avfilter/asubprocess: verify extended wav format guid if available

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

libavfilter/af_asubprocess.c

@@ -53,7 +53,7 @@ enum {
     STATE_SKIP_CHUNK,
     STATE_IN_DATA_CHUNK,
     STATE_IN_FMT_CHUNK,
-    STATE_ERROR
+    STATE_EXT_FMT
 };
 
 typedef struct ASubProcessContext {
@@ -287,7 +287,7 @@ static int process_input(AVFilterContext *ctx)
             sample_rate      = AV_RL32(data + 4);
             s->out_bit_depth = AV_RL16(data + 14);
 
-            if (format != 1 && format != 0xFFFE) { // TODO: check extensible wav format: should be PCM
+            if (format != 1 && format != 0xFFFE) {
                 av_log(ctx, AV_LOG_ERROR,
                        "Unsupported wav format (%d) from subprocess (expected PCM).\n", format);
                 return AVERROR_INVALIDDATA;
@@ -309,6 +309,23 @@ static int process_input(AVFilterContext *ctx)
                 return AVERROR_INVALIDDATA;
             }
             s->chunk_size -= 16;
+            if (format = 0xFFFE)
+                s->state = STATE_EXT_FMT;
+            else
+                s->state = STATE_SKIP_CHUNK;
+        }
+        else if (s->state == STATE_EXT_FMT && can_read >= 24) {
+            unsigned char data[24];
+            static const unsigned char pcm_fmt_guid[16] = {
+               0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00,
+               0x80, 0x00, 0x00, 0xAA, 0x00, 0x38, 0x9B, 0x71
+            };
+            sp_read(s->sp, data, 24);
+            if (memcmp (data + 8, pcm_fmt, 16)) {
+                av_log(ctx, AV_LOG_ERROR, "Unsupported extended wav format from subprocess (expected PCM).\n");
+                return AVERROR_INVALIDDATA;
+            }
+            s->chunk_size -= 24;
             s->state = STATE_SKIP_CHUNK;
         }
         else if (s->state == STATE_SKIP_CHUNK && can_read > 0) {