This document describes some generic features and utilities provided +by the libavutil library. +
+ + +This section documents the syntax and formats employed by the FFmpeg +libraries and tools. +
+ +FFmpeg adopts the following quoting and escaping mechanism, unless +explicitly specified. The following rules are applied: +
+Note that you may need to add a second level of escaping when using +the command line or a script, which depends on the syntax of the +adopted shell language. +
+The function av_get_token defined in
+libavutil/avstring.h can be used to parse a token quoted or
+escaped according to the rules defined above.
+
The tool tools/ffescape in the FFmpeg source tree can be used +to automatically quote or escape a string in a script. +
+ +Crime d'Amour containing the ' special
+character:
+Crime d\'Amour +
' needs to be escaped
+when quoting it:
+'Crime d'\''Amour' +
' this string starts and ends with whitespaces ' +
' The string '\'string\'' is a string ' +
'c:\foo' can be written as c:\\foo +
The accepted syntax is: +
[(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...]]])|(HHMMSS[.m...]]]))[Z] +now +
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. +
+ +There are two accepted syntaxes for expressing time duration. +
+[-][HH:]MM:SS[.m...] +
HH expresses the number of hours, MM the number of minutes +for a maximum of 2 digits, and SS the number of seconds for a +maximum of 2 digits. The m at the end expresses decimal value for +SS. +
+or +
+[-]S+[.m...][s|ms|us] +
S expresses the number of seconds, with the optional decimal part +m. The optional literal suffixes ‘s’, ‘ms’ or ‘us’ +indicate to interpret the value as seconds, milliseconds or microseconds, +respectively. +
+In both expressions, the optional ‘-’ indicates negative duration. +
+ +The following examples are all valid time duration: +
+55 seconds +
+0.2 seconds +
+200 milliseconds, that’s 0.2s +
+200000 microseconds, that’s 0.2s +
+12 hours, 03 minutes and 45 seconds +
+23.189 seconds +
Specify the size of the sourced video, it may be a string of the form +widthxheight, or the name of a size abbreviation. +
+The following abbreviations are recognized: +
720x480 +
720x576 +
352x240 +
352x288 +
640x480 +
768x576 +
352x240 +
352x240 +
128x96 +
176x144 +
352x288 +
704x576 +
1408x1152 +
160x120 +
320x240 +
640x480 +
800x600 +
1024x768 +
1600x1200 +
2048x1536 +
1280x1024 +
2560x2048 +
5120x4096 +
852x480 +
1366x768 +
1600x1024 +
1920x1200 +
2560x1600 +
3200x2048 +
3840x2400 +
6400x4096 +
7680x4800 +
320x200 +
640x350 +
852x480 +
1280x720 +
1920x1080 +
2048x1080 +
1998x1080 +
2048x858 +
4096x2160 +
3996x2160 +
4096x1716 +
640x360 +
240x160 +
400x240 +
432x240 +
480x320 +
960x540 +
2048x1080 +
4096x2160 +
3840x2160 +
7680x4320 +
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 +frame_rate_num/frame_rate_den, an integer number, a float +number or a valid video frame rate abbreviation. +
+The following abbreviations are recognized: +
30000/1001 +
25/1 +
30000/1001 +
25/1 +
30000/1001 +
25/1 +
24/1 +
24000/1001 +
A ratio can be expressed as an expression, or in the form +numerator: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. +
+ +It can be the name of a color as defined below (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’ or ‘0.0’ means completely +transparent, ‘0xff’ or ‘1.0’ completely opaque). If the alpha +component is not specified then ‘0xff’ is assumed. +
