NAME
ffmpegutils  FFmpeg utilities
DESCRIPTION
This document describes some generic features and utilities provided by the libavutil library.
SYNTAX
This section documents the syntax and formats employed by the FFmpeg libraries and tools.
Quoting and escaping
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.
o  ’ and \ are special characters (respectively used for quoting and escaping). In addition to them, there might be other special characters depending on the specific syntax where the escaping and quoting are employed. 
o  A special character is escaped by prefixing it with a \. 
o  All characters enclosed between ’’ are included literally in the parsed string. The quote character ’ itself cannot be quoted, so you may need to close the quote and escape it. 
o  Leading and trailing whitespaces, unless escaped or quoted, are removed from the parsed string. 
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.
Examples
o  Escape the string Crime dAmour containing the special character:

o  The string above contains a quote, so the needs to be escaped when quoting it:

o  Include leading or trailing whitespaces using quoting:

o  Escaping and quoting can be mixed together:

o  To include a literal \ you can use either escaping or quoting:

Date
The accepted syntax is:
[(YYYYMMDDYYYYMMDD)[Tt ]]((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 yearmonthday part is not specified it takes the current yearmonthday.
Time duration
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 expresses the number of seconds, with the optional decimal part m.
In both expressions, the optional  indicates negative duration.
Examples
The following examples are all valid time duration:
55  55 seconds 
12:03:45  12 hours, 03 minutes and 45 seconds 
23.189  23.189 seconds 
Video size
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:
ntsc  720x480 
pal  720x576 
qntsc  352x240 
qpal  352x288 
sntsc  640x480 
spal  768x576 
film  352x240 
ntscfilm  352x240 
sqcif  128x96 
qcif  176x144 
cif  352x288 
4cif  704x576 
16cif  1408x1152 
qqvga  160x120 
qvga  320x240 
vga  640x480 
svga  800x600 
xga  1024x768 
uxga  1600x1200 
qxga  2048x1536 
sxga  1280x1024 
qsxga  2560x2048 
hsxga  5120x4096 
wvga  852x480 
wxga  1366x768 
wsxga  1600x1024 
wuxga  1920x1200 
woxga  2560x1600 
wqsxga  3200x2048 
wquxga  3840x2400 
whsxga  6400x4096 
whuxga  7680x4800 
cga  320x200 
ega  640x350 
hd480  852x480 
hd720  1280x720 
hd1080  1920x1080 
2k  2048x1080 
2kflat  1998x1080 
2kscope  2048x858 
4k  4096x2160 
4kflat  3996x2160 
4kscope  4096x1716 
nhd  640x360 
hqvga  240x160 
wqvga  400x240 
fwqvga  432x240 
hvga  480x320 
qhd  960x540 
2kdci  2048x1080 
4kdci  4096x2160 
uhd2160  3840x2160 
uhd4320  7680x4320 
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 frame_rate_num/frame_rate_den, an integer number, a float number or a valid video frame rate abbreviation.
The following abbreviations are recognized:
ntsc  30000/1001 
pal  25/1 
qntsc  30000/1001 
qpal  25/1 
sntsc  30000/1001 
spal  25/1 
film  24/1 
ntscfilm  24000/1001 
Ratio
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.
Color
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:
AliceBlue  0xF0F8FF 
AntiqueWhite  0xFAEBD7 
Aqua  0x00FFFF 
Aquamarine  0x7FFFD4 
Azure  0xF0FFFF 
Beige  0xF5F5DC 
Bisque  0xFFE4C4 
Black  0x000000 
BlanchedAlmond  0xFFEBCD 
Blue  0x0000FF 
BlueViolet  0x8A2BE2 
Brown  0xA52A2A 
BurlyWood  0xDEB887 
CadetBlue  0x5F9EA0 
Chartreuse  0x7FFF00 
Chocolate  0xD2691E 
Coral  0xFF7F50 
CornflowerBlue  0x6495ED 
Cornsilk  0xFFF8DC 
Crimson  0xDC143C 
Cyan  0x00FFFF 
DarkBlue  0x00008B 
DarkCyan  0x008B8B 
DarkGoldenRod  0xB8860B 
DarkGray  0xA9A9A9 
DarkGreen  0x006400 
DarkKhaki  0xBDB76B 
DarkMagenta  0x8B008B 
DarkOliveGreen  0x556B2F 
Darkorange  0xFF8C00 
DarkOrchid  0x9932CC 
DarkRed  0x8B0000 
DarkSalmon  0xE9967A 
DarkSeaGreen  0x8FBC8F 
DarkSlateBlue  0x483D8B 
DarkSlateGray  0x2F4F4F 
DarkTurquoise  0x00CED1 
DarkViolet  0x9400D3 
DeepPink  0xFF1493 
DeepSkyBlue  0x00BFFF 
DimGray  0x696969 
DodgerBlue  0x1E90FF 
FireBrick  0xB22222 
FloralWhite  0xFFFAF0 
ForestGreen  0x228B22 
Fuchsia  0xFF00FF 
Gainsboro  0xDCDCDC 
GhostWhite  0xF8F8FF 
Gold  0xFFD700 
GoldenRod  0xDAA520 
Gray  0x808080 
Green  0x008000 
GreenYellow  0xADFF2F 
HoneyDew  0xF0FFF0 
HotPink  0xFF69B4 
IndianRed  0xCD5C5C 
Indigo  0x4B0082 
Ivory  0xFFFFF0 
Khaki  0xF0E68C 
Lavender  0xE6E6FA 
LavenderBlush  0xFFF0F5 
LawnGreen  0x7CFC00 
LemonChiffon  0xFFFACD 
LightBlue  0xADD8E6 
LightCoral  0xF08080 
LightCyan  0xE0FFFF 
LightGoldenRodYellow  0xFAFAD2 
LightGreen  0x90EE90 
LightGrey  0xD3D3D3 
LightPink  0xFFB6C1 
