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• Adjust MP3 Files Volume and save it to new file [duplicate]

  5 mai 2017, par Gio Vanno

  This question already has an answer here :

  • Mute specified sections of an audio file using ffmpeg
    
    1 answer
    

  I’m trying to make an audio-editing app here
  This program can adjust(increase and decrease) the mp3 file volume at the specific time(adjust start time and finish time, example : from 00:10 to 00:20) and we can save it to a new mp3 file.

  my questions is :

  -Does ffmpeg work for it ?

  -is there any alternative besides ffmpeg ?

  Thank you

• Read, process and save video and audio with FFMPEG

  3 mai 2017, par sysseon

  I want to open a video resource with ffmpeg on Python, get the read frames from the pipe, modify them (e.g. put the timestamp with OpenCV) and write the result to an output video file. I also want to save the audio source with no changes.

  My code (with no audio and two processes) :

  import subprocess as sp
  
  import numpy as np
  
  # import time
  
  # import cv2
  
  
  
  FFMPEG_BIN = "C:/ffmpeg/bin/ffmpeg.exe"
  
  INPUT_VID = 'input.avi'
  
  res = [320, 240]
  
  
  
  command_in = [FFMPEG_BIN,
  
                '-y',  # (optional) overwrite output file if it exists
  
                '-i', INPUT_VID,
  
                '-f', 'image2pipe',  # image2pipe or rawvideo?
  
                '-pix_fmt', 'bgr24',
  
                '-vcodec', 'rawvideo',
  
                '-']
  
  
  
  command_out = [FFMPEG_BIN,
  
                 '-y',  # (optional) overwrite output file if it exists
  
                 '-f', 'rawvideo',
  
                 '-vcodec', 'rawvideo',
  
                 '-s', '320x240',
  
                 '-pix_fmt', 'bgr24',
  
                 '-r', '25',
  
                 '-i', '-',
  
                 # '-i', INPUT_VID,    # Audio
  
                 '-vcodec', 'mpeg4',
  
                 'output.mp4']
  
  
  
  pipe_in = sp.Popen(command_in, stdout=sp.PIPE, stderr=sp.PIPE)
  
  pipe_out = sp.Popen(command_out, stdin=sp.PIPE, stderr=sp.PIPE)
  
  
  
  while True:
  
      # Read 320*240*3 bytes (= 1 frame)
  
      raw_image = pipe_in.stdout.read(res[0] * res[1] * 3)
  
      # Transform the byte read into a numpy array
  
      image = np.fromstring(raw_image, dtype=np.uint8)
  
      image = image.reshape((res[1], res[0], 3))
  
      # Draw some text in the image
  
      # draw_text(image)
  
  
  
      # Show the image with OpenCV (not working, gray image, why?)
  
      # cv2.imshow("VIDEO", image)
  
  
  
      # Write image to output process
  
      pipe_out.stdin.write(image.tostring())
  
  
  
  print 'done'
  
  pipe_in.kill()
  
  pipe_out.kill()

  1. Could it be done with just a process ? (Read the input from a file,
     put it in the input pipe, get the image, process it, and put it in
     the output pipe to be saved into a video file)
  2. How can I save the audio ? In this example, I could use ’-i
     INPUT_VID’ in the second process to get the audio channel, but my
     source will be a RTSP, and I don’t want to create a connection for
     each process. Could I put video+audio in the pipe and rescue and
     separate it with numpy ? How ?
  3. I use a loop to process the frames and wait until I get an error.
     How can I check if all frames are already read ?
  4. Not important, but if I try to show the images with OpenCV
     (cv2.imshow(...)), I only see a gray screen. Why ?

• Save RTP vp8 payload packets to .webm file

  17 mai 2017, par Ibrahim

  I have saved a video call to a .pcap file with Wireshark, and I want to acquire the video from RTP packets. RTP packets payload type is vp8, I could find out the vp8 RTP packets by using libpcap library in C++. Then I saved the contents of all RTP vp8 packets to a file. But i can not convert this raw vp8 data to .mp4 by using ffmpeg. ffmpeg gives error during conversion. ffmpeg conversion error : Invalid data found when processing input

  What are the steps to get .mp4 or .webm video file from vp8 RTP packets ?

  Edit : I could get raw VP8 data excluding VP8 payload descriptor, payload header and keyframe header. Then I added ivf header and frame header for each vp8 raw frame, according to ivf document
  ivf document

  But When I want to convert my ivf file (output1) to output1.mp4 by using ffmpeg

  ffmpeg -i output1 -c:v vp8 output1.mp4

  I get errors