ffmpeg4.4 学习笔记 -（2）读取视频文件并用SDL 显示

使用SDL 2.0.20 Simple DirectMedia Layer - SDL version 2.0.20 (stable)https://www.libsdl.org/release/SDL2-devel-2.0.20-VC.zip

参考文章：

ffmpeg tutorial

学习文章的同时基于ffmpeg 4.4 和 sdl 2.0 做同样功能的mfc demo。

可以先参考：CSDN

在制作播放器时，我们将使用 SDL 来输出媒体文件的音频和视频。 SDL 是一个出色的跨平台多媒体库，可用于 MPEG 播放软件、模拟器和许多视频游戏。您需要为您的系统下载并安装 SDL 开发库，以便编译本教程中的程序。

所以我们目前的计划是替换教程 1 中的 Saveframe() 函数，而是将我们的帧输出到屏幕上。但首先我们必须先了解如何使用 SDL 库。首先，我们必须包含库并初始化 SDL：

参考SDL2源代码分析1：初始化（SDL_Init()）_雷霄骅(leixiaohua1020)的专栏-CSDN博客_sdl_init

使用SDL 播放一个视频代码流程大体如下：

初始化：

1. SDL_Init() 初始化SDL

2. SDL_CreateWindow(): 创建窗口

3. SDL_CreateRenderer() 基于窗口创建渲染器

4. SDL_CreateTexture() 创建纹理

循环渲染数据

SDL_UpdateTexture 设置纹理的数据

SDL_RenderCopy 纹理复制给渲染器

SDL_RenderPresent 显示

// MFCAudioResampleDlg.cpp: 实现文件
//

#include "pch.h"
#include "framework.h"
#include "MFCAudioResample.h"
#include "MFCAudioResampleDlg.h"
#include "afxdialogex.h"
#include 
#include 

//Refresh Event
#define REFRESH_EVENT  (SDL_USEREVENT + 1)

#define BREAK_EVENT  (SDL_USEREVENT + 2)


std::string GetFFmpegErorString(int errnum)
{
	static CHAR g_av_error[AV_ERROR_MAX_STRING_SIZE] = { 0 };
	return std::string(av_make_error_string(g_av_error, AV_ERROR_MAX_STRING_SIZE, errnum));
}

void msgBoxFFmpegError(int errnum)
{
	::MessageBoxA(0, 0, GetFFmpegErorString(errnum).c_str(), 0);
}

std::wstring GetoneFile(BOOL bOpen = TRUE)
{
	CString FilePathName;
	CFileDialog dlg(bOpen, NULL, NULL, NULL, NULL);//TRUE为OPEN对话框，FALSE为SAVE AS对话框 
	if (dlg.DoModal() == IDOK) {
		//清空
		FilePathName = dlg.GetPathName();
	}

	return std::wstring(FilePathName.GetBuffer());
}

#ifdef _DEBUG
#define new DEBUG_NEW
#endif

// 用于应用程序“关于”菜单项的 CaboutDlg 对话框

class CaboutDlg : public CDialogEx
{
public:
	CaboutDlg();

// 对话框数据
#ifdef AFX_DESIGN_TIME
	enum { IDD = IDD_aboutBOX };
#endif

	protected:
	virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV 支持

// 实现
protected:
	DECLARE_MESSAGE_MAP()
};

CaboutDlg::CaboutDlg() : CDialogEx(IDD_aboutBOX)
{
}

void CaboutDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialogEx::DoDataExchange(pDX);
}

BEGIN_MESSAGE_MAP(CaboutDlg, CDialogEx)
END_MESSAGE_MAP()


// CMFCAudioResampleDlg 对话框



CMFCAudioResampleDlg::CMFCAudioResampleDlg(CWnd* pParent )
	: CDialogEx(IDD_MFCAUDIORESAMPLE_DIALOG, pParent)
{
	m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINframe);
}

void CMFCAudioResampleDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialogEx::DoDataExchange(pDX);
	DDX_Control(pDX, IDC_EDIT_INPUT_FILE, m_targetFilePath);
}

BEGIN_MESSAGE_MAP(CMFCAudioResampleDlg, CDialogEx)
	ON_WM_SYSCOMMAND()
	ON_WM_PAINT()
	ON_WM_QUERYDRAGICON()
	ON_BN_CLICKED(IDC_BUTTON_CHOOSE_FILE, &CMFCAudioResampleDlg::OnBnClickedButtonChooseFile)
END_MESSAGE_MAP()


// CMFCAudioResampleDlg 消息处理程序

BOOL CMFCAudioResampleDlg::onInitDialog()
{
	CDialogEx::onInitDialog();

	// 将“关于...”菜单项添加到系统菜单中。

	// IDM_aboutBOX 必须在系统命令范围内。
	ASSERT((IDM_aboutBOX & 0xFFF0) == IDM_aboutBOX);
	ASSERT(IDM_aboutBOX < 0xF000);

