1@chapter Filtergraph description 2@c man begin FILTERGRAPH DESCRIPTION 3 4A filtergraph is a directed graph of connected filters. It can contain 5cycles, and there can be multiple links between a pair of 6filters. Each link has one input pad on one side connecting it to one 7filter from which it takes its input, and one output pad on the other 8side connecting it to the one filter accepting its output. 9 10Each filter in a filtergraph is an instance of a filter class 11registered in the application, which defines the features and the 12number of input and output pads of the filter. 13 14A filter with no input pads is called a "source", a filter with no 15output pads is called a "sink". 16 17@section Filtergraph syntax 18 19A filtergraph can be represented using a textual representation, which 20is recognized by the @code{-vf} and @code{-af} options in @command{avconv} 21and @command{avplay}, and by the @code{av_parse_graph()} function defined in 22@file{libavfilter/avfiltergraph}. 23 24A filterchain consists of a sequence of connected filters, each one 25connected to the previous one in the sequence. A filterchain is 26represented by a list of ","-separated filter descriptions. 27 28A filtergraph consists of a sequence of filterchains. A sequence of 29filterchains is represented by a list of ";"-separated filterchain 30descriptions. 31 32A filter is represented by a string of the form: 33[@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}] 34 35@var{filter_name} is the name of the filter class of which the 36described filter is an instance of, and has to be the name of one of 37the filter classes registered in the program. 38The name of the filter class is optionally followed by a string 39"=@var{arguments}". 40 41@var{arguments} is a string which contains the parameters used to 42initialize the filter instance, and are described in the filter 43descriptions below. 44 45The list of arguments can be quoted using the character "'" as initial 46and ending mark, and the character '\' for escaping the characters 47within the quoted text; otherwise the argument string is considered 48terminated when the next special character (belonging to the set 49"[]=;,") is encountered. 50 51The name and arguments of the filter are optionally preceded and 52followed by a list of link labels. 53A link label allows to name a link and associate it to a filter output 54or input pad. The preceding labels @var{in_link_1} 55... @var{in_link_N}, are associated to the filter input pads, 56the following labels @var{out_link_1} ... @var{out_link_M}, are 57associated to the output pads. 58 59When two link labels with the same name are found in the 60filtergraph, a link between the corresponding input and output pad is 61created. 62 63If an output pad is not labelled, it is linked by default to the first 64unlabelled input pad of the next filter in the filterchain. 65For example in the filterchain: 66@example 67nullsrc, split[L1], [L2]overlay, nullsink 68@end example 69the split filter instance has two output pads, and the overlay filter 70instance two input pads. The first output pad of split is labelled 71"L1", the first input pad of overlay is labelled "L2", and the second 72output pad of split is linked to the second input pad of overlay, 73which are both unlabelled. 74 75In a complete filterchain all the unlabelled filter input and output 76pads must be connected. A filtergraph is considered valid if all the 77filter input and output pads of all the filterchains are connected. 78 79Follows a BNF description for the filtergraph syntax: 80@example 81@var{NAME} ::= sequence of alphanumeric characters and '_' 82@var{LINKLABEL} ::= "[" @var{NAME} "]" 83@var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}] 84@var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted) 85@var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}] 86@var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}] 87@var{FILTERGRAPH} ::= @var{FILTERCHAIN} [;@var{FILTERGRAPH}] 88@end example 89 90@c man end FILTERGRAPH DESCRIPTION 91 92@chapter Audio Filters 93@c man begin AUDIO FILTERS 94 95When you configure your Libav build, you can disable any of the 96existing filters using --disable-filters. 97The configure output will show the audio filters included in your 98build. 99 100Below is a description of the currently available audio filters. 101 102@section anull 103 104Pass the audio source unchanged to the output. 105 106@c man end AUDIO FILTERS 107 108@chapter Audio Sources 109@c man begin AUDIO SOURCES 110 111Below is a description of the currently available audio sources. 112 113@section anullsrc 114 115Null audio source, never return audio frames. It is mainly useful as a 116template and to be employed in analysis / debugging tools. 117 118It accepts as optional parameter a string of the form 119@var{sample_rate}:@var{channel_layout}. 120 121@var{sample_rate} specify the sample rate, and defaults to 44100. 122 123@var{channel_layout} specify the channel layout, and can be either an 124integer or a string representing a channel layout. The default value 125of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO. 126 127Check the channel_layout_map definition in 128@file{libavcodec/audioconvert.c} for the mapping between strings and 129channel layout values. 130 131Follow some examples: 132@example 133# set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO. 134anullsrc=48000:4 135 136# same as 137anullsrc=48000:mono 138@end example 139 140@c man end AUDIO SOURCES 141 142@chapter Audio Sinks 143@c man begin AUDIO SINKS 144 145Below is a description of the currently available audio sinks. 146 147@section anullsink 148 149Null audio sink, do absolutely nothing with the input audio. It is 150mainly useful as a template and to be employed in analysis / debugging 151tools. 152 153@c man end AUDIO SINKS 154 155@chapter Video Filters 156@c man begin VIDEO FILTERS 157 158When you configure your Libav build, you can disable any of the 159existing filters using --disable-filters. 160The configure output will show the video filters included in your 161build. 162 163Below is a description of the currently available video filters. 164 165@section blackframe 166 167Detect frames that are (almost) completely black. Can be useful to 168detect chapter transitions or commercials. Output lines consist of 169the frame number of the detected frame, the percentage of blackness, 170the position in the file if known or -1 and the timestamp in seconds. 171 172In order to display the output lines, you need to set the loglevel at 173least to the AV_LOG_INFO value. 174 175The filter accepts the syntax: 176@example 177blackframe[=@var{amount}:[@var{threshold}]] 178@end example 179 180@var{amount} is the percentage of the pixels that have to be below the 181threshold, and defaults to 98. 182 183@var{threshold} is the threshold below which a pixel value is 184considered black, and defaults to 32. 185 186@section boxblur 187 188Apply boxblur algorithm to the input video. 189 190This filter accepts the parameters: 191@var{luma_power}:@var{luma_radius}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power} 192 193Chroma and alpha parameters are optional, if not specified they default 194to the corresponding values set for @var{luma_radius} and 195@var{luma_power}. 196 197@var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent 198the radius in pixels of the box used for blurring the corresponding 199input plane. They are expressions, and can contain the following 200constants: 201@table @option 202@item w, h 203the input width and height in pixels 204 205@item cw, ch 206the input chroma image width and height in pixels 207 208@item hsub, vsub 209horizontal and vertical chroma subsample values. For example for the 210pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. 211@end table 212 213The radius must be a non-negative number, and must not be greater than 214the value of the expression @code{min(w,h)/2} for the luma and alpha planes, 215and of @code{min(cw,ch)/2} for the chroma planes. 