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• Generate individual HLS-compatible .ts segments on-demand by downloading as little bytes as possible from a remote input file

  28 juillet 2017, par Romain Cointepas

  I’m trying to generate individual HLS-compatible .ts segments on-demand by downloading/reading as little bytes as possible from a remote input file (hosted on a server supporting byte-ranges requests).

  One of the application for this would be to be able to transcode and play on Apple TV (via Airplay) a remote file that is not Airplay compatible, without having to download the entire file first.

  I am generating the playlist myself, and I have access to the ffprobe results for the remote file (that gives video duration, etc.).

  I have something working that plays via Airplay but with small video and audio glitches between each segments when I use the following command to generate each segment :

  ffmpeg -ss 60 -t 6 -i http://s3.amazonaws.com/misc-12345/avicii.vob -f mpegts -map 0:v:0 -map 0:a:0 -c:v libx264 -bsf:v h264_mp4toannexb -force_key_frames "expr:gte(t,n_forced*6)" -forced-idr 1 -pix_fmt yuv420p -colorspace bt709 -c:a aac -async 1 -preset ultrafast pipe:1

  Note : above command is for segment 11.ts, and in the m3u8 playlist I advertise each segment duration as 6 seconds.

  Here is a Youtube video showing the audio/video glitches between segments :
  https://www.youtube.com/watch?v=0vMwgbSfsu0

  The segment or hls modules of ffmpeg can’t be used because they both generate all the segments at once.

  I’ve been struggling on this for some days now and I would really appreciate some help !

• I'm having difficulties installing ffmpeg on Mac OS so I can use MoviePy. I've done research, but nothing has worked. Any suggestions ?

  31 mars 2018, par shmible

  I’m trying to write a Python program that uses MoviePy on Mac OS 10.11.16 to convert an MP4 file to GIF. I use :

  import moviepy.editor as mp

  and I get an error saying I need to call imageio.plugins.ffmpeg.download() so I can download ffmpeg. I use :

  import imageio
  
  imageio.plugins.ffmpeg.download()

  which gives me the following error :

  Imageio: 'ffmpeg.osx' was not found on your computer; downloading it now.
  
  Error while fetching file: <urlopen error="error" certificate="certificate" verify="verify" failed="failed">.
  
  Error while fetching file: <urlopen error="error" certificate="certificate" verify="verify" failed="failed">.
  
  Error while fetching file: <urlopen error="error" certificate="certificate" verify="verify" failed="failed">.
  
  Error while fetching file: <urlopen error="error" certificate="certificate" verify="verify" failed="failed">.
  
  Traceback (most recent call last):
  
    File "", line 1, in <module>
  
      imageio.plugins.ffmpeg.download()
  
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 55, in download
  
      get_remote_file('ffmpeg/' + FNAME_PER_PLATFORM[plat])
  
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/imageio/core/fetching.py", line 121, in get_remote_file
  
      _fetch_file(url, filename)
  
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/imageio/core/fetching.py", line 177, in _fetch_file
  
      os.path.basename(file_name))
  
  OSError: Unable to download 'ffmpeg.osx'. Perhaps there is a no internet connection? If there is, please report this problem.
  
  </module></urlopen></urlopen></urlopen></urlopen>

  I definitely have an internet connection. I found this link, and tried installing with Homebrew and Static builds, but neither have worked. It seems like compiling it myself would be a little too advanced for me (I’ve only briefly looked into it). I used imageio.plugins.ffmpeg.download() on IDLE. I read something about using PyCharm to run the MoviePy code, but I get the same initial error. ffmpeg is currently in my /usr/local/bin folder. Any suggestions are welcome. Thank for your help.

  Edit : I’m using Python 3.6.1

• My webcam works fine, while using cv2.Videocapture() but while trying to read from hard drive it shows error cap.isOpened() returns false, why ?

  27 septembre 2017, par Hu Yang

  import cv2
  video_capture = cv2.VideoCapture("rtsp ://admin:Trust1986_@10.58.94.47:554/h264/ch1/main/av_stream")
  video_capture.isOpened()

  False

  Other information below here, and ffmpeg I had installed.

    Video I/O:
  
      DC1394 1.x:                  NO
  
      DC1394 2.x:                  NO
  
      FFMPEG:                      NO
  
        avcodec:                   NO
  
        avformat:                  NO
  
        avutil:                    NO
  
        swscale:                   NO
  
        avresample:                NO
  
      GStreamer:                   NO
  
      OpenNI:                      NO
  
      OpenNI PrimeSensor Modules:  NO
  
      OpenNI2:                     NO
  
      PvAPI:                       NO
  
      GigEVisionSDK:               NO
  
      Aravis SDK:                  NO
  
      UniCap:                      NO
  
      UniCap ucil:                 NO
  
      V4L/V4L2:                    NO/NO
  
      XIMEA:                       NO
  
      Xine:                        NO
  
      Intel Media SDK:             NO
  
      gPhoto2:                     NO
  
  
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# ffmpeg -version
  
  ffmpeg version 3.3.4 Copyright (c) 2000-2017 the FFmpeg developers
  
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  
  configuration: 
  
  libavutil      55. 58.100 / 55. 58.100
  
  libavcodec     57. 89.100 / 57. 89.100
  
  libavformat    57. 71.100 / 57. 71.100
  
  libavdevice    57.  6.100 / 57.  6.100
  
  libavfilter     6. 82.100 /  6. 82.100
  
  libswscale      4.  6.100 /  4.  6.100
  
  libswresample   2.  7.100 /  2.  7.100
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# 
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# python3.6m -V
  
  Python 3.6.2
  
  root@ubuntu:/home/face_recognition/opencv/ffmpeg/ffmpeg-3.3.4# pkg-config --modversion opencv  
  
  3.3.0

  what shall I do next step ? Thanks.