LightSalmon  0xFFA07A 
LightSeaGreen  0x20B2AA 
LightSkyBlue  0x87CEFA 
LightSlateGray  0x778899 
LightSteelBlue  0xB0C4DE 
LightYellow  0xFFFFE0 
Lime  0x00FF00 
LimeGreen  0x32CD32 
Linen  0xFAF0E6 
Magenta  0xFF00FF 
Maroon  0x800000 
MediumAquaMarine  0x66CDAA 
MediumBlue  0x0000CD 
MediumOrchid  0xBA55D3 
MediumPurple  0x9370D8 
MediumSeaGreen  0x3CB371 
MediumSlateBlue  0x7B68EE 
MediumSpringGreen  0x00FA9A 
MediumTurquoise  0x48D1CC 
MediumVioletRed  0xC71585 
MidnightBlue  0x191970 
MintCream  0xF5FFFA 
MistyRose  0xFFE4E1 
Moccasin  0xFFE4B5 
NavajoWhite  0xFFDEAD 
Navy  0x000080 
OldLace  0xFDF5E6 
Olive  0x808000 
OliveDrab  0x6B8E23 
Orange  0xFFA500 
OrangeRed  0xFF4500 
Orchid  0xDA70D6 
PaleGoldenRod  0xEEE8AA 
PaleGreen  0x98FB98 
PaleTurquoise  0xAFEEEE 
PaleVioletRed  0xD87093 
PapayaWhip  0xFFEFD5 
PeachPuff  0xFFDAB9 
Peru  0xCD853F 
Pink  0xFFC0CB 
Plum  0xDDA0DD 
PowderBlue  0xB0E0E6 
Purple  0x800080 
Red  0xFF0000 
RosyBrown  0xBC8F8F 
RoyalBlue  0x4169E1 
SaddleBrown  0x8B4513 
Salmon  0xFA8072 
SandyBrown  0xF4A460 
SeaGreen  0x2E8B57 
SeaShell  0xFFF5EE 
Sienna  0xA0522D 
Silver  0xC0C0C0 
SkyBlue  0x87CEEB 
SlateBlue  0x6A5ACD 
SlateGray  0x708090 
Snow  0xFFFAFA 
SpringGreen  0x00FF7F 
SteelBlue  0x4682B4 
Tan  0xD2B48C 
Teal  0x008080 
Thistle  0xD8BFD8 
Tomato  0xFF6347 
Turquoise  0x40E0D0 
Violet  0xEE82EE 
Wheat  0xF5DEB3 
White  0xFFFFFF 
WhiteSmoke  0xF5F5F5 
Yellow  0xFFFF00 
YellowGreen  0x9ACD32 
Channel Layout
A channel layout specifies the spatial disposition of the channels in a multichannel audio stream. To specify a channel layout, FFmpeg makes use of a special syntax.
Standard channel layout compositions can be specified by using the following identifiers:
A custom channel layout can be specified as a sequence of terms, separated by ’+’ or ’’. Each term can be:
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).
Individual channels are identified by an id, as given by the table below:
FL  front left 
FR  front right 
FC  front center 
LFE  low frequency 
BL  back left 
BR  back right 
FLC  front leftofcenter 
FRC  front rightofcenter 
BC  back center 
SL  side left 
SR  side right 
TC  top center 
TFL  top front left 
TFC  top front center 
TFR  top front right 
TBL  top back left 
TBC  top back center 
TBR  top back right 
DL  downmix left 
DR  downmix right 
WL  wide left 
WR  wide right 
SDL  surround direct left 
SDR  surround direct right 
LFE2  low frequency 2 
mono  FC 
stereo  FL+FR 
2.1  FL+FR+LFE 
3.0  FL+FR+FC 
3.0(back)  FL+FR+BC 
4.0  FL+FR+FC+BC 
quad  FL+FR+BL+BR 
quad(side)  FL+FR+SL+SR 
3.1  FL+FR+FC+LFE 
5.0  FL+FR+FC+BL+BR 
5.0(side)  FL+FR+FC+SL+SR 
4.1  FL+FR+FC+LFE+BC 
5.1  FL+FR+FC+LFE+BL+BR 
5.1(side)  FL+FR+FC+LFE+SL+SR 
6.0  FL+FR+FC+BC+SL+SR 
6.0(front)  FL+FR+FLC+FRC+SL+SR 
hexagonal  FL+FR+FC+BL+BR+BC 
6.1  FL+FR+FC+LFE+BC+SL+SR 
6.1  FL+FR+FC+LFE+BL+BR+BC 
6.1(front)  FL+FR+LFE+FLC+FRC+SL+SR 
7.0  FL+FR+FC+BL+BR+SL+SR 
7.0(front)  FL+FR+FC+FLC+FRC+SL+SR 
7.1  FL+FR+FC+LFE+BL+BR+SL+SR 
7.1(wide)  FL+FR+FC+LFE+BL+BR+FLC+FRC 
7.1(wideside)  FL+FR+FC+LFE+FLC+FRC+SL+SR 
octagonal  FL+FR+FC+BL+BR+BC+SL+SR 
downmix  DL+DR 
o  the name of a standard channel layout (e.g. mono, stereo, 4.0, quad, 5.0, etc.) 
o  the name of a single channel (e.g. FL, FR, FC, LFE, etc.) 
o  a number of channels, in decimal, followed by ’c’, yielding the default channel layout for that number of channels (see the function av_get_default_channel_layout ). Note that not all channel counts have a default layout. 
o  a number of channels, in decimal, followed by ’C’, yielding an unknown channel layout with the specified number of channels. Note that not all channel layout specification strings support unknown channel layouts. 
o  a channel layout mask, in hexadecimal starting with 0x (see the AV_CH_* macros in libavutil/channel_layout.h. 
See also the function
av_get_channel_layout
defined in libavutil/channel_layout.h.EXPRESSION EVALUATION
When evaluating an arithmetic expression, FFmpeg uses an internal formula evaluator, implemented through the libavutil/eval.h interface.
The following constants are available:
Assuming that an expression is considered true if it has a nonzero value, note that:
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:
abs(x)  Compute absolute value of x. 
acos(x)  Compute arccosine of x. 
asin(x)  Compute arcsine of x. 
atan(x)  Compute arctangent of x. 
atan2(x, y)  Compute principal value of the arc tangent of y/x. 
between(x, min, max)  Return 1 if x is greater than or equal to min and lesser than or equal to max, 0 otherwise. 
bitand(x, y)  
bitor(x, y)  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).

