10l: WavPack demuxer forgot to seek back to initial position after block

contents parsing (for custom sampling rate).

Originally committed as revision 20468 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/wv.c

@@ -125,6 +125,7 @@ static int wv_read_block_header(AVFormatContext *ctx, ByteIOContext *pb)
             av_log(ctx, AV_LOG_ERROR, "Cannot determine custom sampling rate\n");
             return -1;
         }
+        url_fseek(pb, block_end - wc->blksize + 24, SEEK_SET);
     }
     if(!wc->bpp) wc->bpp = bpp;
     if(!wc->chan) wc->chan = chan;