Ετήσια αρχεία: 2020

Apply low pass and high pass frequency filter using ffmpeg

 στο GNU/Linux  επισημασμένο με ετικέτα ffmpeg / filter / frequency / high pass / highpass / low pass / lowpass Από

Just a quick example that applies both a high pass and a low pass frequency filter to a video file using ffmpeg

ffmpeg -i input.mp4 -filter:a "highpass=f=200, lowpass=f=3000" output.mp4;

The frequency is set in Hz so in this example we are filtering out all frequencies that are out of [200, 3000].

Increase volume in video using ffmpeg 2

 στο Μη κατηγοριοποιημένο  επισημασμένο με ετικέτα audio / boost / ffmpeg / loud / video / volume Από

A quick note on how to boost the audio stream in a video using the volume filter in ffmpeg

#;For newer versions of ffmpeg
ffmpeg -i input.mkv -filter:a "volume=4.0" output.mkv;
#For older versions of ffmpeg (we use multiples of 256)
ffmpeg -i input.mkv -vol 1024 -vcodec copy output.mkv;

Using the above command we were able to make the audio LOUDER!

Ubuntu 18.04 and VOSK Speech Recognition API

 στο GNU/Linux  επισημασμένο με ετικέτα ubuntu / VOSK Από

Just some quick notes on how to install and use VOSK on Ubuntu 18.04 LTS.

  1. Install using: pip3 install vosk
  2. Get samples from https://github.com/alphacep/vosk-api/tree/master/python/example
  3. Using ffmpeg create input audio files ffmpeg -i video.mkv -c:a pcm_s16le -ac 1 output.wav
    It will create a file of the following type output.wav: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, mono 48000 Hz
  4. Export text to JSON python3 ./test_simple.py output.wav