[MEncoder-users] Encoding to DVD, size versus quality

[Jeff Clagg]

On Wed, Dec 20, 2006 at 10:16:09AM +0100, Ismael Valladolid Torres wrote:
> Guillaume POIRIER escribe:
> > No. Players have to support these constraints:
> 
> I read:
> 
> > For instance, if you insist on fitting 20 or so hours on a DVD, you
> > could use vbitrate=400. The resulting video quality would probably
> > be quite bad. If you are trying to squeeze out the maximum possible
> > quality on a DVD, use vbitrate=9800, but be warned that this could
> > constrain you to less than an hour of video on a single-layer DVD.
> 
> Which is very interesting. Given that video downloads are often MPEG2
> ripped from a DVD and reencoded to MPEG4, reencoding again to MPEG2 is
> giving such a loss of quality that probably using a low bitrate is not
> such a big drawback.

Remember that the difference between a typical MPEG-4 dvdrip and the
original dvd goes a lot further than just the choice of codec. DVDs use
very short GOPs, which consumes a lot of bits without helping quality at
all. DVDs also allow a rather small coded picture buffer size. Together,
these constraints probably have a bigger impact on quality than the
choice of MPEG-2 vs. MPEG-4.