ffmpeg 视频过度滤镜 gltransition
上次随笔中提到的 ffmpeg-concat 可以处理视频过度，但是缺点是临时文件超大。
经过查找 ffmpeg 还有 gltransition 滤镜，但是 ffmpeg 的正式版中还没有加进去。
github 上有 ffmpeg-gl-transition 项目，有详细的添加滤镜的说明，参见以下地址
https://github.com/transitive-bullshit/ffmpeg-gl-transition
这个滤镜依赖的库包括 GLEW + glfw3
想静态编译 GLEW 需要加 #define GLEW_STATIC
ffmpeg -i 1.mp4 -i 2.mp4 -filter_complex "gltransition=duration=4:offset=1.5:source=crosswarp.glsl" -y out.mp4
通过下面的脚本可以使用不同视频过度方式
-------------------------------------------------------------------------------------------------
ffmpeg-gl-transition-concat.sh
-------------------------------------------------------------------------------------------------
#!/bin/bash
# Example of concatenating 3 mp4s together with 1-second transitions between them.
tpath="/ffmpeg/transitions/"
x264="-look_ahead 0 -ac 2 -c:v h264_qsv -profile:v high -level 3.1 -preset:v veryfast"
ki="-keyint_min 72 -g 72 -sc_threshold 0"
br="-b:v 3000k -minrate 3000k -maxrate 6000k -bufsize 6000k -b:a 128k"
ffmpeg -hide_banner
-i 1.mp4
-i 2.mp4
-i 3.mp4
-filter_complex "
[0:a] atrim=0:5 [a0];
[1:a] atrim=0:5 [a1];
[2:a] atrim=0:6 [a2];
[0:v] split [v000] [v010];
[1:v] split [v100] [v110];
[2:v] split [v200] [v210];
[v000] trim=0:5 [v001];
[v010] trim=5:6 [v011t];
[v011t] setpts=PTS-STARTPTS [v011];
[v100] trim=0:5 [v101];
[v110] trim=5:6 [v111t];
[v111t] setpts=PTS-STARTPTS [v111];
[v200] trim=0:5 [v201];
[v210] trim=5:6 [v211t];
[v211t] setpts=PTS-STARTPTS [v211];
[v011] [v101] gltransition=duration=1:source=${tpath}WaterDrop.glsl [vt0];
[v111] [v201] gltransition=duration=1:source=${tpath}crosswarp.glsl [vt1];
[v001] [vt0] [vt1] [v211] concat=n=4 [outv];
[a0] [a1] [a2] concat=n=3:v=0:a=1 [outa]"
-map [outv] -map [outa]
${x264} ${ki} ${br}
-y ffmpeg-gl-transition-concat.mp4
-------------------------------------------------------------------------------------------------