| 0,0 → 1,1851 |
|---|
| =head1 NAME |
| |
| ffmpeg-utils - FFmpeg utilities |
| |
| =head1 DESCRIPTION |
| |
| |
| This document describes some generic features and utilities provided |
| by the libavutil library. |
| |
| |
| |
| =head1 SYNTAX |
| |
| |
| This section documents the syntax and formats employed by the FFmpeg |
| libraries and tools. |
| |
| |
| |
| =head2 Quoting and escaping |
| |
| |
| FFmpeg adopts the following quoting and escaping mechanism, unless |
| explicitly specified. The following rules are applied: |
| |
| |
| =over 4 |
| |
| |
| =item * |
| |
| C<'> and C<\> 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. |
| |
| |
| =item * |
| |
| A special character is escaped by prefixing it with a '\'. |
| |
| |
| =item * |
| |
| All characters enclosed between '' are included literally in the |
| parsed string. The quote character C<'> itself cannot be quoted, |
| so you may need to close the quote and escape it. |
| |
| |
| =item * |
| |
| Leading and trailing whitespaces, unless escaped or quoted, are |
| removed from the parsed string. |
| |
| =back |
| |
| |
| 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 C<av_get_token> defined in |
| F<libavutil/avstring.h> can be used to parse a token quoted or |
| escaped according to the rules defined above. |
| |
| The tool F<tools/ffescape> in the FFmpeg source tree can be used |
| to automatically quote or escape a string in a script. |
| |
| |
| =head3 Examples |
| |
| |
| |
| =over 4 |
| |
| |
| =item * |
| |
| Escape the string C<Crime d'Amour> containing the C<'> special |
| character: |
| |
| Crime d\'Amour |
| |
| |
| |
| =item * |
| |
| The string above contains a quote, so the C<'> needs to be escaped |
| when quoting it: |
| |
| 'Crime d'\''Amour' |
| |
| |
| |
| =item * |
| |
| Include leading or trailing whitespaces using quoting: |
| |
| ' this string starts and ends with whitespaces ' |
| |
| |
| |
| =item * |
| |
| Escaping and quoting can be mixed together: |
| |
| ' The string '\'string\'' is a string ' |
| |
| |
| |
| =item * |
| |
| To include a literal C<\> you can use either escaping or quoting: |
| |
| 'c:\foo' can be written as c:\\foo |
| |
| |
| =back |
| |
| |
| |
| |
| =head2 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. |
| |
| |
| |
| =head2 Time duration |
| |
| |
| There are two accepted syntaxes for expressing time duration. |
| |
| |
| [-][<HH>:]<MM>:<SS>[.<m>...] |
| |
| |
| I<HH> expresses the number of hours, I<MM> the number of minutes |
| for a maximum of 2 digits, and I<SS> the number of seconds for a |
| maximum of 2 digits. The I<m> at the end expresses decimal value for |
| I<SS>. |
| |
| I<or> |
| |
| |
| [-]<S>+[.<m>...] |
| |
| |
| I<S> expresses the number of seconds, with the optional decimal part |
| I<m>. |
| |
| In both expressions, the optional B<-> indicates negative duration. |
| |
| |
| =head3 Examples |
| |
| |
| The following examples are all valid time duration: |
| |
| |
| =over 4 |
| |
| |
| =item B<55> |
| |
| 55 seconds |
| |
| |
| =item B<12:03:45> |
| |
| 12 hours, 03 minutes and 45 seconds |
| |
| |
| =item B<23.189> |
| |
| 23.189 seconds |
| |
| =back |
| |
| |
| |
| |
| =head2 Video size |
| |
| Specify the size of the sourced video, it may be a string of the form |
