一、实现逻辑：
ffmpeg解封装->ffmpeg解码->SDL循环一帧帧显示
ffmpeg解码流程：
ffmpeg解码流程
SDL显示流程：
SDL显示流程
二、iOS里的特殊适配
参照SDL官网文档说明，iOS上使用SDL显示图像，需要修改main入口，SDL有自己的appdelegate实现，
- 修改main代码，在main里实现核心逻辑
- 删掉appdelegate.h/m文件
#import <UIKit/UIKit.h>
//#import "AppDelegate.h"
#import <SDL.h>
#import "AudioPlayerSDL2.h"
int main(int argc, char * argv[]) {
@autoreleasepool {
// SDL_Init((SDL_INIT_AUDIO | SDL_INIT_TIMER));
sdlplay();
return 0;
// return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
}
}
//extern int SDL_main(int argc, char * argv[])
//{
// @autoreleasepool {
// RootViewController *viewController = [[RootViewController alloc] initWithNibName:@"ViewController" bundle:nil];
// [UIApplication sharedApplication].keyWindow.rootViewController = viewController;
// [[UIApplication sharedApplication].keyWindow makeKeyAndVisible];
// return 0;
// }
//}三、解码&显示代码
代码语言：javascript复制int thread_exit = 0;
int thread_pause = 0;
int video_refresh_thread(void *data){
thread_exit = 0;
thread_pause = 0;
while (!thread_exit) {
if(!thread_pause){
SDL_Event event;
event.type = REFRESH_EVENT;
printf("while pushn");
SDL_PushEvent(&event);
}
SDL_Delay(40); //每40ms发一次刷新界面的消息
}
printf("thread_exit:%dn", thread_exit);
printf("thread_pause:%dn", thread_pause);
thread_exit = 0;
thread_pause = 0;
SDL_Event event;
event.type = BREAK_EVENT;
SDL_PushEvent(&event);
printf("push eventn");
return 0;
}
int sdlplay(){
printf("sdlplayn");
int ret = -1;
// file path
// NSString *mp4file = [NSString stringWithFormat:@"resource.bundle/war3end.mp4"];
NSString *mp4file = [NSString stringWithFormat:@"resource.bundle/sintel.mov"];
NSString *mp4pth = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:mp4file];
AVFormatContext *pFormatCtx = NULL;
int i, videoStream;
AVCodecParameters *pCodecParameters = NULL;
AVCodecContext *pCodecCtx = NULL;
AVCodec *pCodec = NULL;
AVFrame *pFrame = NULL;
AVPacket packet;
SDL_Rect rect;
Uint32 pixformat;
SDL_Window *win = NULL;
SDL_Renderer *renderer = NULL;
SDL_Texture *texture = NULL;
SDL_Thread *video_thread;
SDL_Event event;
//默认窗口大小
int w_width = 640;
int w_height = 480;
//SDL初始化
if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Could not initialize SDL - %sn", SDL_GetError());
return ret;
}
// 打开输入文件
if (avformat_open_input(&pFormatCtx, [mp4pth UTF8String], NULL, NULL) != 0) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't open video file!");
goto __FAIL;
}
//找到视频流
videoStream = av_find_best_stream(pFormatCtx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);
if (videoStream == -1) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Din't find a video stream!");
goto __FAIL;// Didn't find a video stream
}
// 流参数
pCodecParameters = pFormatCtx->streams[videoStream]->codecpar;
//获取解码器
pCodec = avcodec_find_decoder(pCodecParameters->codec_id);
if (pCodec == NULL) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unsupported codec!n");
goto __FAIL; // Codec not found
}
// 初始化一个编解码上下文
pCodecCtx = avcodec_alloc_context3(pCodec);
if (avcodec_parameters_to_context(pCodecCtx, pCodecParameters) != 0) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't copy codec context");
goto __FAIL;// Error copying codec context
}
// 打开解码器
if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to open decoder!n");
goto __FAIL; // Could not open codec
}
// Allocate video frame
pFrame = av_frame_alloc();
w_width = pCodecCtx->width;
w_height = pCodecCtx->height;
//创建窗口
win = SDL_CreateWindow("Media Player",
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
w_width, w_height,
SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
if (!win) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to create window by SDL");
goto __FAIL;
}
//创建渲染器
renderer = SDL_CreateRenderer(win, -1, 0);
if (!renderer) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to create Renderer by SDL");
goto __FAIL;
}
pixformat = SDL_PIXELFORMAT_IYUV;//YUV格式
// 创建纹理
texture = SDL_CreateTexture(renderer,
pixformat,
SDL_TEXTUREACCESS_STREAMING,
w_width,
w_height);
SDL_CreateThread(video_refresh_thread, "Video Thread", NULL);
printf("create thread n");
int count = 0;
int sret = -1;
for (;;) {
SDL_WaitEvent(&event);
if(event.type == REFRESH_EVENT){
while (1) {
if(av_read_frame(pFormatCtx, &packet) < 0){
thread_exit = 1;
}
if(packet.stream_index == videoStream){
break;
}
}
if (packet.stream_index == videoStream){
avcodec_send_packet(pCodecCtx, &packet);
while (avcodec_receive_frame(pCodecCtx, pFrame) == 0) {
SDL_UpdateYUVTexture(texture, NULL, pFrame->data[0], pFrame->linesize[0], pFrame->data[1], pFrame->linesize[1], pFrame->data[2], pFrame->linesize[2]);
rect.x = 0;
rect.y = 0;
rect.w = pCodecCtx->width;
rect.h = pCodecCtx->height;
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, texture, NULL, &rect);
SDL_RenderPresent(renderer);
}
av_packet_unref(&packet);
} else if(event.type == SDL_KEYDOWN){
if(event.key.keysym.sym == SDLK_SPACE){
thread_pause = !thread_pause;
}
if(event.key.keysym.sym == SDLK_ESCAPE){
thread_exit = 1;
}
} else if(event.type == SDL_QUIT){
thread_exit = 1;
} else if(event.type == BREAK_EVENT){
break;
}
}
}
__QUIT:
ret = 0;
__FAIL:
printf("freen");
// Free the YUV frame
if (pFrame) {
av_frame_free(&pFrame);
}
// Close the codec
if (pCodecCtx) {
avcodec_close(pCodecCtx);
}
if (pCodecParameters) {
avcodec_parameters_free(&pCodecParameters);
}
// Close the video file
if (pFormatCtx) {
avformat_close_input(&pFormatCtx);
}
if (win) {
SDL_DestroyWindow(win);
}
if (renderer) {
SDL_DestroyRenderer(renderer);
}
if (texture) {
SDL_DestroyTexture(texture);
}
SDL_Quit();
return ret;
}
demo运行效果
四、问题
- 解码过程中出现报错：avformat_close_input(&pFormatCtx) 报错 error for object 0x9: pointer being freed was not allocated，找不到原因
- 没研究怎么切换横竖屏
五、参考 FFmpeg SDL2实现视频流播放
