why not working in 4K?

[stweily]

Why fps = 1 or2 only at 3840 * 2160 resolution? if 1920 * 1080 its nomal at 30 fps.

[secile]

I have never tested 4k camera.

The library is based on DirectShow which is legacy technology, so that could be the reason.
please refer the article below.
https://stackoverflow.com/questions/63393696/4k-mjpeg-camera-video-preview-with-delay-on-windows-10

The other possibility is a lack of transfer rate.
I'm not familiar with transfer rate or video codec, forgive me if I tell you wrong information.

What VideoFormat are you using? I assume that you are using YUY2 format with USB2.0 interface.

3840 x 2160 image has 8294400 pixels.
Single pixel is consist of RGB 24bit, so single frame is about 23MB with uncompressed.

Video is compressed with YUY2 which compression rate is 66%, single frame is about 15MB.

USB2.0 band width is 480Mbps in spec, but it actually may 240Mbps(=30MB).
Frame rate 1-2fps may be reasonable.

[stweily]

我从未测试过 4k 相机。

该库基于 DirectShow，这是传统技术，因此这可能就是原因。 请参考下面的文章。 https://stackoverflow.com/questions/63393696/4k-mjpeg-camera-video-preview-with-delay-on-windows-10

另一种可能性是传输速率不足。 我对传输速率或视频编解码器不熟悉，如果我告诉你错误的信息，请原谅我。

您使用什么视频格式？我假设您使用的是带有USB2.0接口的YUY2格式。

3840 x 2160 图像有 8294400 像素。 单个像素由RGB 24bit组成，因此单帧未压缩时约为23MB。

视频采用YUY2压缩，压缩率为66%，单帧约15MB。

USB2.0的带宽规格上是480Mbps，但实际上可能是240Mbps(=30MB)。 帧速率 1-2fps 可能比较合理。

but use AmCap its can 4K 30fps, use WPFMediaKit.Core (also directshow ) it 4K12 FPS!

[secile]

Oh, really?
Could you show me a dump of return value of UsbCamera.GetVideoFormat().

var formats = UsbCamera.GetVideoFormat(cameraIndex);

// select the format you want.
foreach (var item in formats) Console.WriteLine(item);

[stweily]

哦真的吗？ 你能给我看一下 UsbCamera.GetVideoFormat() 返回值的转储吗？

var formats = UsbCamera.GetVideoFormat(cameraIndex);

// select the format you want.
foreach (var item in formats) Console.WriteLine(item);

format.txt

[secile]

(1) which VideoFormat are you using? formats[2]? that is [Video], [MJPG], 3840,2160.
(2) formats[0] works fine in 30fps?

[stweily]

(1) which VideoFormat are you using? formats[2]? that is [Video], [MJPG], 3840,2160. (2) formats[0] works fine in 30fps?

this is amCAP
(1) I will use formats[2] and hope it work,
(2) formats[0] works fine in 24- 28 fps, its ok
this is our UsbCamera

[secile]

Hello.
It has been a long time since last posted.

I finally have HD camera and 4K camera.

• HD camera : Logitech C922 Pro Stream Webcam (connect with USB Type-A)
• 4K camera : Logitech MX BRIO 705 (connect with USB Type-C)

(1) Today, I modified UsbCamera.cs to show frame rate.
6295056

(2) and here are dumps of these 2 cameras. please refer these files. there is a fps column.
MX BRIO 705.txt
C922 Pro Stream Webcam.txt

Generally speaking, it works as expected for the fps value.

(3) for example, as to C922 Pro, there are 2 video formats that have {Width=1920, Height=1080} size as bellows.

32:[Video], [YUY2], {Width=1920, Height=1080}, 2000000, 5fps, [VideoInfo], Guid=05589f80-c356-11ce-bf01-00aa0055595a, VideoStandard=0, InputSize={1920, 1080}, MinCroppingSize={1920, 1080}, MaxCroppingSize={1920, 1080}, CropGranularityX=1, CropGranularityY=1, CropAlignX=1, CropAlignY=1, MinOutputSize={1920, 1080}, MaxOutputSize={1920, 1080}, OutputGranularityX=1, OutputGranularityY=1, StretchTapsX=0, StretchTapsY=0, ShrinkTapsX=0, ShrinkTapsY=0, MinFrameInterval=2000000, MaxFrameInterval=2000000, MinBitsPerSecond=165888000, MaxBitsPerSecond=165888000, 
70:[Video], [MJPG], {Width=1920, Height=1080}, 333333, 30fps, [VideoInfo], Guid=05589f80-c356-11ce-bf01-00aa0055595a, VideoStandard=0, InputSize={1920, 1080}, MinCroppingSize={1920, 1080}, MaxCroppingSize={1920, 1080}, CropGranularityX=1, CropGranularityY=1, CropAlignX=1, CropAlignY=1, MinOutputSize={1920, 1080}, MaxOutputSize={1920, 1080}, OutputGranularityX=1, OutputGranularityY=1, StretchTapsX=0, StretchTapsY=0, ShrinkTapsX=0, ShrinkTapsY=0, MinFrameInterval=333333, MaxFrameInterval=2000000, MinBitsPerSecond=165888000, MaxBitsPerSecond=995328000, 

[32] works 5fps, and [70] works 30 fps.
It seems that [MJPG] is able to high fps than [YUY2].

(4) as to MX BRIO 705, It can be more high fps. and that works 60fps.
I think this is because it connected via USB Type-C.

24:[Video], [YUY2], {Width=1920, Height=1080}, 166666, 60fps, [VideoInfo], Guid=05589f80-c356-11ce-bf01-00aa0055595a, VideoStandard=0, InputSize={1920, 1080}, MinCroppingSize={1920, 1080}, MaxCroppingSize={1920, 1080}, CropGranularityX=1, CropGranularityY=1, CropAlignX=1, CropAlignY=1, MinOutputSize={1920, 1080}, MaxOutputSize={1920, 1080}, OutputGranularityX=1, OutputGranularityY=1, StretchTapsX=0, StretchTapsY=0, ShrinkTapsX=0, ShrinkTapsY=0, MinFrameInterval=166666, MaxFrameInterval=2000000, MinBitsPerSecond=1990656000, MaxBitsPerSecond=1990656000, 

(5) my conclution. please check fps value and use VideoFormat that has fps more higher.