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• Screenrecorder application output video resolution issues [closed]

  23 juin 2022, par JessieK

  Using Github code for ScreenRecorder on Linux
Everything works fine, besides the resolution of output video.
Tried to play with setting, quality has significantly improved, but still no way to change resolution.
I need to get output video with the same size as input video

  


  using namespace std;

    /* initialize the resources*/
    ScreenRecorder::ScreenRecorder()
    {
    
        av_register_all();
        avcodec_register_all();
        avdevice_register_all();
        cout<<"\nall required functions are registered successfully";
    }
    
    /* uninitialize the resources */
    ScreenRecorder::~ScreenRecorder()
    {
    
        avformat_close_input(&pAVFormatContext);
        if( !pAVFormatContext )
        {
            cout<<"\nfile closed sucessfully";
        }
        else
        {
            cout<<"\nunable to close the file";
            exit(1);
        }
    
        avformat_free_context(pAVFormatContext);
        if( !pAVFormatContext )
        {
            cout<<"\navformat free successfully";
        }
        else
        {
            cout<<"\nunable to free avformat context";
            exit(1);
        }
    
    }
    
    /* function to capture and store data in frames by allocating required memory and auto deallocating the memory.   */
    int ScreenRecorder::CaptureVideoFrames()
    {
        int flag;
        int frameFinished;//when you decode a single packet, you still don't have information enough to have a frame [depending on the type of codec, some of them //you do], when you decode a GROUP of packets that represents a frame, then you have a picture! that's why frameFinished will let //you know you decoded enough to have a frame.
    
        int frame_index = 0;
        value = 0;
    
        pAVPacket = (AVPacket *)av_malloc(sizeof(AVPacket));
        av_init_packet(pAVPacket);
    
        pAVFrame = av_frame_alloc();
        if( !pAVFrame )
        {
         cout<<"\nunable to release the avframe resources";
         exit(1);
        }
    
        outFrame = av_frame_alloc();//Allocate an AVFrame and set its fields to default values.
        if( !outFrame )
        {
         cout<<"\nunable to release the avframe resources for outframe";
         exit(1);
        }
    
        int video_outbuf_size;
        int nbytes = av_image_get_buffer_size(outAVCodecContext->pix_fmt,outAVCodecContext->width,outAVCodecContext->height,32);
        uint8_t *video_outbuf = (uint8_t*)av_malloc(nbytes);
        if( video_outbuf == NULL )
        {
            cout<<"\nunable to allocate memory";
            exit(1);
        }
    
        // Setup the data pointers and linesizes based on the specified image parameters and the provided array.
        value = av_image_fill_arrays( outFrame->data, outFrame->linesize, video_outbuf , AV_PIX_FMT_YUV420P, outAVCodecContext->width,outAVCodecContext->height,1 ); // returns : the size in bytes required for src
        if(value < 0)
        {
            cout<<"\nerror in filling image array";
        }
    
        SwsContext* swsCtx_ ;
    
        // Allocate and return swsContext.
        // a pointer to an allocated context, or NULL in case of error
        // Deprecated : Use sws_getCachedContext() instead.
        swsCtx_ = sws_getContext(pAVCodecContext->width,
                            pAVCodecContext->height,
                            pAVCodecContext->pix_fmt,
                            outAVCodecContext->width,
                    outAVCodecContext->height,
                            outAVCodecContext->pix_fmt,
                            SWS_BICUBIC, NULL, NULL, NULL);
    
    
    int ii = 0;
    int no_frames = 100;
    cout<<"\nenter No. of frames to capture : ";
    cin>>no_frames;
    
        AVPacket outPacket;
        int j = 0;
    
        int got_picture;
    
        while( av_read_frame( pAVFormatContext , pAVPacket ) >= 0 )
        {
        if( ii++ == no_frames )break;
            if(pAVPacket->stream_index == VideoStreamIndx)
            {
                value = avcodec_decode_video2( pAVCodecContext , pAVFrame , &frameFinished , pAVPacket );
                if( value < 0)
                {
                    cout<<"unable to decode video";
                }
    
                if(frameFinished)// Frame successfully decoded :)
                {
                    sws_scale(swsCtx_, pAVFrame->data, pAVFrame->linesize,0, pAVCodecContext->height, outFrame->data,outFrame->linesize);
                    av_init_packet(&outPacket);
                    outPacket.data = NULL;    // packet data will be allocated by the encoder
                    outPacket.size = 0;
    
                    avcodec_encode_video2(outAVCodecContext , &outPacket ,outFrame , &got_picture);
    
                    if(got_picture)
                    {
                        if(outPacket.pts != AV_NOPTS_VALUE)
                            outPacket.pts = av_rescale_q(outPacket.pts, video_st->codec->time_base, video_st->time_base);
                        if(outPacket.dts != AV_NOPTS_VALUE)
                            outPacket.dts = av_rescale_q(outPacket.dts, video_st->codec->time_base, video_st->time_base);
                    
