avformat: read id3v2 comment tags

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/id3v2.c

@@ -399,6 +399,45 @@ error:
     av_free(key);
 }
 
+/**
+ * Parse a comment tag.
+ */
+static void read_comment(AVFormatContext *s, AVIOContext *pb, int taglen,
+                      AVDictionary **metadata)
+{
+    const char *key = "comment";
+    uint8_t *dst;
+    int encoding, dict_flags = AV_DICT_DONT_OVERWRITE | AV_DICT_DONT_STRDUP_VAL;
+    int language;
+
+    if (taglen < 4)
+        return;
+
+    encoding = avio_r8(pb);
+    language = avio_rl24(pb);
+    taglen -= 4;
+
+    if (decode_str(s, pb, encoding, &dst, &taglen) < 0) {
+        av_log(s, AV_LOG_ERROR, "Error reading comment frame, skipped\n");
+        return;
+    }
+
+    if (dst && dst[0]) {
+        key = (const char *) dst;
+        dict_flags |= AV_DICT_DONT_STRDUP_KEY;
+    }
+
+    if (decode_str(s, pb, encoding, &dst, &taglen) < 0) {
+        av_log(s, AV_LOG_ERROR, "Error reading comment frame, skipped\n");
+        if (dict_flags & AV_DICT_DONT_STRDUP_KEY)
+            av_freep((void*)&key);
+        return;
+    }
+
+    if (dst)
+        av_dict_set(metadata, key, (const char *) dst, dict_flags);
+}
+
 /**
  * Parse GEOB tag into a ID3v2ExtraMetaGEOB struct.
  */
@@ -908,6 +947,7 @@ static void id3v2_parse(AVIOContext *pb, AVDictionary **metadata,
         /* check for text tag or supported special meta tag */
         } else if (tag[0] == 'T' ||
                    !memcmp(tag, "USLT", 4) ||
+                   !memcmp(tag, "COMM", 4) ||
                    (extra_meta &&
                     (extra_func = get_extra_meta_func(tag, isv34)))) {
             pbx = pb;
@@ -975,6 +1015,8 @@ static void id3v2_parse(AVIOContext *pb, AVDictionary **metadata,
                 read_ttag(s, pbx, tlen, metadata, tag);
             else if (!memcmp(tag, "USLT", 4))
                 read_uslt(s, pbx, tlen, metadata);
+            else if (!memcmp(tag, "COMM", 4))
+                read_comment(s, pbx, tlen, metadata);
             else
                 /* parse special meta tag */
                 extra_func->read(s, pbx, tlen, tag, extra_meta, isv34);