FFmpeg添加了很多濾鏡，查看哪些濾鏡有效可用命令:
# ./ffmpeg -filters.
1. FFmpeg濾鏡文檔
更多的信息和每個濾鏡的使用示例可查看FFmpeg的濾鏡文檔:
http://ffmpeg.org/ffmpeg-filters.html
2. 示例
2.1 縮放
將輸入的640x480縮小到320x240輸出:
# ./ffmpeg -i input -vf scale=iw/2:-1 output
iw : 是輸入的寬度；在本例中，輸入寬度爲640. 640/2 = 320.
-1 : 通知縮放濾鏡在輸出時保持原始的寬高比，因此本例中縮放濾鏡將選擇240.
2.2 視頻加速
1. 加速/減慢視頻
可以使用 “setpts"（http://ffmpeg.org/ffmpeg.html#asetpts_002c-setpts）濾鏡來改變視頻速度。
加速視頻命令:
# ./ffmpeg -i input.mkv -filter:v "setpts=0.5*PTS" output.mkv
Note : 這個方法在實現你想要的速度時，會採取丟幀策略。
如果想避免丟幀，可以指定輸出的幀率比輸入的幀率高的辦法。
例如，輸入的幀率爲4， 指定輸出的幀率爲4x, 即16fps :
# ./ffmpeg -i input.mkv -r 16 -filter:v "setpts=0.125*PTS" -an output.mkv
減慢視頻命令:
# ./ffmpeg -i input.mkv -filter:v "setpts=2.0*PTS" output.mkv
2. 加速/減慢音頻
可以使用" atempo" 音頻濾鏡來加速或減慢音頻。如雙倍速音頻命令:
# ./ffmpeg -i input.mkv -filter:a "atempo=2.0" -vn output.mkv
"atempo"濾鏡對音頻速度調整限制在0.5 到 2.0 之間，（即半速或倍速）。
如果有必要，可以使用多個atempo濾鏡來實現,如下面的命令實現四倍速音頻:
# ./ffmpeg -i input.mkv -filter:a "atempo=2.0,atempo=2.0" -vn output.mkv
使用更復雜的濾鏡圖，可以同時加速視頻和音頻：
# ./ffmpeg -i input.mkv -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]" -map "[v]" -map "[a]" output.mkv
2.3 濾鏡圖，鏈，和濾鏡關係
FFmpeg命令行中，跟在 "-vf"之後的就是一個濾鏡圖。
濾鏡圖可以包含多個濾鏡鏈，而每個濾鏡鏈又可以包含多個濾鏡。
雖然一個完整的濾鏡圖描述很複雜，但可以簡化以避免歧義。
濾鏡鏈使用";"分隔，濾鏡鏈中濾鏡使用","分隔；
並且，濾鏡鏈如果沒有指定輸入或輸出，則默認使用前面的濾鏡鏈的輸出爲輸入，並輸出給後面的濾鏡鏈做輸入。
下面的命令行是相等的:
ffmpeg -i input -vf [in]scale=iw/2:-1[out] output
ffmpeg -i input -vf scale=iw/2:-1 output # the input and output are implied without ambiguity
對於下面:
ffmpeg -i input -vf [in]yadif=0:0:0[middle];[middle]scale=iw/2:-1[out] output
# 兩個鏈的方式，每個鏈一個濾鏡，鏈間使用[middle]填充
ffmpeg -i input -vf [in]yadif=0:0:0,scale=iw/2:-1[out] output
# 一個鏈的方式，鏈包含兩個濾鏡，使用默認鏈接
ffmpeg -i input -vf yadif=0:0:0,scale=iw/2:-1 output # 輸入輸出也使用默認鏈接
2.4. 多個輸入覆蓋同一個2x2網格
下例中有四個輸入，並使用 -filter_complex濾鏡鏈接。
這個例子中四個輸入都是 "-f lavfi -i testsrc", 也可以用別的輸入代替。
在濾鏡圖中，第一個輸入被填充到右下角，並設置成高度的兩倍。
其它三個輸入使用獨立的濾鏡"hflip, negate,和 edgedetect"。
覆蓋視頻濾鏡被使用多次，後面三個都覆蓋到第一個之上。
覆蓋濾鏡的偏移量在輸入上形成一個網格。
# ./ffmpeg -f lavfi -i testsrc -f lavfi -i testsrc -f lavfi -i testsrc -f lavfi -i testsrc
-filter_complex "[0:0]pad=iw*2:ih*2[a];[1:0]negate[b];[2:0]hflip[c];
[3:0]edgedetect[d];[a][b]overlay=w[x];[x][c]overlay=0:h[y];[y][d]overlay=w:h"
-y -c:v ffv1 -t 5 multiple_input_grid.avi
2.5 轉義字符
如文檔中的描述，濾鏡間的"，"分隔符是必須的，但它也會出現在參數中，如下面的"select"濾鏡:
# ./ffmpeg -i input -vf select='eq(pict_type\,PICT_TYPE_I)' output # to select only I frames
作爲一個選擇，在濾鏡圖中同樣可以在雙引號中使用空格，這樣更方便閱讀:
# ./ffmpeg -i input -vf "select=eq(pict_type,PICT_TYPE_I)" output # to select only I frames
# ./ffmpeg -i input -vf "yadif=0:-1:0, scale=iw/2:-1" output # deinterlace then resize
2.6 燒錄時間碼
使用 "drawtext"視頻濾鏡。
PAL 25 fps non drop frame:
