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-rw-r--r--media/libwebp/src/dec/quant_dec.c115
1 files changed, 115 insertions, 0 deletions
diff --git a/media/libwebp/src/dec/quant_dec.c b/media/libwebp/src/dec/quant_dec.c
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+// Copyright 2010 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.
+// -----------------------------------------------------------------------------
+//
+// Quantizer initialization
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include "src/dec/vp8i_dec.h"
+
+static WEBP_INLINE int clip(int v, int M) {
+ return v < 0 ? 0 : v > M ? M : v;
+}
+
+// Paragraph 14.1
+static const uint8_t kDcTable[128] = {
+ 4, 5, 6, 7, 8, 9, 10, 10,
+ 11, 12, 13, 14, 15, 16, 17, 17,
+ 18, 19, 20, 20, 21, 21, 22, 22,
+ 23, 23, 24, 25, 25, 26, 27, 28,
+ 29, 30, 31, 32, 33, 34, 35, 36,
+ 37, 37, 38, 39, 40, 41, 42, 43,
+ 44, 45, 46, 46, 47, 48, 49, 50,
+ 51, 52, 53, 54, 55, 56, 57, 58,
+ 59, 60, 61, 62, 63, 64, 65, 66,
+ 67, 68, 69, 70, 71, 72, 73, 74,
+ 75, 76, 76, 77, 78, 79, 80, 81,
+ 82, 83, 84, 85, 86, 87, 88, 89,
+ 91, 93, 95, 96, 98, 100, 101, 102,
+ 104, 106, 108, 110, 112, 114, 116, 118,
+ 122, 124, 126, 128, 130, 132, 134, 136,
+ 138, 140, 143, 145, 148, 151, 154, 157
+};
+
+static const uint16_t kAcTable[128] = {
+ 4, 5, 6, 7, 8, 9, 10, 11,
+ 12, 13, 14, 15, 16, 17, 18, 19,
+ 20, 21, 22, 23, 24, 25, 26, 27,
+ 28, 29, 30, 31, 32, 33, 34, 35,
+ 36, 37, 38, 39, 40, 41, 42, 43,
+ 44, 45, 46, 47, 48, 49, 50, 51,
+ 52, 53, 54, 55, 56, 57, 58, 60,
+ 62, 64, 66, 68, 70, 72, 74, 76,
+ 78, 80, 82, 84, 86, 88, 90, 92,
+ 94, 96, 98, 100, 102, 104, 106, 108,
+ 110, 112, 114, 116, 119, 122, 125, 128,
+ 131, 134, 137, 140, 143, 146, 149, 152,
+ 155, 158, 161, 164, 167, 170, 173, 177,
+ 181, 185, 189, 193, 197, 201, 205, 209,
+ 213, 217, 221, 225, 229, 234, 239, 245,
+ 249, 254, 259, 264, 269, 274, 279, 284
+};
+
+//------------------------------------------------------------------------------
+// Paragraph 9.6
+
+void VP8ParseQuant(VP8Decoder* const dec) {
+ VP8BitReader* const br = &dec->br_;
+ const int base_q0 = VP8GetValue(br, 7, "global-header");
+ const int dqy1_dc = VP8Get(br, "global-header") ?
+ VP8GetSignedValue(br, 4, "global-header") : 0;
+ const int dqy2_dc = VP8Get(br, "global-header") ?
+ VP8GetSignedValue(br, 4, "global-header") : 0;
+ const int dqy2_ac = VP8Get(br, "global-header") ?
+ VP8GetSignedValue(br, 4, "global-header") : 0;
+ const int dquv_dc = VP8Get(br, "global-header") ?
+ VP8GetSignedValue(br, 4, "global-header") : 0;
+ const int dquv_ac = VP8Get(br, "global-header") ?
+ VP8GetSignedValue(br, 4, "global-header") : 0;
+
+ const VP8SegmentHeader* const hdr = &dec->segment_hdr_;
+ int i;
+
+ for (i = 0; i < NUM_MB_SEGMENTS; ++i) {
+ int q;
+ if (hdr->use_segment_) {
+ q = hdr->quantizer_[i];
+ if (!hdr->absolute_delta_) {
+ q += base_q0;
+ }
+ } else {
+ if (i > 0) {
+ dec->dqm_[i] = dec->dqm_[0];
+ continue;
+ } else {
+ q = base_q0;
+ }
+ }
+ {
+ VP8QuantMatrix* const m = &dec->dqm_[i];
+ m->y1_mat_[0] = kDcTable[clip(q + dqy1_dc, 127)];
+ m->y1_mat_[1] = kAcTable[clip(q + 0, 127)];
+
+ m->y2_mat_[0] = kDcTable[clip(q + dqy2_dc, 127)] * 2;
+ // For all x in [0..284], x*155/100 is bitwise equal to (x*101581) >> 16.
+ // The smallest precision for that is '(x*6349) >> 12' but 16 is a good
+ // word size.
+ m->y2_mat_[1] = (kAcTable[clip(q + dqy2_ac, 127)] * 101581) >> 16;
+ if (m->y2_mat_[1] < 8) m->y2_mat_[1] = 8;
+
+ m->uv_mat_[0] = kDcTable[clip(q + dquv_dc, 117)];
+ m->uv_mat_[1] = kAcTable[clip(q + dquv_ac, 127)];
+
+ m->uv_quant_ = q + dquv_ac; // for dithering strength evaluation
+ }
+ }
+}
+
+//------------------------------------------------------------------------------
+