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

[Tomas Härdin]

fre 2023-07-28 klockan 02:49 +0100 skrev 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!

I would suggest using .kkapture: http://farbrausch.de/~fg/kkapture/

/Tomas