319 lines
13 KiB
C
319 lines
13 KiB
C
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/*
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* Copyright (c) 2010 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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// Declaration of abstract class VideoCapturer
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#ifndef WEBRTC_MEDIA_BASE_VIDEOCAPTURER_H_
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#define WEBRTC_MEDIA_BASE_VIDEOCAPTURER_H_
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#include <algorithm>
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#include <memory>
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#include <string>
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#include <vector>
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#include "webrtc/base/basictypes.h"
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#include "webrtc/base/constructormagic.h"
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#include "webrtc/base/criticalsection.h"
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#include "webrtc/media/base/videosourceinterface.h"
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#include "webrtc/base/sigslot.h"
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#include "webrtc/base/thread_checker.h"
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#include "webrtc/media/base/videoadapter.h"
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#include "webrtc/media/base/videobroadcaster.h"
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#include "webrtc/media/base/videocommon.h"
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#include "webrtc/media/base/videoframefactory.h"
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namespace cricket {
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// Current state of the capturer.
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enum CaptureState {
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CS_STOPPED, // The capturer has been stopped or hasn't started yet.
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CS_STARTING, // The capturer is in the process of starting. Note, it may
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// still fail to start.
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CS_RUNNING, // The capturer has been started successfully and is now
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// capturing.
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CS_FAILED, // The capturer failed to start.
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};
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class VideoFrame;
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struct CapturedFrame {
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static const uint32_t kFrameHeaderSize = 40; // Size from width to data_size.
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static const uint32_t kUnknownDataSize = 0xFFFFFFFF;
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CapturedFrame();
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// Get the number of bytes of the frame data. If data_size is known, return
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// it directly. Otherwise, calculate the size based on width, height, and
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// fourcc. Return true if succeeded.
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bool GetDataSize(uint32_t* size) const;
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// The width and height of the captured frame could be different from those
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// of VideoFormat. Once the first frame is captured, the width, height,
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// fourcc, pixel_width, and pixel_height should keep the same over frames.
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int width; // in number of pixels
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int height; // in number of pixels
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uint32_t fourcc; // compression
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uint32_t pixel_width; // width of a pixel, default is 1
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uint32_t pixel_height; // height of a pixel, default is 1
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int64_t time_stamp; // timestamp of when the frame was captured, in unix
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// time with nanosecond units.
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uint32_t data_size; // number of bytes of the frame data
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webrtc::VideoRotation rotation; // rotation in degrees of the frame.
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void* data; // pointer to the frame data. This object allocates the
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// memory or points to an existing memory.
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private:
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RTC_DISALLOW_COPY_AND_ASSIGN(CapturedFrame);
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};
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// VideoCapturer is an abstract class that defines the interfaces for video
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// capturing. The subclasses implement the video capturer for various types of
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// capturers and various platforms.
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//
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// The captured frames may need to be adapted (for example, cropping).
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// Video adaptation is built into and enabled by default. After a frame has
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// been captured from the device, it is sent to the video adapter, then out to
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// the sinks.
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//
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// Programming model:
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// Create an object of a subclass of VideoCapturer
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// Initialize
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// SignalStateChange.connect()
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// AddOrUpdateSink()
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// Find the capture format for Start() by either calling GetSupportedFormats()
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// and selecting one of the supported or calling GetBestCaptureFormat().
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// video_adapter()->OnOutputFormatRequest(desired_encoding_format)
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// Start()
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// GetCaptureFormat() optionally
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// Stop()
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//
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// Assumption:
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// The Start() and Stop() methods are called by a single thread (E.g., the
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// media engine thread). Hence, the VideoCapture subclasses dont need to be
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// thread safe.
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//
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class VideoCapturer : public sigslot::has_slots<>,
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public rtc::VideoSourceInterface<cricket::VideoFrame> {
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public:
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VideoCapturer();
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virtual ~VideoCapturer() {}
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// Gets the id of the underlying device, which is available after the capturer
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// is initialized. Can be used to determine if two capturers reference the
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// same device.
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const std::string& GetId() const { return id_; }
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// Get the capture formats supported by the video capturer. The supported
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// formats are non empty after the device has been opened successfully.
