From bbd2a006152cce4e5fa28bb2793d239ebdfdb491 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Sun, 13 Oct 2013 08:54:05 +0000
Subject: trimfx: initial bits

This will allow editing individual portions of audio of
a larger file while creating cross fade effects to join
them.
---
 lib/dtas/trimfx.rb | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 lib/dtas/trimfx.rb

(limited to 'lib/dtas')

diff --git a/lib/dtas/trimfx.rb b/lib/dtas/trimfx.rb
new file mode 100644
index 0000000..5cfac26
--- /dev/null
+++ b/lib/dtas/trimfx.rb
@@ -0,0 +1,67 @@
+# Copyright (C) 2013, Eric Wong <normalperson@yhbt.net> and all contributors
+# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
+require_relative '../dtas'
+require 'shellwords'
+
+class DTAS::TrimFX
+  attr_reader :tbeg
+  attr_reader :tlen
+
+  def initialize(args)
+    args = args.dup
+    case args.shift
+    when "trim"
+      parse_trim!(args)
+    when "all"
+      @tbeg = 0
+      @tlen = nil
+    else
+      raise ArgumentError, "#{args.inspect} not understood"
+    end
+  end
+
+  def to_sox_arg(format)
+    if @tbeg && @tlen
+      %W(trim #{@tbeg * format.rate}s #{@tlen * format.rate}s)
+    else
+      []
+    end
+  end
+
+  def parse_time(tbeg)
+    case tbeg
+    when /\A\d+\z/
+      tbeg.to_i
+    when /\A[\d\.]+\z/
+      tbeg.to_f
+    when /\A[:\d\.]+\z/
+      hhmmss = tbeg.dup
+      rv = hhmmss.sub!(/\.(\d+)\z/, "") ? "0.#$1".to_f : 0
+
+      # deal with HH:MM:SS
+      t = hhmmss.split(/:/)
+      raise ArgumentError, "Bad time format: #{hhmmss}" if t.size > 3
+
+      mult = 1
+      while part = t.pop
+        rv += part.to_i * mult
+        mult *= 60
+      end
+      rv
+    else
+      raise ArgumentError, "unparseable: #{tbeg.inspect}"
+    end
+  end
+
+  def parse_trim!(args)
+    tbeg = parse_time(args.shift)
+    tlen = args.shift
+    is_stop_time = tlen.sub!(/\A=/, "") ? true : false
+    tlen = parse_time(tlen)
+    if is_stop_time
+      tlen = tlen - tbeg
+    end
+    @tbeg = tbeg
+    @tlen = tlen
+  end
+end
-- 
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