[FFmpeg-user] 4K 60Hz Directshow Video Capture

[Alex P]

Thank you for that suggestion Roger, I can't believe I forgot about the preset options.

Executing the following on a RAM disk gets me about .9x performance, letting me capture about 5 seconds worth of video before the buffers overflow and I lose frames. Not perfect but enough for what I need. I think this is the best I'm going to get unless the mfg makes a better driver and adds yuv444p support or I get a better CPU. I really appreciate for everyone's input. 

ffmpeg -f dshow -video_size 3840x2160 -framerate 60000/1001 -rtbufsize 210000000  -pixel_format bgr24 -i video="MZ0380 PCI, Analog 01 Capture" -c:v libx264rgb -preset ultrafast -crf 0 -pix_fmt bgr24 -t 00:00:10 -r 60000/1001 out.avi

One more question, what is the command to use the maximum buffer size? -rtbufsize INT_MAX doesn't work. Thanks.

-----Original Message-----
From: ffmpeg-user [mailto:ffmpeg-user-bounces at ffmpeg.org] On Behalf Of Roger Pack
Sent: Tuesday, February 27, 2018 8:03 PM
To: FFmpeg user questions
Subject: Re: [FFmpeg-user] 4K 60Hz Directshow Video Capture

consider also libx264 "ultrafast" preset, GL!

On Tue, Feb 13, 2018 at 7:57 AM, Alex P <alex.p at avenview.com> wrote:

> I think I've figured it out. When I use nv12 or yuv420p as the input 
> and output pixel format, I get x1 performance. If I use bgr24/rgb24 as 
> the input and yuv444p as the output, I get around x0.3.
>
> But even when I use bgr0 for the input and output, I get less than x1.
> Does anyone know what exactly bgr0 is? I can't find any information 
> about it in my googling.
>
> In your testing James, what was the pixel format?
>
> -----Original Message-----
> From: ffmpeg-user [mailto:ffmpeg-user-bounces at ffmpeg.org] On Behalf Of 
> James Girotti
> Sent: Monday, February 12, 2018 7:03 PM
> To: FFmpeg user questions
> Subject: Re: [FFmpeg-user] 4K 60Hz Directshow Video Capture
>
> >
> > ffmpeg -f dshow -video_size 3840x2160 -framerate 60000/1001 
> > -rtbufsize
> > 2100000000 -pixel_format bgr24 -i video="MZ0380 PCI, Analog 01 Capture"
> > -c:v h264_nvenc -preset lossless -f null - Gives me the same error
> >
>
> That's surprising, I can get about 200fps using file-based/ramdisk 
> "-c:v h264_nvenc -preset -lossless". Have you also tried "-c:v 
> hevc_nvenc -preset lossless"? What's the encoding FPS that you're 
> getting? You technically shouldn't be able get much more than 60fps as 
> that's what your capture card is supplying. Can you monitor the "Video 
> Engine Utilization" during encoding? In linux it's listed in the 
> nvidia-settings GUI or "nvidia-smi dmon" on the CLI will show enc/dec%.
>
>
> > ffmpeg -f dshow -video_size 3840x2160 -framerate 60000/1001 
> > -rtbufsize
> > 2100000000 -pixel_format bgr24 -i video="MZ0380 PCI, Analog 01 Capture"
> > -c:v rawvideo -f null -
> > Gets me nearly x1 performance when executing from a ram disk but
> >
> > ffmpeg -f dshow -video_size 3840x2160 -framerate 60000/1001 
> > -rtbufsize
> > 2100000000 -pixel_format bgr24 -i video="MZ0380 PCI, Analog 01 Capture"
> > -c:v rawvideo raw.nut
> > Only gets me x0.5 and the buffer overflows.
>
>
> > Is there a way of accelerating rawvideo decoding? Would using my 
> > colleagues 1080 make a difference? Thanks.
>
>
> I think raw-video is already decoded. So no way/need to accelerate that.
> You might try a different pix_fmt from your capture card while using 
> hw-encoding, but you'd have to test. I don't know the internals, i.e. 
> when the pixel format is converted during hw-encoding. So it might 
> make a difference.
>
> Changing pixel formats might be a concern if you are trying to achieve 
> "100% lossless" capture. I've read that yuv444p should be sufficient 
> colorspace for bgr24.
>
> There isn't a lot of info out there on encoding speed differences 
> based on GPU models. It's a complex subject, but from what I have 
> observed the ASIC is tied to the GPU clock (I have observed that GPU 
> clock speed increases as ASIC load increases). If that's true, then a 
> GTX 1080, with it's higher max clock, could have faster encoding, but I have no data to back that up only.
> _______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>
> To unsubscribe, visit link above, or email 
> ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".
>
> _______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>
> To unsubscribe, visit link above, or email 
> ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".
>
_______________________________________________
ffmpeg-user mailing list
ffmpeg-user at ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".