                        printf("Write frame %3d (size= %2d)\n", j++, outPacket.size/1000);
                        if(av_write_frame(outAVFormatContext , &outPacket) != 0)
                        {
                            cout<<"\nerror in writing video frame";
                        }
    
                    av_packet_unref(&outPacket);
                    } // got_picture
    
                av_packet_unref(&outPacket);
                } // frameFinished
    
            }
        }// End of while-loop


  


  One part of two parts is above...Actually original app seem to record video of same size as does my application, but still it has not any use

  


  ---

  


  Second part of the code

  


  av_free(video_outbuf);

}

/* establishing the connection between camera or screen through its respective folder */
int ScreenRecorder::openCamera()
{

    value = 0;
    options = NULL;
    pAVFormatContext = NULL;

    pAVFormatContext = avformat_alloc_context();//Allocate an AVFormatContext.
/*

X11 video input device.
To enable this input device during configuration you need libxcb installed on your system. It will be automatically detected during configuration.
This device allows one to capture a region of an X11 display. 
refer : https://www.ffmpeg.org/ffmpeg-devices.html#x11grab
*/
    /* current below is for screen recording. to connect with camera use v4l2 as a input parameter for av_find_input_format */ 
    pAVInputFormat = av_find_input_format("x11grab");
    value = avformat_open_input(&pAVFormatContext, ":0.0+10,250", pAVInputFormat, NULL);
    if(value != 0)
    {
       cout<<"\nerror in opening input device";
       exit(1);
    }

    /* set frame per second */
    value = av_dict_set( &options,"framerate","30",0 );
    if(value < 0)
    {
      cout<<"\nerror in setting dictionary value";
       exit(1);
    }

    value = av_dict_set( &options, "preset", "medium", 0 );
    if(value < 0)
    {
      cout<<"\nerror in setting preset values";
      exit(1);
    }

//  value = avformat_find_stream_info(pAVFormatContext,NULL);
    if(value < 0)
    {
      cout<<"\nunable to find the stream information";
      exit(1);
    }

    VideoStreamIndx = -1;

    /* find the first video stream index . Also there is an API available to do the below operations */
    for(int i = 0; i < pAVFormatContext->nb_streams; i++ ) // find video stream posistion/index.
    {
      if( pAVFormatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO )
      {
         VideoStreamIndx = i;
         break;
      }

    } 

    if( VideoStreamIndx == -1)
    {
      cout<<"\nunable to find the video stream index. (-1)";
      exit(1);
    }

    // assign pAVFormatContext to VideoStreamIndx
    pAVCodecContext = pAVFormatContext->streams[VideoStreamIndx]->codec;

    pAVCodec = avcodec_find_decoder(pAVCodecContext->codec_id);
    if( pAVCodec == NULL )
    {
      cout<<"\nunable to find the decoder";
      exit(1);
    }

    value = avcodec_open2(pAVCodecContext , pAVCodec , NULL);//Initialize the AVCodecContext to use the given AVCodec.
    if( value < 0 )
    {
      cout<<"\nunable to open the av codec";
      exit(1);
    }
}

/* initialize the video output file and its properties  */
int ScreenRecorder::init_outputfile()
{
    outAVFormatContext = NULL;
    value = 0;
    output_file = "../media/output.mp4";

    avformat_alloc_output_context2(&outAVFormatContext, NULL, NULL, output_file);
    if (!outAVFormatContext)
    {
        cout<<"\nerror in allocating av format output context";
        exit(1);
    }

/* Returns the output format in the list of registered output formats which best matches the provided parameters, or returns NULL if there is no match. */
    output_format = av_guess_format(NULL, output_file ,NULL);
    if( !output_format )
    {
     cout<<"\nerror in guessing the video format. try with correct format";
     exit(1);
    }

    video_st = avformat_new_stream(outAVFormatContext ,NULL);
    if( !video_st )
    {
        cout<<"\nerror in creating a av format new stream";
        exit(1);
    }

    outAVCodecContext = avcodec_alloc_context3(outAVCodec);
    if( !outAVCodecContext )
    {
        cout<<"\nerror in allocating the codec contexts";
        exit(1);
    }