| I<width>xI<height>, or the name of a size abbreviation. |
| |
| The following abbreviations are recognized: |
| |
| =over 4 |
| |
| |
| =item B<ntsc> |
| |
| 720x480 |
| |
| =item B<pal> |
| |
| 720x576 |
| |
| =item B<qntsc> |
| |
| 352x240 |
| |
| =item B<qpal> |
| |
| 352x288 |
| |
| =item B<sntsc> |
| |
| 640x480 |
| |
| =item B<spal> |
| |
| 768x576 |
| |
| =item B<film> |
| |
| 352x240 |
| |
| =item B<ntsc-film> |
| |
| 352x240 |
| |
| =item B<sqcif> |
| |
| 128x96 |
| |
| =item B<qcif> |
| |
| 176x144 |
| |
| =item B<cif> |
| |
| 352x288 |
| |
| =item B<4cif> |
| |
| 704x576 |
| |
| =item B<16cif> |
| |
| 1408x1152 |
| |
| =item B<qqvga> |
| |
| 160x120 |
| |
| =item B<qvga> |
| |
| 320x240 |
| |
| =item B<vga> |
| |
| 640x480 |
| |
| =item B<svga> |
| |
| 800x600 |
| |
| =item B<xga> |
| |
| 1024x768 |
| |
| =item B<uxga> |
| |
| 1600x1200 |
| |
| =item B<qxga> |
| |
| 2048x1536 |
| |
| =item B<sxga> |
| |
| 1280x1024 |
| |
| =item B<qsxga> |
| |
| 2560x2048 |
| |
| =item B<hsxga> |
| |
| 5120x4096 |
| |
| =item B<wvga> |
| |
| 852x480 |
| |
| =item B<wxga> |
| |
| 1366x768 |
| |
| =item B<wsxga> |
| |
| 1600x1024 |
| |
| =item B<wuxga> |
| |
| 1920x1200 |
| |
| =item B<woxga> |
| |
| 2560x1600 |
| |
| =item B<wqsxga> |
| |
| 3200x2048 |
| |
| =item B<wquxga> |
| |
| 3840x2400 |
| |
| =item B<whsxga> |
| |
| 6400x4096 |
| |
| =item B<whuxga> |
| |
| 7680x4800 |
| |
| =item B<cga> |
| |
| 320x200 |
| |
| =item B<ega> |
| |
| 640x350 |
| |
| =item B<hd480> |
| |
| 852x480 |
| |
| =item B<hd720> |
| |
| 1280x720 |
| |
| =item B<hd1080> |
| |
| 1920x1080 |
| |
| =item B<2k> |
| |
| 2048x1080 |
| |
| =item B<2kflat> |
| |
| 1998x1080 |
| |
| =item B<2kscope> |
| |
| 2048x858 |
| |
| =item B<4k> |
| |
| 4096x2160 |
| |
| =item B<4kflat> |
| |
| 3996x2160 |
| |
| =item B<4kscope> |
| |
| 4096x1716 |
| |
| =item B<nhd> |
| |
| 640x360 |
| |
| =item B<hqvga> |
| |
| 240x160 |
| |
| =item B<wqvga> |
| |
| 400x240 |
| |
| =item B<fwqvga> |
| |
| 432x240 |
| |
| =item B<hvga> |
| |
| 480x320 |
| |
| =item B<qhd> |
| |
| 960x540 |
| |
| =back |
| |
| |
| |
| |
| =head2 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 |
| I<frame_rate_num>/I<frame_rate_den>, an integer number, a float |
| number or a valid video frame rate abbreviation. |
| |
| The following abbreviations are recognized: |
| |
| =over 4 |
| |
| |
| =item B<ntsc> |
| |
| 30000/1001 |
| |
| =item B<pal> |
| |
| 25/1 |
| |
| =item B<qntsc> |
| |
| 30000/1001 |
| |
| =item B<qpal> |
| |
| 25/1 |
| |
| =item B<sntsc> |
| |
| 30000/1001 |
| |
| =item B<spal> |
| |
| 25/1 |
| |
| =item B<film> |
| |
| 24/1 |
| |
| =item B<ntsc-film> |
| |
| 24000/1001 |
| |
| =back |
| |
| |
| |
| |
| =head2 Ratio |
| |
| |
| A ratio can be expressed as an expression, or in the form |
| I<numerator>:I<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. |
| |
| |
| |
| =head2 Color |
| |
| |
| It can be the name of a color as defined below (case insensitive match) or a |
| C<[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 (B<0x00> or B<0.0> means completely |
| transparent, B<0xff> or B<1.0> completely opaque). If the alpha |
| component is not specified then B<0xff> is assumed. |
| |
| The string B<random> will result in a random color. |
