avcodec/wavpack: fix decoding of files with many channels

Fixes decoding of Run_The_Race_-_3rd_Order_Ambisonic_SN3D.wv

libavcodec/wavpack.c

@@ -940,13 +940,23 @@ static int wavpack_decode_block(AVCodecContext *avctx, int block_no,
             case 3:
                 chmask = bytestream2_get_le32(&gb);
                 break;
-            case 5:
+            case 4:
                 size = bytestream2_get_byte(&gb);
-                if (avctx->channels != size)
+                chan  |= (bytestream2_get_byte(&gb) & 0xF) << 8;
+                chan  += 1;
+                if (avctx->channels != chan)
                     av_log(avctx, AV_LOG_WARNING, "%i channels signalled"
-                           " instead of %i.\n", size, avctx->channels);
+                           " instead of %i.\n", chan, avctx->channels);
+                chmask = bytestream2_get_le24(&gb);
+                break;
+            case 5:
+                size = bytestream2_get_byte(&gb);
                 chan  |= (bytestream2_get_byte(&gb) & 0xF) << 8;
-                chmask = bytestream2_get_le16(&gb);
+                chan  += 1;
+                if (avctx->channels != chan)
+                    av_log(avctx, AV_LOG_WARNING, "%i channels signalled"
+                           " instead of %i.\n", chan, avctx->channels);
+                chmask = bytestream2_get_le32(&gb);
                 break;
             default:
                 av_log(avctx, AV_LOG_ERROR, "Invalid channel info size %d\n",

libavformat/wvdec.c

@@ -153,11 +153,18 @@ static int wv_read_block_header(AVFormatContext *ctx, AVIOContext *pb)
                 case 3:
                     chmask = avio_rl32(pb);
                     break;
-                case 5:
+                case 4:
                     avio_skip(pb, 1);
                     chan  |= (avio_r8(pb) & 0xF) << 8;
+                    chan  += 1;
                     chmask = avio_rl24(pb);
                     break;
+                case 5:
+                    avio_skip(pb, 1);
+                    chan  |= (avio_r8(pb) & 0xF) << 8;
+                    chan  += 1;
+                    chmask = avio_rl32(pb);
+                    break;
                 default:
                     av_log(ctx, AV_LOG_ERROR,
                            "Invalid channel info size %d\n", size);