ffmpeg -i in.mp4 -vf "drawtext=fontfile=/usr/share/fonts/truetype/DroidSans.ttf: timecode='09\:57\:00\:00': r=25: \
x=(w-tw)/2: y=h-(2*lh): fontcolor=white: box=1: boxcolor=0x00000000@1" -an -y out.mp4
NTSC 30 fps drop frame
(change the : to a ; before the frame count)_________________________________________________________
\
ffmpeg -i in.mp4 -vf "drawtext=fontfile=/usr/share/fonts/truetype/DroidSans.ttf: timecode='09\:57\:00\;00': r=30: \
x=(w-tw)/2: y=h-(2*lh): fontcolor=white: box=1: boxcolor=0x00000000@1" -an -y out.mp4
2.7 描述命令行參數
構建複雜的濾鏡圖時，會使命令行看起來一團混亂，如何使濾鏡圖命令行可管理就變得很有用了。
下面的例子包含三個濾鏡，yadif, scale, drawtext的濾鏡圖的腳本:
#!/bin/bash
# ffmpeg test script
path="/path/to/file/"
in_file="in.mp4"
out_file="out.mp4"
cd $path
filter="-vf \"yadif=0:-1:0, scale=400:226, drawtext=fontfile=/usr/share/fonts/truetype/DroidSans.ttf: \
text='tod- %X':x=(w-text_w)/2:y=H-60 :fontcolor=white :box=1:boxcolor=0x00000000@1\""
codec="-vcodec libx264 -pix_fmt yuv420p -b:v 700k -r 25 -maxrate 700k -bufsize 5097k"
command_line="ffmpeg -i $in_file $filter $codec -an $out_file"
echo $command_line
eval $command_line
exit
NOTE: 包含整個濾鏡圖的雙引號需要使用轉義符 \",
eval $command_line變量用於避免轉義符丟失。
2.8 測試源
testsrc源濾鏡生成一個測試視頻源，包含有顏色模式，灰度值和時間戳。它在用於測試目的時很有用。
下面的例子生成一個10秒的輸出，30fps,共300幀，幀大小爲 1280x720:
# ./ffmpeg -f lavfi -i testsrc=duration=10:size=1280x720:rate=30 output.mpg
使用 smptebars源濾鏡的例子:
# ./ffmpeg -f lavfi -i "smptebars=duration=5:size=1280x720:rate=30" output.mp4
ffplay同樣能用於查看結果濾鏡圖:
ffplay -f lavfi -i "testsrc=duration=10:size=1280x720:rate=30"
3. 濾鏡列表
濾鏡和libavfilter綁定在一起，如 4.3.100(as configured with --enable-gpl).
使用外部庫的濾鏡並未列在這裏，如frei0r.可以查看FFMPEG的濾鏡文檔。
濾鏡列表約定:
T.. = Timeline support
.S. = Slice threading
..C = Commmand support
A = Audio input/output
V = Video input/output
N = Dynamic number and/or type of input/output
| = Source or sink filter
濾鏡:
... aconvert A->A Convert the input audio to sample_fmt:channel_layout.
T.. adelay A->A 延遲一個或多個音頻通道
... aecho A->A 給音頻添加回音
... aeval A->A Filter audio signal according to a specified expression.
T.. afade A->A Fade in/out input audio.
... aformat A->A Convert the input audio to one of the specified formats.
... ainterleave N->A Temporally interleave audio inputs.
... allpass A->A Apply a two-pole all-pass filter.
... amerge N->A Merge two or more audio streams into a single multi-channel stream.
... amix N->A Audio mixing.
... anull A->A Pass the source unchanged to the output.
T.. apad A->A Pad audio with silence.
... aperms A->A Set permissions for the output audio frame.
... aphaser A->A Add a phasing effect to the audio.
... aresample A->A 重採樣音頻數據
... aselect A->N 選擇音頻幀給輸出
... asendcmd A->A Send commands to filters.