| |
| The following names of colors are recognized: |
| |
| =over 4 |
| |
| |
| =item B<AliceBlue> |
| |
| 0xF0F8FF |
| |
| =item B<AntiqueWhite> |
| |
| 0xFAEBD7 |
| |
| =item B<Aqua> |
| |
| 0x00FFFF |
| |
| =item B<Aquamarine> |
| |
| 0x7FFFD4 |
| |
| =item B<Azure> |
| |
| 0xF0FFFF |
| |
| =item B<Beige> |
| |
| 0xF5F5DC |
| |
| =item B<Bisque> |
| |
| 0xFFE4C4 |
| |
| =item B<Black> |
| |
| 0x000000 |
| |
| =item B<BlanchedAlmond> |
| |
| 0xFFEBCD |
| |
| =item B<Blue> |
| |
| 0x0000FF |
| |
| =item B<BlueViolet> |
| |
| 0x8A2BE2 |
| |
| =item B<Brown> |
| |
| 0xA52A2A |
| |
| =item B<BurlyWood> |
| |
| 0xDEB887 |
| |
| =item B<CadetBlue> |
| |
| 0x5F9EA0 |
| |
| =item B<Chartreuse> |
| |
| 0x7FFF00 |
| |
| =item B<Chocolate> |
| |
| 0xD2691E |
| |
| =item B<Coral> |
| |
| 0xFF7F50 |
| |
| =item B<CornflowerBlue> |
| |
| 0x6495ED |
| |
| =item B<Cornsilk> |
| |
| 0xFFF8DC |
| |
| =item B<Crimson> |
| |
| 0xDC143C |
| |
| =item B<Cyan> |
| |
| 0x00FFFF |
| |
| =item B<DarkBlue> |
| |
| 0x00008B |
| |
| =item B<DarkCyan> |
| |
| 0x008B8B |
| |
| =item B<DarkGoldenRod> |
| |
| 0xB8860B |
| |
| =item B<DarkGray> |
| |
| 0xA9A9A9 |
| |
| =item B<DarkGreen> |
| |
| 0x006400 |
| |
| =item B<DarkKhaki> |
| |
| 0xBDB76B |
| |
| =item B<DarkMagenta> |
| |
| 0x8B008B |
| |
| =item B<DarkOliveGreen> |
| |
| 0x556B2F |
| |
| =item B<Darkorange> |
| |
| 0xFF8C00 |
| |
| =item B<DarkOrchid> |
| |
| 0x9932CC |
| |
| =item B<DarkRed> |
| |
| 0x8B0000 |
| |
| =item B<DarkSalmon> |
| |
| 0xE9967A |
| |
| =item B<DarkSeaGreen> |
| |
| 0x8FBC8F |
| |
| =item B<DarkSlateBlue> |
| |
| 0x483D8B |
| |
| =item B<DarkSlateGray> |
| |
| 0x2F4F4F |
| |
| =item B<DarkTurquoise> |
| |
| 0x00CED1 |
| |
| =item B<DarkViolet> |
| |
| 0x9400D3 |
| |
| =item B<DeepPink> |
| |
| 0xFF1493 |
| |
| =item B<DeepSkyBlue> |
| |
| 0x00BFFF |
| |
| =item B<DimGray> |
| |
| 0x696969 |
| |
| =item B<DodgerBlue> |
| |
| 0x1E90FF |
| |
| =item B<FireBrick> |
| |
| 0xB22222 |
| |
| =item B<FloralWhite> |
| |
| 0xFFFAF0 |
| |
| =item B<ForestGreen> |
| |
| 0x228B22 |
| |
| =item B<Fuchsia> |
| |
| 0xFF00FF |
| |
| =item B<Gainsboro> |
| |
| 0xDCDCDC |
| |
| =item B<GhostWhite> |
| |
| 0xF8F8FF |
| |
| =item B<Gold> |
| |
| 0xFFD700 |
| |
| =item B<GoldenRod> |
| |
| 0xDAA520 |
| |
| =item B<Gray> |
| |
| 0x808080 |
| |
| =item B<Green> |
| |
| 0x008000 |
| |
| =item B<GreenYellow> |
| |
| 0xADFF2F |
| |
| =item B<HoneyDew> |
| |
| 0xF0FFF0 |
| |
| =item B<HotPink> |
| |
| 0xFF69B4 |
| |
| =item B<IndianRed> |
| |
| 0xCD5C5C |
| |
| =item B<Indigo> |
| |
| 0x4B0082 |
| |
| =item B<Ivory> |
| |
| 0xFFFFF0 |
| |
| =item B<Khaki> |
| |
| 0xF0E68C |
| |
| =item B<Lavender> |
| |
| 0xE6E6FA |
| |
| =item B<LavenderBlush> |
| |
| 0xFFF0F5 |
| |
| =item B<LawnGreen> |
| |
| 0x7CFC00 |
| |
| =item B<LemonChiffon> |
| |
| 0xFFFACD |
| |
| =item B<LightBlue> |
| |
| 0xADD8E6 |
| |
| =item B<LightCoral> |
| |
| 0xF08080 |
| |
| =item B<LightCyan> |
| |
| 0xE0FFFF |
| |
| =item B<LightGoldenRodYellow> |
| |
| 0xFAFAD2 |
| |
| =item B<LightGreen> |
| |
| 0x90EE90 |
| |
| =item B<LightGrey> |
| |
| 0xD3D3D3 |
| |
| =item B<LightPink> |
| |
| 0xFFB6C1 |
| |
| =item B<LightSalmon> |
| |
| 0xFFA07A |
| |
| =item B<LightSeaGreen> |
