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。

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，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 mainimport ("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 = truefunc sfp_refresh_thread(opaque ffcommon.FVoidP) uintptr {// thread_exit = 0for thread_exit == 0 {var event sdl.SDL_Eventevent.Type = SFM_REFRESH_EVENTif ispush {event.SDL_PushEvent()ispush = false}sdl.SDL_Delay(40)}fmt.Println("sfp_refresh_thread 发送退出事件")// thread_exit = 0//Breakvar event sdl.SDL_Eventevent.Type = SFM_BREAK_EVENTevent.SDL_PushEvent()return 0
}// Show Dshow Device
func show_dshow_device() {pFormatCtx := libavformat.AvformatAllocContext()var options *libavutil.AVDictionarylibavutil.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.AVDictionarylibavutil.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.AVFormatContextvar i, videoindex ffcommon.FIntvar pCodecCtx *libavcodec.AVCodecContextvar pCodec *libavcodec.AVCodecvar ifmt *libavformat.AVInputFormatlibavformat.AvRegisterAll()libavformat.AvformatNetworkInit()pFormatCtx = libavformat.AvformatAllocContext()//Open File//char filepath[]="src01_480x272_22.h265";//avformat_open_input(&pFormatCtx,filepath,NULL,NULL)//Register Devicelibavdevice.AvdeviceRegisterAll()//Windowsif 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("Couldn't open input stream1.\n")return -1}} else {//Use gdigrabvar 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("Couldn't open input stream2.\n")return -1}}if pFormatCtx.AvformatFindStreamInfo(nil) < 0 {fmt.Println("Couldn't find stream information.")return -1}videoindex = -1for i = 0; i < int32(pFormatCtx.NbStreams); i++ {if pFormatCtx.GetStream(uint32(i)).Codec.CodecType == libavutil.AVMEDIA_TYPE_VIDEO {videoindex = ibreak}}if videoindex == -1 {fmt.Printf("Didn't find a video stream.\n")return -1}pCodecCtx = pFormatCtx.GetStream(uint32(videoindex)).CodecpCodec = 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.AVFramepFrame = 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, 360var 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 Desktop's width and height.screen_w = mode.W / 2screen_h = mode.H / 2window := 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_Rectrect.X = 0rect.Y = 0rect.W = screen_wrect.H = screen_hvar rect2 sdl.SDL_Rectrect2.X = 0rect2.Y = 0rect2.W = mode.Wrect2.H = mode.H//SDL End------------------------// var got_picture ffcommon.FInt//AVPacket *packet=(AVPacket *)av_malloc(sizeof(AVPacket));packet := &libavcodec.AVPacket{}var fp_yuv *os.Fileif OUTPUT_YUV420P != 0 {fp_yuv, _ = os.Create("output.yuv")}var img_convert_ctx *libswscale.SwsContextimg_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 Loopvar event sdl.SDL_Eventfor {//Waitispush = trueevent.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.Heightfp_yuv.Write(ffcommon.ByteSliceFromByteP(pFrameYUV.Data[0], int(y_size)))   //Yfp_yuv.Write(ffcommon.ByteSliceFromByteP(pFrameYUV.Data[1], int(y_size)/4)) //Ufp_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 Threadthread_exit = 1fmt.Println("main 准备退出 1")}} else if event.Type == sdl.SDL_QUIT {thread_exit = 1fmt.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()
}