assign exact codec id, needed when stream copy

Originally committed as revision 5705 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mov.c

@@ -163,7 +163,7 @@ static const CodecTag mov_audio_tags[] = {
     { CODEC_ID_MACE3, MKTAG('M', 'A', 'C', '3') }, /* Macintosh Audio Compression and Expansion 3:1 */
     { CODEC_ID_MACE6, MKTAG('M', 'A', 'C', '6') }, /* Macintosh Audio Compression and Expansion 6:1 */
 
-    { CODEC_ID_MP2, MKTAG('.', 'm', 'p', '3') }, /* MPEG layer 3 */ /* sample files at http://www.3ivx.com/showcase.html use this tag */
+    { CODEC_ID_MP3, MKTAG('.', 'm', 'p', '3') }, /* MPEG layer 3 */ /* sample files at http://www.3ivx.com/showcase.html use this tag */
     { CODEC_ID_MP2, 0x6D730055 }, /* MPEG layer 3 */
     { 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 */