 40.100 / 52. 40.100
  libavcodec     55. 19.100 / 55. 19.100
  libavformat    55. 12.102 / 55. 12.102
  libavdevice    55.  3.100 / 55.  3.100
  libavfilter     3. 82.100 /  3. 82.100
  libswscale      2.  4.100 /  2.  4.100
  libswresample   0. 17.103 /  0. 17.103
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mpeg, from 'VTS_01_1.cut.VOB':
  Duration: 00:01:12.11, start: 0.060000, bitrate: 7840 kb/s
    Stream #0:0[0x1bf]: Data: dvd_nav_packet
    Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x480 [SAR 8:9
DAR 4:3], max. 6000 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
    Stream #0:2[0x8a]: Audio: dts (DTS), 48000 Hz, 5.1(side), fltp, 1536
kb/s
    Stream #0:3[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
File 'zzz.mp4' already exists. Overwrite ? [y/N] y
[libx264 @ 002e2b60] using SAR=8/9
[libx264 @ 002e2b60] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 002e2b60] profile Constrained Baseline, level 3.0
[libx264 @ 002e2b60] 264 - core 135 r2345 f0c1c53 - H.264/MPEG-4 AVC codec -
Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: cabac=0
ref=1 deb
lock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0
me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1
chroma_qp_
offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1
interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0
keyint=250 keyint_m
in=25 scenecut=0 intra_refresh=0 rc=abr mbtree=0 bitrate=1000 ratetol=1.0
qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
[aac @ 002e2f40] The encoder 'aac' is experimental but experimental codecs
are not enabled, add '-strict -2' if you want to use it.
[aac @ 002e2f40] Alternatively use the non experimental encoder
'libvo_aacenc'.