FFmpeg Filtering Guide参数说明
来源:互联网 发布:手机游戏服务端源码 编辑:程序博客网 时间:2024/05/21 08:04
FFmpeg Filtering Guide
Contents
- Documentation
- Examples
- Scaling
- Speed up your video
- Filtergraph,Chain,Filter relationship
- multiple input overlay in 2x2 grid
- Escaping characters
- Burnt in Timecode
- Scripting your command line parameters
- Test Source
- Other Filter Examples
- Developing your own Filters
FFmpeg has access to many filters and more are added on a regular basis. To see what filters are available with your build see ffmpeg -filters.
Documentation
Refer to the FFmpeg filters documentation for more information and examples for each filter. This wiki page is for user contributed examples and tips, and contributions to this page are encouraged.
Examples
Scaling
Starting with something simple. Resize a 640x480 input to a 320x240 output.
ffmpeg -i input -vf scale=iw/2:-1 output
iw is input width. In this example the input width is 640. 640/2 = 320. The -1 tells the scale filter to preserve the aspect ratio of the output, so in this example the scale filter will choose a value of 240. See the FFmpeg documentation for additional information.
Speed up your video
See How to speed up / slow down a video for examples.
Filtergraph,Chain,Filter relationship
What follows the -vf in an ffmpeg command line is a filtergraph description. This filtergraph may contain a number of chains, each of which may contain a number of filters.
Whilst a full filtergraph description can be complicated, it is possible to simplify it for simpler graphs provided ambiguity is avoided.
Remembering that filters in a chain are separated by commas "," chains by a semicolon ";" and that if an input or output is not specified it is assumed to come from the preceding or sent to the following item in the chain.
The following are equivalent:
ffmpeg -i input -vf [in]scale=iw/2:-1[out] outputffmpeg -i input -vf scale=iw/2:-1 output # the input and output are implied without ambiguity
As are:
ffmpeg -i input -vf [in]yadif=0:0:0[middle];[middle]scale=iw/2:-1[out] output # 2 chains form, one filter per chain, chains linked by the [middle] padffmpeg -i input -vf [in]yadif=0:0:0,scale=iw/2:-1[out] output # 1 chain form, with 2 filters in the chain, linking impliedffmpeg -i input -vf yadif=0:0:0,scale=iw/2:-1 output # the input and output are implied without ambiguity
multiple input overlay in 2x2 grid
Here four inputs are filtered together using the -filter_complex option. In this case all of the inputs are the -f lavfi -i testsrc (the testsrc source filter) but could be other inputs.
Within the filtergraph the first input is padded to the right and bottom by double its height, and the other three inputs are individually filtered using hflip, negate, and edgedetect.
The overlay video filter is then used multiple times for placement of each input. The offsets used in the overlay filter arrange the inputs into a grid shape.
ffmpeg -f lavfi -i testsrc -f lavfi -i testsrc -f lavfi -i testsrc -f lavfi -i testsrc -filter_complex \"[0:v]pad=iw*2:ih*2[a]; \ [1:v]negate[b]; \ [2:v]hflip[c]; \ [3:v]edgedetect[d]; \ [a][b]overlay=w[x]; \ [x][c]overlay=0:h[y]; \ [y][d]overlay=w:h[out]" -map "[out]" -c:v ffv1 -t 5 multiple_input_grid.avi
Be aware that frames are taken from each input video in timestamp order, so it is a good idea to pass all overlay inputs through a setpts=PTS-STARTPTS filter to have them begin in the same zero timestamp, such as[0:v]hflip,setpts=PTS-STARTPTS[a];[1:v]setpts=PTS-STARTPTS[b];[a][b]overlay.