216 217@var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent 218how many times the boxblur filter is applied to the corresponding 219plane. 220 221Some examples follow: 222 223@itemize 224 225@item 226Apply a boxblur filter with luma, chroma, and alpha radius 227set to 2: 228@example 229boxblur=2:1 230@end example 231 232@item 233Set luma radius to 2, alpha and chroma radius to 0 234@example 235boxblur=2:1:0:0:0:0 236@end example 237 238@item 239Set luma and chroma radius to a fraction of the video dimension 240@example 241boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1 242@end example 243 244@end itemize 245 246@section copy 247 248Copy the input source unchanged to the output. Mainly useful for 249testing purposes. 250 251@section crop 252 253Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}. 254 255The parameters are expressions containing the following constants: 256 257@table @option 258@item E, PI, PHI 259the corresponding mathematical approximated values for e 260(euler number), pi (greek PI), PHI (golden ratio) 261 262@item x, y 263the computed values for @var{x} and @var{y}. They are evaluated for 264each new frame. 265 266@item in_w, in_h 267the input width and height 268 269@item iw, ih 270same as @var{in_w} and @var{in_h} 271 272@item out_w, out_h 273the output (cropped) width and height 274 275@item ow, oh 276same as @var{out_w} and @var{out_h} 277 278@item n 279the number of input frame, starting from 0 280 281@item pos 282the position in the file of the input frame, NAN if unknown 283 284@item t 285timestamp expressed in seconds, NAN if the input timestamp is unknown 286 287@end table 288 289The @var{out_w} and @var{out_h} parameters specify the expressions for 290the width and height of the output (cropped) video. They are 291evaluated just at the configuration of the filter. 292 293The default value of @var{out_w} is "in_w", and the default value of 294@var{out_h} is "in_h". 295 296The expression for @var{out_w} may depend on the value of @var{out_h}, 297and the expression for @var{out_h} may depend on @var{out_w}, but they 298cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are 299evaluated after @var{out_w} and @var{out_h}. 300 301The @var{x} and @var{y} parameters specify the expressions for the 302position of the top-left corner of the output (non-cropped) area. They 303are evaluated for each frame. If the evaluated value is not valid, it 304is approximated to the nearest valid value. 305 306The default value of @var{x} is "(in_w-out_w)/2", and the default 307value for @var{y} is "(in_h-out_h)/2", which set the cropped area at 308the center of the input image. 309 310The expression for @var{x} may depend on @var{y}, and the expression 311for @var{y} may depend on @var{x}. 312 313Follow some examples: 314@example 315# crop the central input area with size 100x100 316crop=100:100 317 318# crop the central input area with size 2/3 of the input video 319"crop=2/3*in_w:2/3*in_h" 320 321# crop the input video central square 322crop=in_h 323 324# delimit the rectangle with the top-left corner placed at position 325# 100:100 and the right-bottom corner corresponding to the right-bottom 326# corner of the input image. 327crop=in_w-100:in_h-100:100:100 328 329# crop 10 pixels from the left and right borders, and 20 pixels from 330# the top and bottom borders 331"crop=in_w-2*10:in_h-2*20" 332 333# keep only the bottom right quarter of the input image 334"crop=in_w/2:in_h/2:in_w/2:in_h/2" 335 336# crop height for getting Greek harmony 337"crop=in_w:1/PHI*in_w" 338 339# trembling effect 340"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)" 341 342# erratic camera effect depending on timestamp 343"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)" 344 345# set x depending on the value of y 346"crop=in_w/2:in_h/2:y:10+10*sin(n/10)" 347@end example 348 349@section cropdetect 350 351Auto-detect crop size. 352 353Calculate necessary cropping parameters and prints the recommended 354parameters through the logging system. The detected dimensions 355correspond to the non-black area of the input video. 356 357It accepts the syntax: 358@example 359cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]] 360@end example 361 362@table @option 363 364@item limit 365Threshold, which can be optionally specified from nothing (0) to 366everything (255), defaults to 24. 367 368@item round 369Value which the width/height should be divisible by, defaults to 37016. The offset is automatically adjusted to center the video. Use 2 to 371get only even dimensions (needed for 4:2:2 video). 16 is best when 372encoding to most video codecs. 373 374@item reset 375Counter that determines after how many frames cropdetect will reset 376the previously detected largest video area and start over to detect 377the current optimal crop area. Defaults to 0. 378 379This can be useful when channel logos distort the video area. 0 380indicates never reset and return the largest area encountered during 381playback. 382@end table 383 384@section delogo 385 386Suppress a TV station logo by a simple interpolation of the surrounding 387pixels. Just set a rectangle covering the logo and watch it disappear 388(and sometimes something even uglier appear - your mileage may vary). 389 390The filter accepts parameters as a string of the form 391"@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of 392@var{key}=@var{value} pairs, separated by ":". 393 394The description of the accepted parameters follows. 395 396@table @option 397 398@item x, y 399Specify the top left corner coordinates of the logo. They must be 400specified. 401 402@item w, h 403Specify the width and height of the logo to clear. They must be 404specified. 405 406@item band, t 407Specify the thickness of the fuzzy edge of the rectangle (added to 408@var{w} and @var{h}). The default value is 4. 409 410@item show 411When set to 1, a green rectangle is drawn on the screen to simplify 412finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and 413@var{band} is set to 4. The default value is 0. 414 415@end table 416 417Some examples follow. 418 419@itemize 420 421@item 422Set a rectangle covering the area with top left corner coordinates 0,0 423and size 100x77, setting a band of size 10: 424@example 425delogo=0:0:100:77:10 426@end example 427 428@item 429As the previous example, but use named options: 430@example 431delogo=x=0:y=0:w=100:h=77:band=10 432@end example 433 434@end itemize 435 436@section drawbox 437 438Draw a colored box on the input image. 439 440It accepts the syntax: 441@example 442drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color} 443@end example 444 445@table @option 446 447@item x, y 448Specify the top left corner coordinates of the box. Default to 0. 449 450@item width, height 451Specify the width and height of the box, if 0 they are interpreted as 452the input width and height. Default to 0. 453 454@item color 455Specify the color of the box to write, it can be the name of a color 456(case insensitive match) or a 0xRRGGBB[AA] sequence. 457@end table 458 459Follow some examples: 460@example 461# draw a black box around the edge of the input image 462drawbox 463 464# draw a box with color red and an opacity of 50% 465drawbox=10:20:200:60:red@@0.5" 466@end example 467 468@section drawtext 469 470Draw text string or text from specified file on top of video using the 471libfreetype library. 472 473To enable compilation of this filter you need to configure Libav with 474@code{--enable-libfreetype}. 475 476The filter also recognizes strftime() sequences in the provided text 477and expands them accordingly. Check the documentation of strftime(). 478 479The filter accepts parameters as a list of @var{key}=@var{value} pairs, 480separated by ":". 481 482The description of the accepted parameters follows. 483 484@table @option 485 486@item fontfile 487The font file to be used for drawing text. Path must be included. 488This parameter is mandatory. 489 490@item text 491The text string to be drawn. The text must be a sequence of UTF-8 492encoded characters. 493This parameter is mandatory if no file is specified with the parameter 494@var{textfile}. 