| |
| 0x20B2AA |
| |
| =item B<LightSkyBlue> |
| |
| 0x87CEFA |
| |
| =item B<LightSlateGray> |
| |
| 0x778899 |
| |
| =item B<LightSteelBlue> |
| |
| 0xB0C4DE |
| |
| =item B<LightYellow> |
| |
| 0xFFFFE0 |
| |
| =item B<Lime> |
| |
| 0x00FF00 |
| |
| =item B<LimeGreen> |
| |
| 0x32CD32 |
| |
| =item B<Linen> |
| |
| 0xFAF0E6 |
| |
| =item B<Magenta> |
| |
| 0xFF00FF |
| |
| =item B<Maroon> |
| |
| 0x800000 |
| |
| =item B<MediumAquaMarine> |
| |
| 0x66CDAA |
| |
| =item B<MediumBlue> |
| |
| 0x0000CD |
| |
| =item B<MediumOrchid> |
| |
| 0xBA55D3 |
| |
| =item B<MediumPurple> |
| |
| 0x9370D8 |
| |
| =item B<MediumSeaGreen> |
| |
| 0x3CB371 |
| |
| =item B<MediumSlateBlue> |
| |
| 0x7B68EE |
| |
| =item B<MediumSpringGreen> |
| |
| 0x00FA9A |
| |
| =item B<MediumTurquoise> |
| |
| 0x48D1CC |
| |
| =item B<MediumVioletRed> |
| |
| 0xC71585 |
| |
| =item B<MidnightBlue> |
| |
| 0x191970 |
| |
| =item B<MintCream> |
| |
| 0xF5FFFA |
| |
| =item B<MistyRose> |
| |
| 0xFFE4E1 |
| |
| =item B<Moccasin> |
| |
| 0xFFE4B5 |
| |
| =item B<NavajoWhite> |
| |
| 0xFFDEAD |
| |
| =item B<Navy> |
| |
| 0x000080 |
| |
| =item B<OldLace> |
| |
| 0xFDF5E6 |
| |
| =item B<Olive> |
| |
| 0x808000 |
| |
| =item B<OliveDrab> |
| |
| 0x6B8E23 |
| |
| =item B<Orange> |
| |
| 0xFFA500 |
| |
| =item B<OrangeRed> |
| |
| 0xFF4500 |
| |
| =item B<Orchid> |
| |
| 0xDA70D6 |
| |
| =item B<PaleGoldenRod> |
| |
| 0xEEE8AA |
| |
| =item B<PaleGreen> |
| |
| 0x98FB98 |
| |
| =item B<PaleTurquoise> |
| |
| 0xAFEEEE |
| |
| =item B<PaleVioletRed> |
| |
| 0xD87093 |
| |
| =item B<PapayaWhip> |
| |
| 0xFFEFD5 |
| |
| =item B<PeachPuff> |
| |
| 0xFFDAB9 |
| |
| =item B<Peru> |
| |
| 0xCD853F |
| |
| =item B<Pink> |
| |
| 0xFFC0CB |
| |
| =item B<Plum> |
| |
| 0xDDA0DD |
| |
| =item B<PowderBlue> |
| |
| 0xB0E0E6 |
| |
| =item B<Purple> |
| |
| 0x800080 |
| |
| =item B<Red> |
| |
| 0xFF0000 |
| |
| =item B<RosyBrown> |
| |
| 0xBC8F8F |
| |
| =item B<RoyalBlue> |
| |
| 0x4169E1 |
| |
| =item B<SaddleBrown> |
| |
| 0x8B4513 |
| |
| =item B<Salmon> |
| |
| 0xFA8072 |
| |
| =item B<SandyBrown> |
| |
| 0xF4A460 |
| |
| =item B<SeaGreen> |
| |
| 0x2E8B57 |
| |
| =item B<SeaShell> |
| |
| 0xFFF5EE |
| |
| =item B<Sienna> |
| |
| 0xA0522D |
| |
| =item B<Silver> |
| |
| 0xC0C0C0 |
| |
| =item B<SkyBlue> |
| |
| 0x87CEEB |
| |
| =item B<SlateBlue> |
| |
| 0x6A5ACD |
| |
| =item B<SlateGray> |
| |
| 0x708090 |
| |
| =item B<Snow> |
| |
| 0xFFFAFA |
| |
| =item B<SpringGreen> |
| |
| 0x00FF7F |
| |
| =item B<SteelBlue> |
| |
| 0x4682B4 |
| |
| =item B<Tan> |
| |
| 0xD2B48C |
| |
| =item B<Teal> |
| |
| 0x008080 |
| |
| =item B<Thistle> |
| |
| 0xD8BFD8 |
| |
| =item B<Tomato> |
| |
| 0xFF6347 |
| |
| =item B<Turquoise> |
| |
| 0x40E0D0 |
| |
| =item B<Violet> |
| |
| 0xEE82EE |
| |
| =item B<Wheat> |
| |
| 0xF5DEB3 |
| |
| =item B<White> |
| |
| 0xFFFFFF |
| |
| =item B<WhiteSmoke> |
| |
| 0xF5F5F5 |
| |
| =item B<Yellow> |
| |
| 0xFFFF00 |
| |
| =item B<YellowGreen> |
| |
| 0x9ACD32 |
| |
| =back |
| |
| |
| |
| |
| =head2 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: |
| |
| =over 4 |
| |
| |
| =item B<FL> |
| |
| front left |
| |
| =item B<FR> |
| |
| front right |
| |
| =item B<FC> |
| |
| front center |
| |
| =item B<LFE> |
| |
