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

[Roger Pack]

Just enter it manually as you're doing I think it's a signed int.

On 3/2/18, Alex P <alex.p at avenview.com> wrote:
> 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.
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