SDL2绘制ffmpeg解析的mp4文件

Alex1_Code2023-10-03 20:05

文章目录

本项目采用生产者消费者模型，生产者线程：使用ffmpeg将mp4格式数据解析为yuv的帧，消费者线程：利用sdl2将解析的yuv的帧进行消费，绘制到屏幕上。未完成的部分：1.解析音频数据，并与视频数据同步。2.增加界面：暂停，播放按钮，支持视频前进和后退。

学习音视频的参考资料与项目：
playdemo_github
雷神的csdn博客

1.FFMPEG利用命令行将mp4转yuv420

ffmpeg -i input.mp4 -c:v rawvideo -pix_fmt yuv420p output.yuv

2.ffmpeg将mp4解析为yuv数据

2.1 核心api:

  • av_read_frame:读取一帧数据
  • avcodec_send_packet:将数据包发送给解码器
  • avcodec_receive_frame:将数据包从解码器中取
  • sws_scale:格式转换，将解码后的帧数据转为yuv数据，存储在data[0],data[1],data[2]中
cpp 复制代码 
void readFrame()
{
	AVPacket* avPacket = av_packet_alloc();
	AVFrame* frame = av_frame_alloc();
	
	FILE* fp = fopen("F:/VS_Project/ffmpeg_demo/yuv.data","wb+") ;
	while (av_read_frame(formatContext, avPacket) >= 0 && fp)
	{
		if (avPacket->stream_index == videoStreamIndex)
		{
			if (avcodec_send_packet(codecContext, avPacket) < 0) {
				std::cerr << "发送数据包到解码器失败" << std::endl;
				break;
			}
			/*解码*/
			int ret = avcodec_receive_frame(codecContext, frame);
			printf("ret:%d\n", ret);
			if (ret >= 0)
			{
				ret = sws_scale(swsContext, frame->data, frame->linesize, 0, codecContext->height, yuvFrame->data, yuvFrame->linesize);
				printf("sws_scale ret=%d\n", ret);
				std::lock_guard<std::mutex>lck(mtx);
				isFinished = false;
				memcpy(yuvBuf, yuvFrame->data[0], yuvFrame->width * yuvFrame->height);
				memcpy(yuvBuf + yuvFrame->width * yuvFrame->height, yuvFrame->data[1], yuvFrame->width * yuvFrame->height / 4);
				memcpy(yuvBuf + yuvFrame->width * yuvFrame->height*5/4, yuvFrame->data[2], yuvFrame->width * yuvFrame->height / 4);
				isFinished = true;
				condvar.notify_one();
				//保存y分量
				//fwrite(yuvFrame->data[0], 1, yuvFrame->width * yuvFrame->height, fp);
				//保存uv分量
				//fwrite(yuvFrame->data[1], 1, yuvFrame->width * yuvFrame->height/4, fp);
				//fwrite(yuvFrame->data[2], 1, yuvFrame->width * yuvFrame->height / 4, fp);
			}
			
		}
	}
	fclose(fp);
	av_frame_unref(yuvFrame);
	av_packet_free(&avPacket);
	av_frame_unref(frame);
}

3.SDL2进行yuv绘制到屏幕

3.1 核心api

  • SDL_Init
  • SDL_CreateWindow
  • SDL_CreateRenderer
  • SDL_CreateTexture
  • SDL_UpdateTexture
  • SDL_RenderCopy
  • SDL_RenderPresent
  • SDL_Delay:控制帧率
cpp 复制代码 
int sdl_display()
{
	if (SDL_Init(SDL_INIT_VIDEO)) {
		printf("sdl init failed\n");
		return -1;
	}
	SDL_Window* window = SDL_CreateWindow("sdl_demo", 200, 200, codecContext->width, codecContext->height, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
	if (!window) {
		SDL_Quit();
		return -1;
	}
	SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0);
	if (!renderer)
	{
		SDL_DestroyWindow(window);
		SDL_Quit();
		return -1;
	}
	SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
	SDL_RenderClear(renderer);
	Uint32 pixformat = SDL_PIXELFORMAT_IYUV;
	SDL_Texture* sdlTexture = SDL_CreateTexture(renderer, pixformat, SDL_TEXTUREACCESS_STREAMING, codecContext->width, codecContext->height);
	//FILE* fp = fopen("F:/VS_Project/ffmpeg_demo/yuv.data", "rb+");
	
