Class: AudioExtractionService

Inherits:
Object
  • Object
show all
Defined in:
app/services/audio_extraction_service.rb

Overview

Service object: audio extraction service.

Instance Method Summary collapse

Constructor Details

#initialize(video_file_path, ffmpeg_location = nil) ⇒ AudioExtractionService

Returns a new instance of AudioExtractionService.



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# File 'app/services/audio_extraction_service.rb', line 4

def initialize(video_file_path, ffmpeg_location = nil)
  @video_file_path = video_file_path
  @ffmpeg_location = ffmpeg_location || find_ffmpeg_location
  @audio_file = nil
end

Instance Method Details

#cleanup ⇒ Object 



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# File 'app/services/audio_extraction_service.rb', line 76

def cleanup
  return unless @audio_file

  @audio_file.close unless @audio_file.closed?
  @audio_file.unlink if File.exist?(@audio_file.path)
  @audio_file = nil
end

#extract ⇒ Object 



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# File 'app/services/audio_extraction_service.rb', line 10

def extract
  Rails.logger.info "Extracting audio from video: #{@video_file_path}"

  # Verify input file exists and is valid
  raise "Input video file is missing or empty: #{@video_file_path}" unless File.exist?(@video_file_path) && File.size(@video_file_path) > 0

  @audio_file = Tempfile.new(['audio', '.mp3'], binmode: true)

  # Extract audio using FFmpeg with high quality settings for better transcription accuracy
  command = [
    @ffmpeg_location,
    '-i', @video_file_path,
    '-vn', # No video
    '-acodec', 'mp3', # MP3 codec
    '-ar', '44100', # 44.1kHz sample rate (higher quality for speech recognition)
    '-ac', '1', # Mono (good for speech)
    '-q:a', '2', # High quality (lower number = higher quality, range 0-9)
    '-af', 'highpass=f=200,lowpass=f=3000', # Filter to focus on speech frequencies
    '-y', # Overwrite output file
    @audio_file.path
  ]

  Rails.logger.info "Running FFmpeg command: #{command.join(' ')}"

  result = system(*command)
  raise "FFmpeg audio extraction failed for file: #{@video_file_path}" unless result

  # Verify the output file was created and has content
  raise "FFmpeg failed to create valid audio file at: #{@audio_file.path}" unless File.exist?(@audio_file.path) && File.size(@audio_file.path) > 0

  Rails.logger.info "Audio extraction completed: #{@audio_file.path} (size: #{File.size(@audio_file.path)} bytes)"
  @audio_file.path
end

#extract_to_file(output_path) ⇒ Object 



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# File 'app/services/audio_extraction_service.rb', line 44

def extract_to_file(output_path)
  Rails.logger.info "Extracting audio from video: #{@video_file_path} to: #{output_path}"

  # Verify input file exists and is valid
  raise "Input video file is missing or empty: #{@video_file_path}" unless File.exist?(@video_file_path) && File.size(@video_file_path) > 0

  # Extract audio using FFmpeg with high quality settings for better transcription accuracy
  command = [
    @ffmpeg_location,
    '-i', @video_file_path,
    '-vn', # No video
    '-acodec', 'mp3', # MP3 codec
    '-ar', '44100', # 44.1kHz sample rate (higher quality for speech recognition)
    '-ac', '1', # Mono (good for speech)
    '-q:a', '2', # High quality (lower number = higher quality, range 0-9)
    '-af', 'highpass=f=200,lowpass=f=3000', # Filter to focus on speech frequencies
    '-y', # Overwrite output file
    output_path
  ]

  Rails.logger.info "Running FFmpeg command: #{command.join(' ')}"

  result = system(*command)
  raise "FFmpeg audio extraction failed for file: #{@video_file_path}" unless result

  # Verify the output file was created and has content
  raise "FFmpeg failed to create valid audio file at: #{output_path}" unless File.exist?(output_path) && File.size(output_path) > 0

  Rails.logger.info "Audio extraction completed: #{output_path} (size: #{File.size(output_path)} bytes)"
  output_path
end