atrac3p:start
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atrac3p:start [2009/11/14 17:07] – created megadiscman | atrac3p:start [2010/07/24 08:44] (current) – linkfix megadiscman | ||
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- | demo text | + | ===== 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:// | ||
+ | |||
+ | ==== intro ===== | ||
+ | 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 ==== | ||
+ | * 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 ==== | ||
+ | * Spectral residual synthesis | ||
+ | * [[quantization unit joint stereo coefficient cloning]] | ||
+ | * [[quantization unit dequantization]] | ||
+ | * [[band frequency domain dithering]] | ||
+ | * [[band joint stereo post processing]] | ||
+ | * [[muting]] | ||
+ | * [[band IMDCT]] | ||
+ | * [[band envelope processing]] | ||
+ | * Sinusodial tone synthesis | ||
+ | * [[band tone adding]] | ||
+ | * Noise synthesis | ||
+ | * [[time domain dithering]] | ||
+ | * [[final band combination (IMDCT + FIR filtering)|final band combination (IMDCT + FIR filtering => inverse QMF)]] |
atrac3p/start.1258218469.txt.gz · Last modified: 2009/11/14 17:07 by megadiscman