	CMenu* pSysMenu = GetSystemMenu(FALSE);
	if (pSysMenu != nullptr)
	{
		BOOL bNamevalid;
		CString straboutMenu;
		bNamevalid = straboutMenu.LoadString(IDS_aboutBOX);
		ASSERT(bNamevalid);
		if (!straboutMenu.IsEmpty())
		{
			pSysMenu->AppendMenu(MF_SEPARATOR);
			pSysMenu->AppendMenu(MF_STRING, IDM_aboutBOX, straboutMenu);
		}
	}

	// 设置此对话框的图标。  当应用程序主窗口不是对话框时，框架将自动
	//  执行此操作
	SetIcon(m_hIcon, TRUE);			// 设置大图标
	SetIcon(m_hIcon, FALSE);		// 设置小图标

	// TODO: 在此添加额外的初始化代码

	return TRUE;  // 除非将焦点设置到控件，否则返回 TRUE
}

void CMFCAudioResampleDlg::onSysCommand(UINT nID, LPARAM lParam)
{
	if ((nID & 0xFFF0) == IDM_aboutBOX)
	{
		CaboutDlg dlgabout;
		dlgabout.DoModal();
	}
	else
	{
		CDialogEx::onSysCommand(nID, lParam);
	}
}

// 如果向对话框添加最小化按钮，则需要下面的代码
//  来绘制该图标。  对于使用文档/视图模型的 MFC 应用程序，
//  这将由框架自动完成。

void CMFCAudioResampleDlg::onPaint()
{
	if (IsIconic())
	{
		CPaintDC dc(this); // 用于绘制的设备上下文

		SendMessage(WM_ICONERASEBKGND, reinterpret_cast(dc.GetSafeHdc()), 0);

		// 使图标在工作区矩形中居中
		int cxIcon = GetSystemMetrics(SM_CXICON);
		int cyIcon = GetSystemMetrics(SM_CYICON);
		CRect rect;
		GetClientRect(&rect);
		int x = (rect.Width() - cxIcon + 1) / 2;
		int y = (rect.Height() - cyIcon + 1) / 2;

		// 绘制图标
		dc.DrawIcon(x, y, m_hIcon);
	}
	else
	{
		CDialogEx::onPaint();
	}
}

//当用户拖动最小化窗口时系统调用此函数取得光标
//显示。
HCURSOR CMFCAudioResampleDlg::onQueryDragIcon()
{
	return static_cast(m_hIcon);

}
void CMFCAudioResampleDlg::Saveframe(AVframe* pframe, int width, int height, int iframe)
{
	m_frame = pframe;
	SDL_Event event;
	event.type = REFRESH_EVENT;
	SDL_PushEvent(&event);

}

void CMFCAudioResampleDlg::onBnClickedButtonChooseFile()
{

	if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER)) {
		assert(false);
	}


	// TODO: 在此添加控件通知处理程序代码
	auto target = GetoneFile();
	m_targetFilePath.SetWindowTextW(target.c_str());
	UpdateData(TRUE);

	CString strTargetWindowText;
	m_targetFilePath.GetWindowTextW(strTargetWindowText);

	AVFormatContext* avFormatContext = avformat_alloc_context();
	USES_CONVERSION;
	if (!PathFileExists(strTargetWindowText.GetBuffer())) {
		return;
	}
	auto result = avformat_open_input(&avFormatContext, W2A((strTargetWindowText.GetBuffer())), nullptr, nullptr);
	if (result < 0) {
		assert(false);

	}

	result = avformat_find_stream_info(avFormatContext, NULL);
	if (result < 0)
	{
		assert(false);
	}

	av_dump_format(avFormatContext, 0, NULL, 0);

	// Find the first video stream
	int videoStream = -1;
	for (int i = 0; i < avFormatContext->nb_streams; i++)
		if (avFormatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
			videoStream = i;
			break;
		}
	if (videoStream == -1)
		return ; // Didn't find a video stream

	AVCodecContext* avCodecContext = avcodec_alloc_context3(NULL);
	result = avcodec_parameters_to_context(avCodecContext, avFormatContext->streams[videoStream]->codecpar);
	if (result < 0)
	{
		assert(false);
	}
	avCodecContext->pkt_timebase = avFormatContext->streams[videoStream]->time_base;
	AVCodec* codec = avcodec_find_decoder(avCodecContext->codec_id);
	avCodecContext->codec_id = codec->id;

	result = avcodec_open2(avCodecContext, codec, nullptr);
	if (result < 0)
	{
		msgBoxFFmpegError(result);
		assert(false);
	}
	m_sdlThread = std::move(std::thread([this, avCodecContext]() {
		m_sdlWindow = SDL_CreateWindow("sdl display", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, avCodecContext->width, avCodecContext->height, SDL_WINDOW_OPENGL);
		assert(m_sdlWindow);
		m_sdlRender = SDL_CreateRenderer(m_sdlWindow, -1, 0);
		assert(m_sdlRender);

		m_sdlTexture = SDL_CreateTexture(m_sdlRender, SDL_PixelFormatEnum::SDL_PIXELFORMAT_RGB24, SDL_TextureAccess::SDL_TEXTUREACCESS_STREAMING, avCodecContext->width, avCodecContext->height);
		assert(m_sdlTexture);

