[MPlayer-users] set aspect ratio code? or resize?

[Nico Sabbi]

Joonas Koivunen wrote:

>On Sunday 18 April 2004 16:22, Mikhail Ramendik wrote:
>  
>
>>Hello,
>>
>>My source material is 720x576 PAL. I want to create DivX AVIs for
>>playing on computers (with all players inckuding Windoze). As I
>>understand, to play back correctly, the films need to be recoded into a
>>4:3 aspect ratio (aka 1.33:1, from 1.25:1).
>>    
>>
>Aspect ratio itself doesnt have anything to do with you being able to play it 
>under Windows/other players or not. 
>
>I guess you are on the right tracks; libavcodec can encode in the original 
>aspect ratio and store it in the video, only mplayer reads this information 
>and prescales accordingly. Other players just play it unscaled -- as in wrong 
>aspect ratio. As long as you don't use -lavcopts aspect=X option, you'll be 
>safe.
>
>  
>
>>To have maximum quality *and* compatibility, should I set the aspect
>>ratio code in the AVI, or should I resize when encoding?
>>    
>>
>AFAIK AVI doesn't have this aspect ratio code, it can only be stored in the 
>video headers (not avi). You should resize when you encode (like all movie 
>groups do for example, as their rules only support xvid and divx codecs).
>
>  
>

it does: mencoder's options is -force-avi-aspect, the only way to 
correct the AR flag if you didn't
already specify it in the video bitstream, but very few player recognize 
these two flags

>>And if I should set the aspect ratio code: is it possible to just add
>>the code to an AVI *without* re-encoding? i.e. mencoder -ovc copy -oac
>>copy (and some options to add the aspect ratio code).
>>    
>>
>This was discussed/asked a long time ago I think, cannot remember any 
>solutions..
>  
>

read above: mencoder -oac copy -ovc copy -force-avi-aspect X.
You need a very recent version of mencoder for this (checkout the last cvs).