通过 DirectShow 枚举可用的相机分辨率

Question

我正在尝试使用通过 COM 从 WPF 访问的 DirectShow 枚举 USB 摄像头的视频分辨率。我有以下测试代码。

var videoOutPin = this.BaseFilterObject.GetPin(PinDirection.Output, 0);

var streamConfig = (IAMStreamConfig)videoOutPin;

var piCount = 0;
var piSize = 0;

if (streamConfig.GetNumberOfCapabilities(ref piCount, ref piSize) != 0)
{
    return;
}

this.mediaTypes = new Collection<AMMediaType>();

var resolutions = new Collection<string>();

var ptr = Marshal.AllocCoTaskMem(piSize);

for (var i = 0; i < piCount; i++)
{
    var mediaType = new AMMediaType();
    if (streamConfig.GetStreamCaps(i, ref mediaType, ptr) != 0)
    {
        continue;
    }

    var header = (VideoInfoHeader)Marshal.PtrToStructure(mediaType.FormatPtr, typeof(VideoInfoHeader));

    var resolution = header.BmiHeader.BitCount + " bits : " + header.BmiHeader.Width + " * " + header.BmiHeader.Height;

    this.mediaTypes.Add(mediaType);
    resolutions.Add(resolution);
}

不过，我相信 mediaType 正在获得一些音频功能和视频功能。例如。每隔一次迭代都会给我一个 header.BmiHeader.Width 的 0 和一个 header.BmiHeader.BitCount 的 0.

首先，我是否认为这是使用 VideoInfoHeader 投射音频功能的结果？

如何只枚举视频功能并消除音频？

================================

编辑

我使用了 DirectShow Capture Capabilities 工具并获得了以下可疑功能：

能力：1

AM_MEDIA_TYPE:
- 数据：76 69 64 73 00 00 10 00 80 00 00 AA 00 38 9B 71 59 55 59 32 00 00 10 00 80 00 00 AA 00 38 9B 71 01 00 00 00 00 00 00 00 00 60 09 00 A0 76 2A F7 0A EB D0 11 AC E4 00 00 C0 CC 16 BA 00 00 00 00 70 00 00 00 40 07 B3 03
- 格式化数据：00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 CA 08 00 00 00 00 15 16 05 00 00 00 00 00 00 00 00 00 00 00 00 00 04 00 00 00 03 00 00 00 81 26 8D 00 00 00 00 00 28 00 00 00 80 02 00 00 E0 01 00 00 01 00 10 00 59 55 59 32 00 60 09 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
- .subtype: FourCC YUY2
- .bFixedSizeSamples: 1
- .bTemporalCompression: 0
- .lSampleSize: 614,400
- .cbFormat: 112
- VIDEOINFOHEADER2:
未知能力：
- 类型：{F72A76A0-EB0A-11D0-ACE4-0000C0CC16BA}
- 数据：A0 76 2A F7 0A EB D0 11 AC E4 00 00 C0 CC 16 BA 00 00 00 00 80 02 00 00 E0 01 00 00 80 02 00 00 E0 01 00 00 80 02 00 00 E0 01 00 00 01 00 00 00 01 00 00 00 01 00 00 00 01 00 00 00 80 02 00 00 E0 01 00 00 80 02 00 00 E0 01 00 00 01 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 15 16 05 00 00 00 00 00 15 16 05 00 00 00 00 00 00 00 CA 08 00 00 CA 08

这有意义吗？？？

================================

编辑 #2

遵循 Roman R. 的建议（如果我理解正确的话）。

我声明：-

private static readonly Guid VideoInfo =
        new Guid(0x05589F80, 0xC356, 0x11CE, 0xBF, 0x01, 0x00, 0xAA, 0x00, 0x55, 0x59, 0x5A);

然后修改代码如下：

 for (var i = 0; i < piCount; i++)
        {
            var mediaType = new AMMediaType();
            if (streamConfig.GetStreamCaps(i, ref mediaType, ptr) != 0)
            {
                continue;
            }

           if (mediaType.FormatType != VideoInfo)
            {
                continue;
            }

            Marshal.PtrToStructure(mediaType.FormatPtr, typeof(VideoInfoHeader));

            var header = (VideoInfoHeader)Marshal.PtrToStructure(mediaType.FormatPtr, typeof(VideoInfoHeader));

            var resolution = header.BmiHeader.BitCount + " bits : " + header.BmiHeader.Width + " * "
                             + header.BmiHeader.Height;

            this.mediaTypes.Add(mediaType);
            resolutions.Add(resolution);
        }

上述更改似乎有效，例如它正在我的测试相机上工作。这看起来正确吗？这段代码还有什么我应该担心的吗？？？

Answer 1

I believe that mediaType is picking up some audio capabilities as well as video. [...]

How would I enumerate only the video capabilities and eliminate audio?

尽管可能，视频和音频功能以及媒体类型在特定引脚上混合的可能性很小。也就是说，正确枚举它，您将只得到视频的，或者只得到音频的，具体取决于引脚。

您始终可以将枚举与 GraphEdit 显示的媒体类型进行比较，GraphStudioNext or DirectShowCaptureCapabilities。

通过 DirectShow 枚举可用的相机分辨率

Enumerating Available Camera Resolutions via DirectShow

wpf

directshow

编辑

编辑 #2