+The string ‘random’ will result in a random color. +
+The following names of colors are recognized: +
0xF0F8FF +
0xFAEBD7 +
0x00FFFF +
0x7FFFD4 +
0xF0FFFF +
0xF5F5DC +
0xFFE4C4 +
0x000000 +
0xFFEBCD +
0x0000FF +
0x8A2BE2 +
0xA52A2A +
0xDEB887 +
0x5F9EA0 +
0x7FFF00 +
0xD2691E +
0xFF7F50 +
0x6495ED +
0xFFF8DC +
0xDC143C +
0x00FFFF +
0x00008B +
0x008B8B +
0xB8860B +
0xA9A9A9 +
0x006400 +
0xBDB76B +
0x8B008B +
0x556B2F +
0xFF8C00 +
0x9932CC +
0x8B0000 +
0xE9967A +
0x8FBC8F +
0x483D8B +
0x2F4F4F +
0x00CED1 +
0x9400D3 +
0xFF1493 +
0x00BFFF +
0x696969 +
0x1E90FF +
0xB22222 +
0xFFFAF0 +
0x228B22 +
0xFF00FF +
0xDCDCDC +
0xF8F8FF +
0xFFD700 +
0xDAA520 +
0x808080 +
0x008000 +
0xADFF2F +
0xF0FFF0 +
0xFF69B4 +
0xCD5C5C +
0x4B0082 +
0xFFFFF0 +
0xF0E68C +
0xE6E6FA +
0xFFF0F5 +
0x7CFC00 +
0xFFFACD +
0xADD8E6 +
0xF08080 +
0xE0FFFF +
0xFAFAD2 +
0x90EE90 +
0xD3D3D3 +
0xFFB6C1 +
0xFFA07A +
0x20B2AA +
0x87CEFA +
0x778899 +
0xB0C4DE +
0xFFFFE0 +
0x00FF00 +
0x32CD32 +
0xFAF0E6 +
0xFF00FF +
0x800000 +
0x66CDAA +
0x0000CD +
0xBA55D3 +
0x9370D8 +
0x3CB371 +
0x7B68EE +
0x00FA9A +
0x48D1CC +
0xC71585 +
0x191970 +
0xF5FFFA +
0xFFE4E1 +
0xFFE4B5 +
0xFFDEAD +
0x000080 +
0xFDF5E6 +
0x808000 +
0x6B8E23 +
0xFFA500 +
0xFF4500 +
0xDA70D6 +
0xEEE8AA +
0x98FB98 +
0xAFEEEE +
0xD87093 +
0xFFEFD5 +
0xFFDAB9 +
0xCD853F +
0xFFC0CB +
0xDDA0DD +
0xB0E0E6 +
0x800080 +
0xFF0000 +
0xBC8F8F +
0x4169E1 +
0x8B4513 +
0xFA8072 +
0xF4A460 +
0x2E8B57 +
0xFFF5EE +
0xA0522D +
0xC0C0C0 +
0x87CEEB +
0x6A5ACD +
0x708090 +
0xFFFAFA +
0x00FF7F +
0x4682B4 +
0xD2B48C +
0x008080 +
0xD8BFD8 +
0xFF6347 +
0x40E0D0 +
0xEE82EE +
0xF5DEB3 +
0xFFFFFF +
0xF5F5F5 +
0xFFFF00 +
0x9ACD32 +
A channel layout specifies the spatial disposition of the channels in +a multi-channel audio stream. To specify a channel layout, FFmpeg +makes use of a special syntax. +
+Individual channels are identified by an id, as given by the table +below: +
front left +
front right +
front center +
low frequency +
back left +
back right +
front left-of-center +
front right-of-center +
back center +
side left +
side right +
top center +
top front left +
top front center +
top front right +
top back left +
top back center +
top back right +
downmix left +
downmix right +
wide left +
wide right +
surround direct left +
surround direct right +
low frequency 2 +
Standard channel layout compositions can be specified by using the +following identifiers: +
FC +
FL+FR +
FL+FR+LFE +
FL+FR+FC +
FL+FR+BC +
FL+FR+FC+BC +
FL+FR+BL+BR +
FL+FR+SL+SR +
FL+FR+FC+LFE +
FL+FR+FC+BL+BR +
FL+FR+FC+SL+SR +
FL+FR+FC+LFE+BC +
FL+FR+FC+LFE+BL+BR +
FL+FR+FC+LFE+SL+SR +
FL+FR+FC+BC+SL+SR +
FL+FR+FLC+FRC+SL+SR +
FL+FR+FC+BL+BR+BC +
FL+FR+FC+LFE+BC+SL+SR +
FL+FR+FC+LFE+BL+BR+BC +
FL+FR+LFE+FLC+FRC+SL+SR +
FL+FR+FC+BL+BR+SL+SR +
FL+FR+FC+FLC+FRC+SL+SR +
FL+FR+FC+LFE+BL+BR+SL+SR +
FL+FR+FC+LFE+BL+BR+FLC+FRC +
FL+FR+FC+LFE+FLC+FRC+SL+SR +
FL+FR+FC+LFE+BL+BR+TFL+TFR +
FL+FR+FC+BL+BR+BC+SL+SR +
FL+FR+BL+BR+TFL+TFR+TBL+TBR +
FL+FR+FC+BL+BR+BC+SL+SR+WL+WR+TBL+TBR+TBC+TFC+TFL+TFR +
DL+DR +
FL+FR+FC+LFE+BL+BR+FLC+FRC+BC+SL+SR+TC+TFL+TFC+TFR+TBL+TBC+TBR+LFE2+TSL+TSR+BFC+BFL+BFR +
A custom channel layout can be specified as a sequence of terms, separated by ’+’. +Each term can be: +
A standard channel layout can be specified by the following: +
av_channel_layout_default). Note that not all channel counts have a
+default layout.
