Differences

This shows you the differences between two versions of the page.

--- atrac3p:start [2009/11/14 19:23] – time domain dithering is not per-band, although bands are not combined yet megadiscman
+++ atrac3p:start [2010/03/20 11:36] – Add link to spectrum anatomy page megadiscman
@@ Line 1: / Line 1: @@
 ===== ATRAC3+ format documentation =====
-ATRAC3+ is a hybrid subband codec like MP3. The signal is split into 16 bands, that are mostly encoded in the frequency domain. Some of the low frequency bands are split themself into smaller parts, customarily called //bandlets//, to a total of 32 bandlets. The purpose of the bandlets is that each bandlet has its own quantizer. The synthesis of ATRAC3+ sound data consists of:
+==== intro =====
+ATRAC3+ is a hybrid subband codec like MP3. The signal is split into 16 bands, that are mostly encoded in the frequency domain. Some of the low frequency bands are split themself into smaller parts, customarily called [[ATRAC spectrum anatomy|//bandlets//]], to a total of 32 bandlets. The purpose of the bandlets is that each bandlet has its own quantizer. ATRAC3+ can have more than 2 channels - in that case more than one substream is present. This case is not described here.
+==== Parsing ====
+  * First bit must be zero
+  * Array of blocks follows, each block:
+     * two bits type followed by data
+        * type 0 = single channel [[substream data]]
+        * type 1 = dual channel (stereo) [[substream data]]
+        * type 2 = non-audio data (ignored)
+        * type 3 = end of data marker
+==== Synthesis ====
   * [[bandlet joint stereo coefficient cloning]]
   * [[bandlet dequantization]]