doc: add syntax.texi file

doc/Makefile

@@ -8,6 +8,7 @@ HTMLPAGES   = $(PROGS-yes:%=doc/%.html)                                 \
               doc/git-howto.html                                        \
               doc/libavfilter.html                                      \
               doc/platform.html                                         \
+              doc/syntax.html                                           \
 
 TXTPAGES    = doc/fate.txt                                              \
 

doc/ffmpeg.texi

@@ -286,67 +286,6 @@ Set frame rate (Hz value, fraction or abbreviation), (default = 25). For output
 streams implies @code{-vsync cfr}.
 @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
 Set frame size. The format is @samp{wxh} (default - same as source).
-The following abbreviations are recognized:
-@table @samp
-@item sqcif
-128x96
-@item qcif
-176x144
-@item cif
-352x288
-@item 4cif
-704x576
-@item 16cif
-1408x1152
-@item qqvga
-160x120
-@item qvga
-320x240
-@item vga
-640x480
-@item svga
-800x600
-@item xga
-1024x768
-@item uxga
-1600x1200
-@item qxga
-2048x1536
-@item sxga
-1280x1024
-@item qsxga
-2560x2048
-@item hsxga
-5120x4096
-@item wvga
-852x480
-@item wxga
-1366x768
-@item wsxga
-1600x1024
-@item wuxga
-1920x1200
-@item woxga
-2560x1600
-@item wqsxga
-3200x2048
-@item wquxga
-3840x2400
-@item whsxga
-6400x4096
-@item whuxga
-7680x4800
-@item cga
-320x200
-@item ega
-640x350
-@item hd480
-852x480
-@item hd720
-1280x720
-@item hd1080
-1920x1080
-@end table
 
 @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
 Set the video display aspect ratio specified by @var{aspect}.
@@ -1179,6 +1118,7 @@ ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
 @end itemize
 @c man end EXAMPLES
 
+@include syntax.texi
 @include eval.texi
 @include decoders.texi
 @include encoders.texi

doc/ffplay.texi

@@ -178,6 +178,7 @@ Seek to percentage in file corresponding to fraction of width.
 
 @c man end
 
+@include syntax.texi
 @include eval.texi
 @include decoders.texi
 @include demuxers.texi

doc/ffprobe.texi

@@ -348,6 +348,7 @@ DV and GXF timecodes are available in format metadata
 @end itemize
 @c man end TIMECODE
 
+@include syntax.texi
 @include decoders.texi
 @include demuxers.texi
 @include protocols.texi

doc/syntax.texi

@@ -0,0 +1,158 @@
+@chapter Syntax
+@c man begin SYNTAX
+
+When evaluating specific formats, FFmpeg uses internal library parsing
+functions, shared by the tools. This section documents the syntax of
+some of these formats.
+
+@anchor{date syntax}
+@section Date
+
+The accepted syntax is:
+@example
+[(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...]]])|(HHMMSS[.m...]]]))[Z]
+now
+@end example
+
+If the value is "now" it takes the current time.
+
+Time is local time unless Z is appended, in which case it is
+interpreted as UTC.
+If the year-month-day part is not specified it takes the current
+year-month-day.
+
+@anchor{time duration syntax}
+@section Time duration
+
+The accepted syntax is:
+@example
+[-]HH:MM:SS[.m...]
+[-]S+[.m...]
+@end example
+
+@var{HH} expresses the number of hours, @var{MM} the number a of minutes
+and @var{SS} the number of seconds.
+
+@anchor{video size syntax}
+@section Video size
+Specify the size of the sourced video, it may be a string of the form
+@var{width}x@var{height}, or the name of a size abbreviation.
+
+The following abbreviations are recognized:
+@table @samp
+@item sqcif
+128x96
+@item qcif
+176x144
+@item cif
+352x288
+@item 4cif
+704x576
+@item 16cif
+1408x1152
+@item qqvga
+160x120
+@item qvga
+320x240
+@item vga
+640x480
+@item svga
+800x600
+@item xga
+1024x768
+@item uxga
+1600x1200
+@item qxga
+2048x1536
+@item sxga
+1280x1024
+@item qsxga
+2560x2048
+@item hsxga
+5120x4096
+@item wvga
+852x480
+@item wxga
+1366x768
+@item wsxga
+1600x1024
+@item wuxga
+1920x1200
+@item woxga
+2560x1600
+@item wqsxga
+3200x2048
+@item wquxga
+3840x2400
+@item whsxga
+6400x4096
+@item whuxga
+7680x4800
+@item cga
+320x200
+@item ega
+640x350
+@item hd480
+852x480
+@item hd720
+1280x720
+@item hd1080
+1920x1080
+@end table
+
+@anchor{video rate syntax}
+@section Video rate
+
+Specify the frame rate of a video, expressed as the number of frames
+generated per second. It has to be a string in the format
+@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
+number or a valid video frame rate abbreviation.
+
+The following abbreviations are recognized:
+@table @samp
+@item ntsc
+30000/1001
+@item pal
+25/1
+@item qntsc
+30000/1
+@item qpal
+25/1
+@item sntsc
+30000/1
+@item spal
+25/1
+@item film
+24/1
+@item ntsc-film
+24000/1
+@end table
+
+@anchor{ratio syntax}
+@section Ratio
+
+A ratio can be expressed as an expression, or in the form
+@var{numerator}:@var{denominator}.
+
+Note that a ratio with infinite (1/0) or negative value is
+considered valid, so you should check on the returned value if you
+want to exclude those values.
+
+The undefined value can be expressed using the "0:0" string.
+
+@anchor{color syntax}
+@section Color
+
+It can be the name of a color (case insensitive match) or a
+[0x|#]RRGGBB[AA] sequence, possibly followed by "@" and a string
+representing the alpha component.
+
+The alpha component may be a string composed by "0x" followed by an
+hexadecimal number or a decimal number between 0.0 and 1.0, which
+represents the opacity value (0x00/0.0 means completely transparent,
+0xff/1.0 completely opaque).
+If the alpha component is not specified then 0xff is assumed.
+
+The string "random" will result in a random color.
+
+@c man end SYNTAX