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• Convert mp4 video to avi video using imageio package

  3 février 2018, par Li.Chenyang

  I use the python imageio package to convert a .mp4 video to a .avi video, keeping the fps and size same. The following is my code :

  import imageio
  
  
  
  src_dir = "my/source/video.mp4"
  
  dst_dir = "my/dst/video.avi"
  
  
  
  reader = imageio.get_reader(src_dir)
  
  fps = reader.get_meta_data()['fps']
  
  writer = imageio.get_writer(dst_dir, fps=fps)
  
  
  
  for im in reader:
  
      writer.append_data(im[:, :, :])
  
  writer.close()

  I successfully make it.
  However, I find that the video.mp4 is 27.1 MB, while the video.avi is only 3.70 MB.
  Then I use cv2 to do the same thing :

  import cv2
  
  
  
  src_dir = "my/source/video.mp4"
  
  dst_dir = "my/dst/video_1.avi"
  
  
  
  video_cap = cv2.VideoCapture(src_dir)
  
  fps = video_cap.get(cv2.cv.CV_CAP_PROP_FPS)
  
  size = (int(video_cap.get(cv2.cv.CV_CAP_PROP_FRAME_WIDTH)),   
  
          int(video_cap.get(cv2.cv.CV_CAP_PROP_FRAME_HEIGHT)))  
  
  video_writer = cv2.VideoWriter(dst_dir, cv2.cv.CV_FOURCC('M', 'J', 'P', 'G'), fps, size) 
  
  
  
  success, frame = video_cap.read()
  
  while success:
  
      video_writer.write(frame)
  
      success, frame = video_cap.read()

  This time I get a video_1.avi, which is 65.6 MB.
  My questions :

  1. What is the different between these two method, why the video.avi (using imageio method) is so small ;
  2. Is there any problem to use the video.avi (using imageio method) to train a 3D-CNN instead of using video_1.avi (using cv2 method) ?

  ---

  supplement
  Here is the information of my video file :

  lichenyang@lichenyang-All-Series:~/chalearn2014/script$ file video.mp4
  
  video.mp4: ISO Media, MPEG v4 system, version 2
  
  lichenyang@lichenyang-All-Series:~/chalearn2014/script$ file video.avi
  
  video.avi: RIFF (little-endian) data, AVI, 640 x 480, 20.00 fps, video: H.264 X.264 or H.264
  
  lichenyang@lichenyang-All-Series:~/chalearn2014/script$ file video_1.avi
  
  video_1.avi: RIFF (little-endian) data, AVI, 640 x 480, 20.00 fps, video: Motion JPEG

• ffmpeg copy video in video with a specific time

  13 février 2017, par Alkl

  Im new in this topic (beginner) and Im german... So it’s a bit difficult to find the correct words...

  I’ll try to explain what I’ve done and what I want to do :

  1. Extract video area from the original video converted in PRORES codec :

     ffmpeg.exe -i test.mkv -ss 00:06:21.99 -t 00:00:01.94 -async 1 -strict -2 -c:v prores_ks -pix_fmt yuva444p10le -profile:v 4444 -bits_per_mb 8000 -s 1920x1080 cut_video.mov

  2. Edit the cut in After Effects

  3. Convert the PRORES in Matroska

     ffmpeg.exe -i "C :\Users\Alex\Desktop\ffmpeg-20170202-08b0981-win64-static\bin\cut_video\cut_video.mov" -vcodec ffv1 -acodec pcm_s16le temp.mkv

  4. Replace the video area in the originale video file at the time 00:06:21.99...

  I spend 4 hours for the two commands...
  So I despair at the fourth step. Is it possible ? Can you help me ?

  I made a picture, so you can understand better what Im doing... : http://i.imgur.com/HqlNxzW.jpg

  Best regards from germany,

  Alex

• Looking for video libraries for editing video on windows/ios/azure service [on hold]

  17 juillet 2015, par sanyam

  Which library would be a good bet in terms of ...
  1. Richness in features (I want to create a video from short clips and images with effects and filters). Think auto videos created from Google Photos.
  2. Extensibility - I would prefer using similar tech on IOS and Windows apps. Might have to offload some processing to a web service on Azure (windows or linux).
  3. Programmability - An API is preferred over command line as it gives more flexibility and better error handling.

  Given all these options, what is my best bet ? I’ve only looked at ffmpeg till now, is there a better alternative ?