- 09 12月, 2020 40 次提交
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由 Andreas Rheinhardt 提交于
Expressions like array[get_vlc2()] can be optimized by using a symbols table if the array is always the same for a given VLC. This requirement is fulfilled for several VLCs used by the AAC decoders. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
This is possible by switching to ff_init_vlc_from_lengths() which allows to replace tables of codes of size uint16_t or uint32_t by tables of symbols of size uint8_t; in case there already were symbols tables the savings are even bigger. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
MagicYUV transmits its Huffman trees by providing the length of the code corresponding to each symbol; then the decoder has to assemble the table in such a way that (i) longer codes are to the left of the tree and (ii) for codes of the same length the symbols are ascending from left to right. Up until now the decoder did this as follows: It counted the number of codes of each length and derived the first code of a given length via (ii). Then the array of lengths is traversed a second time to create the codes; there is one running counter for each length to do so. This process creates a default symbol table (that is omitted). This commit changes this as follows: Everything is indexed by the position in the tree (with codes to the left first); given (i), we can calculate the ranges occupied by the codes of each length; and with (ii) we can derive the actual symbols of each code; the running counters for each length are now used for the symbols and not for the codes. Doing so allows us to switch to ff_init_vlc_from_lengths(); this has the advantage that the codes table needs only be traversed once and that the codes need not be sorted any more (right now, the codes that are so long that they will be put into subtables need to be sorted so that codes that end up in the same subtable are contiguous). For a sample produced by our encoder (natural content, 4000 frames, YUV420p, ten iterations, GCC 9.3) this decreased the amount of decicycles for each call to build_huffman() from 1336049 to 1309401. Notice that our encoder restricts the code lengths to 12 and our decoder only uses subtables when the code is longer than 12 bits, so the sorting that can be avoided does not happen at the moment. If one reduces the decoder's tables to nine bits, the performance improvement becomes more apparent: The amount of decicycles for build_huffman() decreased from 1165210 to 654055. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
The Huffman trees used by Ut Video have two important characteristics: (i) Longer codes are on the left of the tree and (ii) for codes of the same length, the symbol is descending from left to right in the tree. Therefore all the information that needs to be transmitted is how long the code corresponding to a given symbol is; and this is also all that is transmitted. Before 34191449, the decoder used qsort to sort the (length, symbol) pairs by ascending length and for equal lengths by ascending symbol. Since said commit, the decoder uses a first pass over the lengths table to count how many symbols of each length there are; with (i) one can then easily calculate the code of the left-most code with a given length in the tree and from there one can calculate the codes for all entries, using one running counter for each possible length. This eliminated the explicit qsort in build_huff(). Yet ff_init_vlc_sparse() sorts the table itself as it has to ensure that all the entries that will be placed in the same subtable are contiguous. The tables created now are non-contiguous (they are ordered by symbol and codes of different length aren't ordered at all; only codes of the same length are ordered according to (ii)). This commit therefore modifies the algorithm used to automatically create tables whose codes are sorted from left to right in the tree. The key to do so is the observation that the counts obtained in the first pass can be used to contain the range of the codes of each length in the second pass: If counts[i] is the count of codes with length i, then the first counts[32] codes are of length 32, the next counts[31] codes are of length 31 etc. So one knows the index of the lowest symbol whose code has length 32 (if any): It is counts[32] - 1 due to (ii), whereas the index of the lowest symbol whose code has length 31 (if any) is counts[32] + counts[31] - 1; the index of the second-to-lowest symbol of length 32 (if existing) is counts[32] - 2 etc. If one follows the algorithm outlined above, one can switch to ff_init_vlc_from_lengths() which has no implicit qsort; it also means that one can offload the computation of the codes. This turned out to be beneficial for performance: For the sample from ticket #4044 it decreased the decicycles spent on one call to build_huff() from 508480 to 340688 (GCC 9.3, looping 10 times over the file to get enough runs and then repeating this ten times); for another sample (YUV420p, natural content, 5500 frames, also ten iterations) the time went down from 382346 to 275533 decicycles. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Expressions like array[get_vlc2()] can be optimized by using a symbols table if the array is always the same for a given VLC. This requirement is fulfilled for several VLCs used by ATRAC3, therefore this commit implements this. This comes without any additional costs when using ff_init_vlc_from_lengths() as one can then remove the codes tables. While at it, remove the arrays of pointers to the individual arrays and put all lengths+symbol pairs in one big array. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
By switching from ff_init_vlc_sparse() to ff_init_vlc_from_lengths() one can replace an array of codes of type uint16_t with an array of symbols of type uint8_t, saving space. Also remove some more code duplication while at it. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
theora_init_huffman_tables() does essentially the same as ff_init_vlcs_from_lengths(). Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Expressions like array[get_vlc2()] can be optimized by using a symbols table if the array is always the same for a given VLC. This requirement is fulfilled for the VLC used for VP3 motion vectors. The reason it hasn't been done before is probably that the array in this case contained entries in the range -31..31; but this is no problem with ff_init_vlc_from_lengths(): Just apply an offset of 31 to the symbols before storing them in the table used to initialize VP3 motion vectors and apply an offset of -31 when initializing the actual VLC. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
This is possible by switching to ff_init_vlc_from_lengths() because it allows to replace codes of type uint16_t by symbols of type uint8_t; in some cases (like here) it also allows to replace explicitly coded codes by implicitly coded symbols. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
By switching to ff_init_vlc_from_lengths() one can apply both positive as well as negative offsets for free; in this case it even saves space because one replaces codes tables that don't fit into an uint8_t by symbols tables that fit into an uint8_t or can even be completely avoided as they are trivial. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Also remove code duplication and use a named constant for the number of VLC bits while just at it. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
