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The purpose of ICameraRecordingProxy and ICameraRecordingProxyListener is to
allow applications using the camera during recording.
Camera service allows only one client at a time. Since camcorder application
needs to own the camera to do things like zoom, the media recorder cannot
access the camera directly during recording. So ICameraRecordingProxy is a proxy
of ICamera, which allows the media recorder to start/stop the recording and
release recording frames. ICameraRecordingProxyListener is an interface that
allows the recorder to receive video frames during recording.
ICameraRecordingProxy
startRecording()
stopRecording()
releaseRecordingFrame()
ICameraRecordingProxyListener
dataCallbackTimestamp()
The camcorder app opens the camera and starts the preview. The app passes
ICamera and ICameraRecordingProxy to the media recorder by
MediaRecorder::setCamera(). The recorder uses ICamera to setup the camera in
MediaRecorder::start(). After setup, the recorder disconnects from camera
service. The recorder calls ICameraRecordingProxy::startRecording() and
passes a ICameraRecordingProxyListener to the app. The app connects back to
camera service and starts the recording. The app owns the camera and can do
things like zoom. The media recorder receives the video frames from the
listener and releases them by ICameraRecordingProxy::releaseRecordingFrame.
The recorder calls ICameraRecordingProxy::stopRecording() to stop the
recording.
The call sequences are as follows:
1. The app: Camera.unlock().
2. The app: MediaRecorder.setCamera().
3. Start recording
(1) The app: MediaRecorder.start().
(2) The recorder: ICamera.unlock() and ICamera.disconnect().
(3) The recorder: ICameraRecordingProxy.startRecording().
(4) The app: ICamera.reconnect().
(5) The app: ICamera.startRecording().
4. During recording
(1) The recorder: receive frames from ICameraRecordingProxyListener.dataCallbackTimestamp()
(2) The recorder: release frames by ICameraRecordingProxy.releaseRecordingFrame().
5. Stop recording
(1) The app: MediaRecorder.stop()
(2) The recorder: ICameraRecordingProxy.stopRecording().
(3) The app: ICamera.stopRecording().
bug:2644213
Change-Id: I15269397defc25cbbcae16abc071c8349c123122
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