    /* set property of the video file */
    outAVCodecContext = video_st->codec;
    outAVCodecContext->codec_id = AV_CODEC_ID_MPEG4;// AV_CODEC_ID_MPEG4; // AV_CODEC_ID_H264 // AV_CODEC_ID_MPEG1VIDEO
    outAVCodecContext->codec_type = AVMEDIA_TYPE_VIDEO;
    outAVCodecContext->pix_fmt  = AV_PIX_FMT_YUV420P;
    outAVCodecContext->bit_rate = 2500000; // 2500000
    outAVCodecContext->width = 1920;
    outAVCodecContext->height = 1080;
    outAVCodecContext->gop_size = 3;
    outAVCodecContext->max_b_frames = 2;
    outAVCodecContext->time_base.num = 1;
    outAVCodecContext->time_base.den = 30; // 15fps

    {
     av_opt_set(outAVCodecContext->priv_data, "preset", "slow", 0);
    }

    outAVCodec = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
    if( !outAVCodec )
    {
     cout<<"\nerror in finding the av codecs. try again with correct codec";
    exit(1);
    }

    /* Some container formats (like MP4) require global headers to be present
       Mark the encoder so that it behaves accordingly. */

    if ( outAVFormatContext->oformat->flags & AVFMT_GLOBALHEADER)
    {
        outAVCodecContext->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    }

    value = avcodec_open2(outAVCodecContext, outAVCodec, NULL);
    if( value < 0)
    {
        cout<<"\nerror in opening the avcodec";
        exit(1);
    }

    /* create empty video file */
    if ( !(outAVFormatContext->flags & AVFMT_NOFILE) )
    {
     if( avio_open2(&outAVFormatContext->pb , output_file , AVIO_FLAG_WRITE ,NULL, NULL) < 0 )
     {
      cout<<"\nerror in creating the video file";
      exit(1);
     }
    }

    if(!outAVFormatContext->nb_streams)
    {
        cout<<"\noutput file dose not contain any stream";
        exit(1);
    }

    /* imp: mp4 container or some advanced container file required header information*/
    value = avformat_write_header(outAVFormatContext , &options);
    if(value < 0)
    {
        cout<<"\nerror in writing the header context";
        exit(1);
    }


    cout<<"\n\nOutput file information :\n\n";
    av_dump_format(outAVFormatContext , 0 ,output_file ,1);


  


  Github link https://github.com/abdullahfarwees/screen-recorder-ffmpeg-cpp

  


• Error : Output format mp4 is not available

  12 avril 2024, par alpaca pwaa

  I'm using fluent-ffmpeg in my nextjs application, I'm trying to process the video and specified a format to stream on my s3 bucket but it keeps on failing. My terminal keeps on throwing "Error : Error : Output format mp4 is not available". I already verify my ffmpeg format "ffmpeg -format" and confirm that it supports encoding and decoding mp4 files. I've already tried solutions from other forums but it's not working for me.

  


  createVideo: privateProcedure
    .input(
      z.object({
        fileId: z.string(),
      })
    )
    .mutation(async ({ ctx, input }) => {
      const { getUser } = getKindeServerSession();
      const user = await getUser();

      if (!user || !user.id || !user.email) {
        throw new TRPCError({ code: "UNAUTHORIZED" });
      }

      const dbUser = await db.user.findFirst({
        where: {
          id: user.id,
        },
      });

      if (!dbUser) {
        throw new TRPCError({
          code: "UNAUTHORIZED",
          message: "User not found in the database.",
        });
      }

      const putObjectCommand = new PutObjectCommand({
        Bucket: process.env.AWS_BUCKET_NAME!,
        Key: generateFileName(),
      });

      const s3 = new S3Client({
        region: process.env.AWS_BUCKET_REGION!,
        credentials: {
          accessKeyId: process.env.AWS_ACCESS_KEY!,
          secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY!,
        },
      });

      const singedURL = await getSignedUrl(s3, putObjectCommand, {
        expiresIn: 60,
      });

      const ffmpeg = require("fluent-ffmpeg");
      const passthroughStream = new PassThrough();