| low frequency |
| |
| =item B<BL> |
| |
| back left |
| |
| =item B<BR> |
| |
| back right |
| |
| =item B<FLC> |
| |
| front left-of-center |
| |
| =item B<FRC> |
| |
| front right-of-center |
| |
| =item B<BC> |
| |
| back center |
| |
| =item B<SL> |
| |
| side left |
| |
| =item B<SR> |
| |
| side right |
| |
| =item B<TC> |
| |
| top center |
| |
| =item B<TFL> |
| |
| top front left |
| |
| =item B<TFC> |
| |
| top front center |
| |
| =item B<TFR> |
| |
| top front right |
| |
| =item B<TBL> |
| |
| top back left |
| |
| =item B<TBC> |
| |
| top back center |
| |
| =item B<TBR> |
| |
| top back right |
| |
| =item B<DL> |
| |
| downmix left |
| |
| =item B<DR> |
| |
| downmix right |
| |
| =item B<WL> |
| |
| wide left |
| |
| =item B<WR> |
| |
| wide right |
| |
| =item B<SDL> |
| |
| surround direct left |
| |
| =item B<SDR> |
| |
| surround direct right |
| |
| =item B<LFE2> |
| |
| low frequency 2 |
| |
| =back |
| |
| |
| Standard channel layout compositions can be specified by using the |
| following identifiers: |
| |
| =over 4 |
| |
| |
| =item B<mono> |
| |
| FC |
| |
| =item B<stereo> |
| |
| FL+FR |
| |
| =item B<2.1> |
| |
| FL+FR+LFE |
| |
| =item B<3.0> |
| |
| FL+FR+FC |
| |
| =item B<3.0(back)> |
| |
| FL+FR+BC |
| |
| =item B<4.0> |
| |
| FL+FR+FC+BC |
| |
| =item B<quad> |
| |
| FL+FR+BL+BR |
| |
| =item B<quad(side)> |
| |
| FL+FR+SL+SR |
| |
| =item B<3.1> |
| |
| FL+FR+FC+LFE |
| |
| =item B<5.0> |
| |
| FL+FR+FC+BL+BR |
| |
| =item B<5.0(side)> |
| |
| FL+FR+FC+SL+SR |
| |
| =item B<4.1> |
| |
| FL+FR+FC+LFE+BC |
| |
| =item B<5.1> |
| |
| FL+FR+FC+LFE+BL+BR |
| |
| =item B<5.1(side)> |
| |
| FL+FR+FC+LFE+SL+SR |
| |
| =item B<6.0> |
| |
| FL+FR+FC+BC+SL+SR |
| |
| =item B<6.0(front)> |
| |
| FL+FR+FLC+FRC+SL+SR |
| |
| =item B<hexagonal> |
| |
| FL+FR+FC+BL+BR+BC |
| |
| =item B<6.1> |
| |
| FL+FR+FC+LFE+BC+SL+SR |
| |
| =item B<6.1> |
| |
| FL+FR+FC+LFE+BL+BR+BC |
| |
| =item B<6.1(front)> |
| |
| FL+FR+LFE+FLC+FRC+SL+SR |
| |
| =item B<7.0> |
| |
| FL+FR+FC+BL+BR+SL+SR |
| |
| =item B<7.0(front)> |
| |
| FL+FR+FC+FLC+FRC+SL+SR |
| |
| =item B<7.1> |
| |
| FL+FR+FC+LFE+BL+BR+SL+SR |
| |
| =item B<7.1(wide)> |
| |
| FL+FR+FC+LFE+BL+BR+FLC+FRC |
| |
| =item B<7.1(wide-side)> |
| |
| FL+FR+FC+LFE+FLC+FRC+SL+SR |
| |
| =item B<octagonal> |
| |
| FL+FR+FC+BL+BR+BC+SL+SR |
| |
| =item B<downmix> |
| |
| DL+DR |
| |
| =back |
| |
| |
| A custom channel layout can be specified as a sequence of terms, separated by |
| '+' or '|'. Each term can be: |
| |
| =over 4 |
| |
| |
| =item * |
| |
| the name of a standard channel layout (e.g. B<mono>, |
| B<stereo>, B<4.0>, B<quad>, B<5.0>, etc.) |
| |
| |
| =item * |
| |
| the name of a single channel (e.g. B<FL>, B<FR>, B<FC>, B<LFE>, etc.) |
| |
| |
| =item * |
| |
| a number of channels, in decimal, optionally followed by 'c', yielding |
| the default channel layout for that number of channels (see the |
| function C<av_get_default_channel_layout>) |
| |
| |
| =item * |
| |
| a channel layout mask, in hexadecimal starting with "0x" (see the |
| C<AV_CH_*> macros in F<libavutil/channel_layout.h>. |
| |
| =back |
| |
| |
| 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 C<av_get_channel_layout> defined in |
