Cockpit-cpp/ZjQt/webrtcinterop/video_frame_observer.h

#pragma once
#include "api/video/video_frame.h"
#include "api/video/video_sink_interface.h"
#include "callback.h"

using I420FrameReadyCallback = Callback<const void*,
	const void*,
	const void*,
	const void*,
	int,
	int,
	int,
	int,
	int,
	int>;
using ARGBFrameReadyCallback = Callback< 
	const uint8_t*,int,
	const uint8_t*,int, 
	const uint8_t*, int,
	const int,const int, 
	const int>;

//根据图像的高度和每行数据的字节数,计算出整个图像数据所需的总字节数
constexpr inline size_t ArgbDataSize(int height, int stride) 
{
	return static_cast<size_t>(height) * stride * 4;
}

/*
自定义的视频帧缓冲区管理类
*/
class ArgbBuffer : public webrtc::VideoFrameBuffer {
public:
	// Create a new buffer.
	/*
	静态方法用于创建一个新的 ArgbBuffer实例
	该方法接收视频帧的宽度和高度，并计算出所需的缓冲区大小
	返回类型是rtc::scoped_refptr<ArgbBuffer>,它是一个智能指针,用于管理 ArgbBuffer 的生命周期
	*/
	static inline rtc::scoped_refptr<ArgbBuffer> Create(int width, int height) {
		return new rtc::RefCountedObject<ArgbBuffer>(width, height, width * 4);
	}

	//// Create a new buffer and copy the pixel data.
	// static rtc::scoped_refptr<ArgbBuffer> Copy(const I010BufferInterface&
	// buffer);

	//// Convert and put I420 buffer into a new buffer.
	// static rtc::scoped_refptr<ArgbBuffer> Copy(const I420BufferInterface&
	// buffer);

	//// Return a rotated copy of |src|.
	// static rtc::scoped_refptr<ArgbBuffer> Rotate(const I010BufferInterface&
	// src,
	//                                             VideoRotation rotation);

	// VideoFrameBuffer implementation.

	inline Type type() const override { return VideoFrameBuffer::Type::kNative; }
	inline int width() const override { return width_; }
	inline int height() const override { return height_; }
	rtc::scoped_refptr<webrtc::I420BufferInterface> ToI420() override;

	inline uint8_t* Data() { return data_.get(); }
	inline const uint8_t* Data() const { return data_.get(); }
	inline int Stride() const { return stride_; }
	inline constexpr size_t Size() const {
		return ArgbDataSize(height_, stride_);
	}

protected:
	ArgbBuffer(int width, int height, int stride) ;
	~ArgbBuffer() override = default;

private:
	const int width_;
	const int height_;
	const int stride_;

	//指向视频数据的智能指针,使用 webrtc::AlignedFreeDeleter 来管理内存释放
	const std::unique_ptr<uint8_t, webrtc::AlignedFreeDeleter> data_;
};

/*
管理视频帧的接口类
*/
/// Video frame observer to get notified of newly available video frames.
class VideoFrameObserver : public rtc::VideoSinkInterface<webrtc::VideoFrame> {
public:
	/// Register a callback to get notified on frame available,
	/// and received that frame as a I420-encoded buffer.
	/// This is not exclusive and can be used along another ARGB callback.
	void SetCallback(I420FrameReadyCallback callback) ;

	/// Register a callback to get notified on frame available,
	/// and received that frame as a raw decoded ARGB buffer.
	/// This is not exclusive and can be used along another I420 callback.
	void SetCallback(ARGBFrameReadyCallback callback) ;

protected:
	//获取一个足够容纳指定大小图像数据的缓冲区（ArgbBuffer）,如果已有的缓冲区足够大，则直接返回;否则,创建一个新的缓冲区并返回
	ArgbBuffer* GetArgbScratchBuffer(int width, int height);

	// VideoSinkInterface interface
	void OnFrame(const webrtc::VideoFrame& frame)  override;

private:
	/// Registered callback for receiving I420-encoded frame.
	I420FrameReadyCallback i420_callback_;

	/// Registered callback for receiving raw decoded ARGB frame.
	ARGBFrameReadyCallback argb_callback_;

	/// Mutex protecting all callbacks.
	std::mutex mutex_;

	/// Reusable ARGB scratch buffer to avoid per-frame allocation.
	//定义一个名为argb_scratch_buffer_ 的ArgbBuffer类型的智能指针，指向ARGB暂存缓冲区
	rtc::scoped_refptr<ArgbBuffer> argb_scratch_buffer_;
};