495 496@item textfile 497A text file containing text to be drawn. The text must be a sequence 498of UTF-8 encoded characters. 499 500This parameter is mandatory if no text string is specified with the 501parameter @var{text}. 502 503If both text and textfile are specified, an error is thrown. 504 505@item x, y 506The offsets where text will be drawn within the video frame. 507Relative to the top/left border of the output image. 508They accept expressions similar to the @ref{overlay} filter: 509@table @option 510 511@item x, y 512the computed values for @var{x} and @var{y}. They are evaluated for 513each new frame. 514 515@item main_w, main_h 516main input width and height 517 518@item W, H 519same as @var{main_w} and @var{main_h} 520 521@item text_w, text_h 522rendered text width and height 523 524@item w, h 525same as @var{text_w} and @var{text_h} 526 527@item n 528the number of frames processed, starting from 0 529 530@item t 531timestamp expressed in seconds, NAN if the input timestamp is unknown 532 533@end table 534 535The default value of @var{x} and @var{y} is 0. 536 537@item fontsize 538The font size to be used for drawing text. 539The default value of @var{fontsize} is 16. 540 541@item fontcolor 542The color to be used for drawing fonts. 543Either a string (e.g. "red") or in 0xRRGGBB[AA] format 544(e.g. "0xff000033"), possibly followed by an alpha specifier. 545The default value of @var{fontcolor} is "black". 546 547@item boxcolor 548The color to be used for drawing box around text. 549Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format 550(e.g. "0xff00ff"), possibly followed by an alpha specifier. 551The default value of @var{boxcolor} is "white". 552 553@item box 554Used to draw a box around text using background color. 555Value should be either 1 (enable) or 0 (disable). 556The default value of @var{box} is 0. 557 558@item shadowx, shadowy 559The x and y offsets for the text shadow position with respect to the 560position of the text. They can be either positive or negative 561values. Default value for both is "0". 562 563@item shadowcolor 564The color to be used for drawing a shadow behind the drawn text. It 565can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA] 566form (e.g. "0xff00ff"), possibly followed by an alpha specifier. 567The default value of @var{shadowcolor} is "black". 568 569@item ft_load_flags 570Flags to be used for loading the fonts. 571 572The flags map the corresponding flags supported by libfreetype, and are 573a combination of the following values: 574@table @var 575@item default 576@item no_scale 577@item no_hinting 578@item render 579@item no_bitmap 580@item vertical_layout 581@item force_autohint 582@item crop_bitmap 583@item pedantic 584@item ignore_global_advance_width 585@item no_recurse 586@item ignore_transform 587@item monochrome 588@item linear_design 589@item no_autohint 590@item end table 591@end table 592 593Default value is "render". 594 595For more information consult the documentation for the FT_LOAD_* 596libfreetype flags. 597 598@item tabsize 599The size in number of spaces to use for rendering the tab. 600Default value is 4. 601@end table 602 603For example the command: 604@example 605drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'" 606@end example 607 608will draw "Test Text" with font FreeSerif, using the default values 609for the optional parameters. 610 611The command: 612@example 613drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\ 614 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2" 615@end example 616 617will draw 'Test Text' with font FreeSerif of size 24 at position x=100 618and y=50 (counting from the top-left corner of the screen), text is 619yellow with a red box around it. Both the text and the box have an 620opacity of 20%. 621 622Note that the double quotes are not necessary if spaces are not used 623within the parameter list. 624 625For more information about libfreetype, check: 626@url{http://www.freetype.org/}. 627 628@section fade 629 630Apply fade-in/out effect to input video. 631 632It accepts the parameters: 633@var{type}:@var{start_frame}:@var{nb_frames} 634 635@var{type} specifies if the effect type, can be either "in" for 636fade-in, or "out" for a fade-out effect. 637 638@var{start_frame} specifies the number of the start frame for starting 639to apply the fade effect. 640 641@var{nb_frames} specifies the number of frames for which the fade 642effect has to last. At the end of the fade-in effect the output video 643will have the same intensity as the input video, at the end of the 644fade-out transition the output video will be completely black. 645 646A few usage examples follow, usable too as test scenarios. 647@example 648# fade in first 30 frames of video 649fade=in:0:30 650 651# fade out last 45 frames of a 200-frame video 652fade=out:155:45 653 654# fade in first 25 frames and fade out last 25 frames of a 1000-frame video 655fade=in:0:25, fade=out:975:25 656 657# make first 5 frames black, then fade in from frame 5-24 658fade=in:5:20 659@end example 660 661@section fieldorder 662 663Transform the field order of the input video. 664 665It accepts one parameter which specifies the required field order that 666the input interlaced video will be transformed to. The parameter can 667assume one of the following values: 668 669@table @option 670@item 0 or bff 671output bottom field first 672@item 1 or tff 673output top field first 674@end table 675 676Default value is "tff". 677 678Transformation is achieved by shifting the picture content up or down 679by one line, and filling the remaining line with appropriate picture content. 680This method is consistent with most broadcast field order converters. 681 682If the input video is not flagged as being interlaced, or it is already 683flagged as being of the required output field order then this filter does 684not alter the incoming video. 685 686This filter is very useful when converting to or from PAL DV material, 687which is bottom field first. 688 689For example: 690@example 691./avconv -i in.vob -vf "fieldorder=bff" out.dv 692@end example 693 694@section fifo 695 696Buffer input images and send them when they are requested. 697 698This filter is mainly useful when auto-inserted by the libavfilter 699framework. 700 701The filter does not take parameters. 702 703@section format 704 705Convert the input video to one of the specified pixel formats. 706Libavfilter will try to pick one that is supported for the input to 707the next filter. 708 709The filter accepts a list of pixel format names, separated by ":", 710for example "yuv420p:monow:rgb24". 711 712Some examples follow: 713@example 714# convert the input video to the format "yuv420p" 715format=yuv420p 716 717# convert the input video to any of the formats in the list 718format=yuv420p:yuv444p:yuv410p 719@end example 720 721@anchor{frei0r} 722@section frei0r 723 724Apply a frei0r effect to the input video. 725 726To enable compilation of this filter you need to install the frei0r 727header and configure Libav with --enable-frei0r. 728 729The filter supports the syntax: 730@example 731@var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}] 732@end example 733 734@var{filter_name} is the name to the frei0r effect to load. If the 735environment variable @env{FREI0R_PATH} is defined, the frei0r effect 736is searched in each one of the directories specified by the colon 737separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r 738paths, which are in this order: @file{HOME/.frei0r-1/lib/}, 739@file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}. 740 741@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters 742for the frei0r effect. 743 744A frei0r effect parameter can be a boolean (whose values are specified 745with "y" and "n"), a double, a color (specified by the syntax 746@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float 747numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color 748description), a position (specified by the syntax @var{X}/@var{Y}, 749@var{X} and @var{Y} being float numbers) and a string. 