[MEncoder-users] a/v desync with mencoder that doesn't happen with mplayer -dumpstream

[L. Lee]

I occasionally have to deal with a stream for which audio seems to begin
before video, and MPlayer appears to maintain sync by starting playback at
the point where video enters. When transcoding with MEncoder, I found that I
had to disable  -noskip to allow black frames to be created before entrance
of the video so that sync was maintained. That caused some issues that made
me change other options, because I'm having to perform pullup with encoding,
but it might be worth trying.

Also, because I have to build ffmpeg to build MEncoder now, it's always
available. You can use ffmpeg to offset the sync so you can tell whether the
duration is correct. Here are examples (from
http://lzone.de/fix+async+video+with+ffmpeg)

Make audio 3 seconds later:
ffmpeg -i input.flv -itsoffset 00:00:03.0 -i input.flv -vcodec copy -acodec
copy -map 1:0 -map 0:1 output_shift3s-delay.flv

Make audio 3 seconds earlier:
ffmpeg -i input.flv -itsoffset 00:00:03.0 -i input.flv -vcodec copy -acodec
copy -map 0:1 -map 1:0 output_shift3s-advance.flv

Here's an example for making an iPad (or iPhone) movie's audio about 300
milliseconds earlier:

ffmpeg -i inputmovie.iPad.mp4 -itsoffset 00:00:00.3 -i inputmovie.iPad.mp4
-vcodec copy -acodec copy -map 1:0 -map 0:1
outputmovie.iPad.300ms-advance.mp4

Laine Lee


On 11/7/11 10:23 PM, "Brion Swanson" <deadbeefb5 at gmail.com> wrote:

