SOLVED: Audio out of sync or no audio - mkv/h.264 to avi/xvid

[dwoozle]

I tried to solve this since few days with no luck so far, so please help...

I have a mkv HD file (720p) with video encoded in h.264 format and 5.1 audio in DTS format. What I need is an avi file, the same resolution, video encoded in xvid (or divx), 5.1 audio preferably untouched (DTS) or converted to AC3 if it's not possible. But 5.1, not stereo mp3.

I'm on linux so I worked only with mencoder so far. The first try was:

mencoder movie.mkv -ffourcc XVID -ovc lavc -lavcopts vcodec=mpeg4:threads=8:vbitrate=3000 -oac copy -o movie.avi

Video of the resulting file seems all right, but I get lots of "Skipping frame" errors from mencoder during encoding (like every 2 seconds) and audio (it's DTS all right) goes out of sync after a while.


I also found some option (googling) to get rid of this "skipping frame" errors. The result was an xvid/dts avi file, with audio much more out of sync, than before.


Then I tried to reencode dts into ac3 with this command:

mencoder movie.mkv -ffourcc XVID -ovc lavc -lavcopts vcodec=mpeg4:threads=8:vbitrate=3000 -oac lavc -lavcopts acodec=ac3:abitrate=384 -channels 6 -o movie.avi

Video was all right again, but there is no sound at all when I watch the movie. Media info tool and "codec info" from VLC say there os 5.1 AC3 sound, but can I hear no sound at all.

I also tried:

mencoder movie.mkv -ffourcc XVID -ovc lavc -lavcopts vcodec=mpeg4:threads=8:vbitrate=3000:cmp=2ubcmp=2:trell=yes:v4mv=yes:mbd=2 -oac lavc -lavcopts acodec=ac3:abitrate=384 -channels 6 -af channels=6:6:0:0:4:1:1:2:2:3:3:4:5:5 -o movie.avi

with the same result.


Any ideas?


Edit1: as far as I can tell there is no variable framerate or bitrate anywhere in the input file involved - see output of the MediaInfo below.

Edit2: here info about input file (output from MediaInfo):

General 
Count : 246 
Count of stream of this kind : 1 
Kind of stream : General 
Kind of stream : General 
Stream identifier : 0 
Inform : 
Matroska: 4.37 GiB, 1h 28mn 
Count of video streams : 1 
Count of audio streams : 1 
Video_Format_List : AVC 
Video_Format_WithHint_List : AVC 
Codecs Video : AVC 
Video_Language_List : English 
Audio_Format_List : DTS 
Audio_Format_WithHint_List : DTS 
Audio codecs : DTS 
Complete name : ***
Folder name : ***
File name : ***
File extension : mkv 
Format : Matroska 
Format/Url : http://packs.matroska.org/ 
Format/Extensions usually used : mkv mka mks 
Codec : Matroska 
Codec/Url : http://packs.matroska.org/ 
Codec/Extensions usually used : mkv mka mks 
File size : 4695226405 
File size : 4.37 GiB 
File size : 4 GiB 
File size : 4.4 GiB 
File size : 4.37 GiB 
File size : 4.373 GiB 
Duration : 5309313 
Duration : 1h 28mn 
Duration : 1h 28mn 29s 313ms 
Duration : 1h 28mn 
Duration : 01:28:29.313 
Overall bit rate : 7074702 
Overall bit rate : 7 075 Kbps 
Encoded date : UTC 2008-06-17 22:21:16 
Writing application : mkvmerge v2.2.0 ('Turn It On Again') built on Mar 4 2008 12:58:26 
Writing library : libebml v0.7.7 + libmatroska v0.8.1 
Writing library : libebml v0.7.7 + libmatroska v0.8.1 

