Differences

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--- atrac3p:start [2010/03/20 11:36] – Add link to spectrum anatomy page megadiscman
+++ atrac3p:start [2010/07/24 08:44] (current) – linkfix megadiscman
@@ Line 1: / Line 1: @@
 ===== ATRAC3+ format documentation =====
+This is not the only ATRAC3+ documentation that floats around in the internet. A mostly independently derived specification can be found at [[http://wiki.multimedia.cx/index.php?title=ATRAC3plus]].
 ==== 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.
+ATRAC3+ is a hybrid subband codec like MP3. The signal is split into 16 bands, each band is then divided into two parts: A superposition of sinusodial tones and the spectral residue that is encoded in the frequency domain. For the frequency-domain encoding, some of the low frequency bands are split themself into smaller parts, called //[[ATRAC spectrum anatomy|quantization units]]//, to a total of 32 quantization units. The purpose of the quantization unit is that each unit has its own quantization parameters.
+ATRAC3+ can have more than 2 channels - in that case more than one substream is present. This case is not described here.
 ==== Parsing ====
@@ Line 14: / Line 18: @@
 ==== Synthesis ====
-  * [[bandlet joint stereo coefficient cloning]]
+  * Spectral residual synthesis
-  * [[bandlet dequantization]]
+    * [[quantization unit joint stereo coefficient cloning]]
-  * [[band frequency domain dithering]]
+    * [[quantization unit dequantization]]
-  * [[band joint stereo post processing]]
+    * [[band frequency domain dithering]]
-  * [[muting]]
+    * [[band joint stereo post processing]]
-  * [[band IMDCT]]
+    * [[muting]]
-  * [[band envelope processing]]
+    * [[band IMDCT]]
-  * [[band tone adding]]
+    * [[band envelope processing]]
-  * [[time domain dithering]]
+  * Sinusodial tone synthesis
-  * [[final band combination (IMDCT + FIR filtering)]]
+    * [[band tone adding]]
+  * Noise synthesis
+    * [[time domain dithering]]
+  * [[final band combination (IMDCT + FIR filtering)|final band combination (IMDCT + FIR filtering => inverse QMF)]]