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• FFMPEG segment live video for DASH

  23 décembre 2014, par static

  I’m trying to stream live capture of desktop to my own server, which shall create an MPD with segment template for use with dash.js player.
  Using the following command i managed to get it working
  

  ffmpeg -rtbufsize 6M -f x11grab -s 1366x768 -r 10 -i :0.0 -flags +global_header \
  
  -vcodec libvpx -deadline realtime -profile:v 0 -keyint_min 1 -g 1 -cpu-used 0 \
  
  -vb 1200k -qmin 10 -qmax 42 -threads 4 -bufsize 6000k -slices 4 -map 0 -an \
  
  -f stream_segment -segment_time 2 -segment_format webm **/streams

  The output :

  Input #0, x11grab, from ':0.0': Duration: N/A, start: 1419329032.549498, bitrate: N/A
  
  Stream #0:0: Video: rawvideo (BGRA / 0x41524742), bgra, 1366x768, 10 fps, 10 tbr, 1000k tbn, 10 tbc
  
  [libvpx@ 0x23ccf60] v1.3.0 Output #0, stream_segment, ssegment, to /streams/d':
  
  Metadata:
  
  encoder : Lavf56.15.102
  
  Stream #0:0: Video: vp8 (libvpx), yuva420p, 1366x768, q=10-42, 1200 kb/s, 10 fps, 1k tbn, 10 tbc
  
  Metadata: encoder: Lavc56.13.100 libvpx
  
  Stream mapping: Stream #0:0 -> #0:0 (rawvideo (native) -> vp8 (libvpx))
  
  Press [q] to stop, [?] for help
  
  [swscaler @ 0x23ac0c0] Warning: data is not aligned! This can lead to a speedloss
  
  frame= 2839 fps= 10 q=0.0 Lsize=N/A time=00:04:43.90 bitrate=N/A
  
  video:135246kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

  If I increase the number of frames to produce better quality, the latency drastically increases and the stream is not in sync with the MPD. This is caused by the fact that keyframes are created at every frame -keyint_min 1 -g 1 because otherwise and error MEDIA_ERR_SRC_NOT_SUPPORTED is thrown by the player. This is probably because a keyframe must be found at the beginning of each segment.

  Could ffmpeg be used to generate keyframes as the first frame in each segment ? I try different values for -keyint_min x -g y, for example number of frames but with no result (probably because the number of frames stabilized after a couple a seconds, so the first 2-3 segments were produced with inconsistent number of frames, so all the keyframes were introduced in wrong positions in the segments).

• Create stopmotion video with ffmpeg - error while rendering

  30 mai 2012, par Niklas

  I'm currently creating a stopmotion video with the help of ffmpeg and some scripts I've made. Although in the last clip I attempted to render I had a couple of frames which I've edited. The method I'm using has worked before so I'm certain that it has to do with GIMP changing something with the files. I work with .png-images. This is the command and the output I get :

  ffmpeg -sameq -f image2 -r 7 -i "$src_dir/frame-%06d.png" -r 25 "$dest_dir/$file_name.avi"

  output :

  ffmpeg version 0.8.1-4:0.8.1-0ubuntu1, Copyright (c) 2000-2011 the Libav developers
  
    built on Mar 22 2012 05:09:06 with gcc 4.6.3
  
  This program is not developed anymore and is only provided for compatibility. Use avconv instead (see Changelog for the list of incompatible changes).
  
  Input #0, image2, from '/mnt/storage/selected_frames/005-Middag-Animation/frame-%06d.png':
  
    Duration: 00:00:02.85, start: 0.000000, bitrate: N/A
  
      Stream #0.0: Video: png, bgra, 1280x720, 7 fps, 7 tbr, 7 tbn, 7 tbc
  
  File '/mnt/storage/Videoklipp//005-Middag-Animation.avi' already exists. Overwrite ? [y/N] y
  
  Incompatible pixel format 'bgra' for codec 'mpeg4', auto-selecting format 'yuv420p'
  
  [buffer @ 0x1b88860] w:1280 h:720 pixfmt:bgra
  
  [avsink @ 0x1b8a480] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'out'
  
  [scale @ 0x1b8ab80] w:1280 h:720 fmt:bgra -> w:1280 h:720 fmt:yuv420p flags:0x4
  
  Output #0, avi, to '/mnt/storage/Videoklipp//005-Middag-Animation.avi':
  
    Metadata:
  
      ISFT            : Lavf53.21.0
  
      Stream #0.0: Video: mpeg4, yuv420p, 1280x720, q=2-31, 2 kb/s, 25 tbn, 25 tbc
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press ctrl-c to stop encoding
  
  [buffer @ 0x1b88860] Changing frame properties on the fly is not supported.
  
      Last message repeated 6 times
  
  frame=   13 fps=  0 q=0.0 Lsize=     524kB time=2.20 bitrate=1951.2kbits/s    
  
  video:517kB audio:0kB global headers:0kB muxing overhead 1.323318%

  "[buffer @ 0x1b88860] Changing frame properties on the fly is not supported"

  What can I do to fix this ? Any help is appreciated :)

• How do you run ffmpeg from Java, without crashing ?

  30 juin 2024, par WinnieTheDampoeh

  I try running ffmpeg from Java, and for a couple of moments everything is working fine. I want ffmpeg to record my screen, and split the recording into small clips. The command is working fine from the terminal, but when I run it from Java I get at most 3 clips. Ffmpeg doesn't write anything to the InputStream, so I have no idea what's going wrong.

  


  public static void execute(int frameRate, int width, int height, String windowTitle) {
      String[] args = new String[]{
              path,
              "-hide_banner",
              "-f", "gdigrab",
              "-thread_queue_size", "1024",
              "-rtbufsize", "256M",
              "-framerate", "" + frameRate,
              "-offset_x", "0",
              "-offset_y", "0",
              "-video_size", "" + width + "x" + height,
              "-draw_mouse", "1",
              "-i", "title=" + windowTitle,
              "-c:v", "libx264",
              "-r", "" + frameRate,
              "-preset", "ultrafast",
              "-tune", "zerolatency",
              "-crf", "28",
              "-pix_fmt", "yuv420p",
              "-movflags", "+faststart",
              "-y",
              "-f", "segment",
              "-reset_timestamps", "1",
              "-segment_time", "1",
              "output%06d.mp4"
      };

      try {
          Process p = Runtime.getRuntime().exec(args);
          Thread thread = new Thread(() -> {
              String line;
              BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));

              System.out.println("TEST");
              try {
                  while ((line = input.readLine()) != null)
                      System.out.println(line);

                  System.out.println("Stopping with reading");
                  input.close();
              } catch (IOException e) {
                  e.printStackTrace();
              }
          });
          int exitCode = p.waitFor();
          thread.start();
          thread.join();
          if (exitCode != 0) {
              throw new RuntimeException("FFmpeg exited with code " + exitCode);
          }
      } catch (IOException | InterruptedException e) {
          throw new RuntimeException(e);
      }
  }


  


  I've run the same command in the terminal. That worked fine. I ran the code above, but that resulted in ffmpeg stopping after 3 clips. It kept showing as working from the task manager. As said before, ffmpeg doesn't write anything to the InputStream, even though it normally does write a lot in the terminal. The weird thing is, when I stop my Java program, but accidentally keep ffmpeg running, it suddenly does everything I wanted it to. It didn't capture the things between stopping and closing Java, but after that it continues like it should have.