ceil(expr)  Round the value of expression expr upwards to the nearest integer. For example, ceil(1.5) is 2.0. 
clip(x, min, max)  Return the value of x clipped between min and max. 
cos(x)  Compute cosine of x. 
cosh(x)  Compute hyperbolic cosine of x. 
eq(x, y)  Return 1 if x and y are equivalent, 0 otherwise. 
exp(x)  Compute exponential of x (with base e , the Euler’s number). 
floor(expr)  Round the value of expression expr downwards to the nearest integer. For example, floor(1.5) is 2.0. 
gauss(x)  Compute Gauss function of x, corresponding to exp(x*x/2) / sqrt(2*PI) . 
gcd(x, y)  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. 
gt(x, y)  Return 1 if x is greater than y, 0 otherwise. 
gte(x, y)  Return 1 if x is greater than or equal to y, 0 otherwise. 
hypot(x, y)  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. 
if(x, y)  Evaluate x, and if the result is nonzero return the result of the evaluation of y, return 0 otherwise. 
if(x, y, z)  Evaluate x, and if the result is nonzero return the evaluation result of y, otherwise the evaluation result of z. 
ifnot(x, y)  Evaluate x, and if the result is zero return the result of the evaluation of y, return 0 otherwise. 
ifnot(x, y, z)  Evaluate x, and if the result is zero return the evaluation result of y, otherwise the evaluation result of z. 
isinf(x)  Return 1.0 if x is +/INFINITY, 0.0 otherwise. 
isnan(x)  Return 1.0 if x is NAN, 0.0 otherwise. 
ld(var)  Load the value of the internal variable with number var, which was previously stored with st(var, expr). The function returns the loaded value. 
lerp(x, y, z)  Return linear interpolation between x and y by amount of z. 
log(x)  Compute natural logarithm of x. 
lt(x, y)  Return 1 if x is lesser than y, 0 otherwise. 
lte(x, y)  Return 1 if x is lesser than or equal to y, 0 otherwise. 
max(x, y)  Return the maximum between x and y. 
min(x, y)  Return the minimum between x and y. 
mod(x, y)  Compute the remainder of division of x by y. 
not(expr)  Return 1.0 if expr is zero, 0.0 otherwise. 
pow(x, y)  Compute the power of x elevated y, it is equivalent to "(x)^(y)". 
print(t)  
print(t, l)  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

