c++ ffmpeg如何获取RTP包中的Seq和timestamp

Posted 2023-05-13

在c++程序中，使用ffmpeg拉取rtsp视频流时，如何能获取到网络传输的原始RTP包，我需要取得包中的sequence number和timestamp这两个值。

参考技术A avformat_open_input这些代码打开文件
然后av_read_frame不停的读文件内容
然后decode，然后encode。然后avio_open打开输出文件，然后不停的将encode结果av_interleaved_write_frame到文件里。追问

答非所问，回答前可否先看看提问内容呢？我问的是如何获取网络传输的RTP包中的sequence number和timestamp这两个值。你却回答视频文件转码另存其他文件

参考技术B 请问楼主现在解决了吗，是怎么解决的呢

c++ h264RTP接收和发送程序

目的

制作最为简单的h264rtp接收，掌握h264解码和RTP接收

2 基本架构

2.1 libRtpReceive 静态库

静态库包含decode 解码程序，drawpkt 渲染画面，drawrgb24 画面， ffmpeg封装， h264frame 解封包，udp服务程序， 而LiveRtpDecode则是界面接收显示，负责渲染，liveRTPEncoder是发送界面。

2.2 libRtpDecode 可执行程序

拉一个界面负责显示用

开始和结束接收数据线程，udp端口6666

void CDrawHwndDlg::OnBnClickedButton1()

	DP0("start to receive");
	HWND hwnd = this->GetDlgItem(IDC_PIC0)->GetSafeHwnd();
	v_draw_server.StartServer(hwnd,6666);
	//server1.StartReceive(9200,hwnd);



void CDrawHwndDlg::OnBnClickedButton2()

	v_draw_server.StopServer();

class c_drawpkt:public c_thread

public:
	c_drawpkt(void);
	~c_drawpkt(void);

	void Run();
	void StartServer(HWND hWnd,unsigned short port);
	void StopServer();

private:

	AVFrame * _pFrameRGB;
	uint8_t * _RGBBuffer;
	struct SwsContext *_img_convert_ctx;
	HWND _hWnd0;
//	HWND _hWnd1;
	c_drawrgb24 _Draw;
	H264DecoderContext _decoder;

	c_udp v_udpserver;
	//frame 
	int _fps;
;

以下为cpp文件

#include "common.h"
#include "c_drawpkt.h"
#include <thread>

c_drawpkt::c_drawpkt(void)

	_RGBBuffer = NULL;
	_pFrameRGB = NULL;
	_hWnd0 = NULL;
	_fps = 10;



c_drawpkt::~c_drawpkt(void)




void c_drawpkt::StartServer(HWND hWnd, unsigned short port)

	_hWnd0 = hWnd;
	if(!_decoder.Initialize())
	
		return ;
	
	v_udpserver.StartReceive(port,&_decoder);
	Start();

void c_drawpkt::StopServer()

	//1 stop the draw thread 
	Stop();
	Join();

	//2 stop udp server
	v_udpserver.StopServer();
	//3 delete all the memory
	memory_cache * mc = v_udpserver.GetBufferToDecode();
	while(mc!=NULL)
	
		delete []mc->buf;
		delete mc;
		mc = v_udpserver.GetBufferToDecode();
	

void c_drawpkt::Run()

	//第一次解码时间
	//int64_t firstDecodeTime = 0;
	//int TickCountStart = 0;
	//画帧计数
	unsigned int FrameCount = 1;
	//int fpsTick = 1000/_fps;
	//int b =10;
	int first_keyframe = 0;
	while(!IsStop())
	

		//WaitForSignal();
		memory_cache * mc = v_udpserver.GetBufferToDecode();
		if(mc == NULL)
		
			std::this_thread::sleep_for(std::chrono::milliseconds(20));
		
		else
		
			AVFrame * frame = _decoder.DecodeFrames_2((const u_char*)mc->buf, mc->size);

			if (frame != NULL)
			

				int dw = _decoder.GetContext()->width;
				int dh = _decoder.GetContext()->height;//_pDecode->GetContext()->height;

				if (dw > 0 && dh > 0)
				
					if (_RGBBuffer == NULL)
					
						int numBytes = av_image_get_buffer_size(AV_PIX_FMT_BGR24, dw, dh, 1);

						_RGBBuffer = (uint8_t *)av_malloc(numBytes * sizeof(uint8_t));

						if (_pFrameRGB == NULL)
							_pFrameRGB = av_frame_alloc();
						av_image_fill_arrays(_pFrameRGB->data, _pFrameRGB->linesize, _RGBBuffer
							, AV_PIX_FMT_BGR24, dw, dh, 1);

						_img_convert_ctx = sws_getContext(dw, dh,
							_decoder.GetContext()->pix_fmt,//PIX_FMT_YUV420P, 
							dw,
							dh,
							AV_PIX_FMT_BGR24,
							SWS_BICUBIC,
							NULL,
							NULL,
							NULL);
					

					sws_scale(_img_convert_ctx, frame->data, frame->linesize, 0, dh, _pFrameRGB->data, _pFrameRGB->linesize);

					if (_hWnd0 != NULL)
						_Draw.Draw2(_hWnd0, NULL, _RGBBuffer, dw, dh);

					FrameCount++;
				
			
			delete[]mc->buf;
			delete mc;
		
	

2.3 liveRTPEncoder 测试发送程序

拉一个界面负责发送，找到视频设备和音频设备，分辨率默认，慢慢改进

程序会开源，关注后期会发送源码地址，此篇文章会修改