[MEncoder-users] B-frames and GOP with MPEG-2 for DVD

Nico Sabbi nicola_sabbi at fastwebnet.it
Thu Jun 7 22:25:38 CEST 2007

Nicolas Hesler wrote:

>Can anyone offer any input to the following command line?
>I've been trying to refine for the highest possible quality of MPEG-2 
>while staying DVD compliant.  The source is 24fps.
>(Note: format=mpeg2, because format=dvd does not work with Adobe Encore 
> From what I understand, keeping GOP open, improves quality.  Is this 
>true? Is it 100% DVD compliant?

I'm not sure, but IIRC gops should be closed in dvds

>Do I want to introduce B frames in my encoding? (The vb_strategy part of 
>my command line is currently useless, right?) If parts of my video are 
>reaching into 9-10 Mbs bitrate, would it beneficial to introduce 
>B-Frames? Will it improve quality?
no, they will only harm quality

> (This is probably a stupid question) 
>Are the sync issues with bframes only relevant to mpeg4 or lavf?

with lavf managed by mencoder: always

>mencoder -oac lavc -ovc lavc -of mpeg -mpegopts format=mpeg2:tsaf:telecine /
>-vf scale=720:480,harddup -mc 0 -noskip -srate 48000 -af 
>lavcresample=48000:0:2 -lavcopts / 
>-ofps 24000/1001 -o $output $input

this -mc 0 -noskip is a myth, as far as I'm concerned: it may do some good
with -ovc copy, but not when encoding video

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