Video 
Count : 134 
Count of stream of this kind : 1 
Kind of stream : Video 
Stream identifier : 0 
Inform : English, 5 250 Kbps (5 562 Kbps), 1280*544 (2.35), at 23.976 fps, AVC (Container profile=Unknown@5.1) (High@L5.1) (CABAC / 5 Ref Frames) 
ID : 1 
ID : 1 
UniqueID : 1 
Format : AVC 
Format/Info : Advanced Video Codec 
Format/Url : http://developers.videolan.org/x264.html 
Format profile : High@L5.1 
Format settings : CABAC / 5 Ref Frames 
Format settings, CABAC : Yes 
Format settings, CABAC : Yes 
Format settings, ReFrames : 5 
Format settings, ReFrames : 5 frames 
Muxing mode : Container profile=Unknown@5.1 
Codec ID : V_MPEG4/ISO/AVC 
Codec ID/Url : http://ffdshow-tryout.sourceforge.net/ 
Codec : V_MPEG4/ISO/AVC 
Codec : AVC 
Codec/Family : AVC 
Codec/Info : Advanced Video Codec 
Codec/Url : http://ffdshow-tryout.sourceforge.net/ 
Codec profile : High@L5.1 
Codec settings : CABAC / 5 Ref Frames 
Codec settings, CABAC : Yes 
Codec_Settings_RefFrames : 5 
Duration : 5304000 
Duration : 1h 28mn 
Duration : 1h 28mn 24s 0ms 
Duration : 1h 28mn 
Duration : 01:28:24.000 
Bit rate : 5249684 
Bit rate : 5 250 Kbps 
Nominal bit rate : 5562000 
Nominal bit rate : 5 562 Kbps 
Width : 1280 
Width : 1 280 pixels 
Height : 544 
Height : 544 pixels 
Pixel Aspect Ratio : 1.000 
Display aspect ratio : 2.353 
Display aspect ratio : 2.35 
Frame rate : 23.976 
Frame rate : 23.976 fps 
Frame count : 127296 
Resolution : 24 
Resolution : 24 bits 
Colorimetry : 4:2:0 
Scan type : Progressive 
Scan type : Progressive 
Interlacement : PPF 
Interlacement : Progressive 
Bits/(Pixel*Frame) : 0.314 
Delay : 0 
Writing library : x264 - core 60 r886 1075536 
Writing library : x264 core 60 r886 1075536 
Writing library/Name : x264 
Writing library/Version : core 60 r886 1075536 
Encoding settings : cabac=1 / ref=5 / deblock=1:0:0 / analyse=0x3:0x113 / me=umh / subme=7 / brdo=1 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / chroma_qp_offset=0 / threads=6 / nr=0 / decimate=1 / mbaff=0 / bframes=3 / b_pyramid=1 / b_adapt=1 / b_bias=0 / direct=1 / wpredb=1 / bime=1 / keyint=250 / keyint_min=25 / scenecut=40(pre) / rc=2pass / bitrate=5562 / ratetol=1.0 / rceq='blurCplx^(1-qComp)' / qcomp=1.00 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / pb_ratio=1.30 / aq=2:1.00 
Language : en 
Language : English 

Audio 
Count : 121 
Count of stream of this kind : 1 
Kind of stream : Audio 
Kind of stream : Audio 
Stream identifier : 0 
Inform : 1 536 Kbps, 48.0 KHz, 6 channels, DTS 
ID : 2 
ID : 2 
UniqueID : 2708952726 
Format : DTS 
Format/Info : Digital Theater Systems 
Codec ID : A_DTS 
Codec : DTS 
Codec : DTS 
Duration : 5309313 
Duration : 1h 28mn 
Duration : 1h 28mn 29s 313ms 
Duration : 1h 28mn 
Duration : 01:28:29.313 
Bit rate mode : CBR 
Bit rate mode : Constant 
Bit rate : 1536000 
Bit rate : 1 536 Kbps 
Channel(s) : 6 
Channel(s) : 6 channels 
Channel positions : Front: L C R, Surround: L R, LFE 
Channel positions : 3/2.1 
Sampling rate : 48000 
Sampling rate : 48.0 KHz 
SamplingCount : 254847024 
Resolution : 24 
Resolution : 24 bits 
Delay : 0 
Video delay : 0 
Video0 delay : 0

[poisondeathray]

On linux, you could try avidemux, with the dts addon

http://www.avidemux.org/admForum/viewtopic.php?pid=18985#p18985

If you have access to Windows, there are many more options

[dwoozle]

On linux, you could try avidemux, with the dts addon

http://www.avidemux.org/admForum/viewtopic.php?pid=18985#p18985

If you have access to Windows, there are many more options

Thanks for your advice, poisondeathray.

I tried avidemux (had to compile it from sources to enable dts library under linux), but for some reason it recognizes only 2 channels in the input DTS stream. But MediaInfo, says it's 6 channel DTS. Any ideas why?

Video conversion (h.264->xvid) works as expected, AC3 sound in the output file can be heard, but there are only 2 channels available...

[dwoozle]

It seems I found the solution, so I post it here in case somebody has similar problems.

I managed to transcode my mkv/h.264/dts video to avi/xvid/dts using mencoder without reencoding audio (just copying the audio stream) and without these strange a/v out of sync problems.

Here my understanding, what caused the problems. Somebody correct me if I got it wrong...
The original video was encoded with the standard 23.976 fps. At least this is what MediaInfo and media players displayed. But it seems this value was read just from some file/container header and the real framerate was a bit higher (slightly above 24 fps). Hence the "skipping frame" warnings every 2 seconds from mencoder. Mencoder tried to encode in the same framerate it believed the source material was (23.976 fps), but there was more frames per second in the actual video stream. Automatic skipping of frames tried to remedy the problem, but was inaccurate and after a while the sound went out of sync.

And here the solution. I used -ofps option of mencoder to set fps of the output video to the right value. I found it by trial&error - the goal was to achieve encoding process without "skipping frame" or "duplicate frame" (the opposite) warnings. The right value I found at last was 24.405 fps, which is pretty strange (not one of the standard fps values), but works for this particular file like charm. No a/v out of sync issues at all anymore.

So... here the command I used for reference:

mencoder input.mkv -noodml -ofps 240000/9834 -ffourcc XVID -ovc lavc -lavcopts vcodec=mpeg4:threads=8:vbitrate=4000:cmp=2:subcmp=2:trell=yes:v4mv=yes:mbd=2 -oac copy -channels 6 -o output.avi

The -ofps value is good only for my particular strange input file of course. Mostly the standard values (23.976 fps, 25 fps etc.) should work I think - so no -ofps setting needed here. If not, the right value has to be found by trial&error again.