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

[D Richard Felker III]

On Sun, Jun 06, 2004 at 07:18:30PM -0400, Jason Tackaberry wrote:
> On Sun, 2004-06-06 at 17:48 -0400, D Richard Felker III wrote:
> > 3pass mode should NEVER be used, don't even mention that it exists.
> 
> The only reason for this I can think of is that VBR audio causes sync
> troubles.  You sort of imply that "3-pass is bad" should be common
> wisdom, but I don't really know.

It doesn't work with inverse telecine or other filters that drop
frames (or add them), it doesn't work with field-coded DVDs (and it's
difficult to tell in advance which ones are field-coded), and it
causes A/V desync. Also it has no useful purpose.

> > Leaving audio as AC3 is often a very stupid idea, especially if it's
> > only stereo or if you want to rip a long movie. You won't hear the
> > difference between 96 kbit vorbis and 448 kbit ac3 unless there's lots
> > of music.
> 
> I have an A/V receiver and do AC3 pass-through.  I assure you that I
> will hear the difference between a 96kbit vorbis and a 448bit 5.1 AC3
> stream every single time.  And I'll do a blind test to prove it. :)
> 
> Now, an AC3 2.0 audio track, yes, I probably won't hear the difference.
> But that's 192kbit.  I'm not saving _that_ many bits by compressing that
> to vorbis.  Not to make it worth the effort, IMHO.

Um, let's see. 900/96 video/audio bitrate, or 804/192? I'll take the
former any day! It's an absolutely HUGE difference! For me. I
acknowledge that you're working with different bitrates, but even 1800
vs 1900 could be relevant, especially if you're not denoising,
cropping, etc. very well.

> Still, it might be worth mentioning that those parameters can be
> adjusted and experimented with until you find the right values for the
> given movie.

Definitely. If your guide is only targetted at people who don't care
at all about fitting quality in fixed sizes, you should state that.
Otherwise (whenever you have a size constraint, no matter how big)
most of your recommendations are the exact opposite of what helps, and
stupid users will try them anyway...

> 
> > If you only care about constant quantizer and/or insane bitrates, I
> > guess your guide is ok, but IMO it sucks to switch discs 4 times while
> > watching a movie. And what sucks even more is the bad discontinuities
> 
> Yeah, that was the point, sorry that it wasn't very clear.  I don't
> think 2200kbit is an insane bitrate.  It's definitely quite high, but
> insane?  I have a few hundred gig of space and am happy to use that for

That's not very much. I could fill a few terrabytes at sane qualities
(1200 kbit)...

> high quality video, rather than picking through a library of burned CDs
> and getting lesser quality.

And several hundred more gigs for backups? :) Storing your only copies
on hd is not very smart...

> To each his own.

Agree.

> > Because artifacts and higher quantizers are worse than losing a few
> > irrelevant (probably noisy anyway) pixels at the image edges.
> 
> That assumes that you'll actually see artifacts and higher quantizers if
> you don't crop at multiples of 16.  If that's true, then I definitely
> accept the explanation.  I guess it'd be straight forward enough to
> check that out for myself. :)

I _know_ you'll see them if you leave black borders, but insane
bitrate might mostly compensate, as least with qmin=1. With unaligned
dimensions I haven't tested, but in theory it should have a similar
effect.

> > Correct. After deinterlace or pullup you don't have interlaced viceo
> > anymore, do you? Nope. So rules for interlaced video don't apply.
> 
> That follows my intuition, but then I've made statements based on my
> intuition in the past that have ended up being flat wrong.  So better to
> be humble and say "I think" all the time ...
> 
> ... especially when you're lurking on the list. :)

:))))

Rich