	
	while (1) {
		//int ret = fread(yuvBuf, 1, yuvlen, fp);
		//if (ret <= 0) {
		//	break;
		//}
		std::unique_lock<std::mutex>lck(mtx);
		if (condvar.wait_for(lck, std::chrono::seconds(1), [] {
			return isFinished;}))
		{
			isFinished = false;
			SDL_UpdateTexture(sdlTexture, NULL, yuvBuf, codecContext->width);
			SDL_RenderCopy(renderer, sdlTexture, NULL, NULL);
			SDL_RenderPresent(renderer);
			//控制帧率25fps
			SDL_Delay(40);
		}
		else {
			printf("sdl thread exit!\n");
			break;
		}
	}
	SDL_Quit();
	return 0;
}

4.完整代码

-使用两个线程，生产者消费者模型

cpp 复制代码 
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdexcept>
#include <iostream>
#include <string>
#include <thread>
#include <fstream>

#include <mutex>
#include <condition_variable>
extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/avutil.h>
#include <libswscale/swscale.h>

#include <SDL.h>
}
#undef main
#pragma warning(disable:4996)
AVFormatContext* formatContext = nullptr;
AVCodecContext* codecContext = nullptr;
SwsContext* swsContext = nullptr;
int videoStreamIndex = -1;
AVFrame* yuvFrame;
unsigned char* yuvBuf;
bool isReady = false;
bool isFinished = false;

std::mutex mtx;
std::condition_variable condvar;
void readFrame()
{
	AVPacket* avPacket = av_packet_alloc();
	AVFrame* frame = av_frame_alloc();
	
	FILE* fp = fopen("F:/VS_Project/ffmpeg_demo/yuv.data","wb+") ;
	while (av_read_frame(formatContext, avPacket) >= 0 && fp)
	{
		if (avPacket->stream_index == videoStreamIndex)
		{
			if (avcodec_send_packet(codecContext, avPacket) < 0) {
				std::cerr << "发送数据包到解码器失败" << std::endl;
				break;
			}
			/*解码*/
			int ret = avcodec_receive_frame(codecContext, frame);
			printf("ret:%d\n", ret);
			if (ret >= 0)
			{
				ret = sws_scale(swsContext, frame->data, frame->linesize, 0, codecContext->height, yuvFrame->data, yuvFrame->linesize);
				printf("sws_scale ret=%d\n", ret);
				std::lock_guard<std::mutex>lck(mtx);
				isFinished = false;
				memcpy(yuvBuf, yuvFrame->data[0], yuvFrame->width * yuvFrame->height);
				memcpy(yuvBuf + yuvFrame->width * yuvFrame->height, yuvFrame->data[1], yuvFrame->width * yuvFrame->height / 4);
				memcpy(yuvBuf + yuvFrame->width * yuvFrame->height*5/4, yuvFrame->data[2], yuvFrame->width * yuvFrame->height / 4);
				isFinished = true;
				condvar.notify_one();
				//保存y分量
				//fwrite(yuvFrame->data[0], 1, yuvFrame->width * yuvFrame->height, fp);
				//保存uv分量
				//fwrite(yuvFrame->data[1], 1, yuvFrame->width * yuvFrame->height/4, fp);
				//fwrite(yuvFrame->data[2], 1, yuvFrame->width * yuvFrame->height / 4, fp);
			}
			
