player: support seeking based on embedded cuesheet (FLAC)

This adds the ability to seek internally within FLAC file
based on the internal CUE sheet.  Other formats may be supported
in the future, but FLAC is the only one I know of which supports
embedded cue sheets.

Note: flac 1.3.0 is recommended for users of non-CDDA-compatible
formats.

See updates to dtas-player_protocol(7) for details.

1 files changed, 39 insertions, 0 deletions

diff --git a/lib/dtas/cue_index.rb b/lib/dtas/cue_index.rb
new file mode 100644
index 0000000..09c3709
--- /dev/null
+++ b/lib/dtas/cue_index.rb
@@ -0,0 +1,39 @@
+# 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'
+class DTAS::CueIndex
+  attr_reader :offset
+  attr_reader :index
+
+  def initialize(index, offset)
+    @index = index.to_i
+
+    # must be compatible with the sox "trim" effect
+    @offset = offset # "#{INTEGER}s" (samples) or HH:MM:SS:FRAC
+  end
+
+  def to_hash
+    { "index" => @index, "offset" => @offset }
+  end
+
+  def offset_samples(format)
+    case @offset
+    when /\A(\d+)s\z/
+      $1.to_i
+    else
+      format.hhmmss_to_samples(@offset)
+    end
+  end
+
+  def pregap?
+    @index == 0
+  end
+
+  def track?
+    @index == 1
+  end
+
+  def subindex?
+    @index > 1
+  end
+end