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• ffmpeg concat converts multiple videos to chipmunk version with half the video silence

  27 mai 2020, par inselmensch

  i try to concat multiple videos to one video and add an background music to it.

  



  for some reason the background music is perfectly added to the output video but the audio of each part of the output is speed up to a chipmunk version of the video itself. this results in an output video of 7 minutes with about 5 minutes of silence since everything is so fast that all the audio finishes after about 2 minutes.

  



  my command is :

  



  ffmpeg -safe 0 -i videolist.ffconcat -i bg_loop.mp3 -y -filter_complex "[1:0]volume=0.3[a1];[0:a][a1]amix=inputs=2" -vcodec libx264 -r 25 -filter:v scale=w=1920:h=1080 -map 0:v:0 output.mp4

  



  i tried to remove the background music (since i wasn't able to loop it through the video i thought maybe that's the issue) and still.. all the audio of the video clips is still speed up resulting in chaotic audio at the beginning and silence at the end.

  



  my video list looks like this :

  



  ffconcat version 1.0
file intro.mp4
file clip-x.mp4
file clip-y.mp4
file clip-x.mp4
file clip-y.mp4
[... and so on]


  



  i hope somebody can tell me what i'm doing wrong here (and maybe how to adjust my command to loop the background music through all the clips)

  



  i googled a bit and found the adjustment of my command to add amix=inputs=2:duration=first but that doesn't do the trick and if i add duration=shortest or duration=longest nothing changes the output audio

  


• Android Java (ffmpeg-kit). Assistance(opinion) with combining 4 ffmpeg commands together

  26 novembre 2022, par D-MAN

  I have the following 4 ffmpeg commands. 1. adds a png frame(border) over the entire length of the video. 2. creates a boomerang effect. 3. adds an outro jpeg to the last 2 seconds of the video. 4. Adds an intro jpeg to the first 2 seconds of the video.(these commands work individually)

  


  My aim is to combine all of these individual commands into one command to create a complete edited video. The final video needs all these elements in one final edited video.

  


  Your assistance is greatly appreciated.

  


  /**
 *

 * (Middle overlay filter) String exe = "-i " + input_video_uri + " -framerate 60 -i " + frame + " -filter_complex [0]pad="+mVideoWidth+":"+mVideoHeight+":576:0[vid];[vid][1]overlay -c:a copy -vcodec mpeg4 -crf 0 -preset ultrafast -qscale 0 " + file2.getAbsolutePath();

 * (Boomerang effect) String exe = "-y -i " + input_video_uri + " -filter_complex [0]reverse[r];[0][r][0]concat=n=3,setpts=0.5*PTS " + file2.getAbsolutePath();

 * (Put image at end of video) String exe = "-i "+ input_video_uri +" -i "+ frame +" -filter_complex \"[0:v][1:v] overlay=0:0:enable='between(t,"+ (msec - 2 ) + ","+ msec+")'\" -pix_fmt yuv420p -c:a copy " + file2.getAbsolutePath();

 * (Put image at start of video) String exe = "-i "+ input_video_uri +" -i "+ frame +" -filter_complex \"[0:v][1:v] overlay=0:0:enable='between(t,0,2)'\" -pix_fmt yuv420p -c:a copy " + file2.getAbsolutePath();

 * */


  


  Being new to ffmpeg, I am limited in knowledge. However, I have tried '&&' which produced an unrecognized error from the ffmpeg library.

  


• IP Camera buffer

  29 juin 2018, par Sergei

  I have ip camera and i connect to it using rtsp through local net. I have very large and heavy images that i need to process (some computer vision algorithms).

  The problem is when i processed some image i need to grab from camera an actual frame (that was captured right now), but images are buffered in memory. I used cv2.VideoCature first, but when i used read() i got an old frame. Now i using subprocess popen method and ffmpeg command. It works, but i can’t clear buffer or set it’s size. I need to store in memory only one last frame.

  Here is my code :

  import subprocess as sp
  
  import numpy as np
  
  import cv2
  
  
  
  def start_process(channel, frame_shape):
  
      frame_shape = frame_shape
  
      frame_size = frame_shape[0] * frame_shape[1] * 3
  
      ffmpeg_command = ['ffmpeg', '-rtsp_transport', 'tcp',
  
              #input location
  
              '-i', 'rtsp://ad:HkoPdx@10.250.0.200:554/cam/realmonitor?channel={}&subtype=0'.format(channel),
  
              '-pix_fmt', 'bgr24', '-vcodec', 'rawvideo', # opencv requires bgr24 pixel format
  
              '-vf', 'fps = 3/1', #framerate
  
              '-f', 'image2pipe', '-']  #yield to pipeline stdout
  
      pipe = sp.Popen(ffmpeg_command, stdout=sp.PIPE, bufsize=24883233)
  
  
  
      #Capture frame-by-frame
  
      while True:  
  
          byte_string = pipe.stdout.read(frame_size)
  
          #print(sys.getsizeof(byte_string)) #24883233
  
          # transform the byte string read into a numpy array
  
          frame = np.fromstring(byte_string, dtype='uint8')
  
          frame = frame.reshape((frame_shape[1], frame_shape[0], 3))
  
          frame_small = cv2.resize(frame, (0, 0), fx=0.15, fy=0.15)
  
          #pipe.stdout.flush()
  
          if frame is not None:
  
              cv2.imshow('Stream', frame_small)
  
              k = cv2.waitKey(1)
  
              if k == 27:   #case Esc
  
                  pipe.kill()
  
                  cv2.destroyAllWindows()
  
                  print('Exit was called')
  
                  return
  
              else:
  
                  pass
  
  
  
  if __name__ == '__main__':
  
      start_process(channel = 56, frame_shape = (3840, 2160))

  bufsize parameter of popen doesnt’t change anything whether i set it 2, 24883233 - my images size in bytes as i got it using sys.getsizeof(byte_string) - or more. There are some changes only when bufsize=0 (the program doesnt work due to images are not stored in buffer). pipe.stdout.flush() also doesn’t work.

  How can i solve this ?