riff: Perform full lookup on WAVEFORMATEXTENSIBLE subformat guid

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Signed-off-by: Diego Biurrun <diego@biurrun.de>

libavformat/riff.c

@@ -687,7 +687,6 @@ int ff_get_wav_header(AVIOContext *pb, AVCodecContext *codec, int size)
 
     id                 = avio_rl16(pb);
     codec->codec_type  = AVMEDIA_TYPE_AUDIO;
-    codec->codec_tag   = id;
     codec->channels    = avio_rl16(pb);
     codec->sample_rate = avio_rl32(pb);
     codec->bit_rate    = avio_rl32(pb) * 8;
@@ -696,15 +695,36 @@ int ff_get_wav_header(AVIOContext *pb, AVCodecContext *codec, int size)
         codec->bits_per_coded_sample = 8;
     } else
         codec->bits_per_coded_sample = avio_rl16(pb);
+    if (id == 0xFFFE) {
+        codec->codec_tag = 0;
+    } else {
+        codec->codec_tag = id;
+        codec->codec_id  = ff_wav_codec_get_id(id,
+                                               codec->bits_per_coded_sample);
+    }
     if (size >= 18) {  /* We're obviously dealing with WAVEFORMATEX */
         int cbSize = avio_rl16(pb); /* cbSize */
         size  -= 18;
         cbSize = FFMIN(size, cbSize);
         if (cbSize >= 22 && id == 0xfffe) { /* WAVEFORMATEXTENSIBLE */
+            ff_asf_guid subformat;
             codec->bits_per_coded_sample = avio_rl16(pb);
             codec->channel_layout        = avio_rl32(pb); /* dwChannelMask */
-            id                           = avio_rl32(pb); /* 4 first bytes of GUID */
-            avio_skip(pb, 12); /* skip end of GUID */
+
+            ff_get_guid(pb, &subformat);
+            if (!memcmp(subformat + 4,
+                        (const uint8_t[]){ FF_MEDIASUBTYPE_BASE_GUID }, 12)) {
+                codec->codec_tag = AV_RL32(subformat);
+                codec->codec_id  = ff_wav_codec_get_id(codec->codec_tag,
+                                                       codec->bits_per_coded_sample);
+            } else {
+                codec->codec_id = ff_codec_guid_get_id(ff_codec_wav_guids,
+                                                       subformat);
+                if (!codec->codec_id)
+                    av_log(codec, AV_LOG_WARNING,
+                           "unknown subformat: "FF_PRI_GUID"\n",
+                           FF_ARG_GUID(subformat));
+            }
             cbSize -= 22;
             size   -= 22;
         }
@@ -723,7 +743,6 @@ int ff_get_wav_header(AVIOContext *pb, AVCodecContext *codec, int size)
         if (size > 0)
             avio_skip(pb, size);
     }
-    codec->codec_id = ff_wav_codec_get_id(id, codec->bits_per_coded_sample);
     if (codec->codec_id == AV_CODEC_ID_AAC_LATM) {
         /* Channels and sample_rate values are those prior to applying SBR
          * and/or PS. */