750 751The number and kind of parameters depend on the loaded effect. If an 752effect parameter is not specified the default value is set. 753 754Some examples follow: 755@example 756# apply the distort0r effect, set the first two double parameters 757frei0r=distort0r:0.5:0.01 758 759# apply the colordistance effect, takes a color as first parameter 760frei0r=colordistance:0.2/0.3/0.4 761frei0r=colordistance:violet 762frei0r=colordistance:0x112233 763 764# apply the perspective effect, specify the top left and top right 765# image positions 766frei0r=perspective:0.2/0.2:0.8/0.2 767@end example 768 769For more information see: 770@url{http://piksel.org/frei0r} 771 772@section gradfun 773 774Fix the banding artifacts that are sometimes introduced into nearly flat 775regions by truncation to 8bit colordepth. 776Interpolate the gradients that should go where the bands are, and 777dither them. 778 779This filter is designed for playback only. Do not use it prior to 780lossy compression, because compression tends to lose the dither and 781bring back the bands. 782 783The filter takes two optional parameters, separated by ':': 784@var{strength}:@var{radius} 785 786@var{strength} is the maximum amount by which the filter will change 787any one pixel. Also the threshold for detecting nearly flat 788regions. Acceptable values range from .51 to 255, default value is 7891.2, out-of-range values will be clipped to the valid range. 790 791@var{radius} is the neighborhood to fit the gradient to. A larger 792radius makes for smoother gradients, but also prevents the filter from 793modifying the pixels near detailed regions. Acceptable values are 7948-32, default value is 16, out-of-range values will be clipped to the 795valid range. 796 797@example 798# default parameters 799gradfun=1.2:16 800 801# omitting radius 802gradfun=1.2 803@end example 804 805@section hflip 806 807Flip the input video horizontally. 808 809For example to horizontally flip the input video with @command{avconv}: 810@example 811avconv -i in.avi -vf "hflip" out.avi 812@end example 813 814@section hqdn3d 815 816High precision/quality 3d denoise filter. This filter aims to reduce 817image noise producing smooth images and making still images really 818still. It should enhance compressibility. 819 820It accepts the following optional parameters: 821@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp} 822 823@table @option 824@item luma_spatial 825a non-negative float number which specifies spatial luma strength, 826defaults to 4.0 827 828@item chroma_spatial 829a non-negative float number which specifies spatial chroma strength, 830defaults to 3.0*@var{luma_spatial}/4.0 831 832@item luma_tmp 833a float number which specifies luma temporal strength, defaults to 8346.0*@var{luma_spatial}/4.0 835 836@item chroma_tmp 837a float number which specifies chroma temporal strength, defaults to 838@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial} 839@end table 840 841@section lut, lutrgb, lutyuv 842 843Compute a look-up table for binding each pixel component input value 844to an output value, and apply it to input video. 845 846@var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb} 847to an RGB input video. 848 849These filters accept in input a ":"-separated list of options, which 850specify the expressions used for computing the lookup table for the 851corresponding pixel component values. 852 853The @var{lut} filter requires either YUV or RGB pixel formats in 854input, and accepts the options: 855@table @option 856@var{c0} (first pixel component) 857@var{c1} (second pixel component) 858@var{c2} (third pixel component) 859@var{c3} (fourth pixel component, corresponds to the alpha component) 860@end table 861 862The exact component associated to each option depends on the format in 863input. 864 865The @var{lutrgb} filter requires RGB pixel formats in input, and 866accepts the options: 867@table @option 868@var{r} (red component) 869@var{g} (green component) 870@var{b} (blue component) 871@var{a} (alpha component) 872@end table 873 874The @var{lutyuv} filter requires YUV pixel formats in input, and 875accepts the options: 876@table @option 877@var{y} (Y/luminance component) 878@var{u} (U/Cb component) 879@var{v} (V/Cr component) 880@var{a} (alpha component) 881@end table 882 883The expressions can contain the following constants and functions: 884 885@table @option 886@item E, PI, PHI 887the corresponding mathematical approximated values for e 888(euler number), pi (greek PI), PHI (golden ratio) 889 890@item w, h 891the input width and height 892 893@item val 894input value for the pixel component 895 896@item clipval 897the input value clipped in the @var{minval}-@var{maxval} range 898 899@item maxval 900maximum value for the pixel component 901 902@item minval 903minimum value for the pixel component 904 905@item negval 906the negated value for the pixel component value clipped in the 907@var{minval}-@var{maxval} range , it corresponds to the expression 908"maxval-clipval+minval" 909 910@item clip(val) 911the computed value in @var{val} clipped in the 912@var{minval}-@var{maxval} range 913 914@item gammaval(gamma) 915the computed gamma correction value of the pixel component value 916clipped in the @var{minval}-@var{maxval} range, corresponds to the 917expression 918"pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval" 919 920@end table 921 922All expressions default to "val". 923 924Some examples follow: 925@example 926# negate input video 927lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val" 928lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val" 929 930# the above is the same as 931lutrgb="r=negval:g=negval:b=negval" 932lutyuv="y=negval:u=negval:v=negval" 933 934# negate luminance 935lutyuv=negval 936 937# remove chroma components, turns the video into a graytone image 938lutyuv="u=128:v=128" 939 940# apply a luma burning effect 941lutyuv="y=2*val" 942 943# remove green and blue components 944lutrgb="g=0:b=0" 945 946# set a constant alpha channel value on input 947format=rgba,lutrgb=a="maxval-minval/2" 948 949# correct luminance gamma by a 0.5 factor 950lutyuv=y=gammaval(0.5) 951@end example 952 953@section negate 954 955Negate input video. 956 957This filter accepts an integer in input, if non-zero it negates the 958alpha component (if available). The default value in input is 0. 959 960Force libavfilter not to use any of the specified pixel formats for the 961input to the next filter. 962 963The filter accepts a list of pixel format names, separated by ":", 964for example "yuv420p:monow:rgb24". 965 966Some examples follow: 967@example 968# force libavfilter to use a format different from "yuv420p" for the 969# input to the vflip filter 970noformat=yuv420p,vflip 971 972# convert the input video to any of the formats not contained in the list 973noformat=yuv420p:yuv444p:yuv410p 974@end example 975 976@section null 977 978Pass the video source unchanged to the output. 979 980@section ocv 981 982Apply video transform using libopencv. 983 984To enable this filter install libopencv library and headers and 985configure Libav with --enable-libopencv. 986 987The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}. 988 989@var{filter_name} is the name of the libopencv filter to apply. 990 991@var{filter_params} specifies the parameters to pass to the libopencv 992filter. If not specified the default values are assumed. 993 994Refer to the official libopencv documentation for more precise 995information: 996@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html} 997 998Follows the list of supported libopencv filters. 999 1000@anchor{dilate} 1001@subsection dilate 1002 1003Dilate an image by using a specific structuring element. 1004This filter corresponds to the libopencv function @code{cvDilate}. 1005 1006It accepts the parameters: @var{struct_el}:@var{nb_iterations}. 1007 1008@var{struct_el} represents a structuring element, and has the syntax: 1009@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape} 1010 1011@var{cols} and @var{rows} represent the number of columns and rows of 1012the structuring element, @var{anchor_x} and @var{anchor_y} the anchor 1013point, and @var{shape} the shape for the structuring element, and 1014can be one of the values "rect", "cross", "ellipse", "custom". 