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Contents
module FLV
# The body of an audio tag.
# The data is quite complex stuff. We make no attempt to understand it all
# or to be able to modify any of it. We simply consider it a complex string
# and read the interesting bits to give more info.
class Audio < String
include Body
FORMATS = Hash.new{|h, key| "Unknown audio format: #{key}"}.merge!(
0 => :"Linear PCM, platform endian" ,
1 => :ADPCM ,
2 => :MP3 ,
3 => :"Linear PCM, little endian" ,
4 => :"Nellymoser 16-kHz mono" ,
5 => :"Nellymoser 8-kHz mono" ,
6 => :Nellymoser ,
7 => :"G.711 A-law logarithmic PCM" ,
8 => :"G.711 mu-law logarithmic PCM" ,
10 => :AAC ,
11 => :Speex ,
14 => :"MP3 8-kHz" ,
15 => :"Device-specific sound"
).freeze
EXCEPTIONS = Hash.new({}).merge(
:"Nellymoser 8-kHz mono" => {:channel => :mono, :rate => 8000},
:"Nellymoser 16-kHz mono" => {:channel => :mono, :rate => 16000},
:AAC => {:channel => :stereo,:rate => 44000},
:"MP3 8-kHz" => {:rate => 8000}
).freeze
CHANNELS = {
0 => :mono,
1 => :stereo
}.freeze
def codec_id
read_bits(0..3)
end
# Returns the format (see Audio::FORMATS for list)
def format
FORMATS[codec_id]
end
# returns :mono or :stereo
def channel
EXCEPTIONS[format][:channel] ||
CHANNELS[read_bits(7)]
end
# Returns the sampling rate (in Hz)
def rate
EXCEPTIONS[format][:rate] ||
5500 << read_bits(4..5)
end
# Returns the sample size (in bits)
def sample_size
EXCEPTIONS[format][:sample_size] ||
8 << read_bits(6)
end
def is?(what)
format.to_s.downcase == what.to_s.downcase || super
end
end
end
Version data entries
12 entries across 12 versions & 2 rubygems