... asetnsamples A->A Set the number of samples for each output audio frames.
... asetpts A->A Set PTS for the output audio frame.
... asetrate A->A Change the sample rate without altering the data.
... asettb A->A Set timebase for the audio output link.
... ashowinfo A->A Show textual information for each audio frame.
... asplit A->N Pass on the audio input to N audio outputs.
... astats A->A Show time domain statistics about audio frames.
... astreamsync AA->AA Copy two streams of audio data in a configurable order.
..C atempo A->A Adjust audio tempo.
... atrim A->A Pick one continuous section from the input, drop the rest.
... bandpass A->A Apply a two-pole Butterworth band-pass filter.
... bandreject A->A Apply a two-pole Butterworth band-reject filter.
... bass A->A Boost or cut lower frequencies.
... biquad A->A Apply a biquad IIR filter with the given coefficients.
... channelmap A->A Remap audio channels.
... channelsplit A->N Split audio into per-channel streams.
... compand A->A Compress or expand audio dynamic range.
... earwax A->A Widen the stereo image.
... ebur128 A->N EBU R128 scanner.
... equalizer A->A Apply two-pole peaking equalization (EQ) filter.
... highpass A->A Apply a high-pass filter with 3dB point frequency.
... join N->A Join multiple audio streams into multi-channel output.
... lowpass A->A Apply a low-pass filter with 3dB point frequency.
... pan A->A Remix channels with coefficients (panning).
... replaygain A->A ReplayGain scanner.
... silencedetect A->A 檢測靜音
... treble A->A Boost or cut upper frequencies.
T.C volume A->A 改變輸入音量
... volumedetect A->A 檢測音頻音量
... aevalsrc |->A Generate an audio signal generated by an expression.
... anullsrc |->A Null audio source, return empty audio frames.
... sine |->A Generate sine wave audio signal.
... anullsink A->| Do absolutely nothing with the input audio.
... alphaextract V->N Extract an alpha channel as a grayscale image component.
... alphamerge VV->V Copy the luma value of the second input into the alpha channel of the first input.
T.. bbox V->V Compute bounding box for each frame.
... blackdetect V->V Detect video intervals that are (almost) black.
... blackframe V->V 檢測幾乎全黑的幀
TS. blend VV->V Blend two video frames into each other.
T.. boxblur V->V Blur the input.
T.. colorbalance V->V Adjust the color balance.
T.. colorchannelmixer V->V Adjust colors by mixing color channels.
T.. colormatrix V->V Convert color matrix.
... copy V->V 複製輸入視頻到輸出
... crop V->V 裁剪輸入視頻
T.. cropdetect V->V 自動檢測裁剪尺寸
TS. curves V->V Adjust components curves.
T.. dctdnoiz V->V Denoise frames using 2D DCT.
... decimate N->V Decimate frames (post field matching filter).
... dejudder V->V Remove judder produced by pullup.
T.. delogo V->V 去掉輸入視頻的logo
... deshake V->V Stabilize shaky video.
T.. drawbox V->V 在輸入視頻上畫一個顏色塊
T.. drawgrid V->V 在輸入視頻上畫一個顏色網格
T.. edgedetect V->V 檢測並畫邊緣
... elbg V->V Apply posterize effect, using the ELBG algorithm.
... extractplanes V->N Extract planes as grayscale frames.
.S. fade V->V Fade in/out input video.
... field V->V Extract a field from the input video.
... fieldmatch N->V Field matching for inverse telecine.
T.. fieldorder V->V Set the field order.
... format V->V Convert the input video to one of the specified pixel formats.
... fps V->V 強制成常量幀率Force constant framerate.
... framepack VV->V Generate a frame packed stereoscopic video.
T.. framestep V->V 每N幀中選擇一幀
T.. geq V->V Apply generic equation to each pixel.
T.. gradfun V->V Debands video quickly using gradients.
TS. haldclut VV->V Adjust colors using a Hald CLUT.
.S. hflip V->V Horizontally flip the input video.
T.. histeq V->V Apply global color histogram equalization.
... histogram V->V 計算並畫直方圖
T.. hqdn3d V->V Apply a High Quality 3D Denoiser.
T.C hue V->V Adjust the hue and saturation of the input video.
... idet V->V 隔行檢測濾鏡
T.. il V->V 去隔行或隔行場
... interlace V->V 轉換逐行視頻成隔行視頻
... interleave N->V Temporally interleave video inputs.
... kerndeint V->V Apply kernel deinterlacing to the input.
TS. lut3d V->V Adjust colors using a 3D LUT.
T.. lut V->V Compute and apply a lookup table to the RGB/YUV input video.
T.. lutrgb V->V Compute and apply a lookup table to the RGB input video.
