Commit Graph

12 Commits

Author SHA1 Message Date
Zoltan Szabadka
12eb9bfd70 Align distance code meaning in the brotli encoder.
Two different definitions (offset by 1) were used in
command.h and hash.h. Now they have been made the same,
also consistent with the spec (e.g. 0 means use previous dist, etc...)
2015-05-07 17:40:00 +02:00
Zoltan Szabadka
7cde616c9e Faster encoding for low quality settings.
With this commit, the encoder will skip some
compression optimization steps for quality <= 4,
which results in faster compression but higher
compressed sizes.
2015-05-07 17:30:10 +02:00
Zoltan Szabadka
0f726df1f1 Don't do any block splitting for quality 1. 2015-04-28 10:12:47 +02:00
Zoltan Szabadka
98539223f5 Remove quality parameter from bitstream writing functions.
Fix a few crashes related to some quality and param combinations.
2015-04-23 16:20:29 +02:00
Zoltan Szabadka
89a6fb85fb Add params to disable static dictionary and context modeling.
Disable all slow features for quality <= 9 (literal cost modeling,
dictionary, context modeling, advanced block splitting).

Change vector<Command> arguments of internal functions
to Command* and size_t.
2015-04-23 13:15:42 +02:00
Zoltan Szabadka
b4f39bf540 New version of the backward reference search code.
The new	interface of the backward reference search
function makes it possible to use it in	a streaming
manner.

Using the advanced cost model and static dictionary
can be turned on/off by	template parameters.

The distance short codes are now computed as part of
the backward reference search.

Added a	faster version of the Hasher.
2014-10-28 13:25:22 +01:00
Zoltan Szabadka
e7650080a8 Updates to Brotli compression format, decoder and encoder
This commit contains a batch of changes that were made to the Brotli
compression algorithm in the last month. Most important changes:

   * Format change: don't push distances representing static dictionary words to the distance cache.
   * Fix decoder invalid memory access bug caused by building a non-complete Huffman tree.
   * Add a mode parameter to the encoder interface.
   * Use different hashers for text and font mode.
   * Add a heuristics to the hasher for skipping non-compressible data.
   * Exhaustive search of static dictionary during backward reference search.
2014-03-20 14:32:35 +01:00
Zoltan Szabadka
0454ab4ec0 Updates to Brotli compression format, decoder and encoder
This commit contains a batch of changes that were made to the Brotli
compression algorithm in the last month. Most important changes:

   * Fixes to the spec.
   * Change of code length code order.
   * Use a 2-level Huffman lookup table in the decoder.
   * Faster uncompressed meta-block decoding.
   * Optimized encoding of the Huffman code.
   * Detection of UTF-8 input encoding.
   * UTF-8 based literal cost modeling for improved
     backward reference selection.
2014-02-14 15:04:23 +01:00
Zoltan Szabadka
1447345cbb Brotli format change: improved encoding of Huffman codes
This change removes the redundant HCLEN, HLENINC and HLEN
fields from the encoding of the complex Huffman codes and
derives these from an invariant of the code length sequence.
Based on a patch by Robert Obryk.
2013-12-17 17:17:57 +01:00
Roderick Sheeter
1cdcbd851f Added Brotli compress/decompress utilities and makefiles 2013-11-19 14:32:56 -08:00
Zoltan Szabadka
c6b9c7c5c8 Updates to Brotli compression format, decoder and encoder
This commit contains a batch of changes that were made to the Brotli
compression algorithm in the last three weeks. Most important changes:

  * Added UTF8 context model for good text compression.
  * Simplified context modeling by having only 4 context modes.
  * Per-block context mode selection.
  * Faster backward copying and bit reading functions.
  * More efficient histogram coding.
  * Streaming support for the decoder and encoder.
2013-11-15 19:02:17 +01:00
Zoltan Szabadka
c66e4e3e4f Add brotli compressor
This commit is for the encoder for brotli compression format.
Brotli is a generic byte-level compression algorithm.
2013-10-23 13:06:13 +02:00