FFmpeg-helper

using ffmpeg decode video

AppSettings

ffmepg = "D:\ffmpeng.exe"
args = "-i {0} -c:v libx264 -crf 24 {1}"
flv = "D:"
{0} = "D:test.mp4"
{1} = flv + "test.flv"

the whole command looks like:
"D:\ffmpeng.exe" -i "D:test.mp4" -c:v libx264 -crf 24 "D:\test.flv"

Another effective way to decode mp4 to flv

ffmpeg.exe -i input.flv -y -vcodec copy -acodec copy output.mp4