1 files changed, 165 insertions, 0 deletions
diff --git a/lib/dtas/tfx.rb b/lib/dtas/tfx.rb
new file mode 100644
index 0000000..479ff5c
--- /dev/null
+++ b/lib/dtas/tfx.rb
@@ -0,0 +1,165 @@
+# Copyright (C) 2013-2015 all contributors <dtas-all@nongnu.org>
+# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
+require_relative '../dtas'
+require_relative 'parse_time'
+require_relative 'format'
+require 'shellwords'
+
+# this will represent a trim section inside -splitfx for applying
+# effects to only a part of the output
+class DTAS::TFX
+  include DTAS::ParseTime
+
+  attr_reader :tbeg
+  attr_reader :tlen
+  attr_reader :cmd
+
+  def initialize(args, format = DTAS::Format.new)
+    @format = format
+    args = args.dup
+    case args.shift
+    when :pad # [ :pad, start_time, end_time ]
+      @tbeg = args.shift
+      @tlen = args.shift - @tbeg
+    when "trim"
+      parse_trim!(args)
+    when "all"
+      @tbeg = 0
+      @tlen = nil
+    else
+      raise ArgumentError, "#{args.inspect} not understood"
+    end
+    case tmp = args.shift
+    when "sh" then @cmd = args
+    when "sox" then tfx_sox(args)
+    when "eca" then tfx_eca(args)
+    when nil
+      @cmd = []
+    else
+      raise ArgumentError, "unknown effect type: #{tmp}"
+    end
+  end
+
+  def tfx_sox(args)
+    @cmd = %w(sox $SOXIN $SOXOUT $TRIMFX)
+    @cmd.concat(args)
+  end
+
+  def tfx_eca(args)
+    @cmd = %w(sox $SOXIN $SOX2ECA $TRIMFX)
+    @cmd.concat(%w(| ecasound $ECAFMT -i stdin -o stdout))
+    @cmd.concat(args)
+    @cmd.concat(%w(| sox $ECA2SOX - $SOXOUT))
+  end
+
+  def to_sox_arg
+    if @tbeg && @tlen
+      %W(trim #{@tbeg}s #{@tlen}s)
+    elsif @tbeg
+      return [] if @tbeg == 0
+      %W(trim #{@tbeg}s)
+    else
+      []
+    end
+  end
+
+  # tries to interpret "trim" time args the same way the sox trim effect does
+  # This takes _time_ arguments only, not sample counts;
+  # otherwise, deviations from sox are considered bugs in dtas
+  def parse_trim!(args)
+    tbeg = parse_time(args.shift)
+    if args[0] =~ /\A=?[\d\.]+\z/
+      tlen = args.shift
+      is_stop_time = tlen.sub!(/\A=/, "") ? true : false
+      tlen = parse_time(tlen)
+      tlen = tlen - tbeg if is_stop_time
+      @tlen = (tlen * @format.rate).round
+    else
+      @tlen = nil
+    end
+    @tbeg = (tbeg * @format.rate).round
+  end
+
+  def <=>(other)
+    tbeg <=> other.tbeg
+  end
+
+  # for stable sorting
+  class TFXSort < Struct.new(:tfx, :idx)
+    def <=>(other)
+      cmp = tfx <=> other.tfx
+      0 == cmp ? idx <=> other.idx : cmp
+    end
+  end
+
+  # sorts and converts an array of TFX objects into non-overlapping arrays
+  # of epochs
+  #
+  # input:
+  #   [ tfx1, tfx2, tfx3, ... ]
+  #
+  # output:
+  #   [
+  #     [ tfx1 ],         # first epoch
+  #     [ tfx2, tfx3 ],   # second epoch
+  #     ...
+  #   ]
+  # There are multiple epochs only if ranges overlap,
+  # There is only one epoch if there are no overlaps
+  def self.schedule(ary)
+    sorted = []
+    ary.each_with_index { |tfx, i| sorted << TFXSort[tfx, i] }
+    sorted.sort!
+    rv = []
+    epoch = 0
+    prev_end = 0
+    defer = []
+
+    begin
+      while tfxsort = sorted.shift
+        tfx = tfxsort.tfx
+        if tfx.tbeg >= prev_end
+          # great, no overlap, append to the current epoch
+          prev_end = tfx.tbeg + tfx.tlen
+          (rv[epoch] ||= []) << tfx
+        else
+          # overlapping region, we'll need a new epoch
+          defer << tfxsort
+        end
+      end
+
+      if defer[0] # do we need another epoch?
+        epoch += 1
+        sorted = defer
+        defer = []
+        prev_end = 0
+      end
+    end while sorted[0]
+
+    rv
+  end
+
+  # like schedule, but fills in the gaps with pass-through (no-op) TFX objs
+  # This does not change the number of epochs.
+  def self.expand(ary, total_samples)
+    rv = []
+    schedule(ary).each_with_index do |sary, epoch|
+      tip = 0
+      dst = rv[epoch] = []
+      while tfx = sary.shift
+        if tfx.tbeg > tip
+          # fill in the previous gap
+          nfx = new([:pad, tip, tfx.tbeg])
+          dst << nfx
+          dst << tfx
+          tip = tfx.tbeg + tfx.tlen
+        end
+      end
+      if tip < total_samples # fill until the last chunk
+        nfx = new([:pad, tip, total_samples])
+        dst << nfx
+      end
+    end
+    rv
+  end
+end