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author | Christian Schneppe <christian@pix-art.de> | 2016-08-26 23:48:48 +0200 |
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committer | Christian Schneppe <christian@pix-art.de> | 2016-08-28 21:33:19 +0200 |
commit | b3b3475e93a9b08f9e35edbf74673728b560ad3b (patch) | |
tree | fc72bfce668b358310061c0a94736a0bd14e8b5d /src/main/jni/libwebp/utils/huffman.c | |
parent | 1f7f535d37b844dbd87447e1872c270edbca1302 (diff) |
compress videos bigger than 10 MB before sending
Diffstat (limited to '')
-rw-r--r-- | src/main/jni/libwebp/utils/huffman.c | 319 |
1 files changed, 319 insertions, 0 deletions
diff --git a/src/main/jni/libwebp/utils/huffman.c b/src/main/jni/libwebp/utils/huffman.c new file mode 100644 index 000000000..c4c16d9e6 --- /dev/null +++ b/src/main/jni/libwebp/utils/huffman.c @@ -0,0 +1,319 @@ +// Copyright 2012 Google Inc. All Rights Reserved. +// +// Use of this source code is governed by a BSD-style license +// that can be found in the COPYING file in the root of the source +// tree. An additional intellectual property rights grant can be found +// in the file PATENTS. All contributing project authors may +// be found in the AUTHORS file in the root of the source tree. +// ----------------------------------------------------------------------------- +// +// Utilities for building and looking up Huffman trees. +// +// Author: Urvang Joshi (urvang@google.com) + +#include <assert.h> +#include <stdlib.h> +#include <string.h> +#include "./huffman.h" +#include "../utils/utils.h" +#include "../webp/format_constants.h" + +// Uncomment the following to use look-up table for ReverseBits() +// (might be faster on some platform) +// #define USE_LUT_REVERSE_BITS + +// Huffman data read via DecodeImageStream is represented in two (red and green) +// bytes. +#define MAX_HTREE_GROUPS 0x10000 +#define NON_EXISTENT_SYMBOL (-1) + +static void TreeNodeInit(HuffmanTreeNode* const node) { + node->children_ = -1; // means: 'unassigned so far' +} + +static int NodeIsEmpty(const HuffmanTreeNode* const node) { + return (node->children_ < 0); +} + +static int IsFull(const HuffmanTree* const tree) { + return (tree->num_nodes_ == tree->max_nodes_); +} + +static void AssignChildren(HuffmanTree* const tree, + HuffmanTreeNode* const node) { + HuffmanTreeNode* const children = tree->root_ + tree->num_nodes_; + node->children_ = (int)(children - node); + assert(children - node == (int)(children - node)); + tree->num_nodes_ += 2; + TreeNodeInit(children + 0); + TreeNodeInit(children + 1); +} + +// A Huffman tree is a full binary tree; and in a full binary tree with L +// leaves, the total number of nodes N = 2 * L - 1. +static int HuffmanTreeMaxNodes(int num_leaves) { + return (2 * num_leaves - 1); +} + +static int HuffmanTreeAllocate(HuffmanTree* const tree, int num_nodes) { + assert(tree != NULL); + tree->root_ = + (HuffmanTreeNode*)WebPSafeMalloc(num_nodes, sizeof(*tree->root_)); + return (tree->root_ != NULL); +} + +static int TreeInit(HuffmanTree* const tree, int num_leaves) { + assert(tree != NULL); + if (num_leaves == 0) return 0; + tree->max_nodes_ = HuffmanTreeMaxNodes(num_leaves); + assert(tree->max_nodes_ < (1 << 16)); // limit for the lut_jump_ table + if (!HuffmanTreeAllocate(tree, tree->max_nodes_)) return 0; + TreeNodeInit(tree->root_); // Initialize root. + tree->num_nodes_ = 1; + memset(tree->lut_bits_, 255, sizeof(tree->lut_bits_)); + memset(tree->lut_jump_, 0, sizeof(tree->lut_jump_)); + return 1; +} + +void VP8LHuffmanTreeFree(HuffmanTree* const tree) { + if (tree != NULL) { + WebPSafeFree(tree->root_); + tree->root_ = NULL; + tree->max_nodes_ = 0; + tree->num_nodes_ = 0; + } +} + +HTreeGroup* VP8LHtreeGroupsNew(int num_htree_groups) { + HTreeGroup* const htree_groups = + (HTreeGroup*)WebPSafeCalloc(num_htree_groups, sizeof(*htree_groups)); + assert(num_htree_groups <= MAX_HTREE_GROUPS); + if (htree_groups == NULL) { + return NULL; + } + return htree_groups; +} + +void VP8LHtreeGroupsFree(HTreeGroup* htree_groups, int num_htree_groups) { + if (htree_groups != NULL) { + int i, j; + for (i = 0; i < num_htree_groups; ++i) { + HuffmanTree* const htrees = htree_groups[i].htrees_; + for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) { + VP8LHuffmanTreeFree(&htrees[j]); + } + } + WebPSafeFree(htree_groups); + } +} + +int VP8LHuffmanCodeLengthsToCodes( + const int* const code_lengths, int code_lengths_size, + int* const huff_codes) { + int symbol; + int code_len; + int code_length_hist[MAX_ALLOWED_CODE_LENGTH + 1] = { 0 }; + int curr_code; + int next_codes[MAX_ALLOWED_CODE_LENGTH + 1] = { 0 }; + int max_code_length = 0; + + assert(code_lengths != NULL); + assert(code_lengths_size > 0); + assert(huff_codes != NULL); + + // Calculate max code length. + for (symbol = 0; symbol < code_lengths_size; ++symbol) { + if (code_lengths[symbol] > max_code_length) { + max_code_length = code_lengths[symbol]; + } + } + if (max_code_length > MAX_ALLOWED_CODE_LENGTH) return 0; + + // Calculate code length histogram. + for (symbol = 0; symbol < code_lengths_size; ++symbol) { + ++code_length_hist[code_lengths[symbol]]; + } + code_length_hist[0] = 0; + + // Calculate the initial values of 'next_codes' for each code length. + // next_codes[code_len] denotes the code to be assigned to the next symbol + // of code length 'code_len'. + curr_code = 0; + next_codes[0] = -1; // Unused, as code length = 0 implies code doesn't exist. + for (code_len = 1; code_len <= max_code_length; ++code_len) { + curr_code = (curr_code + code_length_hist[code_len - 1]) << 1; + next_codes[code_len] = curr_code; + } + + // Get symbols. + for (symbol = 0; symbol < code_lengths_size; ++symbol) { + if (code_lengths[symbol] > 0) { + huff_codes[symbol] = next_codes[code_lengths[symbol]]++; + } else { + huff_codes[symbol] = NON_EXISTENT_SYMBOL; + } + } + return 1; +} + +#ifndef USE_LUT_REVERSE_BITS + +static int ReverseBitsShort(int bits, int num_bits) { + int retval = 0; + int i; + assert(num_bits <= 8); // Not a hard requirement, just for coherency. + for (i = 0; i < num_bits; ++i) { + retval <<= 1; + retval |= bits & 1; + bits >>= 1; + } + return retval; +} + +#else + +static const uint8_t kReversedBits[16] = { // Pre-reversed 4-bit values. + 0x0, 0x8, 0x4, 0xc, 0x2, 0xa, 0x6, 0xe, + 0x1, 0x9, 0x5, 0xd, 0x3, 0xb, 0x7, 0xf +}; + +static int ReverseBitsShort(int bits, int num_bits) { + const uint8_t v = (kReversedBits[bits & 0xf] << 4) | kReversedBits[bits >> 4]; + assert(num_bits <= 8); + return v >> (8 - num_bits); +} + +#endif + +static int TreeAddSymbol(HuffmanTree* const tree, + int symbol, int code, int code_length) { + int step = HUFF_LUT_BITS; + int base_code; + HuffmanTreeNode* node = tree->root_; + const HuffmanTreeNode* const