class ActiveStorage::Analyzer::AudioAnalyzer
Active Storage Audio Analyzer¶ ↑
Extracts duration (seconds), bit_rate
(bits/s), sample_rate
(hertz) and tags (internal metadata) from an audio blob.
Example:
ActiveStorage::Analyzer::AudioAnalyzer.new(blob).metadata # => { duration: 5.0, bit_rate: 320340, sample_rate: 44100, tags: { encoder: "Lavc57.64", ... } }
This analyzer requires the FFmpeg system library, which is not provided by Rails.
Public Class Methods
Source
# File lib/active_storage/analyzer/audio_analyzer.rb, line 15 def self.accept?(blob) blob.audio? end
Public Instance Methods
Source
# File lib/active_storage/analyzer/audio_analyzer.rb, line 19 def metadata { duration: duration, bit_rate: bit_rate, sample_rate: sample_rate, tags: tags }.compact end
Private Instance Methods
Source
# File lib/active_storage/analyzer/audio_analyzer.rb, line 44 def audio_stream @audio_stream ||= streams.detect { |stream| stream["codec_type"] == "audio" } || {} end
Source
# File lib/active_storage/analyzer/audio_analyzer.rb, line 29 def bit_rate bit_rate = audio_stream["bit_rate"] Integer(bit_rate) if bit_rate end
Source
# File lib/active_storage/analyzer/audio_analyzer.rb, line 24 def duration duration = audio_stream["duration"] Float(duration) if duration end
Source
# File lib/active_storage/analyzer/audio_analyzer.rb, line 73 def ffprobe_path ActiveStorage.paths[:ffprobe] || "ffprobe" end
Source
# File lib/active_storage/analyzer/audio_analyzer.rb, line 52 def probe @probe ||= download_blob_to_tempfile { |file| probe_from(file) } end
Source
# File lib/active_storage/analyzer/audio_analyzer.rb, line 56 def probe_from(file) instrument(File.basename(ffprobe_path)) do IO.popen([ ffprobe_path, "-print_format", "json", "-show_streams", "-show_format", "-v", "error", file.path ]) do |output| JSON.parse(output.read) end end rescue Errno::ENOENT logger.info "Skipping audio analysis because ffprobe isn't installed" {} end
Source
# File lib/active_storage/analyzer/audio_analyzer.rb, line 34 def sample_rate sample_rate = audio_stream["sample_rate"] Integer(sample_rate) if sample_rate end
Source
# File lib/active_storage/analyzer/audio_analyzer.rb, line 48 def streams probe["streams"] || [] end