[MEncoder-users] low quality decrypt

[Pete Davis]

> 
> Hi,
> 
> On 9/21/05, Pete Davis <pete at petedavis.net> wrote:
> > > Hi,
> > >
> > > On 9/21/05, Pete Davis <pete at petedavis.net> wrote:
> 
> [..]
> 
> 
> > > >
> > > > Modifying their example, I would do something like this instead:
> > > >
> > > > Pass #1:
> > > >
> > > > mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 -oac copy
> -o
> > > > /dev/null
> > > >
> > > > Pass #2
> > > >
> > > > mencoder dvd://2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -oac
> mp3lame
> > > > -lameopts vbr=3 -o pelicula.avi
> > >
> > > I do not think this is a good example, though I have not double
> > > checked myself: you should process "almost" the same audio data on
> > > both pass, otherwise you may/will end-up with A/V desync.
> > >
> > > You may for example do -oac mp3lame -lameopts vbr=3:aq=9 on first pass
> > > to reduce the amount of time sucked up by the mp3 encoding.
> > >
> > >
> >
> > Guillame, I don't know about the inner workings of mencoder, but almost
> > EVERY encoding I've done for the past several months has had -oac copy
> for
> > the first pass and -oac mp3lame ... for the second pass. This includes
> > mpeg-2 to mpeg-4 conversion from my hauppauage capture card, DVD to
> mpeg-4
> > encodings, as well as mpeg-4/AC3 to mpeg-4/MP3 encodings.
> >
> > I have never once experienced audio-video desync with any of my
> conversions
> > using this method.
> >
> > That's not to say it's not possible. I'm sure you know better than I.
> But I
> > have never experienced it over a pretty wide range of encodings.
> 
> If you have not tried NTSC encoding, then that's probably the reason
> why you have not experienced sync issues. I personally always use the
> same kinda audio track on each pass, so I can't say what appends if
> you don't do the same thing than what I do. However, I did read a post
> on the ML with someone who experienced some encoding problems that
> were due to not having the same kind of track on each passes.
> Now, do the way you like, if it works for you, that's good. I just
> wanted to warn you that this solution was not ideal (but what's to be
> considered ideal when talking about video encoding?)
> 

Guillaume,

I'm not trying to disagree. If other people have experienced problems, then
there's certainly a possibility of it happening. All of my stuff is NTSC.
The DVDs I've done were all NTSC. Some telecine, some not. The Hauppauge
captures are all interlaced NTSC. The AVI files on the other hand (which
represent maybe 1/3 of my encodings), have varied greatly in source format.
They've varied in audio codec, video codec, size, frame rate, etc. Again, no
sync issues.

But like I said, I acknowledge that there's probably the potential for it
given what you've heard. That said, I think it's probably pretty unlikely,
unless it's a PAL specific issue, as I've encoded at least 400 files,
probably more.

Pete