I’ve been attempting to do lossless game capture as I’ve been working on a program to do frame rate analysis. I haven’t had much luck finding a program that does lossless capture as AmaRecTV, Dxtory, and Virtualdub all seem to be abandoned. I’m trying to use FFmpeg and have come up with the following command:
ffmpeg -y -f dshow -rtbufsize 500M -i video="Game Capture 4K60 Pro Video 01" -framerate 60 -vsync 0 -c:v libx264 -preset ultrafast -crf 0 -pix_fmt yuv420p "e:\Captures\out.mkv"
Unfortunately, the file size doesn’t seem large enough to be lossless. For example, according to MediaInfo, I got an overall bit rate of 132 Mb/s (16.5 MB/s) for a 720p 60 fps capture. However, I’m pretty sure that a lossless 720p, 60 fps, 4:2:0 file should be closer to 640 Mb/s (80MB/s).
I’m using Windows 10 1809 x64, a nightly build of FFmpeg x64 that is newer than 4.0.2, Nvidia 399.24, and an Elgato 4K60 Pro.
Does this command produce lossless capture? And how can I improve it?