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• Why is image loading from ffmpeg using stdout slow ?

  23 octobre 2017, par Jirka Šáda

  I was just experimenting with FFMPEG, and wrote this testing piece of code, that is reading frames from FFMPEG and displaying them :

  public partial class MainWindow : Window
  
  {
  
      private WriteableBitmap wbm = new WriteableBitmap(1920, 1080, 96, 96, PixelFormats.Rgb24, null);
  
      private IntPtr backBuffer;
  
      private int totalFrames = 0;
  
      private bool drawing = false;
  
  
  
      public MainWindow()
  
      {
  
          InitializeComponent();
  
  
  
          backBuffer = wbm.BackBuffer;
  
  
  
          Thread t = new Thread(new ThreadStart(RunFFMPEG));
  
          t.Start();
  
  
  
          Thread measurer = new Thread(new ThreadStart(Measure));
  
          measurer.Start();
  
      }
  
  
  
      private void Measure()
  
      {
  
          while(true)
  
          {
  
              Thread.Sleep(1000);
  
              Console.Title = "FPS: " + totalFrames;
  
              totalFrames = 0;
  
          }
  
      }
  
  
  
      private void UpdateBitmap()
  
      {
  
          drawing = true;
  
  
  
          wbm.Lock();
  
          wbm.AddDirtyRect(new Int32Rect(0, 0, 1920, 1080));
  
          wbm.Unlock();
  
  
  
          mainImage.Source = wbm;
  
  
  
          drawing = false;
  
      }
  
  
  
      private void RunFFMPEG()
  
      {
  
          totalFrames = 0;
  
  
  
          int length = 1920 * 1080 * 3;
  
  
  
          // start FFMPEG process and pipe standart output
  
          ProcessStartInfo info = new ProcessStartInfo("ffmpeg.exe", "-f dshow -vcodec mjpeg -video_size 1920x1080 -framerate 30 -i video=\"A4 TECH HD PC Camera\" -y -pix_fmt rgb24 -f rawvideo -framerate 30 pipe:1");
  
          info.WindowStyle = ProcessWindowStyle.Hidden;
  
          info.UseShellExecute = false;
  
          info.CreateNoWindow = true;
  
          info.RedirectStandardOutput = true;
  
  
  
          Process p = new Process();
  
          p.StartInfo = info;
  
          p.Start();
  
  
  
          while (true) // read frames from standart output
  
          {
  
  
  
              byte[] data = new byte[length];
  
  
  
              for (int i = 0; i < length; i++) // read byte by byte, if we call normal Read(), the returned array is always mostly empty
  
                  data[i] = (byte)p.StandardOutput.BaseStream.ReadByte();
  
  
  
              if (!drawing)
  
              {
  
                  Marshal.Copy(data, 0, backBuffer, length);
  
                  Dispatcher.Invoke(() => UpdateBitmap()); // we are not in UI thread
  
              }
  
  
  
              totalFrames++;
  
          }
  
      }   
  
  }

  The problem is, although I get around 17-20 FPS reported, the Image is redrawing very very slowly (once or twice per a second) and even though the mainImage.Source =... line takes always similar amount of time, the speed at which the Image visually updates itself is getting progressively slower. What could be the cause ?? Thanks for any tips

  PS : I know the code is ugly and not following MVVM pattern, but it’s just and only for testing, please don’t hate me :-)

  Edit : The problem is not speed at which I’m reading from stdout, that’s fine (20 FPS), the problem is, that WPF Image is visually updating very slowly

• Problems with video playback using the ffplay

  7 octobre 2023, par Anzor Gergov

  everyone. I have problems with video playback using the ffplay. Used the following command

  



  ffplay -i input.avi


  



  But the following error occurred.

  



  ffplay version N-87353-g183fd30 Copyright (c) 2003-2017 the FFmpeg developers
  built with gcc 7.2.0 (GCC)
  configuration: --disable-static --enable-shared --enable-gpl --enable-version3 --enable-cuda --enable-cuvid --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib
  libavutil      55. 76.100 / 55. 76.100
  libavcodec     57.106.101 / 57.106.101
  libavformat    57. 82.101 / 57. 82.101
  libavdevice    57.  8.101 / 57.  8.101
  libavfilter     6.105.100 /  6.105.100
  libswscale      4.  7.103 /  4.  7.103
  libswresample   2.  8.100 /  2.  8.100
  libpostproc    54.  6.100 / 54.  6.100
[avi @ 00000000024bd9e0] Could not find codec parameters for stream 0 (Video: none (HEVC / 0x43564548), none, 1920x1080, 1697 kb/s): unknown codec
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, avi, from 'c:\problem.avi':
  Duration: 00:00:25.00, start: 0.000000, bitrate: 1701 kb/s
    Stream #0:0: Video: none (HEVC / 0x43564548), none, 1920x1080, 1697 kb/s, 30.92 fps, 30.92 tbr, 30.92 tbn, 30.92 tbc
No codec could be found with id 0
Failed to open file 'c:\problem.avi' or configure filtergraph


