improve long_name for ass (de)muxer

Originally committed as revision 24084 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/assdec.c

@@ -177,7 +177,7 @@ static int read_packet(AVFormatContext *s, AVPacket *pkt)
 
 AVInputFormat ass_demuxer = {
     "ass",
-    NULL_IF_CONFIG_SMALL("SSA/ASS format"),
+    NULL_IF_CONFIG_SMALL("Advanced SubStation Alpha subtitle format"),
     sizeof(ASSContext),
     probe,
     read_header,

libavformat/assenc.c

@@ -79,7 +79,7 @@ static int write_trailer(AVFormatContext *s)
 
 AVOutputFormat ass_muxer = {
     "ass",
-    NULL_IF_CONFIG_SMALL("SSA/ASS format"),
+    NULL_IF_CONFIG_SMALL("Advanced SubStation Alpha subtitle format"),
     NULL,
     "ass,ssa",
     sizeof(ASSContext),