[MPlayer-users] Re: mpeg2video for DVD authoring?

[Tobias Diedrich]

Joshua Rothenberg wrote:

> Okay, I haven't gotten around to testing a new stream yet, but I
> managed to find out the real DVD keyframe requirements.  First I was
> searching using the word keyframe, which didn't work.. then I searched
> using i-frame, which didn't work. Finally I realized that what I
> wanted was to search for "GOP length". It's not that DVDs require a
> certain rate of i-frames, oh no, its just that there's one I frame per
> GOP, and there IS a maximum GOP length. grr... Anyway, it turns out
> this length is 18 for MPEG1 NTSC, 15 for MPEG1 PAL, 36 for MPEG2 NTSC,
> and 30 for MPEG2 PAL.  If I'm lucky, mplex creates the GOP's
> accordingly.

AFAIK most DVD players should probably work fine with greater I-Frame
intervals. However the picture quality may degenerate continually until
the next I-Frame if the decoder makes small errors.

It seems that for the Hardware Player I have, the magic word are either
vstrict=1 or vpsize=1000, so far I did not have time to check which one it
is.

I currently use the following command line:
mencoder -nosound -ovc lavc -fps 25 -ofps 25 -lavcopts vcodec=mpeg2video:vbitrate=4000:vqmin=1:vrc_buf_size=230:vrc_minrate=1000:vrc_maxrate=8000:mbd=2:keyint=25:vmax_b_frames=2:autoaspect:vlelim=-4:vcelim=7:vstrict=1:vpsize=1000:lumi_mask=0.05:dark_mask=0.01:tcplx_mask=0.2:scplx_mask=0.2:trell -sws 2 -vf hqdn3d,scale=672:544,expand=704:576 -of mpeg -o test.mpg test.avi

Then I extract the video stream:
mplayer -dumpfile test.m2v -dumpvideo test.mpg

And multiplex it:
mplex -f8 -V -b230 -o test.mpg test.m2?

To create the dvd imagefile:
dvddirgen -o dvd
dvdauthor -o dvd test.mpg
dvdauthor -T -o dvd
mkisofs -dvd-video -o dvd.iso dvd

-- 
Tobias						PGP: http://9ac7e0bc.2ya.com
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