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• ffmpeg : Send mp4 to fake webcam, "Invalid argument"

  9 avril 2020, par Joe Bid

  Trying to create a new fake webcam device (/dev/video2) and play a video on it so I can use it as a virtual webcam.

  



  Steps I took :

  



  sudo apt-get install v4l2loopback-dkms
sudo modprobe v4l2loopback
sudo depmod -a

ffmpeg -i vid1.mp4 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video2


  



  The error from the ffmpeg command :

  



  ioctl(VIDIOC_G_FMT): Invalid argument
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 0:0
Conversion failed!


  



  No idea what to do.

  


• Pydub wma to mp3 fixing "library configuration mismatch"

  21 juillet 2020, par Rich

  Python novice, looking to change that.

  


  I am trying to convert a song from wma to mp3 while keeping the metadata on the song. Here is my code.

  


  #musicproject.py
import os
import glob
from pydub import AudioSegment

music_dir ='/mnt/c/renameproject'
extension_list = ('*.wma')

os.chdir(music_dir)
for extension in extension_list:
    for song in glob.glob(extension):
        mp3_filename = os.path.splitext(os.path.basename(song))[0] + '.mp3'
        AudioSegment.from_file(song).export(mp3_filename, format='mp3')


  


  The program finishes and the song is written as an mp3 in the same folder and plays just fine. Unfortunately all of the metadata has been stripped from the song. I get the following warning at the command line when I run the program. My theory on the problem is that there is a mismatch between pydub and ffmpeg as far as the metadata library goes so pydub is feeding in something that ffmpeg doesn't understand so it pukes. I have absolutely no idea what steps to take to fix it from here. Any breadcrumbs would be appreciated. Thanks.

  


  File "./musicproject.py", line 12, in <module>&#xA;    AudioSegment.from_file(song).export(mp3_filename, format=&#x27;mp3&#x27;)&#xA;  File "/home/tom/.local/lib/python2.7/site-packages/pydub/audio_segment.py", line 725, in from_file&#xA;    p.returncode, p_err.decode(errors=&#x27;ignore&#x27;) ))&#xA;pydub.exceptions.CouldntDecodeError: Decoding failed. ffmpeg returned error code: 1&#xA;&#xA;Output from ffmpeg/avlib:&#xA;&#xA;ffmpeg version 3.4.6-0ubuntu0.18.04.1 Copyright (c) 2000-2019 the FFmpeg developers&#xA;  built with gcc 7 (Ubuntu 7.3.0-16ubuntu3)&#xA;  configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy &#xA;--enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared&#xA;  WARNING: library configuration mismatch&#xA;  avcodec     configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared --enable-version3 --disable-doc --disable-programs --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libtesseract --enable-libvo_amrwbenc&#xA;  libavutil      55. 78.100 / 55. 78.100&#xA;  libavcodec     57.107.100 / 57.107.100&#xA;  libavformat    57. 83.100 / 57. 83.100&#xA;  libavdevice    57. 10.100 / 57. 10.100&#xA;  libavfilter     6.107.100 /  6.107.100&#xA;  libavresample   3.  7.  0 /  3.  7.  0&#xA;  libswscale      4.  8.100 /  4.  8.100&#xA;  libswresample   2.  9.100 /  2.  9.100&#xA;  libpostproc    54.  7.100 / 54.  7.100&#xA;musicproject.py: Invalid data found when processing input&#xA;</module>

  


• How to fix "moov atom not found" when extracting an image from partial video mp4 file ?

  1er septembre 2020, par Epsiloncool

  I think the problem is relatively common, but I can't find any good solution to my problem.
Well, I need to create a preview of the video while it uploads. It can be a very big video, so I decided to use only the first 10 Mb of video to make image extraction with ffmpeg.

  


  The command-line looks like this

  


  ffmpeg -ss 00:00:00 -i "src.mp4" -frames:v 1 -q:v 2 "preview.jpg"

  


  It works fine for lots of video files, but for mp4 it always failed with the error message "Moov atom not found". I guess the mp4 format is not streamable and the cut file looks like a broken video for the FFmpeg.

  


  But there should be a solution to this. Could you help me ?