class WaveFile::Format
Represents information about the data format for a Wave file, such as number of channels, bits per sample, sample rate, and so forth. A Format instance is used by Reader to indicate what format to read samples out as, and by Writer to indicate what format to write samples as.
Public
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Returns¶ ↑
Returns the number of bytes contained in 1 second of sample data. Is equivalent to #block_align * sample_rate.
Public Class Methods
Constructs a new immutable Format.
- channels
-
The number of channels in the format. Can either be an Integer (e.g. 1, 2, 3) or the symbols
:mono(equivalent to 1) or:stereo(equivalent to 2). - format_code
-
A symbol indicating the format of each sample. Consists of two parts: a format code, and the bits per sample. The valid values are
:pcm_8,:pcm_16,:pcm_24,:pcm_32,:float_32,:float_64, and:float(equivalent to:float_32) - #sample_rate
-
The number of samples per second, such as 44100
- #speaker_mapping
-
An optional array which indicates which speaker each channel should be mapped to. Each value in the array should be one of these values:
:front_left,:front_right,:front_center,:low_frequency,:back_left,:back_right,:front_left_of_center,:front_right_of_center,:back_center,:side_left,:side_right,:top_center,:top_front_left,:top_front_center,:top_front_right,:top_back_left,:top_back_center,:top_back_right. Each value should only appear once, and the channels must follow the ordering above. For example, [:front_center, :back_left] is a valid speaker mapping, but [:back_left, :front_center] is not. If a given channel should not be mapped to a specific speaker, the value :undefined can be used. If this field is omitted, a default value for the given number of channels. For example, if there are 2 channels, this will be set to [:front_left, :front_right].
Examples¶ ↑
format = Format.new(1, :pcm_16, 44100) format = Format.new(:mono, :pcm_16, 44100) # Equivalent to above format = Format.new(:stereo, :float_32, 44100) format = Format.new(:stereo, :float, 44100) # Equivalent to above format = Format.new(2, :pcm_16, 44100, speaker_mapping: [:front_right, :front_center]) # Channels should explicitly not be mapped to particular speakers # (otherwise, if no speaker_mapping set, it will be set to a default # value for the number of channels). format = Format.new(2, :pcm_16, 44100, speaker_mapping: [:undefined, :undefined]) # Will result in InvalidFormatError, because speakers are defined in # invalid order format = Format.new(2, :pcm_16, 44100, speaker_mapping: [:front_right, :front_left]) # speaker_mapping will be set to [:front_left, :undefined, :undefined], # because channels without a speaker mapping will be mapped to :undefined format = Format.new(3, :pcm_16, 44100, speaker_mapping: [:front_left])
Raises InvalidFormatError if the given arguments are invalid.
# File lib/wavefile/format.rb, line 70 def initialize(channels, format_code, sample_rate, speaker_mapping: nil) channels = normalize_channels(channels) validate_channels(channels) validate_format_code(format_code) validate_sample_rate(sample_rate) sample_format, bits_per_sample = normalize_format_code(format_code) speaker_mapping = normalize_speaker_mapping(channels, speaker_mapping) validate_speaker_mapping(channels, speaker_mapping) @channels = channels @sample_format = sample_format @bits_per_sample = bits_per_sample @sample_rate = sample_rate @block_align = (@bits_per_sample / 8) * @channels @byte_rate = @block_align * @sample_rate @speaker_mapping = speaker_mapping end