[FFmpeg-devel] [PATCH 6/6] mp3enc: support for id3v2.3 tags using a per-muxer AVOption

[Anton Khirnov]

fixes issue2562.
---
 libavformat/mp3enc.c |   39 ++++++++++++++++++++++++++++++++++-----
 1 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/libavformat/mp3enc.c b/libavformat/mp3enc.c
index edd6619..b2681b4 100644
--- a/libavformat/mp3enc.c
+++ b/libavformat/mp3enc.c
@@ -24,6 +24,7 @@
 #include "id3v1.h"
 #include "id3v2.h"
 #include "libavutil/intreadwrite.h"
+#include "libavutil/opt.h"
 
 static int id3v1_set_string(AVFormatContext *s, const char *key,
                             uint8_t *buf, int buf_size)
@@ -142,6 +143,24 @@ AVOutputFormat mp2_muxer = {
 #endif
 
 #if CONFIG_MP3_MUXER
+typedef struct MP3Context {
+    const AVClass *class;
+    int id3v2_version;
+} MP3Context;
+
+static const AVOption options[] = {
+    { "id3v2_version", "Select ID3v2 version to write. Currently 3 and 4 are supported.",
+      offsetof(MP3Context, id3v2_version), FF_OPT_TYPE_INT, 4, 3, 4, AV_OPT_FLAG_ENCODING_PARAM},
+    { NULL },
+};
+
+static const AVClass mp3_muxer_class = {
+    "MP3 muxer",
+    av_default_item_name,
+    options,
+    LIBAVUTIL_VERSION_INT,
+};
+
 static int id3v2_check_write_tag(AVFormatContext *s, AVMetadataTag *t, const char table[][4])
 {
     uint32_t tag;
@@ -157,16 +176,17 @@ static int id3v2_check_write_tag(AVFormatContext *s, AVMetadataTag *t, const cha
 }
 
 /**
- * Write an ID3v2.4 header at beginning of stream
+ * Write an ID3v2 header at beginning of stream
  */
 
 static int mp3_write_header(struct AVFormatContext *s)
 {
+    MP3Context *mp3 = s->priv_data;
     AVMetadataTag *t = NULL;
     int totlen = 0;
     int64_t size_pos, cur_pos;
 
-    put_be32(s->pb, MKBETAG('I', 'D', '3', 0x04)); /* ID3v2.4 */
+    put_be32(s->pb, MKBETAG('I', 'D', '3', mp3->id3v2_version));
     put_byte(s->pb, 0);
     put_byte(s->pb, 0); /* flags */
 
@@ -175,7 +195,9 @@ static int mp3_write_header(struct AVFormatContext *s)
     put_be32(s->pb, 0);
 
     ff_metadata_conv(&s->metadata, ff_id3v2_34_metadata_conv, NULL);
-    ff_metadata_conv(&s->metadata, ff_id3v2_4_metadata_conv, NULL);
+    if (mp3->id3v2_version == 4)
+        ff_metadata_conv(&s->metadata, ff_id3v2_4_metadata_conv, NULL);
+
     while ((t = av_metadata_get(s->metadata, "", t, AV_METADATA_IGNORE_SUFFIX))) {
         int ret;
 
@@ -183,7 +205,13 @@ static int mp3_write_header(struct AVFormatContext *s)
             totlen += ret;
             continue;
         }
-        if ((ret = id3v2_check_write_tag(s, t, ff_id3v2_4_tags)) > 0) {
+        if (mp3->id3v2_version == 4 &&
+            (ret = id3v2_check_write_tag(s, t, ff_id3v2_4_tags)) > 0) {
+            totlen += ret;
+            continue;
+        }
+        if (mp3->id3v2_version == 3 &&
+            (ret = id3v2_check_write_tag(s, t, ff_id3v2_3_tags)) > 0) {
             totlen += ret;
             continue;
         }
@@ -205,12 +233,13 @@ AVOutputFormat mp3_muxer = {
     NULL_IF_CONFIG_SMALL("MPEG audio layer 3"),
     "audio/x-mpeg",
     "mp3",
-    0,
+    sizeof(MP3Context),
     CODEC_ID_MP3,
     CODEC_ID_NONE,
     mp3_write_header,
     mp3_write_packet,
     mp3_write_trailer,
     AVFMT_NOTIMESTAMPS,
+    .priv_class = &mp3_muxer_class,
 };
 #endif
-- 
1.7.2.3