[MPlayer-users] Creating a letterbox (PAL) VCD

[Giacomo Comes]

On Thu, Aug 30, 2007 at 02:38:18PM +0200, Colin Rosenthal wrote:
> RC wrote:
> > On Thu, 30 Aug 2007 11:02:10 +0200
> > Colin Rosenthal <csr at statsbiblioteket.dk> wrote:
> >
> >   
> >>     vcodec=mpeg1video:keyint=15:vrc_buf_size=327:vrc_minrate=1150:\
> >> vbitrate=1150:vrc_maxrate=1150:acodec=mp2:abitrate=224:aspect=4/3
> >>     
> >
> > No options?  You're just asking for horrible video quality.  
> >
> > This is all extensive covered in the docs.
> >
> >   
> Well quite. The problem is that it is so extensively covered in the docs 
> that it's rather hard to know which of the many filter options,
> for example, might make a significant difference. For example, we tried 
> the following two-pass encoding:
> 
> FILTER="pp=hb/vb/dr/al/fd"
> 
> mencoder -oac twolame -twolameopts br=224 -ovc lavc -of mpeg -mpegopts 
> format=xvcd -vf \
>     scale=352:198,expand=352:288:0:45,$FILTER,harddup -srate 44100 -af 
> lavcresample=44100 -lavcopts \
>     vcodec=mpeg1video:keyint=15:vrc_buf_size=327:vrc_minrate=1150:\
> vbitrate=1150:vrc_maxrate=1150:acodec=mp2:abitrate=224:aspect=4/3:vpass=1 
> -ofps 25  \
>     -o /dev/null 070507_1210.wmv
> 
> mencoder -oac twolame -twolameopts br=224 -ovc lavc -of mpeg -mpegopts 
> format=xvcd -vf \
>     scale=352:198,expand=352:288:0:45,$FILTER,harddup -srate 44100 -af 
> lavcresample=44100 -lavcopts \
>     vcodec=mpeg1video:keyint=15:vrc_buf_size=327:vrc_minrate=1150:\
> vbitrate=1150:vrc_maxrate=1150:acodec=mp2:abitrate=224:aspect=4/3:vpass=2 
> -ofps 25  \
>     -o two_pass_filtered.mpeg 070507_1210.wmv
> 
> but really couldn't see any improvement.

My comments about this thread.

your command line needs the following:
remove "acodec=mp2:abitrate=224", you are using twolame so no need to set 
options for the libavcodec mp2 encoder.
I suggest to add vstrict=0
You may also want to add vmax_b_frames=2 because VCD standard requires
2 B-frames but players should be able to play VCD without B-frames as well.

About the comments to use stereo audio:
that's the default. No need to do anything.

And about the video quality options:
it depends of the source, of course, but my experience shows that adding
mbd=2 is enough. The fact that you are forcing constant video bit rate,
as required by the VCD standard, makes almost useless most of the options
that improve quality. You should notice a difference if you use variable
video bit rate (most DVD players can play VCD with variable video bitrate).

Ciao
Giacomo