		}
	}
	fclose(fp);
	av_frame_unref(yuvFrame);
	av_packet_free(&avPacket);
	av_frame_unref(frame);
}

int sdl_display()
{
	if (SDL_Init(SDL_INIT_VIDEO)) {
		printf("sdl init failed\n");
		return -1;
	}
	SDL_Window* window = SDL_CreateWindow("sdl_demo", 200, 200, codecContext->width, codecContext->height, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
	if (!window) {
		SDL_Quit();
		return -1;
	}
	SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0);
	if (!renderer)
	{
		SDL_DestroyWindow(window);
		SDL_Quit();
		return -1;
	}
	SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
	SDL_RenderClear(renderer);
	Uint32 pixformat = SDL_PIXELFORMAT_IYUV;
	SDL_Texture* sdlTexture = SDL_CreateTexture(renderer, pixformat, SDL_TEXTUREACCESS_STREAMING, codecContext->width, codecContext->height);
	//FILE* fp = fopen("F:/VS_Project/ffmpeg_demo/yuv.data", "rb+");
	
	
	while (1) {
		//int ret = fread(yuvBuf, 1, yuvlen, fp);
		//if (ret <= 0) {
		//	break;
		//}
		std::unique_lock<std::mutex>lck(mtx);
		if (condvar.wait_for(lck, std::chrono::seconds(1), [] {
			return isFinished;}))
		{
			isFinished = false;
			SDL_UpdateTexture(sdlTexture, NULL, yuvBuf, codecContext->width);
			SDL_RenderCopy(renderer, sdlTexture, NULL, NULL);
			SDL_RenderPresent(renderer);
			//控制帧率25fps
			SDL_Delay(40);
		}
		else {
			printf("sdl thread exit!\n");
			break;
		}
	}
	SDL_Quit();
	return 0;
}

/*ffmpeg -i input.mp4 -c:v rawvideo -pix_fmt yuv420p output.yuv*/
int main(int argc, char* argv[])
{
	/*if (argc != 2) {
		std::cerr << "文件名未指定" << std::endl;
		return -1;
	}*/
	std::string filename = "F:/VS_Project/ffmpeg_demo/1.mkv";
	if (avformat_open_input(&formatContext, filename.c_str(), nullptr, nullptr) != 0)
	{
		std::cerr << "无法打开文件" << std::endl;
		return -1;
	}
	if (avformat_find_stream_info(formatContext, nullptr) < 0) {
		std::cerr << "无法找到视频流" << std::endl;
		return -1;
	}
	for (int i = 0; i < formatContext->nb_streams; i++)
	{
		enum AVMediaType type = AVMEDIA_TYPE_VIDEO;
		AVStream* st = formatContext->streams[i];
		AVCodecParameters* codecpar = st->codecpar;
		if (codecpar->codec_type == type)
		{
			
			videoStreamIndex = i;
			const AVCodec* codec = avcodec_find_decoder(codecpar->codec_id);
			codecContext = avcodec_alloc_context3(codec);
			avcodec_parameters_to_context(codecContext, codecpar);
			avcodec_open2(codecContext, codec, nullptr);
			swsContext = sws_getContext(codecContext->width, codecContext->height, codecContext->pix_fmt,
				codecContext->width, codecContext->height, AV_PIX_FMT_YUV420P,
				SWS_BILINEAR, nullptr, nullptr, nullptr);
			std::cout << "w:" << codecpar->width << std::endl;
			std::cout << "h:" << codecpar->height << std::endl;
		}
	}
	yuvFrame = av_frame_alloc();
	yuvFrame->width = codecContext->width;
	yuvFrame->height = codecContext->height;
	yuvFrame->format = AV_PIX_FMT_YUV420P;

	int yuvlen = codecContext->width * codecContext->height * 3 / 2;
	yuvBuf = new unsigned char[yuvlen];
	int ret = av_frame_get_buffer(yuvFrame, 0);
	if (ret < 0) {
		printf("分配缓冲区失败\n");
		return -1;
	}
	//sdl_init();
	std::thread th1(readFrame);
	std::thread th2(sdl_display);
	th1.join();
	th2.join();
	delete[]yuvBuf;
	return 0;
}

5.效果展示

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