1015 1016If the value for @var{shape} is "custom", it must be followed by a 1017string of the form "=@var{filename}". The file with name 1018@var{filename} is assumed to represent a binary image, with each 1019printable character corresponding to a bright pixel. When a custom 1020@var{shape} is used, @var{cols} and @var{rows} are ignored, the number 1021or columns and rows of the read file are assumed instead. 1022 1023The default value for @var{struct_el} is "3x3+0x0/rect". 1024 1025@var{nb_iterations} specifies the number of times the transform is 1026applied to the image, and defaults to 1. 1027 1028Follow some example: 1029@example 1030# use the default values 1031ocv=dilate 1032 1033# dilate using a structuring element with a 5x5 cross, iterate two times 1034ocv=dilate=5x5+2x2/cross:2 1035 1036# read the shape from the file diamond.shape, iterate two times 1037# the file diamond.shape may contain a pattern of characters like this: 1038# * 1039# *** 1040# ***** 1041# *** 1042# * 1043# the specified cols and rows are ignored (but not the anchor point coordinates) 1044ocv=0x0+2x2/custom=diamond.shape:2 1045@end example 1046 1047@subsection erode 1048 1049Erode an image by using a specific structuring element. 1050This filter corresponds to the libopencv function @code{cvErode}. 1051 1052The filter accepts the parameters: @var{struct_el}:@var{nb_iterations}, 1053with the same syntax and semantics as the @ref{dilate} filter. 1054 1055@subsection smooth 1056 1057Smooth the input video. 1058 1059The filter takes the following parameters: 1060@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}. 1061 1062@var{type} is the type of smooth filter to apply, and can be one of 1063the following values: "blur", "blur_no_scale", "median", "gaussian", 1064"bilateral". The default value is "gaussian". 1065 1066@var{param1}, @var{param2}, @var{param3}, and @var{param4} are 1067parameters whose meanings depend on smooth type. @var{param1} and 1068@var{param2} accept integer positive values or 0, @var{param3} and 1069@var{param4} accept float values. 1070 1071The default value for @var{param1} is 3, the default value for the 1072other parameters is 0. 1073 1074These parameters correspond to the parameters assigned to the 1075libopencv function @code{cvSmooth}. 1076 1077@anchor{overlay} 1078@section overlay 1079 1080Overlay one video on top of another. 1081 1082It takes two inputs and one output, the first input is the "main" 1083video on which the second input is overlayed. 1084 1085It accepts the parameters: @var{x}:@var{y}. 1086 1087@var{x} is the x coordinate of the overlayed video on the main video, 1088@var{y} is the y coordinate. The parameters are expressions containing 1089the following parameters: 1090 1091@table @option 1092@item main_w, main_h 1093main input width and height 1094 1095@item W, H 1096same as @var{main_w} and @var{main_h} 1097 1098@item overlay_w, overlay_h 1099overlay input width and height 1100 1101@item w, h 1102same as @var{overlay_w} and @var{overlay_h} 1103@end table 1104 1105Be aware that frames are taken from each input video in timestamp 1106order, hence, if their initial timestamps differ, it is a a good idea 1107to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to 1108have them begin in the same zero timestamp, as it does the example for 1109the @var{movie} filter. 1110 1111Follow some examples: 1112@example 1113# draw the overlay at 10 pixels from the bottom right 1114# corner of the main video. 1115overlay=main_w-overlay_w-10:main_h-overlay_h-10 1116 1117# insert a transparent PNG logo in the bottom left corner of the input 1118movie=logo.png [logo]; 1119[in][logo] overlay=10:main_h-overlay_h-10 [out] 1120 1121# insert 2 different transparent PNG logos (second logo on bottom 1122# right corner): 1123movie=logo1.png [logo1]; 1124movie=logo2.png [logo2]; 1125[in][logo1] overlay=10:H-h-10 [in+logo1]; 1126[in+logo1][logo2] overlay=W-w-10:H-h-10 [out] 1127 1128# add a transparent color layer on top of the main video, 1129# WxH specifies the size of the main input to the overlay filter 1130color=red@.3:WxH [over]; [in][over] overlay [out] 1131@end example 1132 1133You can chain together more overlays but the efficiency of such 1134approach is yet to be tested. 1135 1136@section pad 1137 1138Add paddings to the input image, and places the original input at the 1139given coordinates @var{x}, @var{y}. 1140 1141It accepts the following parameters: 1142@var{width}:@var{height}:@var{x}:@var{y}:@var{color}. 1143 1144The parameters @var{width}, @var{height}, @var{x}, and @var{y} are 1145expressions containing the following constants: 1146 1147@table @option 1148@item E, PI, PHI 1149the corresponding mathematical approximated values for e 1150(euler number), pi (greek PI), phi (golden ratio) 1151 1152@item in_w, in_h 1153the input video width and height 1154 1155@item iw, ih 1156same as @var{in_w} and @var{in_h} 1157 1158@item out_w, out_h 1159the output width and height, that is the size of the padded area as 1160specified by the @var{width} and @var{height} expressions 1161 1162@item ow, oh 1163same as @var{out_w} and @var{out_h} 1164 1165@item x, y 1166x and y offsets as specified by the @var{x} and @var{y} 1167expressions, or NAN if not yet specified 1168 1169@item a 1170input display aspect ratio, same as @var{iw} / @var{ih} 1171 1172@item hsub, vsub 1173horizontal and vertical chroma subsample values. For example for the 1174pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. 1175@end table 1176 1177Follows the description of the accepted parameters. 1178 1179@table @option 1180@item width, height 1181 1182Specify the size of the output image with the paddings added. If the 1183value for @var{width} or @var{height} is 0, the corresponding input size 1184is used for the output. 1185 1186The @var{width} expression can reference the value set by the 1187@var{height} expression, and vice versa. 1188 1189The default value of @var{width} and @var{height} is 0. 1190 1191@item x, y 1192 1193Specify the offsets where to place the input image in the padded area 1194with respect to the top/left border of the output image. 1195 1196The @var{x} expression can reference the value set by the @var{y} 1197expression, and vice versa. 1198 1199The default value of @var{x} and @var{y} is 0. 1200 1201@item color 1202 1203Specify the color of the padded area, it can be the name of a color 1204(case insensitive match) or a 0xRRGGBB[AA] sequence. 1205 1206The default value of @var{color} is "black". 1207 1208@end table 1209 1210Some examples follow: 1211 1212@example 1213# Add paddings with color "violet" to the input video. Output video 1214# size is 640x480, the top-left corner of the input video is placed at 1215# column 0, row 40. 1216pad=640:480:0:40:violet 1217 1218# pad the input to get an output with dimensions increased bt 3/2, 1219# and put the input video at the center of the padded area 1220pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2" 1221 1222# pad the input to get a squared output with size equal to the maximum 1223# value between the input width and height, and put the input video at 1224# the center of the padded area 1225pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2" 1226 1227# pad the input to get a final w/h ratio of 16:9 1228pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2" 1229 1230# double output size and put the input video in the bottom-right 1231# corner of the output padded area 1232pad="2*iw:2*ih:ow-iw:oh-ih" 1233@end example 1234 1235@section pixdesctest 1236 1237Pixel format descriptor test filter, mainly useful for internal 1238testing. The output video should be equal to the input video. 1239 1240For example: 1241@example 1242format=monow, pixdesctest 1243@end example 1244 1245can be used to test the monowhite pixel format descriptor definition. 1246 1247@section scale 1248 1249Scale the input video to @var{width}:@var{height} and/or convert the image format. 