Add some help for the analyzeduration option.

patch by Víctor Paesa, wzrlpy arsystel com


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@8631 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavformat/utils.c

@@ -296,7 +296,7 @@ static const AVOption options[]={
 {"genpts", "generate pts", 0, FF_OPT_TYPE_CONST, AVFMT_FLAG_GENPTS, INT_MIN, INT_MAX, D, "fflags"},
 {"track", " set the track number", OFFSET(track), FF_OPT_TYPE_INT, DEFAULT, 0, INT_MAX, E},
 {"year", "set the year", OFFSET(year), FF_OPT_TYPE_INT, DEFAULT, INT_MIN, INT_MAX, E},
-{"analyzeduration", NULL, OFFSET(max_analyze_duration), FF_OPT_TYPE_INT, 3*AV_TIME_BASE, 0, INT_MAX, D},
+{"analyzeduration", "how many microseconds are analyzed to estimate duration", OFFSET(max_analyze_duration), FF_OPT_TYPE_INT, 3*AV_TIME_BASE, 0, INT_MAX, D},
 {NULL},
 };