[MPlayer-users] RFC: docs update for "how to create a high quality DVD rip"

[D Richard Felker III]

On Mon, Jun 07, 2004 at 09:26:46PM +0200, Hans du Plooy wrote:
> On Monday 07 June 2004 06:05, D Richard Felker III wrote:
> > > known.  Given that, I don't see why filters that add/drop frames don't
> > > work with 3-pass.
> > >
> > > Require enlightenment ...
> >
> > Nope, the first (frameno) pass does the a/v sync (choosing which
> > frames to drop or duplicate) which can't be done correctly without
> > decoding and filtering them. And it doesn't decode them. So it's
> > broken.
> 
> Either of us are misinterpreting the way 3-pass works.  This is my take:
> 
> In 3-pass mode, the first pass only decodes the audio and encodes it into 
> whatever you want.  It does not decode the video at all (else it would be a 
> lot slower than it is).  It probably only looks at the size of the video and 
> gives you a rough estimate of what bitrate you should use to get the desired 
> size.  That estimate is not 100% correct, but mostly quite accurate.  If you 

No, this is nonsense. You do not need to know ANYTHING about the video
except the length in seconds to pick the bitrate. This is obvious to
anyone who's completed middle school math.

> do a 1st pass (of 3), and do it again, but crop a healthy chunk of the movie 
> away, you'll see the estimated video bitrate doesn't differ much (if at all).  
> So I think it's safe to say the first pass doesn't care about the video, so 
> it doesn't do a/v sync at all.

Nope, wrong again. It does a/v sync incorrectly by trying to count
frames, but it counts wrong if the movie is field-coded or if you want
to use various filters. That's why it shouldn't be used.

> the a/v sync trouble you have has nothing to do with 3-pass mode.   I'll tell 

Yes it does.

> you what does screw you around on a/v sync though:  encoding your audio in 
> vbr with lame (not sure about ogg or other formats).  It has for a long time 

This is an entirely different problem. Downgrading your lame to 3.90
will fix it almost entirely.

> bugged me that my DVD rips come out with audio all over the place.  
> Strangely,  this symptom was worst in MPlayer, which I found strange, having 
> encoded the movies with mencoder.   Eventually I found out that vbr audio 
> causes a/v sync problems, 2-pass or 3-pass all the same.  This was two or so 
> years ago though, it might have been fixed in the meantime.

Another fix is to encode the audio separately then remux it with
-audiofile and -oac copy.

Rich