| F<libavutil/channel_layout.h>. |
| |
| |
| =head1 EXPRESSION EVALUATION |
| |
| |
| When evaluating an arithmetic expression, FFmpeg uses an internal |
| formula evaluator, implemented through the F<libavutil/eval.h> |
| interface. |
| |
| An expression may contain unary, binary operators, constants, and |
| functions. |
| |
| Two expressions I<expr1> and I<expr2> can be combined to form |
| another expression "I<expr1>;I<expr2>". |
| I<expr1> and I<expr2> are evaluated in turn, and the new |
| expression evaluates to the value of I<expr2>. |
| |
| The following binary operators are available: C<+>, C<->, |
| C<*>, C</>, C<^>. |
| |
| The following unary operators are available: C<+>, C<->. |
| |
| The following functions are available: |
| |
| =over 4 |
| |
| |
| =item B<abs(x)> |
| |
| Compute absolute value of I<x>. |
| |
| |
| =item B<acos(x)> |
| |
| Compute arccosine of I<x>. |
| |
| |
| =item B<asin(x)> |
| |
| Compute arcsine of I<x>. |
| |
| |
| =item B<atan(x)> |
| |
| Compute arctangent of I<x>. |
| |
| |
| =item B<between(x, min, max)> |
| |
| Return 1 if I<x> is greater than or equal to I<min> and lesser than or |
| equal to I<max>, 0 otherwise. |
| |
| |
| =item B<bitand(x, y)> |
| |
| |
| =item B<bitor(x, y)> |
| |
| Compute bitwise and/or operation on I<x> and I<y>. |
| |
| The results of the evaluation of I<x> and I<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). |
| |
| |
| =item B<ceil(expr)> |
| |
| Round the value of expression I<expr> upwards to the nearest |
| integer. For example, "ceil(1.5)" is "2.0". |
| |
| |
| =item B<cos(x)> |
| |
| Compute cosine of I<x>. |
| |
| |
| =item B<cosh(x)> |
| |
| Compute hyperbolic cosine of I<x>. |
| |
| |
| =item B<eq(x, y)> |
| |
| Return 1 if I<x> and I<y> are equivalent, 0 otherwise. |
| |
| |
| =item B<exp(x)> |
| |
| Compute exponential of I<x> (with base C<e>, the Euler's number). |
| |
| |
| =item B<floor(expr)> |
| |
| Round the value of expression I<expr> downwards to the nearest |
| integer. For example, "floor(-1.5)" is "-2.0". |
| |
| |
| =item B<gauss(x)> |
| |
| Compute Gauss function of I<x>, corresponding to |
| C<exp(-x*x/2) / sqrt(2*PI)>. |
| |
| |
| =item B<gcd(x, y)> |
| |
| Return the greatest common divisor of I<x> and I<y>. If both I<x> and |
| I<y> are 0 or either or both are less than zero then behavior is undefined. |
| |
| |
| =item B<gt(x, y)> |
| |
| Return 1 if I<x> is greater than I<y>, 0 otherwise. |
| |
| |
| =item B<gte(x, y)> |
| |
| Return 1 if I<x> is greater than or equal to I<y>, 0 otherwise. |
| |
| |
| =item B<hypot(x, y)> |
| |
| This function is similar to the C function with the same name; it returns |
| "sqrt(I<x>*I<x> + I<y>*I<y>)", the length of the hypotenuse of a |
| right triangle with sides of length I<x> and I<y>, or the distance of the |
| point (I<x>, I<y>) from the origin. |
| |
| |
| =item B<if(x, y)> |
| |
| Evaluate I<x>, and if the result is non-zero return the result of |
| the evaluation of I<y>, return 0 otherwise. |
| |
| |
| =item B<if(x, y, z)> |
| |
| Evaluate I<x>, and if the result is non-zero return the evaluation |
| result of I<y>, otherwise the evaluation result of I<z>. |
| |
| |
| =item B<ifnot(x, y)> |
| |
| Evaluate I<x>, and if the result is zero return the result of the |