Escaping characters
As described in the documentation, it can be necessary to escape commas "," that need to appear in some arguments, for example the select filter:
ffmpeg -i input -vf select='eq(pict_type\,PICT_TYPE_I)' output # to select only I frames
However an alternative, which also allows for white space within the filtergraph, and which may assist in clarity of reading complex graphs, is to enclose the whole filtergraph within double quotes " " thus:
ffmpeg -i input -vf "select=eq(pict_type,PICT_TYPE_I)" output # to select only I framesffmpeg -i input -vf "yadif=0:-1:0, scale=iw/2:-1" output # deinterlace then resize
Note that the examples given in the documentation mix and match the use of "full quoting" and "\" escaping, and that use of unusual shells may upset escaping. See Notes on filtergraph escaping for more information.
Burnt in Timecode
Using the drawtext video filter.
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
Scripting your command line parameters
If building complex filtergraphs the command line can get very messy so it can help to break things down into manageable pieces. However one needs to be careful when joining them all together to avoid issues due to your shell and escaped characters.
The following example shows a sample bash script containing a filtergraph of one chain with three filters; yadif, scale and drawtext.
#!/bin/bash# ffmpeg test scriptpath="/path/to/file/"in_file="in.mp4"out_file="out.mp4"cd $pathfilter="yadif=0:-1:0, scale=400:226, drawtext=fontfile=/usr/share/fonts/truetype/DroidSans.ttf: \text='tod- %X':x=(w-text_w)/2:y=H-60 :fontcolor=white :box=1:boxcolor=0x00000000@1"codec="-vcodec libx264 -pix_fmt yuv420p -b:v 700k -r 25 -maxrate 700k -bufsize 5097k"command_line=(ffmpeg -i "$in_file" -vf "$filter" "$codec" -an $out_file")echo "${command_line[@]}""${command_line[@]}"exit
Note that the filtergraph spans more than one line. The echo command shows the full command as it is executed. Useful for debugging.
The array in the $command_line variable helps avoid loss of the quotes which occurs otherwise. Other shells may behave differently.
Test Source
The testsrc source filter generates a test video pattern showing a color pattern, a scrolling gradient, and a timestamp. This is useful for testing purposes.
This example will create a 10 second output, 30 fps (300 frames total), with a frame size of 1280x720:
ffmpeg -f lavfi -i testsrc=duration=10:size=1280x720:rate=30 output.mpg
Another example using the smptebars source filter:
ffmpeg -f lavfi -i "smptebars=duration=5:size=1280x720:rate=30" output.mp4
ffplay can also be used to view the resulting filtergraph:
ffplay -f lavfi -i "testsrc=duration=10:size=1280x720:rate=30"
Other Filter Examples
- Fancy Filtering Examples – Examples for various psychedelic effects and other weird filtering.
Developing your own Filters
- See FFmpeg filter HOWTO
Attachments (1)
- FFmpeg Filtering Guide参数说明
- FFmpeg Filtering Guide
- FFmpeg 参数说明
- ffmpeg configure参数说明
- ffmpeg ./configure参数说明
- ffmpeg configure参数说明
- ffmpeg ./configure参数说明
- ffmpeg ./configure参数说明
- ffmpeg ./configure参数说明
- ffmpeg ./configure参数说明
- ffmpeg configure参数说明
- ffmpeg参数说明
- FFmpeg参数说明
- FFmpeg参数说明
- FFmpeg参数说明
- ffmpeg参数说明
- ffmpeg参数说明
- ffmpeg参数说明
- iOS下如何获取一个类的所有子类
- GCD 深入理解(一)
- 关于dicom参数信息和数据读写的理解
- java获取视频播放时长
- 黑马程序员训练营-------反射原理
- FFmpeg Filtering Guide参数说明
- 北京大学ACM/ICPC竞赛训练暑期课练习之怪盗基德的滑翔翼
- python使用mysql数据库
- swift url scheme(应用之间的调用)
- PAT (Advenced Level) 1026. Table Tennis (30) 模拟排队,有vip
- Codeforces Round #313 (Div. 2)
- C#读取XML文件,以及对XML文件的增删改查
- python 机器学习库:Numpy
- Android Hook Java