[Ffmpeg-devel] Re: [MPlayer-dev-eng] WMA MAX_CODED_SUPERFRAME_SIZE too small

[Diego Biurrun]

On Mon, Jun 27, 2005 at 03:37:49PM +0100, Mark Weaver wrote:
> I have a few WMA file examples where there are superframes >4K.  (These 
> files were created with WMP 10, but playback ok with WMP 9/10).  I have 
> placed a short sample at http://www.blushingpenguin.com/mark/test.wma 
> that exhibits the glitch.  I chopped the file off at 128K but there is 
> enough there to show the problem.
> 
> On playback these frames are simply dropped causing audio glitches. 
> During testing I have seen frames of about 8,900 bytes.  The resolution 
> is pretty straightforward -- just increasing the 
> MAX_CODED_SUPERFRAME_SIZE fixes it.  I picked 16K, but there's no real 
> rationale behind that.
> 
> The code is in libavcodec/wmadec.c, patch is simply:
> 
> --- wmadec_org.c        2005-06-27 15:34:31.114852300 +0100
> +++ wmadec.c    2005-06-27 15:05:31.149199000 +0100
> @@ -47,7 +47,7 @@
>  #define NB_LSP_COEFS 10
> 
>  /* XXX: is it a suitable value ? */
> -#define MAX_CODED_SUPERFRAME_SIZE 4096
> +#define MAX_CODED_SUPERFRAME_SIZE 16384
> 
>  #define MAX_CHANNELS 2

This does indeed fix playback of the above mentioned sample.  The proper
place to discuss this is ffmpeg-devel, not mplayer-dev-eng since
wmadec.c is a file from the FFmpeg project, not from MPlayer.

It seems trivial enough, though, I have CCed ffmpeg-devel and uploaded
the sample to

http://mplayerhq.hu/MPlayer/samples/A-codecs/WMA/large_superframe.wma

Diego