> On 11/05/2011 08:14 PM, The Wanderer wrote:
>> On 11/05/2011 01:37 PM, Brion Swanson wrote:
>> 
>>> On 11/04/2011 09:33 AM, The Wanderer wrote:
>> 
>>>> Is the size of the desync consistent within any given rip, or does
>>>> it vary
>>>> over time as you let the movie play?
>>> 
>>> It appears consistent but since it's so far off it's hard to tell for
>>> sure if
>>> it's getting farther apart or not.
>> 
>> Yeah, that would be a bit tricky.
>> 
>> Does the MPlayer status line report the difference (in the 'A-V:'
>> value), or
>> does that claim to be in sync? If it does show the difference there,
>> then you
>> could use that to judge whether the desync is varying or not.
>> 
>>>> Do you get the same desync with e.g. ffplay?
>>> 
>>> I'm not sure how to use ffplay to play the DVD directly, but if I
>>> play the
>>> stream.dump file there is no desync (though there is no desync in
>>> mplayer
>>> with that file either).
>> 
>> I meant, do you get the desync when you play the transcoded file using
>> ffplay?
>> 
>> You've answered this in another response. That rules out one
>> possibility, or at
>> least makes it less likely; I've seen at least one case where MPlayer
>> got the
>> frame rate wrong on a particular VFR file (which had apparently been
>> created
>> using MEncoder), but ffplay could handle it just fine.
>> 
>> (I really should get around to putting together a formal report about
>> that.)
>> 
>> Unfortunately, off the top of my head I don't have anything else to
>> suggest,
>> aside from perhaps posting a full console log of at least a playback
>> session and
>> possibly even the actual encoding process. There's no guarantee anyone
>> would be
>> able to help based on that, but it could hardly hurt... though the
>> encoding log
>> would probably be excessively large.
>> 
> Poking around some more on this I found out a few interesting facts:
> 
> 1. specifying -ofps 24000/1001 caused the audio to out of sync behind
> the video instead of in front of it
> 2. specifying -ofps 30000/1001 caused the audio to be very much behind
> the video
> 3. Benchmarking the video without audio (-nosound) did not result in
> errors although allowing the video gave a VC% of about 52% while -vo
> null gave a VC% of about 92% -- I don't know if that's usual or expected
> 4. Playing the video does not produce any significant errors (just a
> couple changes from soft telecine (24000/1) to hard telecine
> (30000/1001) and back
> 5. I tried doing a normal transcoding (instead of -oac copy and -ovc
> copy) and the audio delay was still there (though the video quality was
> considerably lower) and with the same amount of delay
> 6. There was nothing special in the encoding log that I haven't already
> mentioned even when I let it complete.
> 
> Any other ideas you guys might have is appreciated.  This is truly
> baffling to me.
> 
> Here's my OS info:
> 
> brion at lightyear:~$ lsb_release -a
> No LSB modules are available.
> Distributor ID:    Ubuntu
> Description:    Ubuntu 11.10
> Release:    11.10
> Codename:    oneiric
> 
> Here's the output of playing the video straight from the DVD (has no
> audio issues):
> 
> brion at lightyear:~$ mplayer -v dvd://44 -forcedsubsonly
> mplayer: Symbol `ff_codec_bmp_tags' has different size in shared object,
> consider re-linking
> MPlayer SVN-r33713-4.6.1 (C) 2000-2011 MPlayer Team
> CPU vendor name: GenuineIntel  max cpuid level: 10
> CPU: Intel(R) Core(TM)2 Quad CPU    Q6600  @ 2.40GHz (Family: 6, Model:
> 15, Stepping: 11)
> extended cpuid-level: 8
> extended cache-info: 268468288
> Detected cache-line size is 64 bytes
> CPUflags:  MMX: 1 MMX2: 1 3DNow: 0 3DNowExt: 0 SSE: 1 SSE2: 1 SSSE3: 1
> Compiled with runtime CPU detection.
> get_path('codecs.conf') -> '/home/brion/.mplayer/codecs.conf'
> Reading /home/brion/.mplayer/codecs.conf: Can't open
> '/home/brion/.mplayer/codecs.conf': No such file or directory
> Reading /etc/mplayer/codecs.conf: Can't open '/etc/mplayer/codecs.conf':
> No such file or directory
> Using built-in default codecs.conf.
> init_freetype
> Using MMX (with tiny bit MMX2) Optimized OnScreenDisplay
> get_path('fonts') -> '/home/brion/.mplayer/fonts'
> Configuration: --prefix=/usr --confdir=/etc/mplayer --enable-xvmc
> --enable-menu --disable-arts --language=all --disable-libdvdcss-internal
> --disable-dvdread-internal --disable-ffmpeg_a --enable-joystick
> --enable-runtime-cpudetection --enable-debug --enable-mga --enable-3dfx
> --enable-tdfxfb --disable-gui
> CommandLine: '-v' 'dvd://44' '-forcedsubsonly'
> Using nanosleep() timing
> get_path('input.conf') -> '/home/brion/.mplayer/input.conf'
> Can't open input config file /home/brion/.mplayer/input.conf: No such
> file or directory
> Parsing input config file /etc/mplayer/input.conf
> Input config file /etc/mplayer/input.conf parsed: 92 binds
> Setting up LIRC support...
> mplayer: could not connect to socket
> mplayer: No such file or directory
> Failed to open LIRC support. You will not be able to use your remote
> control.
> get_path('44.conf') -> '/home/brion/.mplayer/44.conf'
> 
> Playing dvd://44.
> get_path('sub/') -> '/home/brion/.mplayer/sub/'
> URL: dvd://44
> libdvdread: Using libdvdcss version 1.2.10 for DVD access
> Reading disc structure, please wait...
> There are 99 titles on this DVD.
> There are 1 angles in this DVD title.
> 
> libdvdread: Attempting to retrieve all CSS keys
> libdvdread: This can take a _long_ time, please be patient
> 
> libdvdread: Get key for /VIDEO_TS/VIDEO_TS.VOB at 0x00006a12
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_01_0.VOB at 0x00006ca7
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_01_1.VOB at 0x000071e7
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_02_0.VOB at 0x00007209
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_02_1.VOB at 0x0000728c
