New helper class AdaptedVideoSource.

webrtc/media/base/adaptedvideosource.cc

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/media/base/adaptedvideosource.h"
+
+namespace rtc {
+
+AdaptedVideoSource::AdaptedVideoSource() : enable_video_adapter_(true) {}
+
+bool AdaptedVideoSource::AdaptFrame(int width,
+                                    int height,
+                                    int64_t camera_time_us,
+                                    int64_t system_time_us,
+                                    int* out_width,
+                                    int* out_height,
+                                    int* crop_width,
+                                    int* crop_height,
+                                    int* crop_x,
+                                    int* crop_y,
+                                    int64_t* translated_camera_time_us) {
+  int64_t offset_us =
+      translated_camera_time_us
+          ? timestamp_aligner_.UpdateOffset(camera_time_us, system_time_us)
+          : 0;
+
+  if (!frame_wanted()) {
+    return false;
+  }
+
+  if (enable_video_adapter_) {
+    if (!video_adapter_.AdaptFrameResolution(
+            width, height, camera_time_us * rtc::kNumNanosecsPerMicrosec,
+            crop_width, crop_height, out_width, out_height)) {
+      // VideoAdapter dropped the frame.
+      return false;
+    }
+    *crop_x = (width - *crop_width) / 2;
+    *crop_y = (height - *crop_height) / 2;
+  } else {
+    *out_width = width;
+    *out_height = height;
+    *crop_width = width;
+    *crop_height = height;
+    *crop_x = 0;
+    *crop_y = 0;
+  }
+
+  if (translated_camera_time_us) {
+    *translated_camera_time_us = timestamp_aligner_.ClipTimestamp(
+        camera_time_us + offset_us, system_time_us);
+  }
+  return true;
+}
+
+// TODO(nisse): OK to call OnResolutionRequest while holding
+// sinks_and_wants_lock_?
+void AdaptedVideoSource::UpdateWants() {
+  VideoBroadcaster::UpdateWants();
+  video_adapter_.OnResolutionRequest(current_wants_.max_pixel_count,
+                                     current_wants_.max_pixel_count_step_up);
+}
+
+}  // namespace rtc