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# frozen_string_literal: true
module ActiveStorage
# Extracts duration (seconds) and bit_rate (bits/s) from an audio blob.
#
# Example:
#
# ActiveStorage::Analyzer::AudioAnalyzer.new(blob).metadata
# # => { duration: 5.0, bit_rate: 320340 }
#
# This analyzer requires the {FFmpeg}[https://www.ffmpeg.org] system library, which is not provided by Rails.
class Analyzer::AudioAnalyzer < Analyzer
def self.accept?(blob)
blob.audio?
end
def metadata
{ duration: duration, bit_rate: bit_rate }.compact
end
private
def duration
duration = audio_stream["duration"]
Float(duration) if duration
end
def bit_rate
bit_rate = audio_stream["bit_rate"]
Integer(bit_rate) if bit_rate
end
def audio_stream
@audio_stream ||= streams.detect { |stream| stream["codec_type"] == "audio" } || {}
end
def streams
probe["streams"] || []
end
def probe
@probe ||= download_blob_to_tempfile { |file| probe_from(file) }
end
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 FFmpeg isn't installed"
{}
end
def ffprobe_path
ActiveStorage.paths[:ffprobe] || "ffprobe"
end
end
end
Version data entries
7 entries across 7 versions & 1 rubygems