ffmpeg调用directshow camera 并sdl渲染
基础
ffmpeg使用设备先注册
avdevice_register_all();
使用常用得CCameraDS 取获取名称，这里使用第一个摄像头。这里我们使用SDL来渲染得时候，启动一个定时器来定时给一个事件让SDL来刷新
SDLSDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER);
所以使用video和timer来完成这种渲染。
渲染流程
这里使用bgr24来渲染，使用sdl 创建表面，指定opengl来做
1 创建窗口
2 创建刷新线程
3 线程中发送更新事件
4 main主循环捕获事件，获取一帧rgb24，刷新界面渲染
这里面可以修改变成这样
刷新线程渲染获取一帧，推给主线程，主线程负责编码发送,同时渲染，这里是示例，没有这么做。
int main()
{
avdevice_register_all();
int w = 1280;
int h = 720;
g_fps = 10;
std::wstring cname;
CCameraDS::CameraName(0, cname);
std::string name = UnicodeToUTF8(cname);
TFFCap cap;
int ret = cap.OpenCameraRGB(name.c_str(), 1280, 720);
if (ret != 0)
return -1;
int screen_w, screen_h;
SDL_Window *screen;
SDL_Renderer *sdlRenderer;
SDL_Texture *sdlTexture;
SDL_Rect sdlRect;
SDL_Thread *video_tid;
SDL_Event event;
SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER);
screen_w = w; //w;
screen_h = h;
//screen_h = screen_w * 9 / 16;
screen = SDL_CreateWindow("FF", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
screen_w, screen_h, SDL_WINDOW_OPENGL);
if (!screen)
{
std::cout << "SDL: could not create window - exiting: " << SDL_GetError() << std::endl;
return -1;
}
sdlRenderer = SDL_CreateRenderer(screen, -1, SDL_RENDERER_ACCELERATED);
sdlTexture = SDL_CreateTexture(sdlRenderer,
SDL_PIXELFORMAT_BGR24 , //SDL_PIXELFORMAT_IYUV, //SDL_PIXELFORMAT_BGR24
SDL_TEXTUREACCESS_STREAMING,/*SDL_TEXTUREACCESS_STREAMING,*/
screen_w, screen_h);
sdlRect.x = 0;
sdlRect.y = 0;
sdlRect.w = screen_w;
sdlRect.h = screen_h;
video_tid = SDL_CreateThread(sfp_refresh_thread, NULL, NULL);
int got_picture;
for (;;)
{
SDL_WaitEvent(&event);
if (event.type == SFM_REFRESH_EVENT)
{
uint8_t *frame = cap.QueryFrame();
if (frame != NULL)
{
int y = screen_h * 2 / 3;
SDL_UpdateTexture(sdlTexture, NULL/*&sdlRect*/, frame, w * 3);
//SDL_UpdateTexture(sdlTexture, &sdlRect, out_buffer + W * H * 3, -W * 3);
SDL_RenderClear(sdlRenderer);
SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, NULL);
SDL_RenderPresent(sdlRenderer);
}
}
else if (event.type == SDL_KEYDOWN)
{
if (event.key.keysym.sym == SDLK_SPACE)
thread_pause = !thread_pause;
}
else if (event.type == SDL_QUIT)
{
thread_exit = 1;
}
else if (event.type == SFM_BREAK_EVENT)
{
break;
}
}
}
SDL使用得事件如下：
int thread_exit = 0;
int thread_pause = 0;
int g_fps = 30;
int sfp_refresh_thread(void *opaque)
{
thread_exit = 0;
thread_pause = 0;
while (!thread_exit)
{
if (!thread_pause)
{
SDL_Event event;
event.type = SFM_REFRESH_EVENT;
SDL_PushEvent(&event);
}
SDL_Delay(1000/g_fps);
}
thread_exit = 0;
thread_pause = 0;
//Break
SDL_Event event;
event.type = SFM_BREAK_EVENT;
SDL_PushEvent(&event);
return 0;
}
线程里面每隔1000/g_fps得时间就产生一个渲染事件，取得一帧数据后渲染，当然这里也可以编码发送等等都可以做。事件发生等等也可以使用标准c++得事件等待互斥，原理都是一摸一样得。
最后给出实现得FFcap
TFFCap声明
class TFFCap
{
public:
int m_fps = 10;
AVFrame * m_pFrame = NULL;
AVFrame * m_pFrameDst = NULL;
string m_name;
uint8_t * out_buffer = NULL;
int m_videoIndex = -1;
struct SwsContext * m_img_convert_ctx = NULL;
//int _pixelW;
//int _pixelH;
private:
AVFormatContext * m_pFormatCtx = NULL;
AVCodecContext * m_pCodecCtx = NULL;
AVCodec * m_pCodec = NULL;
AVPacket * m_pkt = NULL;
public:
void Init()
{
avdevice_register_all();
}
int OpenCameraRGB(const char * utf8videoname,
int nWidth, int nHeight);
uint8_t *QueryFrame();
int m_w = 0;
int m_h = 0;
// int QueryFrame(uint8_t *buf, int *len);
void UnInit();
TFFCap();
~TFFCap();
};
TFFCap实现
#include "FFCap.h"
#include 效果
代码里面还有一些是可以修改得，仅仅作为示例，代表可行