+
+AV_CH_* macros in libavutil/channel_layout.h.
+Before libavutil version 53 the trailing character "c" to specify a number of +channels was optional, but now it is required, while a channel layout mask can +also be specified as a decimal number (if and only if not followed by "c" or "C"). +
+See also the function av_channel_layout_from_string defined in
+libavutil/channel_layout.h.
+
When evaluating an arithmetic expression, FFmpeg uses an internal +formula evaluator, implemented through the libavutil/eval.h +interface. +
+An expression may contain unary, binary operators, constants, and +functions. +
+Two expressions expr1 and expr2 can be combined to form +another expression "expr1;expr2". +expr1 and expr2 are evaluated in turn, and the new +expression evaluates to the value of expr2. +
+The following binary operators are available: +, -,
+*, /, ^.
+
The following unary operators are available: +, -.
+
The following functions are available: +
Compute absolute value of x. +
+Compute arccosine of x. +
+Compute arcsine of x. +
+Compute arctangent of x. +
+Compute principal value of the arc tangent of y/x. +
+Return 1 if x is greater than or equal to min and lesser than or +equal to max, 0 otherwise. +
+Compute bitwise and/or operation on x and y. +
+The results of the evaluation of x and y are converted to +integers before executing the bitwise operation. +
+Note that both the conversion to integer and the conversion back to +floating point can lose precision. Beware of unexpected results for +large numbers (usually 2^53 and larger). +
+Round the value of expression expr upwards to the nearest +integer. For example, "ceil(1.5)" is "2.0". +
+Return the value of x clipped between min and max. +
+Compute cosine of x. +
+Compute hyperbolic cosine of x. +
+Return 1 if x and y are equivalent, 0 otherwise. +
+Compute exponential of x (with base e, the Euler’s number).
+
Round the value of expression expr downwards to the nearest +integer. For example, "floor(-1.5)" is "-2.0". +
+Compute Gauss function of x, corresponding to
+exp(-x*x/2) / sqrt(2*PI).
+
Return the greatest common divisor of x and y. If both x and +y are 0 or either or both are less than zero then behavior is undefined. +
+Return 1 if x is greater than y, 0 otherwise. +
+Return 1 if x is greater than or equal to y, 0 otherwise. +
+This function is similar to the C function with the same name; it returns +"sqrt(x*x + y*y)", the length of the hypotenuse of a +right triangle with sides of length x and y, or the distance of the +point (x, y) from the origin. +
+Evaluate x, and if the result is non-zero return the result of +the evaluation of y, return 0 otherwise. +
+Evaluate x, and if the result is non-zero return the evaluation +result of y, otherwise the evaluation result of z. +
+Evaluate x, and if the result is zero return the result of the +evaluation of y, return 0 otherwise. +
+Evaluate x, and if the result is zero return the evaluation +result of y, otherwise the evaluation result of z. +
+Return 1.0 if x is +/-INFINITY, 0.0 otherwise. +
+Return 1.0 if x is NAN, 0.0 otherwise. +
+Load the value of the internal variable with number +var, which was previously stored with st(var, expr). +The function returns the loaded value. +
+Return linear interpolation between x and y by amount of z. +
+Compute natural logarithm of x. +
+Return 1 if x is lesser than y, 0 otherwise. +
+Return 1 if x is lesser than or equal to y, 0 otherwise. +
+Return the maximum between x and y. +
+Return the minimum between x and y. +
+Compute the remainder of division of x by y. +
+Return 1.0 if expr is zero, 0.0 otherwise. +
+Compute the power of x elevated y, it is equivalent to +"(x)^(y)". +
+Print the value of expression t with loglevel l. If +l is not specified then a default log level is used. +Returns the value of the expression printed. +
+Prints t with loglevel l +
+Return a pseudo random value between 0.0 and 1.0. x is the index of the +internal variable which will be used to save the seed/state. +
+Find an input value for which the function represented by expr +with argument ld(0) is 0 in the interval 0..max. +
+The expression in expr must denote a continuous function or the +result is undefined. +
+ld(0) is used to represent the function input value, which means
+that the given expression will be evaluated multiple times with
+various input values that the expression can access through
+ld(0). When the expression evaluates to 0 then the
+corresponding input value will be returned.