1250 1251The parameters @var{width} and @var{height} are expressions containing 1252the following constants: 1253 1254@table @option 1255@item E, PI, PHI 1256the corresponding mathematical approximated values for e 1257(euler number), pi (greek PI), phi (golden ratio) 1258 1259@item in_w, in_h 1260the input width and height 1261 1262@item iw, ih 1263same as @var{in_w} and @var{in_h} 1264 1265@item out_w, out_h 1266the output (cropped) width and height 1267 1268@item ow, oh 1269same as @var{out_w} and @var{out_h} 1270 1271@item dar, a 1272input display aspect ratio, same as @var{iw} / @var{ih} 1273 1274@item sar 1275input sample aspect ratio 1276 1277@item hsub, vsub 1278horizontal and vertical chroma subsample values. For example for the 1279pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. 1280@end table 1281 1282If the input image format is different from the format requested by 1283the next filter, the scale filter will convert the input to the 1284requested format. 1285 1286If the value for @var{width} or @var{height} is 0, the respective input 1287size is used for the output. 1288 1289If the value for @var{width} or @var{height} is -1, the scale filter will 1290use, for the respective output size, a value that maintains the aspect 1291ratio of the input image. 1292 1293The default value of @var{width} and @var{height} is 0. 1294 1295Some examples follow: 1296@example 1297# scale the input video to a size of 200x100. 1298scale=200:100 1299 1300# scale the input to 2x 1301scale=2*iw:2*ih 1302# the above is the same as 1303scale=2*in_w:2*in_h 1304 1305# scale the input to half size 1306scale=iw/2:ih/2 1307 1308# increase the width, and set the height to the same size 1309scale=3/2*iw:ow 1310 1311# seek for Greek harmony 1312scale=iw:1/PHI*iw 1313scale=ih*PHI:ih 1314 1315# increase the height, and set the width to 3/2 of the height 1316scale=3/2*oh:3/5*ih 1317 1318# increase the size, but make the size a multiple of the chroma 1319scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub" 1320 1321# increase the width to a maximum of 500 pixels, keep the same input aspect ratio 1322scale='min(500\, iw*3/2):-1' 1323@end example 1324 1325@section select 1326Select frames to pass in output. 1327 1328It accepts in input an expression, which is evaluated for each input 1329frame. If the expression is evaluated to a non-zero value, the frame 1330is selected and passed to the output, otherwise it is discarded. 1331 1332The expression can contain the following constants: 1333 1334@table @option 1335@item PI 1336Greek PI 1337 1338@item PHI 1339golden ratio 1340 1341@item E 1342Euler number 1343 1344@item n 1345the sequential number of the filtered frame, starting from 0 1346 1347@item selected_n 1348the sequential number of the selected frame, starting from 0 1349 1350@item prev_selected_n 1351the sequential number of the last selected frame, NAN if undefined 1352 1353@item TB 1354timebase of the input timestamps 1355 1356@item pts 1357the PTS (Presentation TimeStamp) of the filtered video frame, 1358expressed in @var{TB} units, NAN if undefined 1359 1360@item t 1361the PTS (Presentation TimeStamp) of the filtered video frame, 1362expressed in seconds, NAN if undefined 1363 1364@item prev_pts 1365the PTS of the previously filtered video frame, NAN if undefined 1366 1367@item prev_selected_pts 1368the PTS of the last previously filtered video frame, NAN if undefined 1369 1370@item prev_selected_t 1371the PTS of the last previously selected video frame, NAN if undefined 1372 1373@item start_pts 1374the PTS of the first video frame in the video, NAN if undefined 1375 1376@item start_t 1377the time of the first video frame in the video, NAN if undefined 1378 1379@item pict_type 1380the type of the filtered frame, can assume one of the following 1381values: 1382@table @option 1383@item I 1384@item P 1385@item B 1386@item S 1387@item SI 1388@item SP 1389@item BI 1390@end table 1391 1392@item interlace_type 1393the frame interlace type, can assume one of the following values: 1394@table @option 1395@item PROGRESSIVE 1396the frame is progressive (not interlaced) 1397@item TOPFIRST 1398the frame is top-field-first 1399@item BOTTOMFIRST 1400the frame is bottom-field-first 1401@end table 1402 1403@item key 14041 if the filtered frame is a key-frame, 0 otherwise 1405 1406@item pos 1407the position in the file of the filtered frame, -1 if the information 1408is not available (e.g. for synthetic video) 1409@end table 1410 1411The default value of the select expression is "1". 1412 1413Some examples follow: 1414 1415@example 1416# select all frames in input 1417select 1418 1419# the above is the same as: 1420select=1 1421 1422# skip all frames: 1423select=0 1424 1425# select only I-frames 1426select='eq(pict_type\,I)' 1427 1428# select one frame every 100 1429select='not(mod(n\,100))' 1430 1431# select only frames contained in the 10-20 time interval 1432select='gte(t\,10)*lte(t\,20)' 1433 1434# select only I frames contained in the 10-20 time interval 1435select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)' 1436 1437# select frames with a minimum distance of 10 seconds 1438select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)' 1439@end example 1440 1441@anchor{setdar} 1442@section setdar 1443 1444Set the Display Aspect Ratio for the filter output video. 1445 1446This is done by changing the specified Sample (aka Pixel) Aspect 1447Ratio, according to the following equation: 1448@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR} 1449 1450Keep in mind that this filter does not modify the pixel dimensions of 1451the video frame. Also the display aspect ratio set by this filter may 1452be changed by later filters in the filterchain, e.g. in case of 1453scaling or if another "setdar" or a "setsar" filter is applied. 1454 1455The filter accepts a parameter string which represents the wanted 1456display aspect ratio. 1457The parameter can be a floating point number string, or an expression 1458of the form @var{num}:@var{den}, where @var{num} and @var{den} are the 1459numerator and denominator of the aspect ratio. 1460If the parameter is not specified, it is assumed the value "0:1". 1461 1462For example to change the display aspect ratio to 16:9, specify: 1463@example 1464setdar=16:9 1465# the above is equivalent to 1466setdar=1.77777 1467@end example 1468 1469See also the @ref{setsar} filter documentation. 1470 1471@section setpts 1472 1473Change the PTS (presentation timestamp) of the input video frames. 1474 1475Accept in input an expression evaluated through the eval API, which 1476can contain the following constants: 1477 1478@table @option 1479@item PTS 1480the presentation timestamp in input 1481 1482@item PI 1483Greek PI 1484 1485@item PHI 1486golden ratio 1487 1488@item E 1489Euler number 1490 1491@item N 1492the count of the input frame, starting from 0. 1493 1494@item STARTPTS 1495the PTS of the first video frame 1496 1497@item INTERLACED 1498tell if the current frame is interlaced 1499 1500@item POS 1501original position in the file of the frame, or undefined if undefined 1502for the current frame 1503 1504@item PREV_INPTS 1505previous input PTS 1506 1507@item PREV_OUTPTS 1508previous output PTS 1509 1510@end table 1511 1512Some examples follow: 1513 1514@example 1515# start counting PTS from zero 1516setpts=PTS-STARTPTS 1517 1518# fast motion 1519setpts=0.5*PTS 1520 1521# slow motion 1522setpts=2.0*PTS 1523 1524# fixed rate 25 fps 1525setpts=N/(25*TB) 1526 1527# fixed rate 25 fps with some jitter 1528setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))' 1529@end example 1530 1531@anchor{setsar} 1532@section setsar 1533 1534Set the Sample (aka Pixel) Aspect Ratio for the filter output video. 1535 1536Note that as a consequence of the application of this filter, the 1537output display aspect ratio will change according to the following 1538equation: 1539@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR} 1540 1541Keep in mind that the sample aspect ratio set by this filter may be 1542changed by later filters in the filterchain, e.g. if another "setsar" 1543or a "setdar" filter is applied. 