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_03_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_03_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_04_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_04_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_05_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_05_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_06_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_06_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_07_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_07_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_08_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_08_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_09_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_09_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_10_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_10_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_11_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_11_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_12_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_12_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_13_0.VOB at 0x0000757e
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_13_1.VOB at 0x0000f2b8
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_14_0.VOB at 0x001efdb0
> libdvdread: Elapsed time 0
> libdvdread: Get key for /VIDEO_TS/VTS_14_1.VOB at 0x001f2425
> libdvdread: Elapsed time 0
> libdvdread: Found 14 VTS's
> libdvdread: Elapsed time 0
> 
> DVD successfully opened.
> audio stream: 0 format: ac3 (5.1) language: en aid: 128.
> number of audio channels on disk: 1.
> subtitle ( sid ): 1 language: en
> subtitle ( sid ): 3 language: fr
> subtitle ( sid ): 5 language: es
> subtitle ( sid ): 7 language: pt
> number of subtitles on disk: 4
> 
> DVD start cell: 0  pack: 0x1010-0x2432
> DVD start=4112 end=1968350
> STREAM: [null] dvd://44
> STREAM: Description: DVD stream
> STREAM: Author:
> STREAM: Comment:
> DVD Seek! lba=0x1010  cell=0  packs: 0x1010-0x2432
> Angle-seek synced by cell/vob IDN search!
> system stream synced at 0x80800D (8421389)!
> ==> Found video stream: 0
> MPEG-PS file format detected.
> ==> Found subtitle: 0
> ==> Found subtitle: 1
> ==> Found subtitle: 2
> ==> Found subtitle: 3
> ==> Found subtitle: 4
> ==> Found subtitle: 5
> ==> Found subtitle: 6
> ==> Found subtitle: 7
> ==> Found audio stream: 128
> Searching for sequence header... OK!
> VIDEO:  MPEG2  720x480  (aspect 3)  29.970 fps  9800.0 kbps (1225.0 kbyte/s)
> [V] filefmt:2  fourcc:0x10000002  size:720x480  fps:29.970  ftime:=0.0334
> get_path('sub/') -> '/home/brion/.mplayer/sub/'
> open: No such file or directory
> [MGA] Couldn't open: /dev/mga_vid
> open: No such file or directory
> [MGA] Couldn't open: /dev/mga_vid
> [VO_TDFXFB] Can't open /dev/fb0: Permission denied.
> [VO_3DFX] Unable to open /dev/3dfx.
> X11 opening display: :0
> vo: X11 color mask:  FFFFFF  (R:FF0000 G:FF00 B:FF)
> vo: X11 running at 3600x1080 with depth 24 and 32 bpp (":0" => local
> display)
> [x11] Detected wm supports NetWM.
> [x11] Detected wm supports FULLSCREEN state.
> [x11] Detected wm supports ABOVE state.
> [x11] Detected wm supports BELOW state.
> [x11] Current fstype setting honours FULLSCREEN ABOVE BELOW X atoms
> Disabling DPMS
> DPMSDisable stat: 1
> ==========================================================================
> Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
> INFO: libavcodec init OK!
> Selected video codec: [ffmpeg2] vfm: ffmpeg (FFmpeg MPEG-2)
> ==========================================================================
> ==========================================================================
> Opening audio decoder: [ffmpeg] FFmpeg/libavcodec audio decoders
> dec_audio: Allocating 192000 + 65536 = 257536 bytes for output buffer.
> FFmpeg's libavcodec audio codec
> INFO: libavcodec "ac3" init OK!
> AUDIO: 48000 Hz, 2 ch, s16le, 448.0 kbit/29.17% (ratio: 56000->192000)
> Selected audio codec: [ffac3] afm: ffmpeg (FFmpeg AC-3)
> ==========================================================================
> Building audio filter chain for 48000Hz/2ch/s16le -> 0Hz/0ch/??...
> [libaf] Adding filter dummy
> [dummy] Was reinitialized: 48000Hz/2ch/s16le
> [dummy] Was reinitialized: 48000Hz/2ch/s16le
> Trying preferred audio driver 'pulse', options '[none]'
> AO: [pulse] 48000Hz 2ch s16le (2 bytes per sample)
> AO: Description: PulseAudio audio output
> AO: Author: Lennart Poettering
> Building audio filter chain for 48000Hz/2ch/s16le -> 48000Hz/2ch/s16le...
> [dummy] Was reinitialized: 48000Hz/2ch/s16le
> [dummy] Was reinitialized: 48000Hz/2ch/s16le
> Starting playback...
> Increasing filtered audio buffer size from 0 to 50048
> Unsupported PixelFormat 61
> Unsupported PixelFormat 53
> [ffmpeg] aspect_ratio: 1.777778
> VDec: vo config request - 720 x 480 (preferred colorspace: Planar YV12)
> Trying filter chain: vo
> VDec: using Planar YV12 as output csp (no 0)
> Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
> VO Config (720x480->854x480,flags=0,'MPlayer',0x32315659)
> VO: [vdpau] 720x480 => 854x480 Planar YV12
> VO: Description: VDPAU with X11
> VO: Author: Rajib Mahapatra <rmahapatra at nvidia.com> and others
> [vdpau] Updating CSC matrix for BT.601
> *** [vo] Allocating mp_image_t, 720x480x12bpp YUV planar, 518400 bytes
> [mpeg2video @ 0x7fa4ed8404c0]qscale == 0
> [mpeg2video @ 0x7fa4ed8404c0]Warning MVs not available
> [mpeg2video @ 0x7fa4ed8404c0]concealing 1035 DC, 1035 AC, 1035 MV errors
> DVD sub: len=66  v_pts=0.033  s_pts=0.183  ts=16483
> *** [vo] Allocating mp_image_t, 720x480x12bpp YUV planar, 518400 bytes
> Unicode font: 5179 glyphs.
> Unicode font: 5179 glyphs.
> A:   0.5 V:   0.2 A-V:  0.246 ct:  0.003   3/  3 ??% ??% ??,?% 2 0
> *** [vo] Allocating mp_image_t, 720x480x12bpp YUV planar, 518400 bytes
> A:   0.6 V:   0.6 A-V:  0.008 ct:  0.014  13/ 11 ??% ??% ??,?% 4 0
> 
> demux_mpg: 24000/1001fps progressive NTSC content detected, switching
> framerate.
> A:   1.9 V:   1.9 A-V:  0.001 ct:  0.032  45/ 42 10%  7%  0.7% 4 0
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