用媒体基金会在UVC摄像头上设置高分辨率曝光

发布于 2025-02-04 02:26:06 字数 1405 浏览 4 评论 0原文

我需要在本机C ++应用程序中以毫秒的分辨率设置媒体基础的UVC相机上的曝光。

通过MediaFoundation在UVC摄像机上设置暴露的标准方法似乎正在使用 iamcameracontrol 和 cameracontrol_ exposure 属性，使用这样的log2缩放：

ComPtr<IAMCameraControl> videoProc;

HRESULT hr = m_mediaSource.As(&videoProc);

long exposure_val = long(std::roundf(std::log2(exposure_ms/1000.0f)));

hr = videoProc->Set(CameraControl_Exposure, exposure_val, CameraControl_Flags_Manual);

根据MS Docs中的表，这会导致低端的设置非常粗糙，使得无法获得准确的曝光控制，哪个对于更高的帧速率尤其重要。

val | Exposure
 .  | .
-3  | 125ms
-4  | 63ms
-5  | 31ms
-6  | 16ms
-7  | 8ms
-8  | 4ms
-9  | 2ms
 .  | .

UVC标准（4.2.2.1.4曝光时间（绝对）控制）将曝光分辨率定义为100US步骤，由ct_exposure_time_absolute_control控制选择器设置。因此，从理论上讲，所有UVC 1.5兼容的摄像机都应能够在这种高分辨率下进行配置。

我已经浏览了所有mediafoundation文档，找不到以此解决方案而不是缩放方法来控制曝光的方法。因此，这似乎是MF本身的限制。怎么办？

在2020年提出了一个类似的问题，但从未得到正确的回答：

媒体基金会在毫秒

原文

I need to set the exposure on a UVC Camera with Media Foundation in a native C++ application with a resolution of milliseconds.

The standard method for setting exposure on a UVC camera via MediaFoundation appears to be using IAMCameraControl and the CameraControl_Exposure property, using a log2 scaling like this:

ComPtr<IAMCameraControl> videoProc;

HRESULT hr = m_mediaSource.As(&videoProc);

long exposure_val = long(std::roundf(std::log2(exposure_ms/1000.0f)));

hr = videoProc->Set(CameraControl_Exposure, exposure_val, CameraControl_Flags_Manual);

As per the table in the MS docs, this results in a very coarse range of settings in the low end, making it impossible to get accurate exposure control, which is especially important for higher frame rates.

val | Exposure
 .  | .
-3  | 125ms
-4  | 63ms
-5  | 31ms
-6  | 16ms
-7  | 8ms
-8  | 4ms
-9  | 2ms
 .  | .

The UVC standard (4.2.2.1.4 Exposure Time (Absolute) Control) defines the exposure resolution as 100us steps, set by the CT_EXPOSURE_TIME_ABSOLUTE_CONTROL control selector. So in theory, all UVC 1.5 compliant cameras should be capable of being configured at this high resolution of exposure.

I have looked through all the MediaFoundation documentation and cannot find a method for controlling the exposure at this resolution rather than the scaled method. So this seems to be a limitation of MF itself. How can it be done?

A similar question was asked in 2020 but was never properly answered: