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• python3 openCV VideoCapture only black image (Raspbian Stretch)

  21 juin 2018, par PrimuS

  I have a little python function that analyzes a video, chunks it into one image per second and gives me the most dominant color for that image. (Code can be found here : https://github.com/primus852/python-movie-barcode)

  This works great on my Windows testing environment. However, on my Rasbian Stretch Raspberry Pi Setup it only produces a black image, as the source seems to be black.

  I compiled OpenCV (3.4.1) myself with this great article : https://www.pyimagesearch.com/2017/09/04/raspbian-stretch-install-opencv-3-python-on-your-raspberry-pi/, and it worked perfectly fine. I am using python3 and a virtualenv.

  I tried adding the ffmpeg package : apt install ffmpeg, to no avail.

  2 ideas

  • I compiled the openCV source without support for mkv/mp4/similar ? If so, how would I check that and can I just "re-compile" the whole package ?
  • I am missing codecs, where would I be able to check that ?

  The crucial code (I think) is this :

  cap = cv2.VideoCapture(full_path) are there other options that do not break the majority of my code ? I read about skvideo.io from scikit-video but that does not seem to work with my code...

  I am new to python, any hint is appreciated

  // EDIT, I think it is not a duplicate because I pass the I get no error that the capture cannot be opened and :

  OpenCV FFMPEG support :

  • python -c "import cv2; print(cv2.getBuildInformation())" | grep -i ffmpeg
    • returns : FFMPEG: YES

  FFMPEG Codec :

  • ffmpeg -codecs | grep -i avc (file is using AVC)
    • returns : DEV.LS h264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (decoders: h264 h264_mmal h264_vdpau ) (encoders: libx264 libx264rgb h264_omx h264_vaapi )

  File PATH

  It exists and the path is correct...

  Any other ideas ? Could it possibly the virtualenv ?

  //EDIT2

  Tried with an AVI file

  works...

• Android encode video with ffmpeg while it is still recording

  30 décembre 2016, par Andreas Pabst

  I want to develop an android aplication which allows me to continuously record a video and upload parts of the video to a server without stopping the recording.
  It is crucial for the application that I can record up to 60 min without stopping the video.

  Initial approach

  Application consits of two parts :

  1. MediaRecorder which records a video continuously from the camera.
  2. Cutter/Copy - Part : While the video is recorded I have to take out certain segments and send them to a server.
     This part was implemented using http://ffmpeg4android.netcompss.com/
     libffmpeg.so. I used their VideoKit Wrapper which allows me to directly run ffmpeg with any params I need.

  My Problem

  I tried the ffmpeg command with the params

  ffmpeg -ss 00:00:03 -i  -t 00:00:05 -vcodec copy -acodec copy  

  which worked great for me as long as Android’s MediaRecorder finished recording.

  When I execute the same command, while the MediaRecorder is recording the file, ffmpeg exits with the error message "Operation not permitted".

  • I think that the error message doesn’t mean that android prevents the access to the file. I think that ffmpeg needs the "moov-atoms" to find the proper position in the video.

  For that reason I thought of other approaches (which don’t need the moov-atom) :

  1. Create a rtsp stream with android and access the rtsp stream later. The problem is that to my knowledge android SDK doesn’t support the recording to a rtsp stream.
  2. Maybe it is possible to access the camera directly with ffmpeg (/dev/video0 seems to be a video device ?!)
  3. I read about webm as an alternative for streaming, maybe android can record webm streams ?!

  TLDR : Too long didn’t read :

  I want to access a video file with ffmpeg (libffmpeg.so) while it is recording. Fffmpeg exits with the error message "Operation not permitted"

  Goal :

  My goal is to record a video (and audio) and take parts of the video while it is still recording and upload them to the server.

  Maybe you can help me solve the probelm or you have other ideas on how to approach my problem.

  Thanks a lot in advance.

• ffmpeg transcoding move to mp4

  16 août 2022, par Paul

  I currently use windows free software called : AnyVideoConverter to convert my iPhone huge MOV files to MP4s that can be played on other devices via my plex server.
I want to automate that process so it runs in the background on one of my linux machines.
However I am struggling to get it working. Here is what I have so far.

  


  Original file details :
Duration : 00:00:13.53
Original Video : 40MB
Video details : Stream #0:0(und) : Video : hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, bt709), 3840x2160, 23453 kb/s, 30 fps, 30 tbr, 600 tbn, 600 tbc (default)

  


  AnyVideoConverted file :
File Size : 5MB
Video Details : Stream #0:0(und) : Video : h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 3840x2160, 2870 kb/s, 24 fps, 24 tbr, 12288 tbn, 48 tbc (default)

  


  This format works great on all my devices

  


  So far the closes I managed to get to that is this ffmpeg command :

  


  ffmpeg -i original.mov -c:v libx264 -profile:v baseline -maxrate 3M -bufsize 3M -c:a aac -b:a 128k x264.mp4


File size:5MB
Video details :     Stream #0:0(und) : Video : h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 2160x3840, 3063 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)

  


  problem is that when I try to play it via plex I get :

  


  Playback Error : This server is not powerful enough to convert video

  


  What am I doing wrong here ?

  


  My knowledge of ffmpeg or video encoding/transcoding is zero. Can someone advise me how to get my mov files converted to mp4 so they can be played via plex without additional transcoding by plex and without reducing the resolution size of the converted video.

  


  Any pointers ?
Thanks