[XviD-devel] Bitstream header information

[peter ross]

>However after having reread your post (and rereading is sometimes helpful)
>this functionality is not sufficient to allow an application to use XviD
>without specifying resolution information. The problem is that the memory
>initializing is done _before_ BitstreamReadHeaders is called...
>
>you're right, we should implement proper support for this asap


bill from mpeg4ip posted a patch a few months back; from memory, the
patch provided a XVID_DEC_VOL and XVID_DEC_ALLOC functions to decode
the vol, and reallocate internal buffers.  i think this is roughly what
divx5 does.

the other way is to use an event-based system. when it decodes the vol,
it checks the bitstream dimensions against the current dec->width,
dec->height. if they're different, realloc the internal buffers, and
return an XVID_ERR_RESIZE message.

xparam.width = xparam.height = 0;
err = xvid_decoder(xframe,xstats);
if (err == XVID_ERR_RESIZE)
{
     // application resizes its buffer, window, etc.
     // the bitstream resolution is stored in xstats
     xvid_decoder(xframe,xstats);
}

the statisics argument can be used for other things, such as returning
info about the framerate.

the big questions is: which method do we implement?
- mpeg4ip method is working already (the use it in player), so its not
much work to get going.
- the event based method is more work, but imho makes things just that
little bit easier for the application developer.

-- pete

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