+
Round the value of expression expr to the nearest integer. For example, "round(1.5)" is "2.0". +
+Compute sign of x. +
+Compute sine of x. +
+Compute hyperbolic sine of x. +
+Compute the square root of expr. This is equivalent to +"(expr)^.5". +
+Compute expression 1/(1 + exp(4*x)).
+
Store the value of the expression expr in an internal +variable. var specifies the number of the variable where to +store the value, and it is a value ranging from 0 to 9. The function +returns the value stored in the internal variable. +Note, Variables are currently not shared between expressions. +
+Compute tangent of x. +
+Compute hyperbolic tangent of x. +
+Evaluate a Taylor series at x, given an expression representing
+the ld(id)-th derivative of a function at 0.
+
When the series does not converge the result is undefined. +
+ld(id) is used to represent the derivative order in expr,
+which means that the given expression will be evaluated multiple times
+with various input values that the expression can access through
+ld(id). If id is not specified then 0 is assumed.
+
Note, when you have the derivatives at y instead of 0,
+taylor(expr, x-y) can be used.
+
Return the current (wallclock) time in seconds. +
+Round the value of expression expr towards zero to the nearest +integer. For example, "trunc(-1.5)" is "-1.0". +
+Evaluate expression expr while the expression cond is +non-zero, and returns the value of the last expr evaluation, or +NAN if cond was always false. +
The following constants are available: +
area of the unit disc, approximately 3.14 +
exp(1) (Euler’s number), approximately 2.718 +
golden ratio (1+sqrt(5))/2, approximately 1.618 +
Assuming that an expression is considered "true" if it has a non-zero +value, note that: +
+* works like AND
+
+ works like OR
+
For example the construct: +
if (A AND B) then C +
is equivalent to: +
if(A*B, C) +
In your C code, you can extend the list of unary and binary functions, +and define recognized constants, so that they are available for your +expressions. +
+The evaluator also recognizes the International System unit prefixes. +If ’i’ is appended after the prefix, binary prefixes are used, which +are based on powers of 1024 instead of powers of 1000. +The ’B’ postfix multiplies the value by 8, and can be appended after a +unit prefix or used alone. This allows using for example ’KB’, ’MiB’, +’G’ and ’B’ as number postfix. +
+The list of available International System prefixes follows, with +indication of the corresponding powers of 10 and of 2. +
10^-24 / 2^-80 +
10^-21 / 2^-70 +
10^-18 / 2^-60 +
10^-15 / 2^-50 +
10^-12 / 2^-40 +
10^-9 / 2^-30 +
10^-6 / 2^-20 +
10^-3 / 2^-10 +
10^-2 +
10^-1 +
10^2 +
10^3 / 2^10 +
10^3 / 2^10 +
10^6 / 2^20 +
10^9 / 2^30 +
10^12 / 2^40 +
10^15 / 2^50 +
10^18 / 2^60 +
10^21 / 2^70 +
10^24 / 2^80 +
ffmpeg, ffplay, ffprobe, +libavutil +
+ + +The FFmpeg developers. +
+For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
+
Maintainers for the specific components are listed in the file +MAINTAINERS in the source code tree. +
+ ++ This document was generated using makeinfo. +
+