SDL2绘制ffmpeg解析的mp4文件
文章目录
- 1.FFMPEG利用命令行将mp4转yuv420
- 2.ffmpeg将mp4解析为yuv数据
-
- 2.1 核心api:
- 3.SDL2进行yuv绘制到屏幕
-
- 3.1 核心api
- 4.完整代码
- 5.效果展示
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
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
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
#include 5.效果展示