      ffmpeg({ source: "./template1.mp4" })
        .on("end", async () => {
          console.log("Job done");
          await uploadToS3(passthroughStream);
        })
        .on("error", (error: string) => {
          console.error("Error:", error);
          throw new Error("Error processing video");
        })
        .videoFilter({
          filter: "drawtext",
          options: {
            text: "hi",
            fontsize: 24,
            fontcolor: "white",
            x: "(w-text_w)/2",
            y: "(h-text_h)/2",
            box: 1,
            boxcolor: "black@0.5",
            boxborderw: 5,
            fontfile: "/Windows/fonts/calibri.ttf",
          },
        })
        .videoCodec("libx264")
        .outputFormat("mp4")
        .outputOptions(["-movflags frag_keyframe+empty_moov"])
        .pipe(passthroughStream, { end: true });

      const uploadToS3 = async (stream: PassThrough) => {
        const upload = new Upload({
          client: s3,
          params: {
            Bucket: process.env.AWS_BUCKET_NAME!,
            Key: generateFileName(),
            Body: stream,
          },
        });
        await upload.done();
      };

      await new Promise((resolve, reject) => {
        passthroughStream.on("end", resolve);
        passthroughStream.on("error", reject);
      });

      const createdVideo = await db.video.create({
        data: {
          name: "Test Name",
          url: singedURL.split("?")[0],
          key: singedURL,
          fileId: input.fileId,
        },
      });

      return createdVideo;
    }),


  


  Here's the ffmpeg log.

  


  ffmpeg started on 2024-04-11 at 20:58:56
Report written to "ffmpeg-20240411-205856.log"
Log level: 48
Command line:
"C:\\ProgramData\\chocolatey\\lib\\ffmpeg-full\\tools\\ffmpeg\\bin\\ffmpeg.exe" -i ./template1.mp4 -filter:v "drawtext=text=hi:fontsize=24:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2:box=1:boxcolor=black@0.5:boxborderw=5:fontfile=/Windows/fonts/calibri.ttf" -report pipe:1
ffmpeg version 7.0-full_build-www.gyan.dev Copyright (c) 2000-2024 the FFmpeg developers
  built with gcc 13.2.0 (Rev5, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libxevd --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxeve --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-dxva2 --enable-d3d11va --enable-d3d12va --enable-f  libavutil      59.  8.100 / 59.  8.100
  libavcodec     61.  3.100 / 61.  3.100
  libavformat    61.  1.100 / 61.  1.100
  libavdevice    61.  1.100 / 61.  1.100
  libavfilter    10.  1.100 / 10.  1.100
  libswscale      8.  1.100 /  8.  1.100
  libswresample   5.  1.100 /  5.  1.100
  libpostproc    58.  1.100 / 58.  1.100
Splitting the commandline.
Reading option '-i' ... matched as input url with argument './template1.mp4'.
Reading option '-filter:v' ... matched as option 'filter' (apply specified filters to audio/video) with argument 'drawtext=text=hi:fontsize=24:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2:box=1:boxcolor=black@0.5:boxborderw=5:fontfile=/Windows/fonts/calibri.ttf'.
Reading option '-report' ... matched as option 'report' (generate a report) with argument '1'.
Reading option 'pipe:1' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option report (generate a report) with argument 1.
Successfully parsed a group of options.
Parsing a group of options: input url ./template1.mp4.
Successfully parsed a group of options.
Opening an input file: ./template1.mp4.
[AVFormatContext @ 00000262cd0888c0] Opening './template1.mp4' for reading
[file @ 00000262cd0a94c0] Setting default whitelist 'file,crypto,data'
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000262cd0888c0] Format mov,mp4,m4a,3gp,3g2,mj2 probed with size=2048 and score=100
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000262cd0888c0] ISO: File Type Major Brand: isom
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000262cd0888c0] Unknown dref type 0x206c7275 size 12
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000262cd0888c0] Processing st: 0, edit list 0 - media time: 1024, duration: 126981
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000262cd0888c0] Offset DTS by 1024 to make first pts zero.
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000262cd0888c0] Setting codecpar->delay to 2 for stream st: 0
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000262cd0888c0] Before avformat_find_stream_info() pos: 6965 bytes read:32768 seeks:0 nb_streams:1
[h264 @ 00000262cd0bb140] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 00000262cd0bb140] Decoding VUI
[h264 @ 00000262cd0bb140] nal_unit_type: 8(PPS), nal_ref_idc: 3
[h264 @ 00000262cd0bb140] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 00000262cd0bb140] Decoding VUI
[h264 @ 00000262cd0bb140] nal_unit_type: 8(PPS), nal_ref_idc: 3
[h264 @ 00000262cd0bb140] Decoding VUI
[h264 @ 00000262cd0bb140] nal_unit_type: 6(SEI), nal_ref_idc: 0
[h264 @ 00000262cd0bb140] nal_unit_type: 7(SPS), nal_ref_idc: 3
[h264 @ 00000262cd0bb140] nal_unit_type: 8(PPS), nal_ref_idc: 3
[h264 @ 00000262cd0bb140] nal_unit_type: 5(IDR), nal_ref_idc: 3
[h264 @ 00000262cd0bb140] Decoding VUI
[h264 @ 00000262cd0bb140] Format yuv420p chosen by get_format().
[h264 @ 00000262cd0bb140] Reinit context to 1088x1920, pix_fmt: yuv420p
[h264 @ 00000262cd0bb140] no picture 
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000262cd0888c0] All info found
[mov,mp4,m4a,3gp,3g2,mj2 @ 00000262cd0888c0] After avformat_find_stream_info() pos: 82242 bytes read:82242 seeks:0 frames:1
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from './template1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.76.100
  Duration: 00:00:08.27, start: 0.000000, bitrate: 3720 kb/s
  Stream #0:0[0x1](und), 1, 1/15360: Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1080x1920, 3714 kb/s, 30 fps, 30 tbr, 15360 tbn (default)
      Metadata:
        handler_name    : VideoHandler
        vendor_id       : [0][0][0][0]
Successfully opened the file.
Parsing a group of options: output url pipe:1.
Applying option filter:v (apply specified filters to audio/video) with argument drawtext=text=hi:fontsize=24:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2:box=1:boxcolor=black@0.5:boxborderw=5:fontfile=/Windows/fonts/calibri.ttf.
Successfully parsed a group of options.
Opening an output file: pipe:1.
[AVFormatContext @ 00000262cd0b2240] Unable to choose an output format for 'pipe:1'; use a standard extension for the filename or specify the format manually.
[out#0 @ 00000262cd0bb300] Error initializing the muxer for pipe:1: Invalid argument
Error opening output file pipe:1.
Error opening output files: Invalid argument
[AVIOContext @ 00000262cd0a9580] Statistics: 82242 bytes read, 0 seeks


