不幸的是不可能:/

摘自 HTML 媒体捕获 - 安全和隐私注意事项:

此外，建议用户代理实现提供一个在启用输入设备时向用户指示并使其用户可以终止此类捕获.同样，用户建议代理提供用户控制，例如允许用户:

In addition, the User Agent implementation is advised to provide an indication to the user when an input device is enabled and make it possible for the user to terminate such capture. Similarly, the User Agent is advised to offer user control, such as to allow the user to:

• 选择要使用的确切媒体捕获设备(如果存在)
  多个相同类型的设备(例如，
  中的前置摄像头除了主摄像头).

• select the exact media capture device to be used if there exist
  multiple devices of the same type (e.g. a front-facing camera in
  addition to a primary camera).

在
中禁用声音捕捉视频拍摄模式.

disable sound capture when in the
video capture mode.