The ATRAC9 decoder creates VLCs with parameters contained in HuffmanCodebooks; some of these HuffmanCodebooks are empty and yet VLCs (that were completely unused*) were created from them. Said VLC contained a single table with 512 VLC_TYPE[2] entries, each of which indicated that this is an invalid code. This commit stops creating said VLCs. *: read_coeffs_coarse() uses the HuffmanCodebook at9_huffman_coeffs[cb][prec][cbi]. prec is c->precision_coarse[i] + 1 and every precision_coarse entry is in the 1..15 range after calc_precision(), so prec is >= 2 (all codebooks with prec < 2 are empty). The remaining empty codebooks are those with cb == 1 and cbi == 0, yet this is impossible, too: cb is given by c->codebookset[i] and this is always 0 if i < 8 (because those are never set to anything else in calc_codebook_idx()) and cbi is given by at9_q_unit_to_codebookidx[i] which is never zero if i >= 8. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Using separate tables has the downside that one needs a big number of pointers to the separate tables (currently 77); unifying them avoids this. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
The ATRAC9 decoder uses VLCs which are currently initialized with static length tables of type uint8_t and code tables of type uint16_t. Furthermore, in one case the actually desired symbols are in the range -16..15 and in order to achieve this an ad-hoc symbols table of type int16_t is calculated. This commit modifies this process by replacing the codes tables by symbols tables and switching to ff_init_vlc_from_lengths(); the signed symbols are stored in the table after having been shifted by 16 to fit into an uint8_t and are shifted back when the VLC is created. This makes all symbols fit into an uint8_t, saving space. Furthermore, the earlier tables had holes in them (entries with length zero that were inserted because the actually used symbols were not contiguous); these holes are unnecessary in the new approach, leading to further saving. Finally, given that now both lengths as well as symbols are of the same type, they can be combined; this saves a pointer for each VLC. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
This is very beneficial for the scale factor tables where 4*64+4*15 bytes of length information can be replaced by eight codebooks of 12 bytes each; furthermore the number of codes as well as the maximum length of a code can be easily derived from said codebooks, making tables containing said information superfluous. This and combining the symbols into one big array also made an array of pointers to the tables redundant. For the wordlen and code table tables the benefits are not that big (given these tables don't contain that many elements), but all in all using codebooks is also advantageouos for them. Therefore it has been done. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
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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由 Andreas Rheinhardt 提交于
This allows to remove lots of pointers (130) to small symbol tables; it has the downside that some of the default tables must now be coded explicitly, but this costs only 6 + 4 + 8 + 16 + 8 bytes and is therefore dwarfed by the gains. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
The earlier code used several different offset parameters that were initialized to magic values. This is unnecessary. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
The ATRAC3+ decoder currently uses ff_init_vlc_sparse() to initialize several VLCs; sometimes a symbols table is used, sometimes not; some of the codes tables are uint16_t, some are uint8_t. Because of these two latter facts it makes sense to switch to ff_init_vlc_from_lengths() because it allows to remove the codes at the cost of adding symbols tables of type uint8_t in the cases where there were none before. Notice that sometimes the same codes and lengths tables were reused with two different symbols tables; this could have been preserved (meaning one could use a lengths table twice), but hasn't, because this allows to use only one pointer to both the symbols and lengths instead of two pointers. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Use ff_init_vlc_from_lengths() to offload the computation of the codes. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
ff_init_vlc_from_lengths() can be used to offload the computation of the codes; it also allows to omit the check whether the codes are already properly ordered (they are). In this case, this also allows to avoid the allocation of the buffer for the codes. This improves performance: The amount of decicycles for one call to tm2_build_huff_tables() when decoding tm20.avi from the FATE-suite decreased from 46239 to 40035. This test consisted of looping 50 times over the file and iterating the test ten times. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Reviewed-by: NMichael Niedermayer <michael@niedermayer.cc> Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Switching from ff_init_vlc_sparse() to ff_init_vlc_from_lengths() allows to replace codes which are so long that they need to be stored in an uint16_t by symbols which fit into an uint8_t; and even these can be avoided in case of the sprite trajectory VLC. Reviewed-by: NMichael Niedermayer <michael@niedermayer.cc> Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Switching from ff_init_vlc_sparse() to ff_init_vlc_from_lengths() allows to replace codes which are so long that they need to be stored in an uint16_t by symbols which fit into an uint8_t; furthermore, it is also easily possible to already incorporate the offset (the real range of Indeo 2 symbols starts at one, not zero) into the symbols. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
ff_init_vlc_from_lengths() can be used to offload the computation of the codes; it also allows to omit the check whether the codes are already properly ordered (they are). Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
ff_init_vlc_from_lengths() can be used to offload the computation of the codes; it also needn't check whether the codes are already properly ordered (they are). Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
The lengths of the codes used by the mss4 decoder are ascending from left to right and therefore the lengths can be run-length encoded and the codes can be easily derived from them. And this is how it is indeed done. Yet some things can nevertheless be improved: a) The number of entries of the current VLC is implicitly contained in the run-length table and needn't be externally prescribed. b) The maximum length of a code is just the length of the last code (given that the lengths are ascending), so there is no point in setting max_bits in the loop itself. c) One can offload the actual calculation of the codes to ff_init_vlc_from_lengths(). Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Besides removing code duplication the method for determining the offset of each VLC table in the VLC_TYPE buffer also has the advantage of not wasting space for skipped AIC mode 1 VLCs. Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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由 Andreas Rheinhardt 提交于
Signed-off-by: NAndreas Rheinhardt <andreas.rheinhardt@gmail.com>
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