1544 1545The filter accepts a parameter string which represents the wanted 1546sample aspect ratio. 1547The parameter can be a floating point number string, or an expression 1548of the form @var{num}:@var{den}, where @var{num} and @var{den} are the 1549numerator and denominator of the aspect ratio. 1550If the parameter is not specified, it is assumed the value "0:1". 1551 1552For example to change the sample aspect ratio to 10:11, specify: 1553@example 1554setsar=10:11 1555@end example 1556 1557@section settb 1558 1559Set the timebase to use for the output frames timestamps. 1560It is mainly useful for testing timebase configuration. 1561 1562It accepts in input an arithmetic expression representing a rational. 1563The expression can contain the constants "PI", "E", "PHI", "AVTB" (the 1564default timebase), and "intb" (the input timebase). 1565 1566The default value for the input is "intb". 1567 1568Follow some examples. 1569 1570@example 1571# set the timebase to 1/25 1572settb=1/25 1573 1574# set the timebase to 1/10 1575settb=0.1 1576 1577#set the timebase to 1001/1000 1578settb=1+0.001 1579 1580#set the timebase to 2*intb 1581settb=2*intb 1582 1583#set the default timebase value 1584settb=AVTB 1585@end example 1586 1587@section showinfo 1588 1589Show a line containing various information for each input video frame. 1590The input video is not modified. 1591 1592The shown line contains a sequence of key/value pairs of the form 1593@var{key}:@var{value}. 1594 1595A description of each shown parameter follows: 1596 1597@table @option 1598@item n 1599sequential number of the input frame, starting from 0 1600 1601@item pts 1602Presentation TimeStamp of the input frame, expressed as a number of 1603time base units. The time base unit depends on the filter input pad. 1604 1605@item pts_time 1606Presentation TimeStamp of the input frame, expressed as a number of 1607seconds 1608 1609@item pos 1610position of the frame in the input stream, -1 if this information in 1611unavailable and/or meaningless (for example in case of synthetic video) 1612 1613@item fmt 1614pixel format name 1615 1616@item sar 1617sample aspect ratio of the input frame, expressed in the form 1618@var{num}/@var{den} 1619 1620@item s 1621size of the input frame, expressed in the form 1622@var{width}x@var{height} 1623 1624@item i 1625interlaced mode ("P" for "progressive", "T" for top field first, "B" 1626for bottom field first) 1627 1628@item iskey 16291 if the frame is a key frame, 0 otherwise 1630 1631@item type 1632picture type of the input frame ("I" for an I-frame, "P" for a 1633P-frame, "B" for a B-frame, "?" for unknown type). 1634Check also the documentation of the @code{AVPictureType} enum and of 1635the @code{av_get_picture_type_char} function defined in 1636@file{libavutil/avutil.h}. 1637 1638@item checksum 1639Adler-32 checksum of all the planes of the input frame 1640 1641@item plane_checksum 1642Adler-32 checksum of each plane of the input frame, expressed in the form 1643"[@var{c0} @var{c1} @var{c2} @var{c3}]" 1644@end table 1645 1646@section slicify 1647 1648Pass the images of input video on to next video filter as multiple 1649slices. 1650 1651@example 1652./avconv -i in.avi -vf "slicify=32" out.avi 1653@end example 1654 1655The filter accepts the slice height as parameter. If the parameter is 1656not specified it will use the default value of 16. 1657 1658Adding this in the beginning of filter chains should make filtering 1659faster due to better use of the memory cache. 1660 1661@section transpose 1662 1663Transpose rows with columns in the input video and optionally flip it. 1664 1665It accepts a parameter representing an integer, which can assume the 1666values: 1667 1668@table @samp 1669@item 0 1670Rotate by 90 degrees counterclockwise and vertically flip (default), that is: 1671@example 1672L.R L.l 1673. . -> . . 1674l.r R.r 1675@end example 1676 1677@item 1 1678Rotate by 90 degrees clockwise, that is: 1679@example 1680L.R l.L 1681. . -> . . 1682l.r r.R 1683@end example 1684 1685@item 2 1686Rotate by 90 degrees counterclockwise, that is: 1687@example 1688L.R R.r 1689. . -> . . 1690l.r L.l 1691@end example 1692 1693@item 3 1694Rotate by 90 degrees clockwise and vertically flip, that is: 1695@example 1696L.R r.R 1697. . -> . . 1698l.r l.L 1699@end example 1700@end table 1701 1702@section unsharp 1703 1704Sharpen or blur the input video. 1705 1706It accepts the following parameters: 1707@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount} 1708 1709Negative values for the amount will blur the input video, while positive 1710values will sharpen. All parameters are optional and default to the 1711equivalent of the string '5:5:1.0:5:5:0.0'. 1712 1713@table @option 1714 1715@item luma_msize_x 1716Set the luma matrix horizontal size. It can be an integer between 3 1717and 13, default value is 5. 1718 1719@item luma_msize_y 1720Set the luma matrix vertical size. It can be an integer between 3 1721and 13, default value is 5. 1722 1723@item luma_amount 1724Set the luma effect strength. It can be a float number between -2.0 1725and 5.0, default value is 1.0. 1726 1727@item chroma_msize_x 1728Set the chroma matrix horizontal size. It can be an integer between 3 1729and 13, default value is 5. 1730 1731@item chroma_msize_y 1732Set the chroma matrix vertical size. It can be an integer between 3 1733and 13, default value is 5. 1734 1735@item luma_amount 1736Set the chroma effect strength. It can be a float number between -2.0 1737and 5.0, default value is 0.0. 1738 1739@end table 1740 1741@example 1742# Strong luma sharpen effect parameters 1743unsharp=7:7:2.5 1744 1745# Strong blur of both luma and chroma parameters 1746unsharp=7:7:-2:7:7:-2 1747 1748# Use the default values with @command{avconv} 1749./avconv -i in.avi -vf "unsharp" out.mp4 1750@end example 1751 1752@section vflip 1753 1754Flip the input video vertically. 1755 1756@example 1757./avconv -i in.avi -vf "vflip" out.avi 1758@end example 1759 1760@section yadif 1761 1762Deinterlace the input video ("yadif" means "yet another deinterlacing 1763filter"). 1764 1765It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}. 1766 1767@var{mode} specifies the interlacing mode to adopt, accepts one of the 1768following values: 1769 1770@table @option 1771@item 0 1772output 1 frame for each frame 1773@item 1 1774output 1 frame for each field 1775@item 2 1776like 0 but skips spatial interlacing check 1777@item 3 1778like 1 but skips spatial interlacing check 1779@end table 1780 1781Default value is 0. 1782 1783@var{parity} specifies the picture field parity assumed for the input 1784interlaced video, accepts one of the following values: 1785 1786@table @option 1787@item 0 1788assume top field first 1789@item 1 1790assume bottom field first 1791@item -1 1792enable automatic detection 1793@end table 1794 1795Default value is -1. 1796If interlacing is unknown or decoder does not export this information, 1797top field first will be assumed. 1798 1799@var{auto} specifies if deinterlacer should trust the interlaced flag 1800and only deinterlace frames marked as interlaced 1801 1802@table @option 1803@item 0 1804deinterlace all frames 1805@item 1 1806only deinterlace frames marked as interlaced 1807@end table 1808 1809Default value is 0. 1810 1811@c man end VIDEO FILTERS 1812 1813@chapter Video Sources 1814@c man begin VIDEO SOURCES 1815 1816Below is a description of the currently available video sources. 1817 1818@section buffer 1819 1820Buffer video frames, and make them available to the filter chain. 1821 1822This source is mainly intended for a programmatic use, in particular 1823through the interface defined in @file{libavfilter/vsrc_buffer.h}. 1824 1825It accepts the following parameters: 1826@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den} 1827 1828All the parameters need to be explicitly defined. 1829 1830Follows the list of the accepted parameters. 1831 1832@table @option 1833 1834@item width, height 1835Specify the width and height of the buffered video frames. 1836 1837@item pix_fmt_string 1838A string representing the pixel format of the buffered video frames. 