2023-03-15：屏幕录制并且显示视频，代码用go语言编写

2023-03-15：屏幕录制并且显示视频，不要用命令。代码用go语言编写。

答案2023-03-15：

使用moonfdd/ffmpeg-go和moonfdd/sdl2-go库来实现屏幕录制并显示视频，大体流程如下：

1.使用libavdevice库中的AVInputFormat（输入格式）、AVDeviceCapabilitiesQuery（设备能力查询）和AVFormatContext（格式上下文）获取桌面录制器的设备信息。

2.使用libavcodec库中的AVCodec、AVCodecContext、AVFrame和AVPacket结构体编码和解码视频帧。

3.使用libavutil库中的函数分配内存空间，并创建一个SwsContext（色彩空间转换上下文）对象，以及SDL库中的窗口和渲染器对象。

4.在循环中，读取屏幕捕获器的每一帧数据并将其解码。然后，直接将YUV420P格式的图像传递给SDL库中的渲染器进行显示。

代码调用了以下结构体：

AVInputFormat

AVDeviceCapabilitiesQuery

AVFormatContext

AVCodec

AVCodecContext

AVFrame

AVPacket

SwsContext

SDL窗口对象

SDL渲染器对象

释放资源的步骤包括：

1.关闭SDL渲染器和窗口。

2.释放AVFrame和AVPacket对象。

3.关闭libavcodec库中的AVCodecContext。

4.关闭libavformat库中的AVFormatContext。

5.关闭libavdevice库中的AVInputFormat。

6.释放libavutil库中的内存空间。

代码见

github.com/moonfdd/ffmpeg-go-examples。

执行命令：

go run ./examples/leixiaohua1020/simplest_ffmpeg_grabdesktop/main.go

代码参考了[雷霄骅的屏幕录制并播放显示](

https://github.com/leixiaohua1020/simplest_ffmpeg_device/blob/master/simplest_ffmpeg_grabdesktop/simplest_ffmpeg_grabdesktop.cpp)，代码用golang编写。代码如下： // https://github.com/leixiaohua1020/simplest_ffmpeg_device/blob/master/simplest_ffmpeg_grabdesktop/simplest_ffmpeg_grabdesktop.cpp package main import ( "fmt" "os" "time" "unsafe" "github.com/moonfdd/ffmpeg-go/ffcommon" "github.com/moonfdd/ffmpeg-go/libavcodec" "github.com/moonfdd/ffmpeg-go/libavdevice" "github.com/moonfdd/ffmpeg-go/libavformat" "github.com/moonfdd/ffmpeg-go/libavutil" "github.com/moonfdd/ffmpeg-go/libswscale" sdl "github.com/moonfdd/sdl2-go/sdl2" "github.com/moonfdd/sdl2-go/sdlcommon" ) // Output YUV420P const OUTPUT_YUV420P = 0 // 1 Use Dshow // 0 Use GDIgrab const USE_DSHOW = 0 // Refresh Event const SFM_REFRESH_EVENT = (sdl.SDL_USEREVENT + 1) const SFM_BREAK_EVENT = (sdl.SDL_USEREVENT + 2) var thread_exit ffcommon.FInt = 0 var ispush = true func sfp_refresh_thread(opaque ffcommon.FVoidP) uintptr { // thread_exit = 0 for thread_exit == 0 { var event sdl.SDL_Event event.Type = SFM_REFRESH_EVENT if ispush { event.SDL_PushEvent() ispush = false } sdl.SDL_Delay(40) } fmt.Println("sfp_refresh_thread 发送退出事件") // thread_exit = 0 //Break var event sdl.SDL_Event event.Type = SFM_BREAK_EVENT event.SDL_PushEvent() return 0 } // Show Dshow Device func show_dshow_device() { pFormatCtx := libavformat.AvformatAllocContext() var options *libavutil.AVDictionary libavutil.AvDictSet(&options, "list_devices", "true", 0) iformat := libavformat.AvFindInputFormat("dshow") fmt.Printf("========Device Info=============\n") libavformat.AvformatOpenInput(&pFormatCtx, "video=dummy", iformat, &options) fmt.Printf("================================\n") } // Show AVFoundation Device func show_avfoundation_device() { pFormatCtx := libavformat.AvformatAllocContext() var options *libavutil.AVDictionary libavutil.AvDictSet(&options, "list_devices", "true", 0) iformat := libavformat.AvFindInputFormat("avfoundation") fmt.Printf("==AVFoundation Device Info===\n") libavformat.AvformatOpenInput(&pFormatCtx, "", iformat, &options) fmt.Printf("=============================\n") } func main0() (ret ffcommon.FInt) { var pFormatCtx *libavformat.AVFormatContext var i, videoindex ffcommon.FInt var pCodecCtx *libavcodec.AVCodecContext var pCodec *libavcodec.AVCodec var ifmt *libavformat.AVInputFormat libavformat.AvRegisterAll() libavformat.AvformatNetworkInit() pFormatCtx = libavformat.AvformatAllocContext() //Open File //char filepath[]="src01_480x272_22.h265"; //avformat_open_input(&pFormatCtx,filepath,NULL,NULL) //Register Device libavdevice.AvdeviceRegisterAll() //Windows if USE_DSHOW != 0 { //Use dshow // //Need to Install screen-capture-recorder //screen-capture-recorder //Website: http://sourceforge.net/projects/screencapturer/ // ifmt = libavformat.AvFindInputFormat("dshow") if libavformat.AvformatOpenInput(&pFormatCtx, "video=screen-capture-recorder", ifmt, nil) != 0 { fmt.Printf("Couldnt open input stream1.