avcodec/atrac3plus: Combine codebooks into one array
ATRAC3+ uses VLCs whose code lengths are ascending from left to right in the tree; ergo it is possible (and done) to run-length encode the lengths into so-called codebooks. These codebooks were variable-sized: The first byte contained the minimum length of a code, the second the maximum length; this was followed by max - min + 1 bytes containing the actual numbers. The minimal min was 1, the maximal max 12. While one saves a few bytes by only containing the range that is actually used, this is more than offset by the fact that there needs to be a pointer to each of these codebooks. Furthermore, since 5f8de7b7 the content of the Atrac3pSpecCodeTab structure (containing data for spectrum decoding) can be cleanly separated into fields that are only used during initialization and fields used during actual decoding: The pointers to the codebooks and the field indicating whether an earlier codebook should be reused constitute the former category. Therefore the new codebooks are not placed into the Atrac3pSpecCodeTab (which is now unused during init), but in an array of its own. The information whether an earlier codebook should be reused is encoded in the first number of each spectrum codebook: If it is negative, an earlier codebook (given by the number) should be reused. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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