[MPlayer-users] Re: Tools for mpeg* to DVD

[Andrew Stevens]

Hi,

rcooley wrote:

> Still does a better job than mplex.  mplex is too strict, it needs to
> be dealt with carefully, and tends to just about have a heart attack if
> you give it something as simple as a VBR stream (which tcmplex doesn't
> even complain about).

The reason for this 'pickiness' is that mplex takes what you tell it about the 
limitations of the decoder it is multiplexing for seriously.  VBR isn't 
really the issue, its whether the stream goes outside  the spec range or not.
Being 'picky' about this is vital if you are muxing for hardware DVD/SVCD 
players if you want to avoid burning 'coffee coasters' instead of reliably 
playable CDs/DVDs.  If you want mplex to be less picky (for example because 
you intend to use a software player - these handle just about anything) 
simply tell it to forget about the standards and specify some nice generous 
settings, big buffers, high maximum decode rate and away you go...

> > You're definately sure out of luck if
> > you want more than basic AC3 or MPEG layer II audio muxing.
>
>Why would anyone want it to do anything more than that?  DVDs/SVCD/VCDs
>don't support much of anything else.  

The classic scenario is a high-quality multi-channel DTS or LPCM audio-track 
that you would like to mux back into a video stream you have reduced down in 
size.

The current major work-in-progress for the new year is multiplexing of 
'subtitles' (SVCD and DVD subpictures - used also for menus in DVDs).

> Since the MPEG4 standard suggests a MOV container, it doesn't look like
> the MPEG file format has much future anyhow.

MPEG-2 is the format used for essentially all broadcast TV (standard and HD), 
and there very very stand-alone MPEG-4 players available.   A common 
application is taking a digital TV MPEG-2 stream via a suitable tuner card 
and transcoding / muxing to DVD.

Of course, for PC based play-back you are very much better off coding to 
MPEG-4 or other more modern formats.

> I think I speak for about 90% of the complaintees when I say, it
> works well, it's just too slow.  ffmpeg's mpeg2 codec is young, but is
> already about 3x faster than mpeg2enc.

Unless I'm very much mistaken ffmpeg encodes MPEG-2 with interlaced support 
and B frames off.  These are on by default in mpeg2enc. If you turn them off  
mpeg2enc runs a little over twice as fast (17 fps vs. 9 fps on my Athlon/XP 
2100+).  These features are expensive to code properly... B frames require 
big motion estimate search radii and are unfriendly to predictive motion 
estimators and interlaced coding requires you to motion estimate a frame once 
as a frame and then a second time as two fields.

The upcomng release of mpeg2enc has the defaults set to ffmpeg like 
behaviour...

Andrew