Add one more avc intra fourcc and extend the description

Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

libavformat/isom.c

@@ -134,10 +134,11 @@ const AVCodecTag codec_movvideo_tags[] = {
     { CODEC_ID_RAWVIDEO, MKTAG('W', 'R', 'A', 'W') },
 
     { CODEC_ID_H264, MKTAG('a', 'v', 'c', '1') }, /* AVC-1/H.264 */
-    { CODEC_ID_H264, MKTAG('a', 'i', '5', '5') }, /* AVC Intra  50 / 1080 */
+    { CODEC_ID_H264, MKTAG('a', 'i', '5', '5') }, /* AVC Intra  50 / 1080 interlace */
     { CODEC_ID_H264, MKTAG('a', 'i', '5', 'q') }, /* AVC Intra  50 /  720 */
-    { CODEC_ID_H264, MKTAG('a', 'i', '1', '5') }, /* AVC Intra 100 / 1080 */
+    { CODEC_ID_H264, MKTAG('a', 'i', '1', '5') }, /* AVC Intra 100 / 1080 interlace */
     { CODEC_ID_H264, MKTAG('a', 'i', '1', 'q') }, /* AVC Intra 100 /  720 */
+    { CODEC_ID_H264, MKTAG('a', 'i', '1', '2') }, /* AVC Intra 100 / 1080 */
 
     { CODEC_ID_MPEG1VIDEO, MKTAG('m', '1', 'v', '1') }, /* Apple MPEG-1 Camcorder */
     { CODEC_ID_MPEG1VIDEO, MKTAG('m', 'p', 'e', 'g') }, /* MPEG */