Differences

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

--- atrac3p:serialized_quantization_unit_tree_choice_info [2010/07/23 17:01] – moved on bandlet -> QU megadiscman
+++ atrac3p:serialized_quantization_unit_tree_choice_info [2010/10/16 22:36] (current) – linkfix megadiscman
@@ Line 1: / Line 1: @@
 ===== Serialized quantization unit tree IDs =====
-The frequency space data of the quantization units is generally Huffman encoded. There are two tree sets, which will be called tree set A and tree set B. Each of the tree sets consists of 8 trees for each quantizer (except quantizer 0 which means that no data is present). Some of the trees are duplicate.
+The frequency space data of the quantization units is generally Huffman encoded. There are two tree sets, which will be called tree set A and tree set B. Each of the tree sets consists of 8 trees for each quantization precision (except precision 0 which means that no data is present). Some of the trees are duplicate.
-As opposed to the quantization unit levels, which are stored for all quantization units up to the last quantization unit with a non-zero quantizer, Tree IDs are not stored for quantization units with a zero quantizer //at all//, even if the zero quantized quantization unit is followed by a quantization unit with a non-zero quantizer.
+As opposed to the quantization unit levels, which are stored for all quantization units up to the last quantization unit with a non-zero precision, Tree IDs are not stored for quantization units with a zero precision //at all//, even if the zero quantized quantization unit is followed by a quantization unit with a non-zero precision.
-The tree choice may either be complete (each quantization unit chooses one of the eight trees for it's quantizer) or restricted (each quantization unit chooses one of the four most common trees for it's quantizer). The choice between complete or restricted selection is global for the whole substream, not just for the channel! Thus the bit is not descibed here, in the per-channel tree choice data, but in the parent page [[substream data]].
+The tree choice may either be complete (each quantization unit chooses one of the eight trees for it's quantization precision) or restricted (each quantization unit chooses one of the four most common trees for it's precision). The choice between complete or restricted selection is global for the whole substream, not just for the channel! Thus the bit is not described here, in the per-channel tree choice data, but in the parent page [[substream data]].
-Another catch is that the Tree ID is reused as a joint stereo flag. If the quantizer is zero for the slave channel, but non-zero for the master channel, the slave channel has (contradicting to the simplified introduction) still one bit stored. If this bit is zero, The data from the master channel is reused, if this bit is one, the zero quantizer is taken literally (as it is always for the master channel) and the frequency data is completely zero.
+Another catch is that the Tree ID is reused as a joint stereo flag. If the quantization precision is zero for the slave channel, but non-zero for the master channel, the slave channel has (contradicting to the simplified introduction) still one bit stored. If this bit is zero, The data from the master channel is reused, if this bit is one, the precision value of zero is taken literally (as it is always for the master channel) and the frequency data is completely zero.
 If quantization unit specific info is given at all (i.e. not mode 3 on master channel), then a bit indicates whether tree IDs are stored for all quantization units that need them, or only for the some first quantization units (number given) and the remaining tree IDs are implicitly zero.
@@ Line 18: / Line 18: @@
 === Mode 2: Delta encoding ===
-For quantization units needing a joint-stereo flag this mode works like mode 0 and mode 1 do, too, it just fetches a bit. For restricted or complete tree IDs, a code from the [[quantization unit tree id trees#restricted tree id|restricted tree ID tree]] or [[quantization unit tree id trees#delta prev tree id|delta-to-prev tree ID tree]] respectively. These codes are interpreted relative to the previous full or restricted tree ID, wrapping around after 3 or 7 respectively.
+For quantization units needing a joint-stereo flag this mode works like mode 0 and mode 1 do, too, it just fetches a bit. Otherwise, the Tree ID for the first quantization unit is loaded as in mode 1 (if needed). All further tree IDs are encoded relatively to the last tree ID (starting at 0 if the first quantization unit has no tree ID) using a code from the [[quantization unit tree id trees#restricted tree id|restricted tree ID tree]] or [[quantization unit tree id trees#delta prev tree id|delta-to-prev tree ID tree]]. The application of the differences wraps around after 3 or 7 respectively.
 === Mode 3 on master channel: Just zero ===
@@ Line 48: / Line 48: @@
 ==== Encoding mode 2: Delta encoding ====
+  * for the first quantization unit:
+     * non-zero quant, full IDs: code from [[quantization unit tree id trees#full tree ID tree|full tree id]]
+     * non-zero quant, restricted trees: code from [[quantization unit tree id trees#restricted tree id|restricted tree ID tree]]
+     * zero quant, master non-zero: 1 bit "don't copy" flag
   * for each explicit quantization unit
      * non-zero quant, full IDs: code from [[quantization unit tree id trees#delta prev tree id|delta-to-prev tree ID tree]] (delta to previous ID/to zero)