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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

• lavc/hevcdec : Put slice address checking after hwaccel decode slice

  24 juin 2024, par Fei Wang

  lavc/hevcdec : Put slice address checking after hwaccel decode slice
  Slice address tab only been updated in software decode slice data.
  Fixes hwaccel decoding after d725c737fe2a19091b481d4d115fd939e0a674b2.
  Signed-off-by : Fei Wang <fei.w.wang@intel.com>
  

  • [DH] libavcodec/hevc/hevcdec.c

• lavc/vaapi_encode_h264 : disable B frames in baseline profile

  8 janvier 2017, par Jun Zhao

  lavc/vaapi_encode_h264 : disable B frames in baseline profile
  Disable B frames when using baseline/constrained baseline profile,
  
  following H.264 spec Annex A.2.1.
  Signed-off-by : Jun Zhao <jun.zhao@intel.com>
  
  Signed-off-by : Yi A Wang <yi.a.wang@intel.com>
  
  Signed-off-by : Mark Thompson <sw@jkqxz.net>
  

  • [DH] libavcodec/vaapi_encode_h264.c