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FFMPEG-UTILS(1)

NAME

ffmpeg-utils - 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:

[(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.

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.

[-]<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.

Examples

The following examples are all valid time duration:

55: 55 seconds

0.2: 0.2 seconds

200ms: 200 milliseconds, that's 0.2s

200000us: 200000 microseconds, that's 0.2s

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

ntsc-film: 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

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

ntsc-film: 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 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:

FL: front left

FR: front right

FC: front center

LFE: low frequency

BL: back left

BR: back right

FLC: front left-of-center

FRC: front right-of-center

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

3.1.2: FL+FR+FC+LFE+TFL+TFR

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(wide-side): FL+FR+FC+LFE+FLC+FRC+SL+SR

5.1.2: FL+FR+FC+LFE+BL+BR+TFL+TFR

octagonal: FL+FR+FC+BL+BR+BC+SL+SR

cube: FL+FR+BL+BR+TFL+TFR+TBL+TBR

5.1.4: FL+FR+FC+LFE+BL+BR+TFL+TFR+TBL+TBR

7.1.2: FL+FR+FC+LFE+BL+BR+SL+SR+TFL+TFR

7.1.4: FL+FR+FC+LFE+BL+BR+SL+SR+TFL+TFR+TBL+TBR

7.2.3: FL+FR+FC+LFE+BL+BR+SL+SR+TFL+TFR+TBC+LFE2

9.1.4: FL+FR+FC+LFE+BL+BR+FLC+FRC+SL+SR+TFL+TFR+TBL+TBR

hexadecagonal: FL+FR+FC+BL+BR+BC+SL+SR+WL+WR+TBL+TBR+TBC+TFC+TFL+TFR

downmix: DL+DR

22.2: 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:

•: the name of a single channel (e.g. FL, FR, FC, LFE, etc.), each optionally containing a custom name after a '@', (e.g. FL@Left, FR@Right, FC@Center, LFE@Low_Frequency, etc.)

A standard channel layout can be specified by the following:

•: the name of a single channel (e.g. FL, FR, FC, LFE, etc.)

•: the name of a standard channel layout (e.g. mono, stereo, 4.0, quad, 5.0, etc.)

•: a number of channels, in decimal, followed by 'c', yielding the default channel layout for that number of channels (see the function "av_channel_layout_default"). 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_channel_layout_from_string" 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(y, x): 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 non-zero return the result of the evaluation of y, return 0 otherwise.

if(x, y, z): Evaluate x, and if the result is non-zero 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(idx): Return a pseudo random value between 0.0 and 1.0. idx is the index of the internal variable which will be used to save the seed/state.

randomi(idx, min, max): Return a pseudo random value in the interval between min and max. idx 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".

sgn(x): Compute sign of x.

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, x-y)" 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 non-zero, 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 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.

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 / 2^50

E: 10^18 / 2^60

Z: 10^21 / 2^70

Y: 10^24 / 2^80

AUTHORS

The FFmpeg developers.

For details about the authorship, see the Git history of the project (https://git.ffmpeg.org/ffmpeg), e.g. by typing the command git log in the FFmpeg source directory, or browsing the online repository at < https://git.ffmpeg.org/ffmpeg>.

Maintainers for the specific components are listed in the file MAINTAINERS in the source code tree.