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

[Nicolas Hesler]

Nico Sabbi wrote:
> 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
>   
Really??? Good to know.

So, get rid of the vb_strategy thing too? This doesn't affect the GOP on 
2pass without B frames right?