Re: [Encode2mpeg-users] encoding for the Philips DVP642

[Giacomo C. <enc...@us...>]

On Tue, Nov 08, 2005 at 09:16:36PM -0800, Adam Monsen wrote:
> Finally got around to this; sorry it took me so long to respond.
> 
> On 10/31/05, Giacomo Comes <enc...@us... > wrote:
> [...]
> 
> > I do not have a simple answer to your doubts. For the moment I'm busy
> > working on the next relase of encode2mpeg. It should be ready in about two
> > weeks. After the next relase I will concentrate on DivX Mode and find a way
> > to make your player work.
> >
> > I have a question. The a/v desync appears always after about 10 minutes?
> 
> 
> Yes... usually seems to start after 5 to 10 minutes.
> 
> It is related to the choppy video?
> 
> 
> Tough to tell, but I think so. However, it seems like there could be 10
> minutes of low-action shots, and the audio will still drift out of sync.
> 
> Once the desync appears, it stays always there or at some point
> > it disappears?
> 
> 
> Stays.
> 
> And if it stays, the delay is constant or increase with the time?
> 
> 
> I think it increases over time.
> 
> I also assume that the desync and choppy video do not appear if you use
> > mplayer to play the avi, isn't it?
> 
> 
> Well, to be honest, it actually seems a little bit jerky when viewed with
> mplayer, too. Definitely not as smooth as when I encode using basic SVCD
> settings (-n n -stdvid 6 -mpegonly).
> 
> In the mean time I can only ask you to test some other encoding combination
> > in order to see if we can track down the problems to a specific audio codec.
> >
> >
> > For the tests I suggest to use -encode n:1:1 or -encode n:2:1 (if the
> > previous do not work). They are faster and for the tests you are doing now
> > speed may be important for you.
> > Check if the a/v desync appears with mp2, ac3, mp3 cbr.
> > Use -encode 4:m:i -encode 6:m:i -encode 5:m:i
> > Do not use -fixasync for this test.
> 
> 
> Ok, here's what I did. I tried to pay more attention to the
> choppiness/jerkiness and audio desync this time around.
> 
> #!/bin/sh
> mencoder -quiet dvd://1 -dvd-device /media/cdrom \
> -ovc copy -oac copy -o rip.avi
> encode2mpeg -avionly -encode 2:1:1 -ffourcc DIVX -setaspect 4 \
> -vbitrate 1200 rip.avi -o audio_tests/enc211
> encode2mpeg -avionly -encode 2:2:1 -ffourcc DIVX -setaspect 4 \
> -vbitrate 1200 rip.avi -o audio_tests/enc221
> encode2mpeg -avionly -encode 4:2:1 -ffourcc DIVX -setaspect 4 \
> -vbitrate 1200 rip.avi -o audio_tests/enc421
> encode2mpeg -avionly -encode 5:2:1 -ffourcc DIVX -setaspect 4 \
> -vbitrate 1200 rip.avi -o audio_tests/enc521
> encode2mpeg -avionly -encode 6:2:1 -ffourcc DIVX -setaspect 4 \
> -vbitrate 1200 rip.avi -o audio_tests/enc621
> 
> Results were the same for all of the following:
> enc211.avi
> enc221.avi
> enc421.avi
> enc521.avi
> enc621.avi
> 
> Video starts out blocky and pixelated for the first 1min of the video
> (opening credits). After that, video quality is excellent. Audio quality is
> excellent, but drifts out of sync with the video.

The pixelation at the beginning is something I'm aware, but I have not
figured yet how to avoid it. Usually the fade in at the start of
the movie makes the problem irrelevant, but if the video begin with
full action then you can see it.

The audio drift is not codec related so I have to think to other causes.

I have a good news for you. I got a dvp642, so very soon encode2mpeg 
will make good avi's for that player.
In the mean time I can tell you that all combinations of -encode n:m:i
should be playable (well, I have not tested pcm audio) 
and the option -ffourcc DIVX is not necessary.
What is important is the usage of -setaspect and that the video
resolution is 720x576 or less. But I have noticed some distortion if
the resolution is higher than 640x480, so 640x480 should not be exceed.

Be patient another couple of weeks and the sync problem should
hopefully disappear :-).

In the mean time I can suggest you another 2 tests:

1) add the option -vfr with the value corresponding to your source
video. It should be -vfr 3 for PAL and -vfr 1 or -vfr 4 for NTSC.
If the argument of -vfr is not the correct one, you will see
constantly repeated the message:
Skipping frame!
or
1 duplicate frame(s)!
during the encoding. With the good -vfr n option no such messages
should appear except may be a couple of times at the beginning.

2) Instead of making a local copy of the dvd with mencoder, encode
directly from the dvd source:
encode2mpeg -avionly -encode 4:2:1 -setaspect 3 -vbitrate 2000 dvd://1 -o tests_enc221 -vfr n

you could also let encode2mpeg make a copy of your source with the option -cache
(encode2mpeg -doc cache.html), but this is not related to the audio desync.

Check if also these two encodings show the audio drift.
(by the way, are you sure that your source dvd is ok?
have you observed the audio drift also encoding from 
another source?)

Giacomo