[MPlayer-dev-eng] [BUG][PATCH] Decoding of WMV3 files fail, shows only black screen

[Shachar Raindel]

On 7/2/05, Alexander Strasser <eclipse7 at gmx.net> wrote:
> Hi,
> 
> Shachar Raindel wrote:
> > On 7/2/05, Alexander Strasser <eclipse7 at gmx.net> wrote:
> > > Ismail Donmez wrote:
> > > > On Saturday 02 July 2005 02:56, Shachar Raindel wrote:
> > > > >  I have been having a problem with decoding WMV3 files, getting the
> > > > > following (interesting) messages (sorry, long post to show what is
> > > > > going on):
> > > > [...]
> > > >
> > > > wmv3 decoding is in pre-alpha stage so its not su??pposed to work at all.
> >
> > I am not talking about the pre-alpha native codec in FFmpeg. I am
> > talking about the x86 DMO loader, which works pretty good for most of
> > the WMV3 (aka WMV9/VC1) clips.
> >
> > >
> > > "Selected video codec: [wmv9dmo] vfm:dmo (Windows Media Video 9 DMO)"
> > > Did you read this?
> > >
> > >   This works already for many files containing WMV9 video.
> > >
> >
> > Yep, but it has a bug that my patch fixes, will you please
> > comment/apply my patch, instead of arguing on what the state of WMV3
> > support is right now?
> 
>   Sorry, that I annoyed you by `defending' your position.

Sorry for being bit impolite - I worked on it till 3 AM last night,
and when in the morning I found only the reply about "wmv is
pre-alpha" from someone who seemed not to understand what he is
talking about, I was quite angry. I shouldn't reply to your post
(which was indeed supporting my case) but his. Conclusion: never post
replies before eating brakefast :)

> But please
> be a little patient (i know this little can become very long). On the
> one hand i can understand you want your patch/bugreport handled quickly
> but on the other hand you say your solution is buggy. 

Yes, it is not perfect, but the current logic there is even more
broken (anything is a keyframe unless we want to drop this frame, than
it is not considered as a keyframe).

> In other words
> it will take us time to find an acceptable fix (correct me if i understood
> something wrong).

The current patch will fix the things and make them work for most
codecs (since most of the DMO codecs silently ignore the
DMO_INPUT_DATA_BUFFERF_SYNCPOINT flag if the data fed in is not a
key-frame, probably causing only small CPU overhead. On the other
hand, when this flag is not set and we feed the codec with data,
starting from the beginning of the file, it will not look for a
keyframe, and therefore will not show anything on screen until it will
get both the keyframe flag from MPlayer, and a keyframe in the stream
(which is rather rare). Note that I am only guessing how the codec
behaves, but I can tell that with this patch, all the wmv files I have
are playing correctly, and without it I get only a black screen and a
bunch of error messages.

>   BTW could you upload a stream or a portion of a stream triggering this
> problem?
> 

Uploading now - buggyDMOdecoding.wmv and the attached description
buggyDMOdecoding.wmv.txt

   Shachar