Using the extension m4a for audio only MPEG-4 files is increasingly

common, especially since Apple iTunes treats files with the two
extensions differently. Without the patch, FFmpeg won't know that m4a
is for MPEG-4 files
patch by (Dan Christiansen <danchr at daimi dot au dot dk>)

Originally committed as revision 2398 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mov.c

@@ -120,7 +120,7 @@ static const CodecTag mov_audio_tags[] = {
     { CODEC_ID_MP2, 0x5500736D }, /* MPEG layer 3 *//* XXX: check endianness */
 /*    { CODEC_ID_OGG_VORBIS, MKTAG('O', 'g', 'g', 'S') }, *//* sample files at http://heroinewarrior.com/xmovie.php3 use this tag */
 /* MP4 tags */
-    { CODEC_ID_AAC, MKTAG('m', 'p', '4', 'a') }, /* MPEG 4 AAC or audio ? */
+    { CODEC_ID_MPEG4AAC, MKTAG('m', 'p', '4', 'a') }, /* MPEG-4 AAC */
     /* The standard for mpeg4 audio is still not normalised AFAIK anyway */
     { CODEC_ID_AMR_NB, MKTAG('s', 'a', 'm', 'r') }, /* AMR-NB 3gp */
     { CODEC_ID_AMR_WB, MKTAG('s', 'a', 'w', 'b') }, /* AMR-WB 3gp */
@@ -1658,7 +1658,7 @@ static int mov_read_close(AVFormatContext *s)
 }
 
 static AVInputFormat mov_iformat = {
-    "mov",
+    "mov,mp4,m4a,3gp",
     "QuickTime/MPEG4 format",
     sizeof(MOVContext),
     mov_probe,

libavformat/movenc.c

@@ -889,8 +889,8 @@ static AVOutputFormat _3gp_oformat = {
 static AVOutputFormat mp4_oformat = {
     "mp4",
     "mp4 format",
-    NULL,
-    "mp4",
+    "application/mp4",
+    "mp4,m4a",
     sizeof(MOVContext),
     CODEC_ID_AAC,
     CODEC_ID_MPEG4,