| FFMPEG-UTILS(1) 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: | |
| 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. | |
| 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 | |
| o Escape the string "Crime d'Amour" containing the "'" special | |
| character: | |
| Crime d\'Amour | |
| o The string above contains a quote, so the "'" needs to be escaped | |
| when quoting it: | |
| 'Crime d'\''Amour' | |
| o Include leading or trailing whitespaces using quoting: | |
| ' this string starts and ends with whitespaces ' | |
| o Escaping and quoting can be mixed together: | |
| ' The string '\'string\'' is a string ' | |
| o 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|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 | |
| 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 | |
| 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 | |
| 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: | |
| o 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: | |
| o the name of a single channel (e.g. FL, FR, FC, LFE, etc.) | |
| o the name of a standard channel layout (e.g. mono, stereo, 4.0, | |
| quad, 5.0, 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_channel_layout_default"). 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. | |
| 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(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 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(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". | |
| 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 | |
| SEE ALSO | |
| ffmpeg(1), ffplay(1), ffprobe(1), libavutil(3) | |
| 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. | |
| FFMPEG-UTILS(1) | |