前言

代码分析

h:\webrtc-20210315\webrtc-20210315\webrtc\webrtc-checkout\src\modules\video_capture\windows\video_capture_ds.cc

VideoCaptureDS::Init

int32_t VideoCaptureDS::Init(const char* deviceUniqueIdUTF8) {
****
  // Create the sink filte used for receiving Captured frames.
  sink_filter_ = new ComRefCount<CaptureSinkFilter>(this);
  hr = _graphBuilder->AddFilter(sink_filter_, SINK_FILTER_NAME);
  if (FAILED(hr)) {
    RTC_LOG(LS_INFO) << "Failed to add the send filter to the graph.";
    return -1;
  }
***
***
}

—》 sinkfilter = new ComRefCount(this);

CaptureSinkFilter::CaptureSinkFilter

CaptureSinkFilter::CaptureSinkFilter(VideoCaptureImpl* capture_observer)
    : input_pin_(new ComRefCount<CaptureInputPin>(this)),
      capture_observer_(capture_observer) {}

CaptureSinkFilter获取数据后，就可以调用captureobserver的函数传递了。
—》

CaptureInputPin::CaptureInputPin(CaptureSinkFilter* filter) {
  capture_checker_.Detach();
  // No reference held to avoid circular references.
  info_.pFilter = filter;
  info_.dir = PINDIR_INPUT;
}