ffmpeg

g729 to wav

ffmpeg -f g729 -i "C:\Video\wav\123.g729" -f wav "C:\Video\wav\123.wav"

avi to mov с использованием GPU

ffmpeg -i video.avi -c:v h264_nvenc -preset p7 -pix_fmt yuv420p -an test.mov
 50\50 CPU и GPU
ffmpeg -hwaccel cuda -c:v h264_cuvid -i input.avi -c:v h264_nvenc -preset p7 -pix_fmt yuv420p -an output.mov
100% GPU

mov to mov 

ffmpeg -hwaccel cuvid -i input.mov -c:v h264_nvenc -bsf:v h264_mp4toannexb -b:v 5M -c:a copy output.mov

100%GPU