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

[Nico Sabbi]

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 
>2.0).
>
> 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 / 
>vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=7000:vbitrate=6000:keyint=12 
>/
>:trell:mbd=2:precmp=2:subcmp=2:cmp=2:dia=-10:predia=-10:cbp:mv0:vqmin=1:lmin=1 
>/
>:dc=10:vpass=1:vb_strategy=2:acodec=ac3:abitrate=224:aspect=16/9:vstrict=0 
>-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