使用SDL进行音视频的播放
SDL(Simple DirectMedia Layer)是一套开放源代码的跨平台多媒体开发库,使用C语言写成。SDL提供了数种控制图像、声音、输出入的函数,让开发者只要用相同或是相似的代码就可以开发出跨多个平台(Linux、Windows、Mac OS X等)的应用软件。目前SDL多用于开发游戏、模拟器、媒体播放器等多媒体应用领域。
SDL的下载地址: https://www.libsdl.org/
现在较为新的版本在main函数中需要添加#define SDL_MAIN_HANDLED定义, 初步代码如下:文章来源地址https://www.toymoban.com/news/detail-806447.html
#include <stdio.h>
#include <string.h>
#include <malloc.h>
#define SDL_MAIN_HANDLED
#include <SDL.h>
//自定义消息类型
#define REFRESH_EVENT (SDL_USEREVENT + 1) // 请求画面刷新事件
#define QUIT_EVENT (SDL_USEREVENT + 2) // 退出事件
//定义分辨率
// YUV像素分辨率
#define YUV_WIDTH 320
#define YUV_HEIGHT 240
//定义YUV格式
#define YUV_FORMAT SDL_PIXELFORMAT_IYUV
int s_thread_exit = 0; // 退出标志 = 1则退出
int refresh_video_timer(void *data)
{
while (!s_thread_exit)
{
SDL_Event event;
event.type = REFRESH_EVENT;
SDL_PushEvent(&event);
SDL_Delay(40);
}
s_thread_exit = 0;
//push quit event
SDL_Event event;
event.type = QUIT_EVENT;
SDL_PushEvent(&event);
return 0;
}
int main()
{
if (SDL_Init(SDL_INIT_VIDEO)) {
fprintf(stderr, "Can't not initialize SDL, err: %s\n", SDL_GetError());
}
SDL_Event event; // 事件
SDL_Rect rect; // 矩形
SDL_Window *window = NULL; // 窗口
SDL_Renderer *renderer = NULL; // 渲染
SDL_Texture *texture = NULL; // 纹理
SDL_Thread *timer_thread = NULL; // 请求刷新线程
uint32_t pixformat = YUV_FORMAT; // YUV420P,即是SDL_PIXELFORMAT_IYUV
// 分辨率
// 1. YUV的分辨率
int video_width = YUV_WIDTH;
int video_height = YUV_HEIGHT;
// 2.显示窗口的分辨率
int win_width = YUV_WIDTH;
int win_height = YUV_WIDTH;
// YUV文件句柄
FILE *video_fd = NULL;
const char *yuv_path = "yuv420p_320x240.yuv";
size_t video_buff_len = 0;
uint8_t *video_buf = NULL; //读取数据后先把放到buffer里面
// 我们测试的文件是YUV420P格式
uint32_t y_frame_len = video_width * video_height;
uint32_t u_frame_len = video_width * video_height / 4; // 420p是4个y对应一个u
uint32_t v_frame_len = video_width * video_height / 4; // 420p是4个y对应一个v
uint32_t yuv_frame_len = y_frame_len + u_frame_len + v_frame_len;
window = SDL_CreateWindow("Simplest YUV Player",
SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED,
video_width, video_height,
SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
if (!window) {
printf("Can't create window, err: %s\n", SDL_GetError());
goto _FAIL;
}
// 基于窗口创建渲染器
renderer = SDL_CreateRenderer(window, -1, 0);
// 基于渲染器创建纹理
texture = SDL_CreateTexture(renderer,
pixformat,
SDL_TEXTUREACCESS_STREAMING,
video_width,
video_height);
// 分配空间
video_buf = (uint8_t*)malloc(yuv_frame_len);
if (!video_buf) {
fprintf(stderr, "Failed to alloce yuv frame space!\n");
goto _FAIL;
}
// 打开YUV文件
video_fd = fopen(yuv_path, "rb");
if (!video_fd) {
fprintf(stderr, "Failed to open yuv file\n");
goto _FAIL;
}
// 创建请求刷新线程
timer_thread = SDL_CreateThread(refresh_video_timer, NULL, NULL);
while (1) {
SDL_WaitEvent(&event);
if (event.type == REFRESH_EVENT) {
video_buff_len = fread(video_buf, 1, yuv_frame_len, video_fd);
if (video_buff_len <= 0) {
fprintf(stderr, "Failed to read data from yuv file!\n");
goto _FAIL;
}
// 设置纹理的数据
SDL_UpdateTexture(texture, NULL, video_buf, video_width);
// 显示区域, 可以通过修改w和h进行缩放
rect.x = 0;
rect.y = 0;
float w_ratio = win_width * 1.0 / video_width;
float h_ratio = win_height * 1.0 / video_height;
rect.w = video_width * w_ratio;
rect.h = video_height * h_ratio;
// 清屏
SDL_RenderClear(renderer);
// 将纹理的数据拷贝给渲染器
SDL_RenderCopy(renderer, texture, NULL, &rect);
// 显示
SDL_RenderPresent(renderer);
} else if (event.type == SDL_WINDOWEVENT) {
SDL_GetWindowSize(window, &win_width, &win_height);
printf("SDL_WINDOWEVENT win_width:%d, win_height:%d\n", win_width, win_height);
} else if (event.type == SDL_QUIT) {
s_thread_exit = 1;
} else if (event.type == QUIT_EVENT) {
break;
}
}
_FAIL:
s_thread_exit = 1;
// 释放资源
if(timer_thread)
SDL_WaitThread(timer_thread, NULL); // 等待线程退出
if(video_buf)
free(video_buf);
if(video_fd)
fclose(video_fd);
if(texture)
SDL_DestroyTexture(texture);
if(renderer)
SDL_DestroyRenderer(renderer);
if(window)
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
文章来源:https://www.toymoban.com/news/detail-806447.html
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