[Ffmpeg-devel] [RFC] VC-1 I-frames decoder

jserv at linux2.cc.ntu.edu.tw jserv
Sun Jun 18 07:00:20 CEST 2006

On Sun, Jun 18, 2006 at 06:32:30AM +0300, Kostya wrote:
> On Sat, Jun 17, 2006 at 07:43:18AM +0300, Kostya wrote:
> > Here is my VC-1 decoder which decodes I-frames only. And not all of them are decoded properly too.
> > Nevertheless I want to get opinions on this implementation before moving to P-frames support.
> > P.S. If somebody will find and fix bugs in AC prediction it would be incredibly great.
> And this one for testing: it outputs color and frames are now decoded correctly.
> Please test and report samples with distorted pictures (if some movie doesn't play at all it's fine).

hi Kostya,

  Excellent work! It works for me as far.

However, I found that free_bitplane is not done well, which causes
double-free, so that I did a quick fix against vc1.c in attachment.

Jim Huang (jserv)
-------------- next part --------------
--- libavcodec/vc1.c	2006-06-18 12:53:08.000000000 +0800
+++ libavcodec/vc1.c-fixed	2006-06-18 12:51:09.000000000 +0800
@@ -509,7 +509,7 @@ static int alloc_bitplane(BitPlane *bp, 
 static void free_bitplane(BitPlane *bp)
     bp->width = bp->stride = bp->height = 0;
-    if (bp->data) av_freep(&bp->data);
+    if (bp->data[0]) av_freep(&bp->data);
 /** Decode rows by checking if they are skipped

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