chinwagsocial/app/lib/video_metadata_extractor.rb

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# frozen_string_literal: true
class VideoMetadataExtractor
attr_reader :duration, :bitrate, :video_codec, :audio_codec,
:colorspace, :width, :height, :frame_rate, :r_frame_rate
def initialize(path)
@path = path
@metadata = Oj.load(ffmpeg_command_output, mode: :strict, symbol_keys: true)
parse_metadata
rescue Terrapin::ExitStatusError, Oj::ParseError
@invalid = true
rescue Terrapin::CommandNotFoundError
raise Paperclip::Errors::CommandNotFoundError, 'Could not run the `ffprobe` command. Please install ffmpeg.'
end
def valid?
!@invalid
end
private
def ffmpeg_command_output
command = Terrapin::CommandLine.new('ffprobe', '-i :path -print_format :format -show_format -show_streams -show_error -loglevel :loglevel')
command.run(path: @path, format: 'json', loglevel: 'fatal')
end
def parse_metadata
if @metadata.key?(:format)
@duration = @metadata[:format][:duration].to_f
@bitrate = @metadata[:format][:bit_rate].to_i
end
if @metadata.key?(:streams)
video_streams = @metadata[:streams].select { |stream| stream[:codec_type] == 'video' }
audio_streams = @metadata[:streams].select { |stream| stream[:codec_type] == 'audio' }
if (video_stream = video_streams.first)
@video_codec = video_stream[:codec_name]
@colorspace = video_stream[:pix_fmt]
@width = video_stream[:width]
@height = video_stream[:height]
@frame_rate = video_stream[:avg_frame_rate] == '0/0' ? nil : Rational(video_stream[:avg_frame_rate])
@r_frame_rate = video_stream[:r_frame_rate] == '0/0' ? nil : Rational(video_stream[:r_frame_rate])
# For some video streams the frame_rate reported by `ffprobe` will be 0/0, but for these streams we
# should use `r_frame_rate` instead. Video screencast generated by Gnome Screencast have this issue.
@frame_rate ||= @r_frame_rate
end
if (audio_stream = audio_streams.first)
@audio_codec = audio_stream[:codec_name]
end
end
@invalid = true if @metadata.key?(:error)
end
end