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const std::vector<VideoFormat>* GetSupportedFormats() const;
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// Get the best capture format for the desired format. The best format is the
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// same as one of the supported formats except that the frame interval may be
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// different. If the application asks for 16x9 and the camera does not support
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// 16x9 HD or the application asks for 16x10, we find the closest 4x3 and then
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// crop; Otherwise, we find what the application asks for. Note that we assume
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// that for HD, the desired format is always 16x9. The subclasses can override
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// the default implementation.
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// Parameters
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// desired: the input desired format. If desired.fourcc is not kAnyFourcc,
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// the best capture format has the exactly same fourcc. Otherwise,
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// the best capture format uses a fourcc in GetPreferredFourccs().
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// best_format: the output of the best capture format.
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// Return false if there is no such a best format, that is, the desired format
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// is not supported.
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virtual bool GetBestCaptureFormat(const VideoFormat& desired,
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VideoFormat* best_format);
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// TODO(hellner): deprecate (make private) the Start API in favor of this one.
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// Also remove CS_STARTING as it is implied by the return
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// value of StartCapturing().
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bool StartCapturing(const VideoFormat& capture_format);
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// Start the video capturer with the specified capture format.
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// Parameter
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// capture_format: The caller got this parameter by either calling
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// GetSupportedFormats() and selecting one of the supported
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// or calling GetBestCaptureFormat().
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// Return
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// CS_STARTING: The capturer is trying to start. Success or failure will
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// be notified via the |SignalStateChange| callback.
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// CS_RUNNING: if the capturer is started and capturing.
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// CS_FAILED: if the capturer failes to start..
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// CS_NO_DEVICE: if the capturer has no device and fails to start.
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virtual CaptureState Start(const VideoFormat& capture_format) = 0;
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// Get the current capture format, which is set by the Start() call.
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// Note that the width and height of the captured frames may differ from the
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// capture format. For example, the capture format is HD but the captured
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// frames may be smaller than HD.
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const VideoFormat* GetCaptureFormat() const {
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return capture_format_.get();
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}
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// Stop the video capturer.
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virtual void Stop() = 0;
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// Check if the video capturer is running.
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virtual bool IsRunning() = 0;
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CaptureState capture_state() const {
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return capture_state_;
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}
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virtual bool apply_rotation() { return apply_rotation_; }
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// Returns true if the capturer is screencasting. This can be used to
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// implement screencast specific behavior.
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virtual bool IsScreencast() const = 0;
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// Caps the VideoCapturer's format according to max_format. It can e.g. be
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// used to prevent cameras from capturing at a resolution or framerate that
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// the capturer is capable of but not performing satisfactorily at.
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// The capping is an upper bound for each component of the capturing format.
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// The fourcc component is ignored.
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void ConstrainSupportedFormats(const VideoFormat& max_format);
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void set_enable_camera_list(bool enable_camera_list) {
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enable_camera_list_ = enable_camera_list;
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}
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bool enable_camera_list() {
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return enable_camera_list_;
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}
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// Signal all capture state changes that are not a direct result of calling
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// Start().
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sigslot::signal2<VideoCapturer*, CaptureState> SignalStateChange;
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// Frame callbacks are multithreaded to allow disconnect and connect to be
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// called concurrently. It also ensures that it is safe to call disconnect
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// at any time which is needed since the signal may be called from an
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// unmarshalled thread owned by the VideoCapturer.
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// Signal the captured frame to downstream.
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sigslot::signal2<VideoCapturer*, const CapturedFrame*,
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sigslot::multi_threaded_local> SignalFrameCaptured;
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// If true, run video adaptation. By default, video adaptation is enabled
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// and users must call video_adapter()->OnOutputFormatRequest()
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// to receive frames.
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bool enable_video_adapter() const { return enable_video_adapter_; }
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void set_enable_video_adapter(bool enable_video_adapter) {
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enable_video_adapter_ = enable_video_adapter;
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}
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// Takes ownership.