T.. lutyuv V->V Compute and apply a lookup table to the YUV input video.
... mcdeint V->V Apply motion compensating deinterlacing.
... mergeplanes N->V Merge planes.
... mp V->V Apply a libmpcodecs filter to the input video.
... mpdecimate V->V Remove near-duplicate frames.
T.. negate V->V Negate input video.
... noformat V->V Force libavfilter not to use any of the specified pixel formats for the input to the next filter.
TS. noise V->V Add noise.
... null V->V Pass the source unchanged to the output.
T.C overlay VV->V Overlay a video source on top of the input.
T.. owdenoise V->V Denoise using wavelets.
... pad V->V Pad the input video.
... perms V->V Set permissions for the output video frame.
T.. perspective V->V Correct the perspective of video.
... phase V->V Phase shift fields.
... pixdesctest V->V Test pixel format definitions.
T.C pp V->V Filter video using libpostproc.
... psnr VV->V Calculate the PSNR between two video streams.
... pullup V->V Pullup from field sequence to frames.
T.. removelogo V->V Remove a TV logo based on a mask image.
TSC rotate V->V Rotate the input image.
T.. sab V->V Apply shape adaptive blur.
... scale V->V Scale the input video size and/or convert the image format.
... select V->N 選擇視頻幀並傳給輸出
... sendcmd V->V Send commands to filters.
... separatefields V->V Split input video frames into fields.
... setdar V->V Set the frame display aspect ratio.
... setfield V->V Force field for the output video frame.
... setpts V->V Set PTS for the output video frame.
... setsar V->V Set the pixel sample aspect ratio.
... settb V->V Set timebase for the video output link.
... showinfo V->V Show textual information for each video frame.
... shuffleplanes V->V Shuffle video planes
T.. smartblur V->V Blur the input video without impacting the outlines.
... split V->N Pass on the input to N video outputs.
T.C spp V->V Apply a simple post processing filter.
... stereo3d V->V Convert video stereoscopic 3D view.
... super2xsai V->V Scale the input by 2x using the Super2xSaI pixel art algorithm.
... swapuv V->V Swap U and V components.
... telecine V->V Apply a telecine pattern.
... thumbnail V->V Select the most representative frame in a given sequence of consecutive frames.
... tile V->V Tile several successive frames together.
... tinterlace V->V Perform temporal field interlacing.
.S. transpose V->V Transpose input video.
... trim V->V Pick one continuous section from the input, drop the rest.
T.. unsharp V->V Sharpen or blur the input video.
... vflip V->V Flip the input video vertically.
T.. vignette V->V Make or reverse a vignette effect.
T.. w3fdif V->V Apply Martin Weston three field deinterlace.
TS. yadif V->V 對輸入圖像去隔行
... cellauto |->V Create pattern generated by an elementary cellular automaton.
..C color |->V Provide an uniformly colored input.
... haldclutsrc |->V Provide an identity Hald CLUT.
... life |->V Create life.
... mandelbrot |->V Render a Mandelbrot fractal.
... mptestsrc |->V Generate various test pattern.
... nullsrc |->V Null video source, return unprocessed video frames.
... rgbtestsrc |->V Generate RGB test pattern.
... smptebars |->V Generate SMPTE color bars.
... smptehdbars |->V Generate SMPTE HD color bars.
... testsrc |->V Generate test pattern.
... nullsink V->| Do absolutely nothing with the input video.
... avectorscope A->V Convert input audio to vectorscope video output.
... concat N->N Concatenate audio and video streams.
... showspectrum A->V Convert input audio to a spectrum video output.
... showwaves A->V Convert input audio to a video output.
... amovie |->N Read audio from a movie source.
... movie |->N Read from a movie source.
... ffbuffersink V->| Buffer video frames, and make them available to the end of the filter graph.
... ffabuffersink A->| Buffer audio frames, and make them available to the end of the filter graph.
... abuffer |->A Buffer audio frames, and make them accessible to the filterchain.
... buffer |->V Buffer video frames, and make them accessible to the filterchain.
... abuffersink A->| Buffer audio frames, and make them available to the end of the filter graph.
... buffersink V->| Buffer video frames, and make them available to the end of the filter graph.
... afifo A->A Buffer input frames and send them when they are requested.
... fifo V->V Buffer input images and send them when they are requested.
4. 其它濾鏡示例
Fancy Filtering Examples （http://trac.ffmpeg.org/wiki/FancyFilteringExamples）
– 各種迷幻效果和怪異濾鏡的示例
5. 開發自己的濾鏡
See FFmpeg filter HOWTO（http://blog.chinaunix.net/uid-26000296-id-3068068.html）
ffmpeg常用濾鏡命令
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