  


  I should be able to stream the processed video to my s3, but it keeps on throwing "Error : Error : Output format mp4 is not available"

  


• Screen Recording with FFmpeg-Lib with c++

  27 janvier 2020, par Baschdel

  I’m trying to record the whole desktop stream with FFmpeg on Windows.
  I found a working example here. The Problem is that some og the functions depricated. So I tried to replace them with the updated ones.

  But there are some slight problems. The error "has triggered a breakpoint." occurse and also "not able to read the location."
  The bigger problem is that I don’t know if this is the right way to do this..

  My code looks like this :

  using namespace std;
  
  
  
  /* initialize the resources*/
  
  Recorder::Recorder()
  
  {
  
  
  
      av_register_all();
  
      avcodec_register_all();
  
      avdevice_register_all();
  
      cout<<"\nall required functions are registered successfully";
  
  }
  
  
  
  /* uninitialize the resources */
  
  Recorder::~Recorder()
  
  {
  
  
  
      avformat_close_input(&pAVFormatContext);
  
      if( !pAVFormatContext )
  
      {
  
          cout<<"\nfile closed sucessfully";
  
      }
  
      else
  
      {
  
          cout<<"\nunable to close the file";
  
          exit(1);
  
      }
  
  
  
      avformat_free_context(pAVFormatContext);
  
      if( !pAVFormatContext )
  
      {
  
          cout<<"\navformat free successfully";
  
      }
  
      else
  
      {
  
          cout<<"\nunable to free avformat context";
  
          exit(1);
  
      }
  
  
  
  }
  
  
  
  /* establishing the connection between camera or screen through its respective folder */
  
  int Recorder::openCamera()
  
  {
  
  
  
      value = 0;
  
      options = NULL;
  
      pAVFormatContext = NULL;
  
  
  
      pAVFormatContext = avformat_alloc_context();//Allocate an AVFormatContext.
  