  



  This video is playable without any problems via the VLC, Media Player Classic. 
After trying to find out more information about the video file, I used ffprobe command

  



  ffprobe -v 0  c:\problem.avi -print_format json -show_format -show_streams

{
    "streams": [
        {
            "index": 0,
            "codec_type": "video",
            "codec_tag_string": "HEVC",
            "codec_tag": "0x43564548",
            "width": 1920,
            "height": 1080,
            "has_b_frames": 0,
            "sample_aspect_ratio": "0:1",
            "display_aspect_ratio": "0:1",
            "level": -99,
            "r_frame_rate": "773/25",
            "avg_frame_rate": "773/25",
            "time_base": "25/773",
            "start_pts": 0,
            "start_time": "0.000000",
            "duration_ts": 773,
            "duration": "25.000000",
            "bit_rate": "1697304",
            "nb_frames": "773",
            "disposition": {
                "default": 0,
                "dub": 0,
                "original": 0,
                "comment": 0,
                "lyrics": 0,
                "karaoke": 0,
                "forced": 0,
                "hearing_impaired": 0,
                "visual_impaired": 0,
                "clean_effects": 0,
                "attached_pic": 0,
                "timed_thumbnails": 0
            }
        }
    ],
    "format": {
        "filename": "c:\\bin\\Virtual\\problem\\problem.avi",
        "nb_streams": 1,
        "nb_programs": 0,
        "format_name": "avi",
        "format_long_name": "AVI (Audio Video Interleaved)",
        "start_time": "0.000000",
        "duration": "25.000000",
        "size": "5318210",
        "bit_rate": "1701827",
        "probe_score": 100
    }
}


  



  What could be the problem with this videofile ?

  


• How can i merge two videos using ffmpeg ?

  10 novembre 2017, par hasib prince

  I am using writingminds:FFmpegAndroid:0.3.2 library.and facing this permission denied issue.

  D/Video merging :: progress: /storage/emulated/0/DCIM/Camera/VID_20171109_070248.mp4: Permission denied

  11-10 17:35:09.905 10592-10592/com.example.hasib.vjoiner D/Video merging: : failure : ffmpeg version n3.0.1 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 4.8 (GCC)

                                                                           libavutil      55. 17.103 / 55. 17.103
  
                                                                           libavcodec     57. 24.102 / 57. 24.102
  
                                                                           libavformat    57. 25.100 / 57. 25.100
  
                                                                           libavdevice    57.  0.101 / 57.  0.101
  
                                                                           libavfilter     6. 31.100 /  6. 31.100
  
                                                                           libswscale      4.  0.100 /  4.  0.100
  
                                                                           libswresample   2.  0.101 /  2.  0.101
  
                                                                           libpostproc    54.  0.100 / 54.  0.100
  
                                                                         /storage/emulated/0/DCIM/Camera/VID_20171109_070248.mp4: Permission denied

  11-10 17:35:09.905 10592-10592/com.example.hasib.vjoiner D/Video merging: : finished

  and this is the command i was going to execute.

  String[] command = new String[]{"-y", "-i", videoPaths.get(0), "-i", videoPaths.get(1).toString(), "-strict", "experimental", "-filter_complex",
  
              "[0:v]scale=iw*min(1920/iw\\,1080/ih):ih*min(1920/iw\\,1080/ih), pad=1920:1080:(1920-iw*min(1920/iw\\,1080/ih))/2:(1080-ih*min(1920/iw\\,1080/ih))/2,setsar=1:1[v0];[1:v] scale=iw*min(1920/iw\\,1080/ih):ih*min(1920/iw\\,1080/ih), pad=1920:1080:(1920-iw*min(1920/iw\\,1080/ih))/2:(1080-ih*min(1920/iw\\,1080/ih))/2,setsar=1:1[v1];[v0][0:a][v1][1:a] concat=n=2:v=1:a=1",
  
              "-ab", "48000", "-ac", "2", "-ar", "22050", "-s", "1920x1080", "-vcodec", "libx264", "-crf", "27", "-q", "4", "-preset", "ultrafast", outputPath + "/output.mp4"};