C++ 如何控制比特率MEDIASUBTYPE_H264 directshow？

我有一个

logitech c920

网络摄像头，它显示一个编码的

h264捕获pin

（子类型：

MEDIASUBTYPE\u h264

）

h264引脚支持以下分辨率：

FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 640x480 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 160x90 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 160x120 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 176x144 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 320x180 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 320x240 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 352x288 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 432x240 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 640x360 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 800x448 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 800x600 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 864x480 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 960x720 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 1024x576 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 1280x720 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 1600x896 @ 30 fps FORMAT_VideoInfo - subtype: MEDIASUBTYPE_H264 1920x1080 @ 30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 640x480@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 160x90@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 160x120@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 176x144@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 320x180@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE \u H264 320x240@30 fps 格式\视频信息-子类型：媒体子类型\ H264 352x288@30 fps 格式\视频信息-子类型：媒体子类型\ H264 432x240@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 640x360@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 800x448@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 800x600@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 864x480@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 960x720@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 1024x576@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 1280x720@30 fps 格式\视频信息-子类型：媒体子类型\ H264 1600x896@30 fps 格式\u VideoInfo-子类型：MEDIASUBTYPE\u H264 1920x1080@30 fps 在我的测试中，无论选择的分辨率如何，它总是使用3 Mbit。这有点太多了，尤其是对于较低的分辨率

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您知道如何使用directshow以编程方式选择所需的比特率吗？或者其他API

查询IAMStreamConfig接口的pin，通过GetStreamCaps（）获取此格式列表，选择所需的格式，它将包含指向包含dwBitRate字段的VIDEOINFO结构的指针pFormat。将此字段更改为所需的比特率，并使用此新数据调用IAMStreamConfig:：SetFormat。

根据Logitech支持回答，编码为80/20 HW/SW，并且比特率（和GOP）无法控制。然而，他们的捆绑软件显然做到了这一点。除此之外，经过一些限制后，比特率会降低，尽管它发生在非常低的分辨率/fps组合下：

Required bandwidth for size:  ( 1920 , 1080 )  @ 30  is 2.81771 Mbit 
Required bandwidth for size:  ( 1920 , 1080 )  @ 25  is 2.81672 Mbit 
Required bandwidth for size:  ( 1920 , 1080 )  @ 20  is 2.82701 Mbit 
Required bandwidth for size:  ( 1920 , 1080 )  @ 15  is 2.83327 Mbit 
Required bandwidth for size:  ( 1920 , 1080 )  @ 10  is 2.83594 Mbit 
Required bandwidth for size:  ( 1920 , 1080 )  @ 5  is 2.8431 Mbit 
Required bandwidth for size:  ( 1280 , 720 )  @ 30  is 2.82013 Mbit 
Required bandwidth for size:  ( 1280 , 720 )  @ 25  is 2.82436 Mbit 
Required bandwidth for size:  ( 1280 , 720 )  @ 20  is 2.83217 Mbit 
Required bandwidth for size:  ( 1280 , 720 )  @ 15  is 2.83696 Mbit 
Required bandwidth for size:  ( 1280 , 720 )  @ 10  is 2.83721 Mbit 
Required bandwidth for size:  ( 1280 , 720 )  @ 5  is 2.45272 Mbit 
Required bandwidth for size:  ( 864 , 480 )  @ 30  is 2.82089 Mbit 
Required bandwidth for size:  ( 864 , 480 )  @ 25  is 2.82313 Mbit 
Required bandwidth for size:  ( 864 , 480 )  @ 20  is 2.83131 Mbit 
Required bandwidth for size:  ( 864 , 480 )  @ 15  is 2.83343 Mbit 
Required bandwidth for size:  ( 864 , 480 )  @ 10  is 2.79526 Mbit 
Required bandwidth for size:  ( 864 , 480 )  @ 5  is 1.15564 Mbit 
Required bandwidth for size:  ( 320 , 180 )  @ 30  is 1.90123 Mbit 
Required bandwidth for size:  ( 320 , 180 )  @ 25  is 1.89367 Mbit 
Required bandwidth for size:  ( 320 , 180 )  @ 20  is 1.26006 Mbit 
Required bandwidth for size:  ( 320 , 180 )  @ 15  is 0.957935 Mbit 
Required bandwidth for size:  ( 320 , 180 )  @ 10  is 0.637158 Mbit 
Required bandwidth for size:  ( 320 , 180 )  @ 5  is 0.328456 Mbit

如果你提出了解决方案，请分享。谢谢