  
  
      openScreen(pAVFormatContext);
  
  
  
      /* set frame per second */
  
      value = av_dict_set( &options,"framerate","30",0 );
  
      if(value < 0)
  
      {
  
        cout<<"\nerror in setting dictionary value";
  
         exit(1);
  
      }
  
  
  
      value = av_dict_set( &options, "preset", "medium", 0 );
  
      if(value < 0)
  
      {
  
        cout<<"\nerror in setting preset values";
  
        exit(1);
  
      }
  
  
  
  //  value = avformat_find_stream_info(pAVFormatContext,NULL);
  
      if(value < 0)
  
      {
  
        cout<<"\nunable to find the stream information";
  
        exit(1);
  
      }
  
  
  
      VideoStreamIndx = -1;
  
  
  
      /* find the first video stream index . Also there is an API available to do the below operations */
  
      for(int i = 0; i < pAVFormatContext->nb_streams; i++ ) // find video stream posistion/index.
  
      {
  
        if( pAVFormatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO )
  
        {
  
           VideoStreamIndx = i;
  
           break;
  
        }
  
  
  
      } 
  
  
  
      if( VideoStreamIndx == -1)
  
      {
  
        cout<<"\nunable to find the video stream index. (-1)";
  
        exit(1);
  
      }
  
  
  
      // assign pAVFormatContext to VideoStreamIndx
  
      pAVCodecContext = pAVFormatContext->streams[VideoStreamIndx]->codec;
  
  
  
      pAVCodec = avcodec_find_decoder(pAVCodecContext->codec_id);
  
      if( pAVCodec == NULL )
  
      {
  
        cout<<"\nunable to find the decoder";
  
        exit(1);
  
      }
  
  
  
      value = avcodec_open2(pAVCodecContext , pAVCodec , NULL);//Initialize the AVCodecContext to use the given AVCodec.
  
      if( value < 0 )
  
      {
  
        cout<<"\nunable to open the av codec";
  
        exit(1);
  
      }
  
  }
  
  
  
  /* initialize the video output file and its properties  */
  
  int Recorder::init_outputfile()
  
  {
  
      outAVFormatContext = NULL;
  
      value = 0;
  
      output_file = "output.mp4";
  
  
  
      avformat_alloc_output_context2(&outAVFormatContext, NULL, NULL, output_file);
  
      if (!outAVFormatContext)
  
      {
  
          cout<<"\nerror in allocating av format output context";
  
          exit(1);
  
      }
  
  
  
  /* Returns the output format in the list of registered output formats which best matches the provided parameters, or returns NULL if there is no match. */
  
      output_format = av_guess_format(NULL, output_file ,NULL);
  
      if( !output_format )
  
      {
  
       cout<<"\nerror in guessing the video format. try with correct format";
  
       exit(1);
  
      }
  
  
  
      video_st = avformat_new_stream(outAVFormatContext ,NULL);
  
      if( !video_st )
  
      {
  
          cout<<"\nerror in creating a av format new stream";
  
          exit(1);
  
      }
  
  
  
      if (codec_id == AV_CODEC_ID_H264)
  
      {
  
          av_opt_set(outAVCodecContext->priv_data, "preset", "slow", 0);
  
      }
  
  
  
      outAVCodec = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
  
      if (!outAVCodec)
  
      {
  
          cout << "\nerror in finding the av codecs. try again with correct codec";
  
          exit(1);
  
      }
  
  
  
      outAVCodecContext = avcodec_alloc_context3(outAVCodec);
  
      if( !outAVCodecContext )
  
      {
  
          cout<<"\nerror in allocating the codec contexts";
  
          exit(1);
  
      }
  
  
  
      /* set property of the video file */
  
      outAVCodecContext = video_st->codec;
  
      outAVCodecContext->codec_id = AV_CODEC_ID_MPEG4;// AV_CODEC_ID_MPEG4; // AV_CODEC_ID_H264 // AV_CODEC_ID_MPEG1VIDEO
  
      outAVCodecContext->codec_type = AVMEDIA_TYPE_VIDEO;
  
      outAVCodecContext->pix_fmt  = AV_PIX_FMT_YUV420P;
  
      outAVCodecContext->bit_rate = 400000; // 2500000
  
      outAVCodecContext->width = 1920;
  
      outAVCodecContext->height = 1080;
  
      outAVCodecContext->gop_size = 3;
  
      outAVCodecContext->max_b_frames = 2;
  
      outAVCodecContext->time_base.num = 1;
  
      outAVCodecContext->time_base.den = 30; //15fps
  
  
  