random(x)  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. 
root(expr, max)  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(expr)  Round the value of expression expr to the nearest integer. For example, round(1.5) is 2.0. 
sin(x)  Compute sine of x. 
sinh(x)  Compute hyperbolic sine of x. 
sqrt(expr)  Compute the square root of expr. This is equivalent to "(expr)^.5". 
squish(x)  Compute expression 1/(1 + exp(4*x)) . 
st(var, expr)  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. 
tan(x)  Compute tangent of x. 
tanh(x)  Compute hyperbolic tangent of x. 
taylor(expr, x)  
taylor(expr, x, id)  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, xy) can be used. 
time(0)  Return the current (wallclock) time in seconds. 
trunc(expr)  Round the value of expression expr towards zero to the nearest integer. For example, trunc(1.5) is 1.0. 
while(cond, expr)  Evaluate expression expr while the expression cond is nonzero, and returns the value of the last expr evaluation, or NAN if cond was always false. 
PI  area of the unit disc, approximately 3.14 
E  exp(1) (Euler’s number), approximately 2.718 
PHI  golden ratio (1+sqrt(5))/2, approximately 1.618 
*
works like AND+
works like ORFor 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.
y  10^24 / 2^80 
z  10^21 / 2^70 
a  10^18 / 2^60 
f  10^15 / 2^50 
p  10^12 / 2^40 
n  10^9 / 2^30 
u  10^6 / 2^20 
m  10^3 / 2^10 
c  10^2 
d  10^1 
h  10^2 
k  10^3 / 2^10 
K  10^3 / 2^10 
M  10^6 / 2^20 
G  10^9 / 2^30 
T  10^12 / 2^40 
P  10^15 / 2^40 
E  10^18 / 2^50 
Z  10^21 / 2^60 
Y  10^24 / 2^70 
SEE ALSO
AUTHORS
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.