		SDL_Event event;

		while (1)
		{
			SDL_WaitEvent(&event);
			if (event.type == REFRESH_EVENT) {
				SDL_UpdateTexture(m_sdlTexture, nullptr, m_frame->data[0], avCodecContext->width * 3);
				SDL_Rect sdlRect = {};
				sdlRect.x = 0;
				sdlRect.y = 0;
				sdlRect.h = avCodecContext->height;
				sdlRect.w = avCodecContext->width;
				SDL_RenderClear(m_sdlRender);
				SDL_RenderCopy(m_sdlRender, m_sdlTexture, nullptr, &sdlRect);

				SDL_RenderPresent(m_sdlRender);
			}
			else if (event.type == SDL_WINDOWEVENT) {
			}
			else if (event.type == SDL_QUIT) {

			}
			else if (event.type == BREAK_EVENT) {
				break;
			}

		}

				}));
	

	AVframe* pframe = nullptr;

	pframe = av_frame_alloc();

	// 我们最终的目的是将原始视频帧存储为24-bit RGB 视频。

	AVframe* pframeRGB24 = av_frame_alloc();

	uint8_t* bufferRawRGB24 = nullptr;
	const int numBytes = av_image_get_buffer_size(AV_PIX_FMT_RGB24, avCodecContext->width, avCodecContext->height, 1);
	bufferRawRGB24 = (uint8_t*)av_malloc(numBytes * sizeof(uint8_t));
	av_image_fill_arrays(pframeRGB24->data, pframeRGB24->linesize, bufferRawRGB24, AV_PIX_FMT_RGB24, avCodecContext->width, avCodecContext->height, 1);


	// 读取数据

	// sws_ctx 定义了从pix_fmt 到 AV_PIX_FMT_RGB24的转换
	struct SwsContext* sws_ctx = NULL;
	int frameFinished;
	// initialize SWS context for software scaling
	sws_ctx = sws_getContext(avCodecContext->width,
		avCodecContext->height,
		avCodecContext->pix_fmt,
		avCodecContext->width,
		avCodecContext->height,
		AV_PIX_FMT_RGB24,
		SWS_BILINEAR,
		NULL,
		NULL,
		NULL
	);
	int i = 0;
	AVPacket packet;
	bool bReadEof = false;
	while (true)
	{
		Sleep(33);
		int readResult = -1;
		if (!bReadEof)
		{
			readResult = av_read_frame(avFormatContext, &packet);
			if (readResult < 0) {
				::MessageBoxA(0, 0, GetFFmpegErorString(readResult).c_str(), 0);
				bReadEof = true;
			}
			else if (readResult == 0) {
				static int iCnt = 0;
				if (packet.stream_index == videoStream) {
					++iCnt;
				}
				CString str;
				str.Format(L"cunt[%d]rn", iCnt);
				OutputDebugStringW(str.GetBuffer());
			}
		}
		if (bReadEof)
		{
			// 需要给刷空
			avcodec_send_packet(avCodecContext, NULL);
		}
		else
		{
			// Is this a packet from the video stream?
			if (packet.stream_index == videoStream) {
				// Decode video frame
				avcodec_send_packet(avCodecContext, &packet);
				
			}

		}
		
		int receiveResult = avcodec_receive_frame(avCodecContext, pframe);
		// Did we get a video frame?
		if (receiveResult == 0) {
			// Convert the image from its native format to RGB
			sws_scale(sws_ctx, (uint8_t const* const*)pframe->data,
				pframe->linesize, 0, avCodecContext->height,
				pframeRGB24->data, pframeRGB24->linesize);
			++i;
			Saveframe(pframeRGB24, avCodecContext->width,
				avCodecContext->height, i);
		}
		else if (receiveResult == AVERROR_EOF)
		{
			::MessageBoxA(0, 0, "read eof", 0);
			SDL_Event event;
			event.type = BREAK_EVENT;
			SDL_PushEvent(&event);
			break;
		}
		else if(receiveResult == AVERROR(EAGAIN)){
			if (bReadEof) {
				break;
			}
			else {
				
			}
		}
		else {
			msgBoxFFmpegError(receiveResult);
		}
		
		// Free the packet that was allocated by av_read_frame
		if(readResult == 0)
			av_packet_unref(&packet);
	}
	SDL_Quit();

	av_frame_free(&pframe);
	av_frame_free(&pframeRGB24);

	av_free(bufferRawRGB24);
	avcodec_close(avCodecContext);
	avformat_close_input(&avFormatContext);
}

完整项目ffmpegsdl2.0rgb24player-互联网文档类资源-CSDN下载