[FFmpeg-devel] looking to hire expert for a short project: lossless screen and sound capture 4k at 60hz

[Misha Aizatulin]

Hi all,

   I've been directed here from https://ffmpeg.org/consulting.html as I'm looking to hire an expert 
for what should hopefully be a simple but well-paid job. Please let me know if anyone has availability!

   What I'm trying to do is capture demoscene demos in full quality: 4k at 60hz (with sound of course). 
My rig is presentable: nvidia A6000 and 192G RAM. I am a software engineer, but don't know very much 
about video processing or ffmpeg.

   I tried:
ffmpeg -filter_complex ddagrab=0,hwdownload,format=bgra,framerate=60 -c:v utvideo output.mkv

   What happened: the first minute or so (always roughly the same length of time) is captured fine. 
Then it drops off the cliff, something like 1 frame per 3 seconds, but also trying to interpolate 
between them, so it looks really weird.

   I was not able to get ffmpeg to report to me any dropped frames which is upsetting and worrying. 
I also don't understand where the interpolation comes from and would love to turn it off.

   I can't think of a reason for the droppage: my RAM is big enough to hold the full video (about 
50G total). My only theory is that GPU memory might be getting full (will check tomorrow), but I'd 
expect hwdownload rates to not be that slow.

   Maybe I should use hevc_nvenc with lossless setting, but there's some talk about the yuv420 
conversion being not lossless...

   Anyway, would really appreciate someone educating me on these and would happily pay for your time!

Best,
   Misha