[MEncoder-users] How to convert mkv to mkv?

[Carlo Wood]

On Wed, Jun 27, 2007 at 09:39:46PM -0700, RC wrote:
> On Thu, 28 Jun 2007 05:47:40 +0200
> Carlo Wood <carlo at alinoe.com> wrote:
> 
> > In documentation I read it said that using -noskip is recommended if
> > you want to be sure that there is no audio desync,
> 
> Exactly where did it say that?  Section # ?  Exact quote?

I had this from

http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-dvd-mpeg4.html

  Paragraph 14.1.9. Notes on Audio/Video synchronization

  MEncoder's audio/video synchronization algorithms were designed with the
  intention of recovering files with broken sync. However, in some cases
  they can cause unnecessary skipping and duplication of frames, and
  possibly slight A/V desync, when used with proper input (of course, A/V
  sync issues apply only if you process or copy the audio track while
  transcoding the video, which is strongly encouraged). Therefore, you may
  have to switch to basic A/V sync with the -mc 0 option, or put this in
  your ~/.mplayer/mencoder config file, as long as you are only working
  with good sources (DVD, TV capture, high quality MPEG-4 rips, etc) and
  not broken ASF/RM/MOV files.

  If you want to further guard against strange frame skips and
  duplication, you can use both -mc 0 and -noskip. This will prevent all
  A/V sync, and copy frames one-to-one, so you cannot use it if you will
  be using any filters that unpredictably add or drop frames, or if your
  input file has variable framerate! Therefore, using -noskip is not in
  general recommended.


All I do is cropping and resizing: I want both - the audio and the video
frame rate unchanged. Therefore -mc 0 -noskip is what I need to "guard
against strange frame skips and duplication". It does "copy frames
one-to-one", which is precisely what I want.

But, I guess that the resizing and using a multi-pass, not to mention
that the input file has a variable framerate, does make the framerate
change a bit here and there... I missed the phrase "or if your input
file has variable framerate". I'll try it again with just -mc 0.

Just using -mc 0 gives the same thing:

[...]
1 duplicate frame(s)!
Pos: 130.8s   3138f ( 1%) 12.89fps Trem: 224min 3074mb  A-V:0.000 [3374:127]
Too many audio packets in the buffer: (3277 in 8389120 bytes).
Maybe you are playing a non-interleaved stream/file or the codec failed?
For AVI files, try to force non-interleaved mode with the -ni option.

Flushing video frames.
Writing index...
Writing header...
ODML: vprp aspect is 16384:6898.
Setting audio delay to 0.096s.

Video stream: 3373.413 kbit/s  (421676 B/s)  size: 55189345 bytes  130.881 secs  3138 frames

Audio stream:  128.000 kbit/s  (15999 B/s)  size: 2104320 bytes  131.520 secs
x264 [info]: slice I:23    Avg QP:10.61  size: 25541
x264 [info]: slice P:1613  Avg QP:11.56  size: 22815
x264 [info]: slice B:1500  Avg QP:12.50  size: 11867
x264 [info]: mb I  I16..4: 38.9% 30.5% 30.7%
x264 [info]: mb P  I16..4:  6.7%  8.7%  6.1%  P16..4: 33.1% 17.0%  9.7%  4.3%  3.5%    skip:11.0%
x264 [info]: mb B  I16..4:  1.4%  1.0%  1.0%  B16..8: 23.3%  5.4% 19.3%  direct:17.0%  skip:31.5%
x264 [info]: final ratefactor: 7.70
x264 [info]: 8x8 transform  intra:38.7%  inter:26.3%
x264 [info]: ref P  73.3% 12.6%  6.5%  4.1%  3.4%
x264 [info]: ref B  76.2% 12.9%  5.2%  3.2%  2.5%
x264 [info]: kb/s:3375.5

How can I get it to use mpg4, like the original, instead of avi?

-- 
Carlo Wood <carlo at alinoe.com>