atrac3p:serialized_quantization_unit_levels
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| atrac3p:serialized_quantization_unit_levels [2010/07/23 18:15] – base table -> prediction vector megadiscman | atrac3p:serialized_quantization_unit_levels [2010/10/25 13:01] (current) – Explain signs of level prediction vectors correctly. megadiscman | ||
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| ==== Prediction Vectors ==== | ==== Prediction Vectors ==== | ||
| - | The prediction vectors (common distributions) of the levels fall into two classes. Three [[basic level prediction vectors]] (one of them completely zero) and 64 different [[extended level prediction vectors]]. The prediction vectors are used in all non-primitive master encoding modes. While modes basing on the extended tables generally wrap around, modes based on the basic tables do not. The usage of the vectors for the levels is different from the precision prediction vectors in that they are subtracted and not added to the data, so the no-wraparound condition means that encoding a delta of 6 (i.e. +6) while the prediction vector says 8 (i.e. -8) is an error. | + | The prediction vectors (common distributions) of the levels fall into two classes. Three [[basic level prediction vectors]] (one of them completely zero) and 64 different [[extended level prediction vectors]]. The prediction vectors are used in all non-primitive master encoding modes. While modes basing on the extended tables generally wrap around, modes based on the basic tables do not. |
| - | If an extended prediction vector is selected, the entries from the extended prediction vector are offset by a 6-bit value stored directly adjacent to the extended prediction vector number. | + | For the basic vectors only, the prediction vectors are to be subtracted from the data instead of added,so the no-wraparound condition means that encoding a delta of 6 (i.e. +6) while the prediction vector says 8 (i.e. -8) is an error. |
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| + | If an extended prediction vector is selected, the entries from the extended prediction vector are offset by a 6-bit value stored directly adjacent to the extended prediction vector number. | ||
| ==== Encoding Modes ==== | ==== Encoding Modes ==== | ||
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| * 6 bit: level of quantization unit 0/1/2 for base | * 6 bit: level of quantization unit 0/1/2 for base | ||
| * 6 bit: selection of level table from [[extended level prediction vectors]] | * 6 bit: selection of level table from [[extended level prediction vectors]] | ||
| - | * 4 bit: level delta for quantization unit 0 | + | * 4 bit: level delta for quantization unit 0, offset by 8 (so -8..7 are possible) |
| * for remaining quantization units | * for remaining quantization units | ||
| * huffman code representing delta between previous and this level (sign expanded) | * huffman code representing delta between previous and this level (sign expanded) | ||
atrac3p/serialized_quantization_unit_levels.1279908918.txt.gz · Last modified: 2010/07/23 18:15 by megadiscman