atrac3p:atrac_spectrum_anatomy
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| Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
| atrac3p:atrac_spectrum_anatomy [2010/07/23 16:25] – bandlet -> QU megadiscman | atrac3p:atrac_spectrum_anatomy [2010/11/16 18:37] (current) – Fix spectral width for 44.1kHz sample rate. megadiscman | ||
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| ===== ATRAC3+ spectrum layout ===== | ===== ATRAC3+ spectrum layout ===== | ||
| - | The spectrum (0..22.5kHz) for 44.1kHz sample rate is divided into 16 bands of equal spectral width of 1406,25Hz. Some of these 16 bands are further divided into quantization units (all quantization units of the same bands have the same spectral), as at low frequencies the same spectral width occupies a higher relative spectrum range (i.e. a higher pitch interval). All quantization units' data has to be combined into the total band data before the IMDCT synthesis can be performed, so all processing steps in time domain work on band basis or even more coarse, while the spectral data itself is encoded on the level of quantization units. | + | The spectrum (0..22.05kHz) for 44.1kHz sample rate is divided into 16 bands of equal spectral width of 1378.125Hz. Some of these 16 bands are further divided into quantization units (all quantization units of the same bands have the same spectral), as at low frequencies the same spectral width occupies a higher relative spectrum range (i.e. a higher pitch interval). All quantization units' data has to be combined into the total band data before the IMDCT synthesis can be performed, so all processing steps in time domain work on band basis or even more coarse, while the spectral data itself is encoded on the level of quantization units. |
| The selection of spectral dither noise amplitude uses a scheme of dither groups that contain several quantization units. Borders of dither groups coincide with borders of bands except for the first dither group that leaves out the first two quantization units of the first band. | The selection of spectral dither noise amplitude uses a scheme of dither groups that contain several quantization units. Borders of dither groups coincide with borders of bands except for the first dither group that leaves out the first two quantization units of the first band. | ||
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| * highest used quantization unit (used to calculate highest non-zero band and highest non-zero dither group) | * highest used quantization unit (used to calculate highest non-zero band and highest non-zero dither group) | ||
| * Mute flag | * Mute flag | ||
| + | * Time-domain dither info | ||
| * Per channel data | * Per channel data | ||
| * Per dither-group data | * Per dither-group data | ||
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| * Envelopes | * Envelopes | ||
| * Tone data | * Tone data | ||
| - | * Time-domain dither info | ||
| * Per quantization unit data | * Per quantization unit data | ||
| * Spectral quantizers | * Spectral quantizers | ||
atrac3p/atrac_spectrum_anatomy.1279902315.txt.gz · Last modified: 2010/07/23 16:25 by megadiscman