From 3e09ac0c10c95bb24a08af62393b4f761e2743d0 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Sat, 24 Aug 2013 09:54:45 +0000
Subject: initial commit

---
 lib/dtas/format.rb | 152 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)
 create mode 100644 lib/dtas/format.rb

(limited to 'lib/dtas/format.rb')

diff --git a/lib/dtas/format.rb b/lib/dtas/format.rb
new file mode 100644
index 0000000..1ba5487
--- /dev/null
+++ b/lib/dtas/format.rb
@@ -0,0 +1,152 @@
+# -*- encoding: binary -*-
+# :stopdoc:
+# Copyright (C) 2013, Eric Wong <normalperson@yhbt.net>
+# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
+# class represents an audio format (type/bits/channels/sample rate/...)
+require_relative '../dtas'
+require_relative 'process'
+require_relative 'serialize'
+
+class DTAS::Format
+  include DTAS::Process
+  include DTAS::Serialize
+  NATIVE_ENDIAN = [1].pack("l") == [1].pack("l>") ? "big" : "little"
+
+  attr_accessor :type # s32, f32, f64 ... any point in others?
+  attr_accessor :channels # 1..666
+  attr_accessor :rate     # 44100, 48000, 88200, 96000, 176400, 192000 ...
+  attr_accessor :bits # only set for playback on 16-bit DACs
+  attr_accessor :endian
+
+  FORMAT_DEFAULTS = {
+    "type" => "s32",
+    "channels" => 2,
+    "rate" => 44100,
+    "bits" => nil,   # default: implied from type
+    "endian" => nil, # unspecified
+  }
+  SIVS = FORMAT_DEFAULTS.keys
+
+  def self.load(hash)
+    fmt = new
+    return fmt unless hash
+    (SIVS & hash.keys).each do |k|
+      fmt.instance_variable_set("@#{k}", hash[k])
+    end
+    fmt
+  end
+
+  def initialize
+    FORMAT_DEFAULTS.each do |k,v|
+      instance_variable_set("@#{k}", v)
+    end
+  end
+
+  def to_sox_arg
+   rv = %W(-t#@type -c#@channels -r#@rate)
+   rv.concat(%W(-b#@bits)) if @bits # needed for play(1) to 16-bit DACs
+   rv
+  end
+
+  # returns 'be' or 'le' depending on endianess
+  def endian2
+    case e = @endian || NATIVE_ENDIAN
+    when "big"
+      "be"
+    when "little"
+      "le"
+    else
+      raise"unsupported endian=#{e}"
+    end
+  end
+
+  def to_eca_arg
+    %W(-f #{@type}_#{endian2},#@channels,#@rate)
+  end
+
+  def inspect
+    "<#{self.class}(#{xs(to_sox_arg)})>"
+  end
+
+  def to_hsh
+    to_hash.delete_if { |k,v| v == FORMAT_DEFAULTS[k] }
+  end
+
+  def to_hash
+    ivars_to_hash(SIVS)
+  end
+
+  def from_file(path)
+    @channels = qx(%W(soxi -c #{path})).to_i
+    @type = qx(%W(soxi -t #{path})).strip
+    @rate = qx(%W(soxi -r #{path})).to_i
+    # we don't need to care for bits, do we?
+  end
+
+  # for the _decoded_ output
+  def bits_per_sample
+    return @bits if @bits
+    /\A[fst](8|16|24|32|64)\z/ =~ @type or
+      raise TypeError, "invalid type=#@type (must be s32/f32/f64)"
+    $1.to_i
+  end
+
+  def bytes_per_sample
+    bits_per_sample / 8
+  end
+
+  def to_env
+    rv = {
+      "SOX_FILETYPE" => @type,
+      "CHANNELS" => @channels.to_s,
+      "RATE" => @rate.to_s,
+      "ENDIAN" => @endian || NATIVE_ENDIAN,
+      "SOXFMT" => to_sox_arg.join(' '),
+      "ECAFMT" => to_eca_arg.join(' '),
+      "ENDIAN2" => endian2,
+    }
+    begin # don't set these if we can't get them, SOX_FILETYPE may be enough
+      rv["BITS_PER_SAMPLE"] = bits_per_sample.to_s
+    rescue TypeError
+    end
+    rv
+  end
+
+  def bytes_to_samples(bytes)
+    bytes / bytes_per_sample / @channels
+  end
+
+  def bytes_to_time(bytes)
+    Time.at(bytes_to_samples(bytes) / @rate.to_f)
+  end
+
+  def valid_type?(type)
+    !!(type =~ %r{\A[us](?:8|16|24|32)\z} || type =~ %r{\Af?:(32|64)})
+  end
+
+  def valid_endian?(endian)
+    !!(endian =~ %r{\A(?:big|little|swap)\z})
+  end
+
+  # HH:MM:SS.frac (don't bother with more complex times, too much code)
+  # part of me wants to drop this feature from playq, feels like bloat...
+  def hhmmss_to_samples(hhmmss)
+    time = hhmmss.dup
+    rv = 0
+    if time.sub!(/\.(\d+)\z/, "")
+      # convert fractional second to sample count:
+      rv = ("0.#$1".to_f * @rate).to_i
+    end
+
+    # deal with HH:MM:SS
+    t = time.split(/:/)
+    raise ArgumentError, "Bad time format: #{hhmmss}" if t.size > 3
+
+    mult = 1
+    while part = t.pop
+      rv += part.to_i * mult * @rate
+      mult *= 60
+    end
+    rv
+  end
+end
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