ffmpeg:色度键(绿屏过滤器)短视频连续循环到实时视频

Question

我知道如何对视频流的背景进行色度键/绿屏过滤，并使用 v4l2loopback 将其替换为图像。运行后

$ sudo modprobe v4l2loopback

我的代码如下:

$ ffmpeg -i background.jpg -f v4l2 -pix_fmt mjpeg \
    -framerate 30 -video_size 1280x720 -i /dev/video0 \
    -filter_complex \
        "[0:v]scale=1280x720[bg]; \
         [1:v]colorkey=0x00b140:0.5:0.0[ckout];  
         [bg][ckout]overlay" \
    -pix_fmt yuv420p -f v4l2 /dev/video1

然后我可以简单地在我喜欢的任何视频播放应用程序中选择新的伪网络摄像头作为输入。
我想要一个短视频，而不是静止图像，在后台连续循环。我很确定这是可能的，但不知道如何，非常感谢任何提示!
更新 1 :根据要求，这是响应中建议的命令的完整日志

$ ffmpeg -stream_loop 5 -re -i some_gif.gif \
    -f v4l2 -pix_fmt mjpeg -framerate 30 \
    -video_size 1280x720 -i /dev/video0 \
    -filter_complex \
        "[0:v]scale=1280x720[bg]; \ 
         [1:v]colorkey=0x61A051:0.3:0.0[ckout]; \
         [bg][ckout]overlay" \
    -pix_fmt yuv420p -f v4l2 /dev/video1

ffmpeg version 3.4.8-0ubuntu0.2 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration: --prefix=/usr --extra-version=0ubuntu0.2 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Input #0, gif, from 'some_gif.gif':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: gif, bgra, 640x640, 10 fps, 10 tbr, 100 tbn, 100 tbc
Input #1, video4linux2,v4l2, from '/dev/video0':
  Duration: N/A, start: 433330.420280, bitrate: N/A
    Stream #1:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 1280x720, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
Stream mapping:
  Stream #0:0 (gif) -> scale
  Stream #1:0 (mjpeg) -> colorkey
  overlay -> Stream #0:0 (rawvideo)
Press [q] to stop, [?] for help
[swscaler @ 0x563d17c69e80] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x563d17c69e80] No accelerated colorspace conversion found from yuv422p to argb.
Output #0, v4l2, to '/dev/video1':
  Metadata:
    encoder         : Lavf57.83.100
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 1280x720, q=2-31, 110592 kb/s, 10 fps, 10 tbn, 10 tbc (default)
    Metadata:
      encoder         : Lavc57.107.100 rawvideo
Past duration 0.899986 too largeN/A time=00:00:05.10 bitrate=N/A speed=   1x     
frame=   98 fps= 10 q=-0.0 Lsize=N/A time=00:00:09.80 bitrate=N/A dup=0 drop=20 speed=1.03x    
video:132300kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

更新 2 :通过应用更新后

$ sudo add-apt-repository ppa:jonathonf/ffmpeg-4
$ sudo apt-get update
$ sudo apt-get install ffmpeg

我现在安装了以下版本

ffmpeg version 4.3.1-0york0~18.04 Copyright (c) 2000-2020 the FFmpeg developers

现在答案有效:)

Answer 1

使用-stream_loop循环和 -re实时速度，因为您正在流式传输(否则它将播放超快):

$ ffmpeg -stream_loop -1 -re -i input.mp4 -f v4l2 -pixel_format mjpeg \
    -framerate 30 -video_size 1280x720 -i /dev/video0 \
    -filter_complex \
        "[0:v]scale=1280x720[bg]; \
         [1:v]colorkey=0x00b140:0.5:0.0[ckout];  
         [bg][ckout]overlay,format=yuv420p" \
    -f v4l2 /dev/video1

鉴于您的输入是 YUV，请考虑替换 colorkey (RGB) 与 chromakey (YUV)。