| evaluation of I<y>, return 0 otherwise. |
| |
| |
| =item B<ifnot(x, y, z)> |
| |
| Evaluate I<x>, and if the result is zero return the evaluation |
| result of I<y>, otherwise the evaluation result of I<z>. |
| |
| |
| =item B<isinf(x)> |
| |
| Return 1.0 if I<x> is +/-INFINITY, 0.0 otherwise. |
| |
| |
| =item B<isnan(x)> |
| |
| Return 1.0 if I<x> is NAN, 0.0 otherwise. |
| |
| |
| =item B<ld(var)> |
| |
| Allow to load the value of the internal variable with number |
| I<var>, which was previously stored with st(I<var>, I<expr>). |
| The function returns the loaded value. |
| |
| |
| =item B<log(x)> |
| |
| Compute natural logarithm of I<x>. |
| |
| |
| =item B<lt(x, y)> |
| |
| Return 1 if I<x> is lesser than I<y>, 0 otherwise. |
| |
| |
| =item B<lte(x, y)> |
| |
| Return 1 if I<x> is lesser than or equal to I<y>, 0 otherwise. |
| |
| |
| =item B<max(x, y)> |
| |
| Return the maximum between I<x> and I<y>. |
| |
| |
| =item B<min(x, y)> |
| |
| Return the maximum between I<x> and I<y>. |
| |
| |
| =item B<mod(x, y)> |
| |
| Compute the remainder of division of I<x> by I<y>. |
| |
| |
| =item B<not(expr)> |
| |
| Return 1.0 if I<expr> is zero, 0.0 otherwise. |
| |
| |
| =item B<pow(x, y)> |
| |
| Compute the power of I<x> elevated I<y>, it is equivalent to |
| "(I<x>)^(I<y>)". |
| |
| |
| =item B<print(t)> |
| |
| |
| =item B<print(t, l)> |
| |
| Print the value of expression I<t> with loglevel I<l>. If |
| I<l> is not specified then a default log level is used. |
| Returns the value of the expression printed. |
| |
| Prints t with loglevel l |
| |
| |
| =item B<random(x)> |
| |
| Return a pseudo random value between 0.0 and 1.0. I<x> is the index of the |
| internal variable which will be used to save the seed/state. |
| |
| |
| =item B<root(expr, max)> |
| |
| Find an input value for which the function represented by I<expr> |
| with argument I<ld(0)> is 0 in the interval 0..I<max>. |
| |
| The expression in I<expr> must denote a continuous function or the |
| result is undefined. |
| |
| I<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 |
| C<ld(0)>. When the expression evaluates to 0 then the |
| corresponding input value will be returned. |
| |
| |
| =item B<sin(x)> |
| |
| Compute sine of I<x>. |
| |
| |
| =item B<sinh(x)> |
| |
| Compute hyperbolic sine of I<x>. |
| |
| |
| =item B<sqrt(expr)> |
| |
| Compute the square root of I<expr>. This is equivalent to |
| "(I<expr>)^.5". |
| |
| |
| =item B<squish(x)> |
| |
| Compute expression C<1/(1 + exp(4*x))>. |
| |
| |
| =item B<st(var, expr)> |
| |
| Allow to store the value of the expression I<expr> in an internal |
| variable. I<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. |
| |
| |
| =item B<tan(x)> |
| |
| Compute tangent of I<x>. |
| |
| |
| =item B<tanh(x)> |
| |
| Compute hyperbolic tangent of I<x>. |
| |
| |
| =item B<taylor(expr, x)> |
| |
| |
| =item B<taylor(expr, x, id)> |
| |
| Evaluate a Taylor series at I<x>, given an expression representing |
| the C<ld(id)>-th derivative of a function at 0. |
| |
| When the series does not converge the result is undefined. |
| |
| I<ld(id)> is used to represent the derivative order in I<expr>, |
| which means that the given expression will be evaluated multiple times |
