ffmpegutils man page
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:
 ' 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.
 A special character is escaped by prefixing it with a \.
 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.
 Leading and trailing whitespaces, unless escaped or quoted, are removed from the parsed string.
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.
Examples

Escape the string
"Crime d'Amour"
containing the"'"
special character:Crime d\'Amour

The string above contains a quote, so the
"'"
needs to be escaped when quoting it:'Crime d'\''Amour'

Include leading or trailing whitespaces using quoting:
' this string starts and ends with whitespaces '

Escaping and quoting can be mixed together:
' The string '\'string\'' is a string '

To include a literal \ you can use either escaping or quoting:
'c:\foo' can be written as c:\\foo
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.
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
Standard channel layout compositions can be specified by using the following identifiers:
 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
A custom channel layout can be specified as a sequence of terms, separated by '+' or ''. Each term can be:
 the name of a standard channel layout (e.g. mono, stereo, 4.0, quad, 5.0, etc.)
 the name of a single channel (e.g. FL, FR, FC, LFE, etc.)
 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.  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.
 a channel layout mask, in hexadecimal starting with "0x" (see the
"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_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.
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.
 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.  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.
The following constants are available:
 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
Assuming that an expression is considered "true" if it has a nonzero 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.
 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
Opencl Options
When FFmpeg is configured with "enableopencl"
, it is possible to set the options for the global OpenCL context.
The list of supported options follows:
 build_options

Set build options used to compile the registered kernels.
See reference "OpenCL Specification Version: 1.2 chapter 5.6.4".
 platform_idx

Select the index of the platform to run OpenCL code.
The specified index must be one of the indexes in the device list which can be obtained with
"ffmpeg opencl_bench"
or"av_opencl_get_device_list()"
.  device_idx

Select the index of the device used to run OpenCL code.
The specified index must be one of the indexes in the device list which can be obtained with
"ffmpeg opencl_bench"
or"av_opencl_get_device_list()"
.
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.
Referenced By
ffmpeg(1), ffmpegall(1), ffmpegfilters(1), ffmpegformats(1), ffmpegresampler(1), ffplay(1), ffplayall(1), ffprobe(1), ffprobeall(1), ffserver(1), ffserverall(1), libavutil(3).