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• Distributing a Python module with ffmpeg dependency

  22 janvier 2015, par arafasse

  Rookie software developer here. I’m working on a Python module that harnesses some functionality from the FFmpeg framework - specifically, the ebur128 filter function. Ideally the module will stand on its own as an independent, platform agnostic tool for verifying that audio clips comply with EBU loudness standards. It’s being designed so that end users need only perform one simple, (hopefully !) painless installation procedure, which will encompass the installation of both the FFmpeg libraries and my Python wrapper/GUI.

  I apologize for the rather vague question, but does anyone have general advice for creating Python module with external dependencies, or specific advice for standardizing the FFmpeg installation across platforms ? Distutils seems pretty helpful – are there other guidelines or standard practices for developing a neatly packaged Python tool ? I want to minimize any installation headaches for end users.

  Thanks very much.

• FFMpeg v4l2m2m green output

  16 avril 2020, par Roman Honcharenko

  I'm using hardware encoding via FFMPEG and h264_v4l2m2m codec.

  



  If I'm using FFmpeg h264_v4l2m2m, the encoded video looks like this

  



  ffmpeg -i small.mp4 -vcodec h264_v4l2m2m grb_2-v4l2.avi

[h264_v4l2m2m @ 0x13d24d0] driver 'bcm2835-codec' on card 'bcm2835-codec-isp'
[h264_v4l2m2m @ 0x13d24d0] driver 'bcm2835-codec' on card 'bcm2835-codec-encode'
[h264_v4l2m2m @ 0x13d24d0] Using device /dev/video11
[h264_v4l2m2m @ 0x13d24d0] driver 'bcm2835-codec' on card 'bcm2835-codec-encode'
[h264_v4l2m2m @ 0x13d24d0] Failed to set number of B-frames
    Last message repeated 1 times
[h264_v4l2m2m @ 0x13d24d0] Failed to set header mode
[h264_v4l2m2m @ 0x13d24d0] Failed to set gop size
[h264_v4l2m2m @ 0x13d24d0] h264 profile not found
[h264_v4l2m2m @ 0x13d24d0] Encoder adjusted: qmin (0), qmax (51)
[h264_v4l2m2m @ 0x13d24d0] Failed to set minimum video quantizer scale
[h264_v4l2m2m @ 0x13d24d0] Failed to set maximum video quantizer scale


  



  And while processing :

  



  [avi @ 0x145aa20] Non-monotonous DTS in output stream 0:0; previous: 0, current: 0; changing 
to 1. This may result in incorrect timestamps in the output file.


  



  If the video container is not AVI, then the resulting video is blank.

  



  I want to use this encoder as a backend codec for OpenCV. If I'm trying to use it, I'm getting the following error :

  



  This encoder requires using the avcodec_send_frame() API


  



  What is the workaround and where should I look ?

  



  

  • Machine : Raspberry Pi 4B+

  


  • System : Custom Yocto Distribution (master branches)

  


  • OpenCV version : 4.1.0

  


  • FFMpeg version : 4.2.2

  


  


• ffmpeg record audio from Xvfb on Centos

  25 mai 2017, par boygiandi

  I’m trying to record audio from Xvfb. And I have some problems :

  1. What’s the different between alsa and pulse. I get confuse
  2. Server Centos have no soud card :

  arecord -l

  arecord : device_list:268 : no soundcards found...

  3. I may have many Xvfb process, how to record video and audio from specific Xvfb process. I checked this https://trac.ffmpeg.org/wiki/Capture/ALSA#Recordaudiofromanapplication but still don’t understand how it works.

  ffmpeg -f alsa -ac 2 -i hw:0,0 -acodec pcm_s16le output.wav

  I seen many command like this, but I don’t know how to get hw:0,0 ( id of sound card ? )

  Please help. Thanks