| with various input values that the expression can access through |
| C<ld(id)>. If I<id> is not specified then 0 is assumed. |
| |
| Note, when you have the derivatives at y instead of 0, |
| C<taylor(expr, x-y)> can be used. |
| |
| |
| =item B<time(0)> |
| |
| Return the current (wallclock) time in seconds. |
| |
| |
| =item B<trunc(expr)> |
| |
| Round the value of expression I<expr> towards zero to the nearest |
| integer. For example, "trunc(-1.5)" is "-1.0". |
| |
| |
| =item B<while(cond, expr)> |
| |
| Evaluate expression I<expr> while the expression I<cond> is |
| non-zero, and returns the value of the last I<expr> evaluation, or |
| NAN if I<cond> was always false. |
| |
| =back |
| |
| |
| The following constants are available: |
| |
| =over 4 |
| |
| |
| =item B<PI> |
| |
| area of the unit disc, approximately 3.14 |
| |
| =item B<E> |
| |
| exp(1) (Euler's number), approximately 2.718 |
| |
| =item B<PHI> |
| |
| golden ratio (1+sqrt(5))/2, approximately 1.618 |
| |
| =back |
| |
| |
| Assuming that an expression is considered "true" if it has a non-zero |
| value, note that: |
| |
| C<*> works like AND |
| |
| C<+> 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. |
| |
| =over 4 |
| |
| |
| =item B<y> |
| |
| 10^-24 / 2^-80 |
| |
| =item B<z> |
| |
| 10^-21 / 2^-70 |
| |
| =item B<a> |
| |
| 10^-18 / 2^-60 |
| |
| =item B<f> |
| |
| 10^-15 / 2^-50 |
| |
| =item B<p> |
| |
| 10^-12 / 2^-40 |
| |
| =item B<n> |
| |
| 10^-9 / 2^-30 |
| |
| =item B<u> |
| |
| 10^-6 / 2^-20 |
| |
| =item B<m> |
| |
| 10^-3 / 2^-10 |
| |
| =item B<c> |
| |
| 10^-2 |
| |
| =item B<d> |
| |
| 10^-1 |
| |
| =item B<h> |
| |
| 10^2 |
| |
| =item B<k> |
| |
| 10^3 / 2^10 |
| |
| =item B<K> |
| |
| 10^3 / 2^10 |
| |
| =item B<M> |
| |
| 10^6 / 2^20 |
| |
| =item B<G> |
| |
| 10^9 / 2^30 |
| |
| =item B<T> |
| |
| 10^12 / 2^40 |
| |
| =item B<P> |
| |
| 10^15 / 2^40 |
| |
| =item B<E> |
| |
| 10^18 / 2^50 |
| |
| =item B<Z> |
| |
| 10^21 / 2^60 |
| |
| =item B<Y> |
| |
| 10^24 / 2^70 |
| |
| =back |
| |
| |
| |
| |
| =head1 OPENCL OPTIONS |
| |
| |
| When FFmpeg is configured with C<--enable-opencl>, it is possible |
| to set the options for the global OpenCL context. |
| |
| The list of supported options follows: |
| |
| |
| =over 4 |
| |
| |
| =item B<build_options> |
| |
| Set build options used to compile the registered kernels. |
| |
| See reference "OpenCL Specification Version: 1.2 chapter 5.6.4". |
| |
| |
| =item B<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 C<av_opencl_get_device_list()>. |
| |
| |
| =item B<device_idx> |
| |
| Select the index of the device used to run OpenCL code. |
| |
| The specifed index must be one of the indexes in the device list which |
| can be obtained with C<av_opencl_get_device_list()>. |
| |
| |
| =back |
| |
| |
| |
| |
| =head1 SEE ALSO |
| |
| |
| |
| ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavutil(3) |
| |
| |
| =head1 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 |
| B<git log> in the FFmpeg source directory, or browsing the |
| online repository at E<lt>B<http://source.ffmpeg.org>E<gt>. |
| |
| Maintainers for the specific components are listed in the file |
| F<MAINTAINERS> in the source code tree. |
| |
| |
| |