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• Improving accuracy of Google Cloud Speech API

  17 août 2018, par Shaikat Haque

  I am currently recording audio from a web page on my Mac OS computer and running it through the cloud speech api to produce a transcript. However, the results aren’t that accurate and there are chunks of missing words in the results.

  Are there any steps that would help me yield more accurate results ?

  Here are the steps I am taking to convert audio to text :

  1. Use Soundflower to channel audio output from my soundcard to mic in.
  2. Play audio from website
  3. Use quickTime player to record audio which is saved as a .m4a file.
  4. Use the command line tool ffmpeg to convert the .m4a file to a
     .flac, and also combine 2 audio channels (stereo) to 1 audio channel (mono).
  5. Upload the .flac file to Google Cloud Storage. The file has a sample rate of 44100Hz and has 24 bits per sample.
  6. Use the longRunningRecognize api via the node.js client library,
     pointing to the file in Google cloud storage.

• ffmpeg complex filtering : how to get around

  19 janvier 2020, par Melvin Roest

  Alright, I have my own compiled ffmpeg with --enable-lv2. This allows for 3rd-party plugins to work. The plugin I use is : https://github.com/lucianodato/speech-denoiser it’s a plugin that wraps around this RNN noise reduction library : https://github.com/GregorR/rnnoise-models

  The following commands work :

  (1) ffmpeg -i input.mov -filter_complex '[0:a]lv2=plugin=https\\://github.com/lucianodato/speech-denoiser[audio]' -map "[audio]" output.wav

  (2) ffmpeg -i input.mov -filter_complex '[0:v]copy[video]' -map "[video]" output.mov

  But when I do the combination, that doesn’t work.

  ffmpeg -i input.mov -filter_complex '[0:a]lv2=plugin=https\\://github.com/lucianodato/speech-denoiser[audio];[0:v]copy[video]' -map "[audio]" -map "[video]" output.mov

  I think the error is essentially this :

  Channel layout change is not supported
  
  Error while filtering: Not yet implemented in FFmpeg, patches welcome
  
  Failed to inject frame into filter network: Not yet implemented in FFmpeg, patches welcome
  
  Error while processing the decoded data for stream #0:0

  My guess : this 3rd-party filter is not configure to work with any other output stream other than audio.

  My question : can I somehow trick this 3rd-party plugin that it is outputting to an audio file, while still outputting everything to a video file ?

  Note : I know, I can simply split this up in 2 commands and be done with it, so I’m wondering if I can accomplish this via one ffmpeg command. How I would split it up in 2 commands is as follows :

  ffmpeg -i out_cropped.mov -af 'lv2=plugin=https\\://github.com/lucianodato/speech-denoiser' -vcodec copy out_cropped_denoised.wav 
  
  
  
  &&
  
  
  
  ffmpeg -i out_cropped.mov -i out_cropped_denoised.wav -c:v copy -map 0:v:0 -map 1:a:0 out_cropped_denoised.mov

  But I want to be able to put it all in one complex filter (ideally) or at least in one ffmpeg command.

  Appendix : here is the full interaction

  ffmpeg -i input.mov -filter_complex '[0:a]lv2=plugin=https\\://github.com/lucianodato/speech-denoiser[audio];[0:v]copy[video]' -map "[audio]" -map "[video]" output.mov
  
  ffmpeg version N-95577-g68f623d644 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with Apple clang version 11.0.0 (clang-1100.0.33.8)
  
    configuration: --prefix=/usr/local --enable-gpl --enable-nonfree --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libopus --enable-libxvid --enable-lv2 --samples=fate-suite/
  
    libavutil      56. 35.101 / 56. 35.101
  
    libavcodec     58. 60.100 / 58. 60.100
  
    libavformat    58. 33.100 / 58. 33.100
  
    libavdevice    58.  9.100 / 58.  9.100
  
    libavfilter     7. 65.100 /  7. 65.100
  
    libswscale      5.  6.100 /  5.  6.100
  
    libswresample   3.  6.100 /  3.  6.100
  
    libpostproc    55.  6.100 / 55.  6.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mov':
  
    Metadata:
  
      major_brand     : qt
  
      minor_version   : 512
  
      compatible_brands: qt
  
      encoder         : Lavf58.29.100
  
    Duration: 00:16:19.11, start: 0.000000, bitrate: 1341 kb/s
  
      Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1080x960, 1262 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
  
      Metadata:
  
        handler_name    : Core Media Video
  
        encoder         : Lavc58.54.100 libx264
  
      Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 69 kb/s (default)
  
      Metadata:
  
        handler_name    : Core Media Audio
  
  File 'output.mov' already exists. Overwrite? [y/N] y

  #ote : I typed yes and then this came.

  Stream mapping:
  
    Stream #0:0 (h264) -> copy
  
    Stream #0:1 (aac) -> lv2
  
    lv2 -> Stream #0:0 (aac)
  
    copy -> Stream #0:1 (libx264)
  
  Press [q] to stop, [?] for help
  
  [out_0_0 @ 0x7fa6811066c0] Channel layout change is not supported
  
  Error while filtering: Not yet implemented in FFmpeg, patches welcome
  
  Failed to inject frame into filter network: Not yet implemented in FFmpeg, patches welcome
  
  Error while processing the decoded data for stream #0:0

• matroskadec : properly decode color space in an endian neutral way

  14 juin 2011, par Aurelien Jacobs

  matroskadec : properly decode color space in an endian neutral way