lavf/options_table: improve option help text

Contains text suggested by carl
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

doc/formats.texi

@@ -58,7 +58,8 @@ Reduce the latency introduced by optional buffering
 @end table
 
 @item seek2any @var{integer} (@emph{input})
-Forces seeking to enable seek to any mode if set to 1. Default is 0.
+Allow seeking to non-keyframes on demuxer level when supported if set to 1.
+Default is 0.
 
 @item analyzeduration @var{integer} (@emph{input})
 Specify how many microseconds are analyzed to probe the input. A
@@ -137,7 +138,8 @@ Also note that this affects only leading negative timestamps, and not
 non-monotonic negative timestamps.
 
 @item skip_initial_bytes @var{integer} (@emph{input})
-Set number initial bytes to skip. Default is 0.
+Set number of bytes to skip before reading header and frames if set to 1.
+Default is 0.
 
 @item correct_ts_overflow @var{integer} (@emph{input})
 Correct single timestamp overflows if set to 1. Default is 1.

libavformat/options_table.h

@@ -49,7 +49,7 @@ static const AVOption avformat_options[] = {
 {"keepside", "don't merge side data", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_KEEP_SIDE_DATA }, INT_MIN, INT_MAX, D, "fflags"},
 {"latm", "enable RTP MP4A-LATM payload", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_MP4A_LATM }, INT_MIN, INT_MAX, E, "fflags"},
 {"nobuffer", "reduce the latency introduced by optional buffering", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_NOBUFFER }, 0, INT_MAX, D, "fflags"},
-{"seek2any", "forces seeking to enable seek to any mode", OFFSET(seek2any), AV_OPT_TYPE_INT, {.i64 = 0 }, 0, 1, D},
+{"seek2any", "allow seeking to non-keyframes on demuxer level when supported", OFFSET(seek2any), AV_OPT_TYPE_INT, {.i64 = 0 }, 0, 1, D},
 {"analyzeduration", "specify how many microseconds are analyzed to probe the input", OFFSET(max_analyze_duration), AV_OPT_TYPE_INT, {.i64 = 5*AV_TIME_BASE }, 0, INT_MAX, D},
 {"cryptokey", "decryption key", OFFSET(key), AV_OPT_TYPE_BINARY, {.dbl = 0}, 0, 0, D},
 {"indexmem", "max memory used for timestamp index (per stream)", OFFSET(max_index_size), AV_OPT_TYPE_INT, {.i64 = 1<<20 }, 0, INT_MAX, D},
@@ -74,7 +74,7 @@ static const AVOption avformat_options[] = {
 {"aggressive", "consider things that a sane encoder shouldn't do as an error", 0, AV_OPT_TYPE_CONST, {.i64 = AV_EF_AGGRESSIVE }, INT_MIN, INT_MAX, D, "err_detect"},
 {"use_wallclock_as_timestamps", "use wallclock as timestamps", OFFSET(use_wallclock_as_timestamps), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX-1, D},
 {"avoid_negative_ts", "shift timestamps to make them non-negative. 1 enables, 0 disables, default of -1 enables when required by target format.", OFFSET(avoid_negative_ts), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 1, E},
-{"skip_initial_bytes", "skip initial bytes", OFFSET(skip_initial_bytes), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX-1, D},
+{"skip_initial_bytes", "set number of bytes to skip before reading header and frames", OFFSET(skip_initial_bytes), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX-1, D},
 {"correct_ts_overflow", "correct single timestamp overflows", OFFSET(correct_ts_overflow), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, D},
 {"flush_packets", "enable flushing of the I/O context after each packet", OFFSET(flush_packets), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, E},
 {NULL},