@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