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void set_frame_factory(VideoFrameFactory* frame_factory);
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bool GetInputSize(int* width, int* height);
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// Implements VideoSourceInterface
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void AddOrUpdateSink(rtc::VideoSinkInterface<cricket::VideoFrame>* sink,
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const rtc::VideoSinkWants& wants) override;
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void RemoveSink(rtc::VideoSinkInterface<cricket::VideoFrame>* sink) override;
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protected:
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// OnSinkWantsChanged can be overridden to change the default behavior
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// when a sink changes its VideoSinkWants by calling AddOrUpdateSink.
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virtual void OnSinkWantsChanged(const rtc::VideoSinkWants& wants);
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// Reports the appropriate frame size after adaptation. Returns true
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// if a frame is wanted. Returns false if there are no interested
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// sinks, or if the VideoAdapter decides to drop the frame.
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bool AdaptFrame(int width,
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int height,
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int64_t capture_time_ns,
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int* out_width,
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int* out_height,
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int* crop_width,
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int* crop_height,
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int* crop_x,
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int* crop_y);
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// Callback attached to SignalFrameCaptured where SignalVideoFrames is called.
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void OnFrameCaptured(VideoCapturer* video_capturer,
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const CapturedFrame* captured_frame);
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// Called when a frame has been captured and converted to a
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// VideoFrame. OnFrame can be called directly by an implementation
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// that does not use SignalFrameCaptured or OnFrameCaptured. The
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// orig_width and orig_height are used only to produce stats.
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void OnFrame(const VideoFrame& frame, int orig_width, int orig_height);
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VideoAdapter* video_adapter() { return &video_adapter_; }
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void SetCaptureState(CaptureState state);
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// subclasses override this virtual method to provide a vector of fourccs, in
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// order of preference, that are expected by the media engine.
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virtual bool GetPreferredFourccs(std::vector<uint32_t>* fourccs) = 0;
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// mutators to set private attributes
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void SetId(const std::string& id) {
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id_ = id;
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}
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void SetCaptureFormat(const VideoFormat* format) {
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capture_format_.reset(format ? new VideoFormat(*format) : NULL);
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}
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void SetSupportedFormats(const std::vector<VideoFormat>& formats);
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VideoFrameFactory* frame_factory() { return frame_factory_.get(); }
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private:
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void Construct();
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// Get the distance between the desired format and the supported format.
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// Return the max distance if they mismatch. See the implementation for
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// details.
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int64_t GetFormatDistance(const VideoFormat& desired,
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const VideoFormat& supported);
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// Convert captured frame to readable string for LOG messages.
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std::string ToString(const CapturedFrame* frame) const;
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// Updates filtered_supported_formats_ so that it contains the formats in
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// supported_formats_ that fulfill all applied restrictions.
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void UpdateFilteredSupportedFormats();
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// Returns true if format doesn't fulfill all applied restrictions.
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bool ShouldFilterFormat(const VideoFormat& format) const;
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void UpdateInputSize(int width, int height);
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rtc::ThreadChecker thread_checker_;
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std::string id_;
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CaptureState capture_state_;
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std::unique_ptr<VideoFrameFactory> frame_factory_;
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std::unique_ptr<VideoFormat> capture_format_;
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std::vector<VideoFormat> supported_formats_;
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std::unique_ptr<VideoFormat> max_format_;
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std::vector<VideoFormat> filtered_supported_formats_;
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bool enable_camera_list_;
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int scaled_width_; // Current output size from ComputeScale.
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int scaled_height_;
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rtc::VideoBroadcaster broadcaster_;
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bool enable_video_adapter_;
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VideoAdapter video_adapter_;
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rtc::CriticalSection frame_stats_crit_;
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// The captured frame size before potential adapation.
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bool input_size_valid_ GUARDED_BY(frame_stats_crit_) = false;
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int input_width_ GUARDED_BY(frame_stats_crit_);
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int input_height_ GUARDED_BY(frame_stats_crit_);
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// Whether capturer should apply rotation to the frame before signaling it.
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bool apply_rotation_;
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RTC_DISALLOW_COPY_AND_ASSIGN(VideoCapturer);
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};
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} // namespace cricket
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#endif // WEBRTC_MEDIA_BASE_VIDEOCAPTURER_H_
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