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• Python librosa NoBackendError even though ffmpeg is installed

  11 avril 2020, par Slavko Kovačević

  I recently installed librosa (package I've been using for a while on different PC) on my new PC with Windows 10 running. After that I've downloaded latest static version of ffmpeg and copied it to C: and added it to the Path. Tested ffmpeg and it works like a charm ! For python I am using Anaconda environment and after starting Jupyter Notebook and running librosa.load(path, sr = None) I've got

  



   in <module>&#xA;----> 1 audio = librosa.load(pathToJson)&#xA;&#xA;~\anaconda3\envs\tf_gpu\lib\site-packages\librosa\core\audio.py in load(path, sr, mono, offset, duration, dtype, res_type)&#xA;    117 &#xA;    118     y = []&#xA;--> 119     with audioread.audio_open(os.path.realpath(path)) as input_file:&#xA;    120         sr_native = input_file.samplerate&#xA;    121         n_channels = input_file.channels&#xA;&#xA;~\anaconda3\envs\tf_gpu\lib\site-packages\audioread\__init__.py in audio_open(path, backends)&#xA;    114 &#xA;    115     # All backends failed!&#xA;--> 116     raise NoBackendError()&#xA;&#xA;NoBackendError:&#xA;</module>

  



  strange isn't it ? Then I went all over the internet, doing whatnot trying to fix it and then I've got an idea to run my line of code inside anaconda command interface and it WORKS ?? How is this possible ? It is the same environment.

  



  python
Python 3.7.7 (default, Mar 23 2020, 23:19:08) [MSC v.1916 64 bit (AMD64)] :: Anaconda, Inc. on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import librosa
>>> librosa.load('test.wav')
(array([-0.00027   , -0.00039953, -0.0003659 , ..., -0.16393574,
       -0.17814247,  0.        ], dtype=float32), 22050)


  



  I did a lot of testing and I really prefer my Jupyter so any help would be appreciated. I tried the following : I've added C:\ffmpeg\bin and C:\ffmpeg to my Path for both User and System Variables. After that I've made specific variables for ffmpeg and ffmpeg_bin for both User and System Variables. No luck. After that I've tried installing ffmpeg using conda, without success. The last thing I've tested is this :

  



  import audioread
audioread.ffdec.FFmpegAudioFile('test.wav')


  



  and that works. Thanks

  


• Unknown V4L2 pixel format equivalent for yuvj420p

  23 mars 2020, par c10ud

  I am trying to pipe a mp4 video located in Videos/video.mp4 to a virtual webcam device located at /dev/video0.

  I tried running :
  ffmpeg -re -i Videos/video.mp4 -map 0:v -f v4l2 /dev/video0
  and I keep getting the following error :

  [video4linux2,v4l2 @ 0x5580cf270100] Unknown V4L2 pixel format equivalent for yuvj420p
  
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
  
  Error initializing output stream 0:0 -- 
  
  Conversion failed!

  Full log :

  ffmpeg version 4.2.2-1+b1 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with gcc 9 (Debian 9.2.1-28)
  
    configuration: --prefix=/usr --extra-version=1+b1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  
    libavutil      56. 31.100 / 56. 31.100
  
    libavcodec     58. 54.100 / 58. 54.100
  
    libavformat    58. 29.100 / 58. 29.100
  
    libavdevice    58.  8.100 / 58.  8.100
  
    libavfilter     7. 57.100 /  7. 57.100
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  5.100 /  5.  5.100
  
    libswresample   3.  5.100 /  3.  5.100
  
    libpostproc    55.  5.100 / 55.  5.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Videos/video.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      creation_time   : 2020-03-23T04:24:01.000000Z
  
      com.android.version: 8.1.0
  
    Duration: 00:01:00.14, start: 0.000000, bitrate: 20048 kb/s
  
      Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuvj420p(pc, smpte170m), 1920x1080, 19898 kb/s, SAR 1:1 DAR 16:9, 29.43 fps, 29.58 tbr, 90k tbn, 180k tbc (default)
  
      Metadata:
  
        rotate          : 270
  
        creation_time   : 2020-03-23T04:24:01.000000Z
  
        handler_name    : VideoHandle
  
      Side data:
  
        displaymatrix: rotation of 90.00 degrees
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 96 kb/s (default)
  
      Metadata:
  
        creation_time   : 2020-03-23T04:24:01.000000Z
  
        handler_name    : SoundHandle
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
  
  Press [q] to stop, [?] for help
  
  [video4linux2,v4l2 @ 0x5580cf270100] Unknown V4L2 pixel format equivalent for yuvj420p
  
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
  
  Error initializing output stream 0:0 -- 
  
  Conversion failed!

  The desired result is that the mp4 video is seen by apps that try to view the webcam. I am running this on a desktop without a webcam or video interface, which is why I am using /dev/video0

• How to convert from .srt to .ass with FFmpeg without decoding errors

  10 avril 2020, par symonxd

  When I try the following command with FFmpeg (v. git-2020-03-24-e5d25d1) : ffmpeg -i subs.srt subs.ass, I get a bunch of the following errors :

  



  [srt @ 0000028ea78fa780] Invalid UTF-8 in decoded subtitles text; maybe missing -sub_charenc option
Error while decoding stream #0:0: Invalid data found when processing input


  



  and :

  



  [ass @ 0000028ea78ffe40] ReadOrder gap found between 3 and 4


  



  I found that my .srt file contains the following char : ë
I tried adding the flag -sub_charenc UTF-8 as stated here with no success.

  



  How can I successfully convert .srt to .ass ?