max_node = tree->root_ + tree->max_nodes_; + assert(symbol == (int16_t)symbol); + if (code_length <= HUFF_LUT_BITS) { + int i; + base_code = ReverseBitsShort(code, code_length); + for (i = 0; i < (1 << (HUFF_LUT_BITS - code_length)); ++i) { + const int idx = base_code | (i << code_length); + tree->lut_symbol_[idx] = (int16_t)symbol; + tree->lut_bits_[idx] = code_length; + } + } else { + base_code = ReverseBitsShort((code >> (code_length - HUFF_LUT_BITS)), + HUFF_LUT_BITS); + } + while (code_length-- > 0) { + if (node >= max_node) { + return 0; + } + if (NodeIsEmpty(node)) { + if (IsFull(tree)) return 0; // error: too many symbols. + AssignChildren(tree, node); + } else if (!HuffmanTreeNodeIsNotLeaf(node)) { + return 0; // leaf is already occupied. + } + node += node->children_ + ((code >> code_length) & 1); + if (--step == 0) { + tree->lut_jump_[base_code] = (int16_t)(node - tree->root_); + } + } + if (NodeIsEmpty(node)) { + node->children_ = 0; // turn newly created node into a leaf. + } else if (HuffmanTreeNodeIsNotLeaf(node)) { + return 0; // trying to assign a symbol to already used code. + } + node->symbol_ = symbol; // Add symbol in this node. + return 1; +} + +int VP8LHuffmanTreeBuildImplicit(HuffmanTree* const tree, + const int* const code_lengths, + int* const codes, + int code_lengths_size) { + int symbol; + int num_symbols = 0; + int root_symbol = 0; + + assert(tree != NULL); + assert(code_lengths != NULL); + + // Find out number of symbols and the root symbol. + for (symbol = 0; symbol < code_lengths_size; ++symbol) { + if (code_lengths[symbol] > 0) { + // Note: code length = 0 indicates non-existent symbol. + ++num_symbols; + root_symbol = symbol; + } + } + + // Initialize the tree. Will fail for num_symbols = 0 + if (!TreeInit(tree, num_symbols)) return 0; + + // Build tree. + if (num_symbols == 1) { // Trivial case. + const int max_symbol = code_lengths_size; + if (root_symbol < 0 || root_symbol >= max_symbol) { + VP8LHuffmanTreeFree(tree); + return 0; + } + return TreeAddSymbol(tree, root_symbol, 0, 0); + } else { // Normal case. + int ok = 0; + memset(codes, 0, code_lengths_size * sizeof(*codes)); + + if (!VP8LHuffmanCodeLengthsToCodes(code_lengths, code_lengths_size, + codes)) { + goto End; + } + + // Add symbols one-by-one. + for (symbol = 0; symbol < code_lengths_size; ++symbol) { + if (code_lengths[symbol] > 0) { + if (!TreeAddSymbol(tree, symbol, codes[symbol], + code_lengths[symbol])) { + goto End; + } + } + } + ok = 1; + End: + ok = ok && IsFull(tree); + if (!ok) VP8LHuffmanTreeFree(tree); + return ok; + } +} + +int VP8LHuffmanTreeBuildExplicit(HuffmanTree* const tree, + const int* const code_lengths, + const int* const codes, + const int* const symbols, int max_symbol, + int num_symbols) { + int ok = 0; + int i; + assert(tree != NULL); + assert(code_lengths != NULL); + assert(codes != NULL); + assert(symbols != NULL); + + // Initialize the tree. Will fail if num_symbols = 0. + if (!TreeInit(tree, num_symbols)) return 0; + + // Add symbols one-by-one. + for (i = 0; i < num_symbols; ++i) { + if (codes[i] != NON_EXISTENT_SYMBOL) { + if (symbols[i] < 0 || symbols[i] >= max_symbol) { + goto End; + } + if (!TreeAddSymbol(tree, symbols[i], codes[i], code_lengths[i])) { + goto End; + } + } + } + ok = 1; + End: + ok = ok && IsFull(tree); + if (!ok) VP8LHuffmanTreeFree(tree); + return ok; +} |