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PROGRAM:

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.

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

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

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

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

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

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, optionally followed by 'c', yielding the default
channel layout for that number of channels (see the function
"av_get_default_channel_layout")

· a channel layout mask, in hexadecimal starting with "0x" (see the "AV_CH_*" macros in
libavutil/channel_layout.h.

Starting from libavutil version 53 the trailing character "c" to specify a number of
channels will be required, while a channel layout mask could also be specified as a
decimal number (if and only if not followed by "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.

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.

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 maximum 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, 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 / 2^40

E 10^18 / 2^50

Z 10^21 / 2^60

Y 10^24 / 2^70

OPENCL OPTIONS

When FFmpeg is configured with "--enable-opencl", 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()".

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