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• Modifying CISCO openh264 to take image frames and out compressed frames

  16 mai 2017, par Khurram Amin

  Has anyone tried to modify the CISCO openh264 library to take JPEG images as input and compress them into P and I frames (output as frames, NOT video) and similarly to modify decoder to take compressed P and I frames and generate uncompressed-frames ?

  I have a camera looking at a static scene and taking pictures (1280x720p) every 30 second. The scene is almost static. Currenlty I am using JPEG compression to compress each frame individually and it is resulting in an image size of 270KB. This compressed frame is transferred via internet to a storage server. Since there is very little motion in the scene, the ’I’ frame size will be very small (I think it should be 20-50KB). So it will be very cost effective to transmit I frames over internet instead of JPEG images.

  Can anyone guide me to some project or about how to proceed with this task ?

• Concatenate list of streams with ffmpeg

  16 novembre 2019, par oioioi

  I’d like to write python code, automatically rearranging the scenes of a video. How do I use ffmpeg-python to concatenate a list of n streams/scenes ? What is the easiest way to merge those scenes with their audio counterpart ?
  Unfortunately, I couldn’t figure out how to do it properly.

  The status quo :

  import os
  
  
  
  import scenedetect
  
  from scenedetect.video_manager import VideoManager
  
  from scenedetect.scene_manager import SceneManager
  
  from scenedetect.frame_timecode import FrameTimecode
  
  from scenedetect.stats_manager import StatsManager
  
  from scenedetect.detectors import ContentDetector
  
  
  
  import ffmpeg
  
  
  
  STATS_FILE_PATH = 'stats.csv'
  
  
  
  def main():
  
  
  
      for root, dirs, files in os.walk('material'):
  
          for file in files:
  
              file = os.path.join(root, file)
  
              print(file)
  
              video_manager = VideoManager([file])
  
              stats_manager = StatsManager()
  
              scene_manager = SceneManager(stats_manager)
  
              scene_manager.add_detector(ContentDetector())
  
              base_timecode = video_manager.get_base_timecode()
  
              end_timecode = video_manager.get_duration()
  
  
  
              start_time = base_timecode
  
              end_time = base_timecode + 100.0
  
              #end_time = end_timecode[2]
  
  
  
              video_manager.set_duration(start_time=start_time, end_time=end_time)
  
              video_manager.set_downscale_factor()
  
              video_manager.start()
  
              scene_manager.detect_scenes(frame_source=video_manager)
  
  
  
              scene_list = scene_manager.get_scene_list(base_timecode)
  
  
  
              print('List of scenes obtained:')
  
              for i, scene in enumerate(scene_list):
  
                  print('    Scene %2d: Start %s / Frame %d, End %s / Frame %d' % (
  
                      i+1,
  
                      scene[0].get_timecode(), scene[0].get_frames(),
  
                      scene[1].get_timecode(), scene[1].get_frames(),))
  
  
  
                  start = scene[0].get_frames()
  
                  end = scene[1].get_frames()
  
  
  
                  print(start)
  
                  print(end)
  
  
  
                  (
  
                      ffmpeg
  
                      .input(file)
  
                      .trim(start_frame=start, end_frame=end)
  
                      .setpts ('PTS-STARTPTS')
  
                      .output('scene %d.mp4' % (i+1)) 
  
                      .run()
  
                  )
  
  
  
              if stats_manager.is_save_required():
  
                  with open(STATS_FILE_PATH, 'w') as stats_file:
  
                      stats_manager.save_to_csv(stats_file, base_timecode)
  
  
  
  if __name__ == "__main__":
  
      main()

• ffmpeg timecode change detection for html5 Video

  8 janvier 2021, par andrewk82

  Based on this article timecode of scene change detection ffmpeg

  


  i got a file with time-codes for each scene

  


  frame:0    pts:108859  pts_time:1.20954
lavfi.scene_score=0.436456
frame:1    pts:285285  pts_time:3.16983
lavfi.scene_score=0.444537
frame:2    pts:487987  pts_time:5.42208
lavfi.scene_score=0.494256


  


  Now i wanna play those scenes in my HTML-Video Player with Javascript like :

  


  vid.currentTime = 5;


  


  How can i previously convert those (maybe with php) pts_time oder pts in "real" Seconds for my player ? Is there a formula ?

  


  thanks a lot