\n") return -1 } } else { //Use gdigrab var options *libavutil.AVDictionary //Set some options //grabbing frame rate //av_dict_set(&options,"framerate","5",0); //The distance from the left edge of the screen or desktop //av_dict_set(&options,"offset_x","20",0); //The distance from the top edge of the screen or desktop //av_dict_set(&options,"offset_y","40",0); //Video frame size. The default is to capture the full screen //av_dict_set(&options,"video_size","640x480",0); // libavutil.AvDictSet(&options, "probesize", "100000000", 0) ifmt = libavformat.AvFindInputFormat("gdigrab") if libavformat.AvformatOpenInput(&pFormatCtx, "desktop", ifmt, &options) != 0 { fmt.Printf("Couldnt open input stream2.\n") return -1 } } if pFormatCtx.AvformatFindStreamInfo(nil) < 0 { fmt.Println("Couldnt find stream information.") return -1 } videoindex = -1 for i = 0; i < int32(pFormatCtx.NbStreams); i++ { if pFormatCtx.GetStream(uint32(i)).Codec.CodecType == libavutil.AVMEDIA_TYPE_VIDEO { videoindex = i break } } if videoindex == -1 { fmt.Printf("Didnt find a video stream.\n") return -1 } pCodecCtx = pFormatCtx.GetStream(uint32(videoindex)).Codec pCodec = libavcodec.AvcodecFindDecoder(pCodecCtx.CodecId) if pCodec == nil { fmt.Printf("Codec not found.\n") return -1 } if pCodecCtx.AvcodecOpen2(pCodec, nil) < 0 { fmt.Printf("Could not open codec.\n") return -1 } var pFrame, pFrameYUV *libavutil.AVFrame pFrame = libavutil.AvFrameAlloc() pFrameYUV = libavutil.AvFrameAlloc() //unsigned char *out_buffer=(unsigned char *)av_malloc(avpicture_get_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height)); //avpicture_fill((AVPicture *)pFrameYUV, out_buffer, AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height); out_buffer := (*byte)(unsafe.Pointer(libavutil.AvMalloc(uint64(libavcodec.AvpictureGetSize(int32(libavutil.AV_PIX_FMT_YUV420P), pCodecCtx.Width, pCodecCtx.Height))))) ((*libavcodec.AVPicture)(unsafe.Pointer(pFrameYUV))).AvpictureFill(out_buffer, libavutil.AV_PIX_FMT_YUV420P, pCodecCtx.Width, pCodecCtx.Height) //SDL---------------------------- // if sdl.SDL_Init(sdl.SDL_INIT_VIDEO|sdl.SDL_INIT_AUDIO|sdl.SDL_INIT_TIMER) != 0 { if sdl.SDL_Init(sdl.SDL_INIT_VIDEO) != 0 { fmt.Printf("Could not initialize SDL - %s\n", sdl.SDL_GetError()) return -1 } var screen_w, screen_h ffcommon.FInt = 640, 360 var mode *sdl.SDL_DisplayMode = new(sdl.SDL_DisplayMode) if sdl.SDL_GetCurrentDisplayMode(0, mode) != 0 { fmt.Printf("SDL: could not get current display mode - exiting:%s\n", sdl.SDL_GetError()) return -1 } //Half of the Desktops width and height. screen_w = mode.W / 2 screen_h = mode.H / 2 window := sdl.SDL_CreateWindow("Simplest FFmpeg Grab Desktop", sdl.SDL_WINDOWPOS_UNDEFINED, sdl.SDL_WINDOWPOS_UNDEFINED, screen_w, screen_h, 0) if window == nil { fmt.Printf("SDL: could not create window - exiting:%s\n", sdl.SDL_GetError()) return -1 } defer window.SDL_DestroyWindow() renderer := window.SDL_CreateRenderer(-1, 0) if renderer == nil { fmt.Printf("SDL: could not create renderer - exiting:%s\n", sdl.SDL_GetError()) return -1 } defer renderer.SDL_DestroyRenderer() texture := renderer.SDL_CreateTexture(sdl.SDL_PIXELFORMAT_YV12, sdl.SDL_TEXTUREACCESS_STREAMING, pCodecCtx.Width, pCodecCtx.Height) defer texture.SDL_DestroyTexture() window.SDL_ShowWindow() time.Sleep(2 * time.Second) var rect sdl.SDL_Rect rect.X = 0 rect.Y = 0 rect.W = screen_w rect.H = screen_h