This is the VideoCaptureDevice implementation for windows.

media/video/capture/win/sink_input_pin_win.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/video/capture/win/sink_input_pin_win.h"
+
+// Avoid including strsafe.h via dshow as it will cause build warnings.
+#define NO_DSHOW_STRSAFE
+#include <dshow.h>
+
+#include "base/logging.h"
+
+namespace media {
+
+const REFERENCE_TIME kSecondsToReferenceTime = 10000000;
+
+SinkInputPin::SinkInputPin(IBaseFilter* filter,
+                           SinkFilterObserver* observer)
+    : observer_(observer),
+      PinBase(filter) {
+}
+
+SinkInputPin::~SinkInputPin() {}
+
+bool SinkInputPin::GetValidMediaType(int index, AM_MEDIA_TYPE* media_type) {
+  if (media_type->cbFormat < sizeof(VIDEOINFOHEADER))
+    return false;
+
+  VIDEOINFOHEADER* pvi =
+      reinterpret_cast<VIDEOINFOHEADER*>(media_type->pbFormat);
+
+  ZeroMemory(pvi, sizeof(VIDEOINFOHEADER));
+  pvi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
+  pvi->bmiHeader.biPlanes = 1;
+  pvi->bmiHeader.biClrImportant = 0;
+  pvi->bmiHeader.biClrUsed = 0;
+  if (requested_capability_.frame_rate > 0) {
+    pvi->AvgTimePerFrame = kSecondsToReferenceTime /
+                           requested_capability_.frame_rate;
+  }
+
+  media_type->majortype = MEDIATYPE_Video;
+  media_type->formattype = FORMAT_VideoInfo;
+  media_type->bTemporalCompression = FALSE;
+
+  switch (index) {
+    case 0: {
+      pvi->bmiHeader.biCompression = MAKEFOURCC('I', '4', '2', '0');
+      pvi->bmiHeader.biBitCount = 12;  // bit per pixel
+      pvi->bmiHeader.biWidth = requested_capability_.width;
+      pvi->bmiHeader.biHeight = requested_capability_.height;
+      pvi->bmiHeader.biSizeImage = 3 * requested_capability_.height *
+                                   requested_capability_.width / 2;
+      media_type->subtype = kMediaSubTypeI420;
+      break;
+    }
+    case 1: {
+      pvi->bmiHeader.biCompression = MAKEFOURCC('Y', 'U', 'Y', '2');
+      pvi->bmiHeader.biBitCount = 16;
+      pvi->bmiHeader.biWidth = requested_capability_.width;
+      pvi->bmiHeader.biHeight = requested_capability_.height;
+      pvi->bmiHeader.biSizeImage = 2 * requested_capability_.width *
+                                   requested_capability_.height;
+      media_type->subtype = MEDIASUBTYPE_YUY2;
+      break;
+    }
+    case 2: {
+      pvi->bmiHeader.biCompression = BI_RGB;
+      pvi->bmiHeader.biBitCount = 24;
+      pvi->bmiHeader.biWidth = requested_capability_.width;
+      pvi->bmiHeader.biHeight = requested_capability_.height;
+      pvi->bmiHeader.biSizeImage = 3 * requested_capability_.height *
+                                   requested_capability_.width;
+      media_type->subtype = MEDIASUBTYPE_RGB24;
+      break;
+    }
+    default:
+      return false;
+  }
+
+  media_type->bFixedSizeSamples = TRUE;
+  media_type->lSampleSize = pvi->bmiHeader.biSizeImage;
+  return true;
+}
+
+bool SinkInputPin::IsMediaTypeValid(const AM_MEDIA_TYPE* media_type) {
+  GUID type = media_type->majortype;
+  if (type != MEDIATYPE_Video)
+    return false;
+
+  GUID format_type = media_type->formattype;
+  if (format_type != FORMAT_VideoInfo)
+    return false;
+
+  // Check for the sub types we support.
+  GUID sub_type = media_type->subtype;
+  VIDEOINFOHEADER* pvi =
+      reinterpret_cast<VIDEOINFOHEADER*>(media_type->pbFormat);
+  if (pvi == NULL)
+    return false;
+
+  // Store the incoming width and height.
+  resulting_capability_.width = pvi->bmiHeader.biWidth;
+  resulting_capability_.height = abs(pvi->bmiHeader.biHeight);
+  if (pvi->AvgTimePerFrame > 0) {
+    resulting_capability_.frame_rate =
+        static_cast<int>(kSecondsToReferenceTime / pvi->AvgTimePerFrame);
+  } else {
+    resulting_capability_.frame_rate = requested_capability_.frame_rate;
+  }
+  if (sub_type == kMediaSubTypeI420 &&
+      pvi->bmiHeader.biCompression == MAKEFOURCC('I', '4', '2', '0')) {
+    resulting_capability_.color = VideoCaptureDevice::kI420;
+    return true;  // This format is acceptable.
+  }
+  if (sub_type == MEDIASUBTYPE_YUY2 &&
+      pvi->bmiHeader.biCompression == MAKEFOURCC('Y', 'U', 'Y', '2')) {
+    resulting_capability_.color = VideoCaptureDevice::kYUY2;
+    return true;  // This format is acceptable.
+  }
+  if (sub_type == MEDIASUBTYPE_RGB24 &&
+      pvi->bmiHeader.biCompression == BI_RGB) {
+    resulting_capability_.color = VideoCaptureDevice::kRGB24;
+    return true;  // This format is acceptable.
+  }
+  return false;
+}
+
+HRESULT SinkInputPin::Receive(IMediaSample* sample) {
+  const int length = sample->GetActualDataLength();
+  uint8* buffer = NULL;
+  if (FAILED(sample->GetPointer(&buffer)))
+    return S_FALSE;
+
+  observer_->FrameReceived(buffer, length);
+  return S_OK;
+}
+
+void SinkInputPin::SetRequestedMediaCapability(
+    const VideoCaptureDevice::Capability& capability) {
+  requested_capability_ = capability;
+  resulting_capability_ = VideoCaptureDevice::Capability();
+}
+
+const VideoCaptureDevice::Capability& SinkInputPin::ResultingCapability() {
+  return resulting_capability_;
+}
+
+}  // namespace media