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• Writing frames from camera using skvideo.io.FFmpegWriter

  28 juin 2018, par Liam Deacon

  I’m trying to finely control the video encoding of camera image frames captured on the fly using skvideo.io.FFmpegWriter and cv2.VideoCapture, e.g.

  from skvideo import io
  
  import cv2
  
  
  
  fps = 60
  
  stream = cv2.VideoCapture(0)                    # 0 is for /dev/video0
  
  print("fps: {}".format(stream.set(cv2.CAP_PROP_FPS, fps)))
  
  
  
  stream.set(cv2.CAP_PROP_FRAME_WIDTH, 1920)
  
  stream.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080)
  
  print("bit_depth: {}".format(stream.set(cv2.CAP_PROP_FORMAT, cv2.CV_8U)))
  
  
  
  video = io.FFmpegWriter('/tmp/test_ffmpeg.avi', 
  
              inputdict={'-r': fps, '-width': 1920, '-height': 1080},
  
              outputdict={'-r': fps, '-vcodec': 'libx264', '-pix_fmt': 'h264'}
  
  )
  
  
  
  try:
  
      for i in range(fps*10):  # 10s of video
  
          ret, frame = stream.read()
  
          video.writeFrame(frame)
  
  finally:
  
      stream.release()
  
  
  
  try:
  
      video.close()
  
  except:
  
      pass

  However, I get the following exception (in Jupyter notebook) :

  ---------------------------------------------------------------------------
  
  TypeError                                 Traceback (most recent call last)
  
  
  
   in <module>()
  
       18     while range(fps*10):
  
       19         ret, frame = stream.read()
  
  ---> 20         video.writeFrame(frame)
  
       21 except BaseException as err:
  
       22     raise err
  
  
  
  /usr/local/lib/python3.6/site-packages/skvideo/io/ffmpeg.py in writeFrame(self, im)
  
      446         T, M, N, C = vid.shape
  
      447         if not self.warmStarted:
  
  --> 448             self._warmStart(M, N, C)
  
      449 
  
      450         # Ensure that ndarray image is in uint8
  
  
  
  /usr/local/lib/python3.6/site-packages/skvideo/io/ffmpeg.py in _warmStart(self, M, N, C)
  
      412         cmd = [_FFMPEG_PATH + "/" + _FFMPEG_APPLICATION, "-y"] + iargs + ["-i", "-"] + oargs + [self._filename]
  
      413 
  
  --> 414         self._cmd = " ".join(cmd)
  
      415 
  
      416         # Launch process
  
  
  
  TypeError: sequence item 3: expected str instance, int found
  
  </module>

  Changing this to video.writeFrame(frame.tostring()) results in ValueError: Improper data input, leaving me stumped.

  How should I go about writing each frame (as returned by OpenCV) to my FFmpegWriter instance ?

  EDIT

  The code works fine if I remove inputdict and outputdict from the io.FFmpegWriter call, however this defeats the purpose for me as I need fine control over the video encoding (I am experimenting with lossless/near-lossless compression of the raw video captured from the camera and trying to establish the best compromise in terms of compression vs fidelity for my needs).

• Convert .heic to .jpg using ffmpeg ?

  19 novembre 2018, par Ketan Chauhan

  Using MP4Box :

  MP4Box -info IMG_5915.HEIC

  I get :

  prof colour profile not supported

  prof colour profile not supported

  Root Meta type : "pict" - 52 resource item(s)

  Primary Item - ID 49

  Item #1 - ID 1 - Name :
  .

  .

  .

  Item #49 - ID 49 - Name :

  Item #50 - ID 50 - Name : Item #51 - ID 51 - Name :

  File has no movie (moov) - static data container

  Then if I extract all of these :

  for i in seq 51 ; do MP4Box -dump-item $i:path=item$i.hevc
  IMG_5915.HEIC ; done

  Then if i continue, and convert these tiles to jpeg with ffmpeg it convert one tile to jpeg i.e it creates 51 HEVC tiles.

  ffmpeg -i item1.hevc -frames:v 1 -vsync vfr -q:v 1 -an image1.jpg

  How can I combine these tiles into a single jpg file ?

• How to encode HEVC tile in JPEG ?

  3 juillet 2018, par Ketan Chauhan

  I am trying to convert HEIF file into a JPEG file, I extract HEIC images tiles using MP4Box but when convert these tiles into JPEG using FFMPEG I get this :

  SAKATA-INX:desktop stellar$ MP4Box -dump-item 1:path=item1.hevc
  still_rear.HEIC

  ICC colour profile not supported ICC colour profile not supported

  SAKATA-INX:desktop stellar$ ffmpeg -i item1.hevc -frames:v 1 -vsync
  vfr -q:v 1 -an test.jpg

  ffmpeg version 4.0 Copyright (c) 2000-2018 the FFmpeg developers built
  with Apple LLVM version 9.1.0 (clang-902.0.39.1)

  configuration : —prefix=/usr/local/Cellar/ffmpeg/4.0 —enable-shared
  —enable-pthreads —enable-version3 —enable-hardcoded-tables —enable-avresample —cc=clang —host-cflags= —host-ldflags= —enable-gpl —enable-libmp3lame —enable-libx264 —enable-libx265 —enable-libxvid —enable-opencl —enable-videotoolbox —disable-lzma

  libavutil 56. 14.100 / 56. 14.100

  libavcodec 58. 18.100 / 58. 18.100

  libavformat 58. 12.100 / 58. 12.100

  libavdevice 58. 3.100 / 58. 3.100

  libavfilter 7. 16.100 / 7. 16.100

  libavresample 4. 0. 0 / 4. 0. 0

  libswscale 5. 1.100 / 5. 1.100

  libswresample 3. 1.100 / 3. 1.100

  libpostproc 55. 1.100 / 55. 1.100

  [hevc @ 0x7fc56e808e00] Format hevc detected only with low score of 1,
  misdetection possible !

  [hevc @ 0x7fc56f800000] No start code is found.

  [hevc @ 0x7fc56f800000] missing picture in access unit

  [AVBSFContext @ 0x7fc56e505e00] No start code is found.

  item1.hevc : could not find codec parameters

  Input #0, hevc, from ’item1.hevc’ :

  Duration : N/A, bitrate : N/A

  Stream #0:0: Video: hevc, none, 1200k tbn

  Output #0, image2, to ’test.jpg’ :

  Output file #0 does not contain any stream

  Could any one tell me how I can do this ?