var rect2 sdl.SDL_Rect rect2.X = 0 rect2.Y = 0 rect2.W = mode.W rect2.H = mode.H //SDL End------------------------ // var got_picture ffcommon.FInt //AVPacket *packet=(AVPacket *)av_malloc(sizeof(AVPacket)); packet := &libavcodec.AVPacket{} var fp_yuv *os.File if OUTPUT_YUV420P != 0 { fp_yuv, _ = os.Create("output.yuv") } var img_convert_ctx *libswscale.SwsContext img_convert_ctx = libswscale.SwsGetContext(pCodecCtx.Width, pCodecCtx.Height, pCodecCtx.PixFmt, pCodecCtx.Width, pCodecCtx.Height, libavutil.AV_PIX_FMT_YUV420P, libswscale.SWS_BICUBIC, nil, nil, nil) //------------------------------ //video_tid := sdl.SDL_CreateThread(sfp_refresh_thread, nil) // go sfp_refresh_thread(uintptr(0)) //sdl.SDL_CreateThread(sfp_refresh_thread, "", uintptr(0)) //Event Loop var event sdl.SDL_Event for { //Wait ispush = true event.SDL_WaitEvent() if event.Type == SFM_REFRESH_EVENT { //------------------------------ if pFormatCtx.AvReadFrame(packet) >= 0 { if int32(packet.StreamIndex) == videoindex { if pCodecCtx.AvcodecSendPacket(packet) < 0 { packet.AvPacketUnref() continue } ret = pCodecCtx.AvcodecReceiveFrame(pFrame) if ret < 0 { fmt.Printf("Decode Error.\n") return -1 } if ret >= 0 { // if got_picture != 0 { img_convert_ctx.SwsScale((**byte)(unsafe.Pointer(&pFrame.Data)), (*int32)(unsafe.Pointer(&pFrame.Linesize)), 0, uint32(pCodecCtx.Height), (**byte)(unsafe.Pointer(&pFrameYUV.Data)), (*int32)(unsafe.Pointer(&pFrameYUV.Linesize))) if OUTPUT_YUV420P != 0 { y_size := pCodecCtx.Width * pCodecCtx.Height fp_yuv.Write(ffcommon.ByteSliceFromByteP(pFrameYUV.Data[0], int(y_size))) //Y fp_yuv.Write(ffcommon.ByteSliceFromByteP(pFrameYUV.Data[1], int(y_size)/4)) //U fp_yuv.Write(ffcommon.ByteSliceFromByteP(pFrameYUV.Data[2], int(y_size)/4)) //V } texture.SDL_UpdateYUVTexture(&rect2, pFrameYUV.Data[0], pFrameYUV.Linesize[0], pFrameYUV.Data[1], pFrameYUV.Linesize[1], pFrameYUV.Data[2], pFrameYUV.Linesize[2]) renderer.SDL_RenderClear() renderer.SDL_RenderCopy(texture, nil, &rect) renderer.SDL_RenderPresent() } } packet.AvPacketUnref() } else { //Exit Thread thread_exit = 1 fmt.Println("main 准备退出 1") } } else if event.Type == sdl.SDL_QUIT { thread_exit = 1 fmt.Println("main 准备退出 2") } else if event.Type == SFM_BREAK_EVENT { fmt.Println("退出循环 3") break } } img_convert_ctx.SwsFreeContext() if OUTPUT_YUV420P != 0 { fp_yuv.Close() } sdl.SDL_Quit() libavutil.AvFree(uintptr(unsafe.Pointer(out_buffer))) libavutil.AvFree(uintptr(unsafe.Pointer(pFrame))) libavutil.AvFree(uintptr(unsafe.Pointer(pFrameYUV))) pCodecCtx.AvcodecClose() libavformat.AvformatCloseInput(&pFormatCtx) return 0 } func main() { os.Setenv("Path", os.Getenv("Path")+";./lib/windows/ffmpeg") ffcommon.SetAvutilPath("./lib/windows/ffmpeg/avutil-56.dll") ffcommon.SetAvcodecPath("./lib/windows/ffmpeg/avcodec-58.dll") ffcommon.SetAvdevicePath("./lib/windows/ffmpeg/avdevice-58.dll") ffcommon.SetAvfilterPath("./lib/windows/ffmpeg/avfilter-56.dll") ffcommon.SetAvformatPath("./lib/windows/ffmpeg/avformat-58.dll") ffcommon.SetAvpostprocPath("./lib/windows/ffmpeg/postproc-55.dll") ffcommon.SetAvswresamplePath("./lib/windows/ffmpeg/swresample-3.dll") ffcommon.SetAvswscalePath("./lib/windows/ffmpeg/swscale-5.dll") sdlcommon.SetSDL2Path("./lib/windows/sdl/SDL2.0.16.dll") genDir := "./out" _, err := os.Stat(genDir) if err != nil { if os.IsNotExist(err) { os.Mkdir(genDir, 0777) // Everyone can read write and execute } } // go func() { // time.Sleep(1000) // exec.Command("./lib/ffplay.exe", "rtmp://localhost/publishlive/livestream").Output() // if err != nil { // fmt.Println("play err = ", err) // } // }() main0() }

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