  
  
      /* Some container formats (like MP4) require global headers to be present
  
         Mark the encoder so that it behaves accordingly. */
  
  
  
      if ( outAVFormatContext->oformat->flags & AVFMT_GLOBALHEADER)
  
      {
  
          outAVCodecContext->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  
      }
  
  
  
      value = avcodec_open2(outAVCodecContext, outAVCodec, NULL);
  
      if( value < 0)
  
      {
  
          cout<<"\nerror in opening the avcodec";
  
          exit(1);
  
      }
  
  
  
      /* create empty video file */
  
      if ( !(outAVFormatContext->flags & AVFMT_NOFILE) )
  
      {
  
       if( avio_open2(&outAVFormatContext->pb , output_file , AVIO_FLAG_WRITE ,NULL, NULL) < 0 )
  
       {
  
        cout<<"\nerror in creating the video file";
  
        exit(1);
  
       }
  
      }
  
  
  
      if(!outAVFormatContext->nb_streams)
  
      {
  
          cout<<"\noutput file dose not contain any stream";
  
          exit(1);
  
      }
  
  
  
      /* imp: mp4 container or some advanced container file required header information*/
  
      value = avformat_write_header(outAVFormatContext , &options);
  
      if(value < 0)
  
      {
  
          cout<<"\nerror in writing the header context";
  
          exit(1);
  
      }
  
  
  
      /*
  
      // uncomment here to view the complete video file informations
  
      cout<<"\n\nOutput file information :\n\n";
  
      av_dump_format(outAVFormatContext , 0 ,output_file ,1);
  
      */
  
  }
  
  
  
  int Recorder::stop() {
  
      threading = false;
  
  
  
      demux->join();
  
      rescale->join();
  
      mux->join();
  
  
  
      return 0;
  
  }
  
  
  
  int Recorder::start() {
  
      initVideoThreads();
  
      return 0;
  
  }
  
  
  
  int Recorder::initVideoThreads() {
  
      demux = new thread(&Recorder::demuxVideoStream, this, pAVCodecContext, pAVFormatContext, VideoStreamIndx);
  
  
  
      rescale = new thread(&Recorder::rescaleVideoStream, this, pAVCodecContext, outAVCodecContext);
  
  
  
      demux = new thread(&Recorder::encodeVideoStream, this, outAVCodecContext);
  
      return 0;
  
  }
  
  
  
  void Recorder::demuxVideoStream(AVCodecContext* codecContext, AVFormatContext* formatContext, int streamIndex)
  
  {
  
      // init packet
  
      AVPacket* packet = (AVPacket*)av_malloc(sizeof(AVPacket));
  
      av_init_packet(packet);
  
  
  
      int ctr = 0;
  
  
  
      while (threading)
  
      {
  
          if (av_read_frame(formatContext, packet) < 0) {
  
              exit(1);
  
          }
  
  
  
          if (packet->stream_index == streamIndex)
  
          {
  
              int return_value; // = 0;
  
              ctr++;
  
  
  
              do
  
              {
  
                  return_value = avcodec_send_packet(codecContext, packet);
  
              } while (return_value == AVERROR(EAGAIN) && threading);
  
  
  
              //int i = avcodec_send_packet(codecContext, packet);
  
              if (return_value < 0 && threading) { // call Decoder
  
                  cout << "unable to decode video";
  
                  exit(1);
  
              }
  
          }
  
      }
  
  
  
      avcodec_send_packet(codecContext, NULL); // flush decoder
  
  
  
      // return 0;
  
  }
  
  
  
  void Recorder::rescaleVideoStream(AVCodecContext* inCodecContext, AVCodecContext* outCodecContext)
  
  {
  
      bool closing = false;
  
      AVFrame* inFrame = av_frame_alloc();
  
      if (!inFrame)
  
      {
  
          cout << "\nunable to release the avframe resources";
  
          exit(1);
  
      }
  
  
  
      int nbytes = av_image_get_buffer_size(outAVCodecContext->pix_fmt, outAVCodecContext->width, outAVCodecContext->height, 32);
  
      uint8_t* video_outbuf = (uint8_t*)av_malloc(nbytes);
  
      if (video_outbuf == NULL)
  
      {
  
          cout << "\nunable to allocate memory";
  
          exit(1);
  
