Fix PCM DVD divide by zero bug introduced in r14659. Patch supplied by lars...

Fix PCM DVD divide by zero bug introduced in r14659. Patch supplied by lars dot taeuber at gmx dot net.

Originally committed as revision 14864 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/pcm.c

@@ -350,11 +350,12 @@ static int pcm_decode_frame(AVCodecContext *avctx,
 
     sample_size = av_get_bits_per_sample(avctx->codec_id)/8;
 
-    n = avctx->channels * sample_size;
     /* av_get_bits_per_sample returns 0 for CODEC_ID_PCM_DVD */
     if (CODEC_ID_PCM_DVD == avctx->codec_id)
         /* 2 samples are interleaved per block in PCM_DVD */
-        n = 2 * avctx->channels * avctx->bits_per_sample/8;
+        sample_size = avctx->bits_per_sample * 2 / 8;
+
+    n = avctx->channels * sample_size;
 
     if(n && buf_size % n){
         av_log(avctx, AV_LOG_ERROR, "invalid PCM packet\n");