[MPlayer-users] Re: mencoder/crop => image distortion

[D Richard Felker III]

On Thu, Jul 31, 2003 at 03:08:11PM +0200, Hans Meine wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> On Thursday 31 July 2003 13:10, ROED,HAAVARD (HP-Norway,ex1) wrote:
> > expect it to support the mpeg4 aspect tag :( And finally, when a player is
> > able to play ie mpeg4 video, it would be nice if it actually supported the
> > -whole- standard.
> 
> There are many "standards" out there which are not anywhere near fully 
> supported by most packages claiming just "support of foo". Even "full support 
> of foo" often means "(except some stuff which we found unimportant)", and 
> importance is often defined as "I think thats what many most people need". 
> ATM I am thinking of IMAP, HTML, CSS, Postscript, SVG and others..
> (It gets worse because there is often not "the" standard but an endless number 
> of subversions and dialects.)
> 
> MPEG4 defines the mentioned tag, but no player except MPlayer supports it at 
> the moment. (That might - hopefully - change in the future of course.)
> It's a strange thing IMHO, because the same players recognize aspect tags of 
> DVDs and SVCDs (which are both MPEG2). :-( 

The problem is that these (broken) players assume they'll find the
aspect header in the container headers, not the codec headers. For
mpeg1/2 in mpeg ps/pes/ts container, these boundaries are a bit
blurred anyway. But avi has no such headers, so these players assume
avi files always have square pixels, before even initializing the
codec and reading the headers in the video stream.

Rich