      }
  
  
  
      AVFrame* outFrame = av_frame_alloc();//Allocate an AVFrame and set its fields to default values.
  
      if (!outFrame)
  
      {
  
          cout << "\nunable to release the avframe resources for outframe";
  
          exit(1);
  
      }
  
  
  
      // Setup the data pointers and linesizes based on the specified image parameters and the provided array.
  
      int value = av_image_fill_arrays(outFrame->data, outFrame->linesize, video_outbuf, AV_PIX_FMT_YUV420P, outAVCodecContext->width, outAVCodecContext->height, 1); // returns : the size in bytes required for src
  
      if (value < 0)
  
      {
  
          cout << "\nerror in filling image array";
  
      }
  
      int ctr = 0;
  
  
  
      while (threading || !closing) {
  
          int value = avcodec_receive_frame(inCodecContext, inFrame);
  
          if (value == 0) {
  
              ctr++;
  
              SwsContext* swsCtx_ = sws_getContext(inCodecContext->width,
  
                  inCodecContext->height,
  
                  inCodecContext->pix_fmt,
  
                  outAVCodecContext->width,
  
                  outAVCodecContext->height,
  
                  outAVCodecContext->pix_fmt,
  
                  SWS_BICUBIC, NULL, NULL, NULL);
  
              sws_scale(swsCtx_, inFrame->data, inFrame->linesize, 0, inCodecContext->height, outFrame->data, outFrame->linesize);
  
  
  
  
  
              int return_value;
  
              do
  
              {
  
                  return_value = avcodec_send_frame(outCodecContext, outFrame);
  
              } while (return_value == AVERROR(EAGAIN) && threading);
  
          }
  
          closing = (value == AVERROR_EOF);
  
      }
  
      avcodec_send_frame(outCodecContext, NULL);
  
  
  
  
  
      // av_free(video_outbuf);
  
  
  
      // return 0;
  
  }
  
  
  
  void Recorder::encodeVideoStream(AVCodecContext* codecContext)
  
  {
  
      bool closing = true;
  
      AVPacket* packet = (AVPacket*)av_malloc(sizeof(AVPacket));
  
      av_init_packet(packet);
  
  
  
      int ctr = 0;
  
  
  
      while (threading || !closing) {
  
          packet->data = NULL;    // packet data will be allocated by the encoder
  
          packet->size = 0;
  
          ctr++;
  
          int value = avcodec_receive_packet(codecContext, packet);
  
          if (value == 0) {
  
              if (packet->pts != AV_NOPTS_VALUE)
  
                  packet->pts = av_rescale_q(packet->pts, video_st->codec->time_base, video_st->time_base);
  
              if (packet->dts != AV_NOPTS_VALUE)
  
                  packet->dts = av_rescale_q(packet->dts, video_st->codec->time_base, video_st->time_base);
  
  
  
              //printf("Write frame %3d (size= %2d)\n", j++, packet->size / 1000);
  
              if (av_write_frame(outAVFormatContext, packet) != 0)
  
              {
  
                  cout << "\nerror in writing video frame";
  
              }
  
          }
  
  
  
          closing = (value == AVERROR_EOF);
  
      }
  
  
  
      value = av_write_trailer(outAVFormatContext);
  
      if (value < 0)
  
      {
  
          cout << "\nerror in writing av trailer";
  
          exit(1);
  
      }
  
  
  
      // av_free(packet);
  
  
  
      // return 0;
  
  }
  
  
  
  
  
  int Recorder::openScreen(AVFormatContext* pFormatCtx) {
  
      /*
  
  
  
      X11 video input device.
  
      To enable this input device during configuration you need libxcb installed on your system. It will be automatically detected during configuration.
  
      This device allows one to capture a region of an X11 display.
  
      refer : https://www.ffmpeg.org/ffmpeg-devices.html#x11grab
  
      */
  
      /* current below is for screen recording. to connect with camera use v4l2 as a input parameter for av_find_input_format */
  
      pAVInputFormat = av_find_input_format("gdigrab");
  
      //value = avformat_open_input(&pAVFormatContext, ":0.0+10,250", pAVInputFormat, NULL);
  
  
  
      value = avformat_open_input(&pAVFormatContext, "desktop", pAVInputFormat, NULL);
  
      if (value != 0)
  
      {
  
          cout << "\nerror in opening input device";
  
          exit(1);
  
      }
  
      return 0;
  
  }