Flutter 音视频处理FFmpeg

只能说 Flutter 确实很强大
https://pub.flutter-io.cn/packages/flutter_ffmpeg

ffmpeg 插件，文档没给出如何给视频添加水印, 但是给出了执行命令的方法演示，这就足够了。

添加一个水印:
String command = "-i " + inputVideoPath +
" -i "+waterMarkPath+" -filter_complex overlay "+
outVideoPath+"";

添加多个水印命令:
String command = "-i " + inputVideoPath +
" -i "+waterMarkPath2+" -i "+waterMarkPath+
" -filter_complex overlay=10:10,overlay=5:5 "+
outVideoPath+"";

将视频转换成小尺寸视频:
String command = "-i " + inputVideoPath +" -b:v 10000k -s 216x384 "+ outVideoPath+"";

如果碰到 App crash with error message: couldn't find "libmobileffmpeg_abidetect.so"
执行
flutter clean
flutter doctor -v