1839It may be a number corresponding to a pixel format, or a pixel format 1840name. 1841 1842@item timebase_num, timebase_den 1843Specify numerator and denomitor of the timebase assumed by the 1844timestamps of the buffered frames. 1845 1846@item sample_aspect_ratio.num, sample_aspect_ratio.den 1847Specify numerator and denominator of the sample aspect ratio assumed 1848by the video frames. 1849@end table 1850 1851For example: 1852@example 1853buffer=320:240:yuv410p:1:24:1:1 1854@end example 1855 1856will instruct the source to accept video frames with size 320x240 and 1857with format "yuv410p", assuming 1/24 as the timestamps timebase and 1858square pixels (1:1 sample aspect ratio). 1859Since the pixel format with name "yuv410p" corresponds to the number 6 1860(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}), 1861this example corresponds to: 1862@example 1863buffer=320:240:6:1:24 1864@end example 1865 1866@section color 1867 1868Provide an uniformly colored input. 1869 1870It accepts the following parameters: 1871@var{color}:@var{frame_size}:@var{frame_rate} 1872 1873Follows the description of the accepted parameters. 1874 1875@table @option 1876 1877@item color 1878Specify the color of the source. It can be the name of a color (case 1879insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an 1880alpha specifier. The default value is "black". 1881 1882@item frame_size 1883Specify the size of the sourced video, it may be a string of the form 1884@var{width}x@var{height}, or the name of a size abbreviation. The 1885default value is "320x240". 1886 1887@item frame_rate 1888Specify the frame rate of the sourced video, as the number of frames 1889generated per second. It has to be a string in the format 1890@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float 1891number or a valid video frame rate abbreviation. The default value is 1892"25". 1893 1894@end table 1895 1896For example the following graph description will generate a red source 1897with an opacity of 0.2, with size "qcif" and a frame rate of 10 1898frames per second, which will be overlayed over the source connected 1899to the pad with identifier "in". 1900 1901@example 1902"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]" 1903@end example 1904 1905@section movie 1906 1907Read a video stream from a movie container. 1908 1909It accepts the syntax: @var{movie_name}[:@var{options}] where 1910@var{movie_name} is the name of the resource to read (not necessarily 1911a file but also a device or a stream accessed through some protocol), 1912and @var{options} is an optional sequence of @var{key}=@var{value} 1913pairs, separated by ":". 1914 1915The description of the accepted options follows. 1916 1917@table @option 1918 1919@item format_name, f 1920Specifies the format assumed for the movie to read, and can be either 1921the name of a container or an input device. If not specified the 1922format is guessed from @var{movie_name} or by probing. 1923 1924@item seek_point, sp 1925Specifies the seek point in seconds, the frames will be output 1926starting from this seek point, the parameter is evaluated with 1927@code{av_strtod} so the numerical value may be suffixed by an IS 1928postfix. Default value is "0". 1929 1930@item stream_index, si 1931Specifies the index of the video stream to read. If the value is -1, 1932the best suited video stream will be automatically selected. Default 1933value is "-1". 1934 1935@end table 1936 1937This filter allows to overlay a second video on top of main input of 1938a filtergraph as shown in this graph: 1939@example 1940input -----------> deltapts0 --> overlay --> output 1941 ^ 1942 | 1943movie --> scale--> deltapts1 -------+ 1944@end example 1945 1946Some examples follow: 1947@example 1948# skip 3.2 seconds from the start of the avi file in.avi, and overlay it 1949# on top of the input labelled as "in". 1950movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie]; 1951[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out] 1952 1953# read from a video4linux2 device, and overlay it on top of the input 1954# labelled as "in" 1955movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie]; 1956[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out] 1957 1958@end example 1959 1960@section nullsrc 1961 1962Null video source, never return images. It is mainly useful as a 1963template and to be employed in analysis / debugging tools. 1964 1965It accepts as optional parameter a string of the form 1966@var{width}:@var{height}:@var{timebase}. 1967 1968@var{width} and @var{height} specify the size of the configured 1969source. The default values of @var{width} and @var{height} are 1970respectively 352 and 288 (corresponding to the CIF size format). 1971 1972@var{timebase} specifies an arithmetic expression representing a 1973timebase. The expression can contain the constants "PI", "E", "PHI", 1974"AVTB" (the default timebase), and defaults to the value "AVTB". 1975 1976@section frei0r_src 1977 1978Provide a frei0r source. 1979 1980To enable compilation of this filter you need to install the frei0r 1981header and configure Libav with --enable-frei0r. 1982 1983The source supports the syntax: 1984@example 1985@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}] 1986@end example 1987 1988@var{size} is the size of the video to generate, may be a string of the 1989form @var{width}x@var{height} or a frame size abbreviation. 1990@var{rate} is the rate of the video to generate, may be a string of 1991the form @var{num}/@var{den} or a frame rate abbreviation. 1992@var{src_name} is the name to the frei0r source to load. For more 1993information regarding frei0r and how to set the parameters read the 1994section @ref{frei0r} in the description of the video filters. 1995 1996Some examples follow: 1997@example 1998# generate a frei0r partik0l source with size 200x200 and framerate 10 1999# which is overlayed on the overlay filter main input 2000frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay 2001@end example 2002 2003@section rgbtestsrc, testsrc 2004 2005The @code{rgbtestsrc} source generates an RGB test pattern useful for 2006detecting RGB vs BGR issues. You should see a red, green and blue 2007stripe from top to bottom. 2008 2009The @code{testsrc} source generates a test video pattern, showing a 2010color pattern, a scrolling gradient and a timestamp. This is mainly 2011intended for testing purposes. 2012 2013Both sources accept an optional sequence of @var{key}=@var{value} pairs, 2014separated by ":". The description of the accepted options follows. 2015 2016@table @option 2017 2018@item size, s 2019Specify the size of the sourced video, it may be a string of the form 2020@var{width}x@var{height}, or the name of a size abbreviation. The 2021default value is "320x240". 2022 2023@item rate, r 2024Specify the frame rate of the sourced video, as the number of frames 2025generated per second. It has to be a string in the format 2026@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float 2027number or a valid video frame rate abbreviation. The default value is 2028"25". 2029 2030@item sar 2031Set the sample aspect ratio of the sourced video. 2032 2033@item duration 2034Set the video duration of the sourced video. The accepted syntax is: 2035@example 2036[-]HH[:MM[:SS[.m...]]] 2037[-]S+[.m...] 2038@end example 2039See also the function @code{av_parse_time()}. 2040 2041If not specified, or the expressed duration is negative, the video is 2042supposed to be generated forever. 2043@end table 2044 2045For example the following: 2046@example 2047testsrc=duration=5.3:size=qcif:rate=10 2048@end example 2049 2050will generate a video with a duration of 5.3 seconds, with size 2051176x144 and a framerate of 10 frames per second. 2052 2053@c man end VIDEO SOURCES 2054 2055@chapter Video Sinks 2056@c man begin VIDEO SINKS 2057 2058Below is a description of the currently available video sinks. 2059 2060@section nullsink 2061 2062Null video sink, do absolutely nothing with the input video. It is 2063mainly useful as a template and to be employed in analysis / debugging 2064tools. 2065 2066@c man end VIDEO SINKS 2067 2068