1 // Copyright 2011 Google Inc. All Rights Reserved.
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
10 // Paginated token buffer
12 // A 'token' is a bit value associated with a probability, either fixed
13 // or a later-to-be-determined after statistics have been collected.
14 // For dynamic probability, we just record the slot id (idx) for the probability
15 // value in the final probability array (uint8_t* probas in VP8EmitTokens).
17 // Author: Skal (pascal.massimino@gmail.com)
24 #include "./vp8enci.h"
26 #if !defined(DISABLE_TOKEN_BUFFER)
28 // we use pages to reduce the number of memcpy()
29 #define MAX_NUM_TOKEN 8192 // max number of token per page
30 #define FIXED_PROBA_BIT (1u << 14)
33 uint16_t tokens_[MAX_NUM_TOKEN]; // bit#15: bit
34 // bit #14: constant proba or idx
35 // bits 0..13: slot or constant proba
39 //------------------------------------------------------------------------------
41 void VP8TBufferInit(VP8TBuffer* const b) {
44 b->last_page_ = &b->pages_;
49 void VP8TBufferClear(VP8TBuffer* const b) {
51 const VP8Tokens* p = b->pages_;
53 const VP8Tokens* const next = p->next_;
61 static int TBufferNewPage(VP8TBuffer* const b) {
62 VP8Tokens* const page = b->error_ ? NULL : (VP8Tokens*)malloc(sizeof(*page));
67 *b->last_page_ = page;
68 b->last_page_ = &page->next_;
69 b->left_ = MAX_NUM_TOKEN;
70 b->tokens_ = page->tokens_;
75 //------------------------------------------------------------------------------
77 #define TOKEN_ID(t, b, ctx, p) \
78 ((p) + NUM_PROBAS * ((ctx) + NUM_CTX * ((b) + NUM_BANDS * (t))))
80 static WEBP_INLINE int AddToken(VP8TBuffer* const b,
81 int bit, uint32_t proba_idx) {
82 assert(proba_idx < FIXED_PROBA_BIT);
83 assert(bit == 0 || bit == 1);
84 if (b->left_ > 0 || TBufferNewPage(b)) {
85 const int slot = --b->left_;
86 b->tokens_[slot] = (bit << 15) | proba_idx;
91 static WEBP_INLINE void AddConstantToken(VP8TBuffer* const b,
94 assert(bit == 0 || bit == 1);
95 if (b->left_ > 0 || TBufferNewPage(b)) {
96 const int slot = --b->left_;
97 b->tokens_[slot] = (bit << 15) | FIXED_PROBA_BIT | proba;
101 int VP8RecordCoeffTokens(int ctx, int coeff_type, int first, int last,
102 const int16_t* const coeffs,
103 VP8TBuffer* const tokens) {
105 uint32_t base_id = TOKEN_ID(coeff_type, n, ctx, 0);
106 if (!AddToken(tokens, last >= 0, base_id + 0)) {
111 const int c = coeffs[n++];
112 const int sign = c < 0;
113 int v = sign ? -c : c;
114 if (!AddToken(tokens, v != 0, base_id + 1)) {
116 base_id = TOKEN_ID(coeff_type, VP8EncBands[n], ctx, 0);
119 if (!AddToken(tokens, v > 1, base_id + 2)) {
122 if (!AddToken(tokens, v > 4, base_id + 3)) {
123 if (AddToken(tokens, v != 2, base_id + 4))
124 AddToken(tokens, v == 4, base_id + 5);
125 } else if (!AddToken(tokens, v > 10, base_id + 6)) {
126 if (!AddToken(tokens, v > 6, base_id + 7)) {
127 AddConstantToken(tokens, v == 6, 159);
129 AddConstantToken(tokens, v >= 9, 165);
130 AddConstantToken(tokens, !(v & 1), 145);
135 if (v < 3 + (8 << 1)) { // VP8Cat3 (3b)
136 AddToken(tokens, 0, base_id + 8);
137 AddToken(tokens, 0, base_id + 9);
141 } else if (v < 3 + (8 << 2)) { // VP8Cat4 (4b)
142 AddToken(tokens, 0, base_id + 8);
143 AddToken(tokens, 1, base_id + 9);
147 } else if (v < 3 + (8 << 3)) { // VP8Cat5 (5b)
148 AddToken(tokens, 1, base_id + 8);
149 AddToken(tokens, 0, base_id + 10);
153 } else { // VP8Cat6 (11b)
154 AddToken(tokens, 1, base_id + 8);
155 AddToken(tokens, 1, base_id + 10);
161 AddConstantToken(tokens, !!(v & mask), *tab++);
167 AddConstantToken(tokens, sign, 128);
168 base_id = TOKEN_ID(coeff_type, VP8EncBands[n], ctx, 0);
169 if (n == 16 || !AddToken(tokens, n <= last, base_id + 0)) {
178 //------------------------------------------------------------------------------
179 // This function works, but isn't currently used. Saved for later.
183 static void Record(int bit, proba_t* const stats) {
185 if (p >= 0xffff0000u) { // an overflow is inbound.
186 p = ((p + 1u) >> 1) & 0x7fff7fffu; // -> divide the stats by 2.
188 // record bit count (lower 16 bits) and increment total count (upper 16 bits).
189 p += 0x00010000u + bit;
193 void VP8TokenToStats(const VP8TBuffer* const b, proba_t* const stats) {
194 const VP8Tokens* p = b->pages_;
196 const int N = (p->next_ == NULL) ? b->left_ : 0;
197 int n = MAX_NUM_TOKEN;
199 const uint16_t token = p->tokens_[n];
200 if (!(token & FIXED_PROBA_BIT)) {
201 Record((token >> 15) & 1, stats + (token & 0x3fffu));
210 //------------------------------------------------------------------------------
211 // Final coding pass, with known probabilities
213 int VP8EmitTokens(VP8TBuffer* const b, VP8BitWriter* const bw,
214 const uint8_t* const probas, int final_pass) {
215 const VP8Tokens* p = b->pages_;
217 if (b->error_) return 0;
219 const VP8Tokens* const next = p->next_;
220 const int N = (next == NULL) ? b->left_ : 0;
221 int n = MAX_NUM_TOKEN;
223 const uint16_t token = p->tokens_[n];
224 const int bit = (token >> 15) & 1;
225 if (token & FIXED_PROBA_BIT) {
226 VP8PutBit(bw, bit, token & 0xffu); // constant proba
228 VP8PutBit(bw, bit, probas[token & 0x3fffu]);
231 if (final_pass) free((void*)p);
234 if (final_pass) b->pages_ = NULL;
239 size_t VP8EstimateTokenSize(VP8TBuffer* const b, const uint8_t* const probas) {
241 const VP8Tokens* p = b->pages_;
242 if (b->error_) return 0;
244 const VP8Tokens* const next = p->next_;
245 const int N = (next == NULL) ? b->left_ : 0;
246 int n = MAX_NUM_TOKEN;
248 const uint16_t token = p->tokens_[n];
249 const int bit = token & (1 << 15);
250 if (token & FIXED_PROBA_BIT) {
251 size += VP8BitCost(bit, token & 0xffu);
253 size += VP8BitCost(bit, probas[token & 0x3fffu]);
261 //------------------------------------------------------------------------------
263 #else // DISABLE_TOKEN_BUFFER
265 void VP8TBufferInit(VP8TBuffer* const b) {
268 void VP8TBufferClear(VP8TBuffer* const b) {
272 #endif // !DISABLE_TOKEN_BUFFER