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author | hkuang <hkuang@google.com> | 2013-07-25 11:11:39 -0700 |
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committer | hkuang <hkuang@google.com> | 2013-07-25 12:03:12 -0700 |
commit | 91037db265ecdd914a26e056cf69207b4f50924e (patch) | |
tree | c78c618cf6d0ffb187e2734d524bca19698b3c0d /libvpx/vp9/decoder/vp9_dsubexp.c | |
parent | ba164dffc5a6795bce97fae02b51ccf3330e15e4 (diff) | |
download | android_external_libvpx-91037db265ecdd914a26e056cf69207b4f50924e.tar.gz android_external_libvpx-91037db265ecdd914a26e056cf69207b4f50924e.tar.bz2 android_external_libvpx-91037db265ecdd914a26e056cf69207b4f50924e.zip |
Roll latest libvpx into Android.
Make the VP9 decoding 2X faster than the old one.
Checkout is from master branch(hash:242157c756314827ad9244952c7253e8900b9626).
Change-Id: Ibe67b3ee19f82b87df2416826b63a67f7f79b63a
Diffstat (limited to 'libvpx/vp9/decoder/vp9_dsubexp.c')
-rw-r--r-- | libvpx/vp9/decoder/vp9_dsubexp.c | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/libvpx/vp9/decoder/vp9_dsubexp.c b/libvpx/vp9/decoder/vp9_dsubexp.c new file mode 100644 index 0000000..8cc64f7 --- /dev/null +++ b/libvpx/vp9/decoder/vp9_dsubexp.c @@ -0,0 +1,106 @@ +/* + Copyright (c) 2010 The WebM project authors. All Rights Reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE 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. + */ + +#include "vp9/common/vp9_entropy.h" + +#include "vp9/decoder/vp9_dsubexp.h" + +static int inv_recenter_nonneg(int v, int m) { + if (v > 2 * m) + return v; + + return v % 2 ? m - (v + 1) / 2 : m + v / 2; +} + +static int decode_uniform(vp9_reader *r, int n) { + int v; + const int l = get_unsigned_bits(n); + const int m = (1 << l) - n; + if (!l) + return 0; + + v = vp9_read_literal(r, l - 1); + return v < m ? v : (v << 1) - m + vp9_read_bit(r); +} + + +static int merge_index(int v, int n, int modulus) { + int max1 = (n - 1 - modulus / 2) / modulus + 1; + if (v < max1) { + v = v * modulus + modulus / 2; + } else { + int w; + v -= max1; + w = v; + v += (v + modulus - modulus / 2) / modulus; + while (v % modulus == modulus / 2 || + w != v - (v + modulus - modulus / 2) / modulus) v++; + } + return v; +} + +static int inv_remap_prob(int v, int m) { + static int inv_map_table[MAX_PROB - 1] = { + // generated by: + // inv_map_table[j] = merge_index(j, MAX_PROB - 1, MODULUS_PARAM); + 6, 19, 32, 45, 58, 71, 84, 97, 110, 123, 136, 149, 162, 175, 188, + 201, 214, 227, 240, 253, 0, 1, 2, 3, 4, 5, 7, 8, 9, 10, + 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, + 27, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, + 43, 44, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 59, + 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, + 76, 77, 78, 79, 80, 81, 82, 83, 85, 86, 87, 88, 89, 90, 91, + 92, 93, 94, 95, 96, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, + 108, 109, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 124, + 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 137, 138, 139, 140, + 141, 142, 143, 144, 145, 146, 147, 148, 150, 151, 152, 153, 154, 155, 156, + 157, 158, 159, 160, 161, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, + 173, 174, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 189, + 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 202, 203, 204, 205, + 206, 207, 208, 209, 210, 211, 212, 213, 215, 216, 217, 218, 219, 220, 221, + 222, 223, 224, 225, 226, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, + 238, 239, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, + + }; + // v = merge_index(v, MAX_PROBS - 1, MODULUS_PARAM); + v = inv_map_table[v]; + m--; + if ((m << 1) <= MAX_PROB) { + return 1 + inv_recenter_nonneg(v + 1, m); + } else { + return MAX_PROB - inv_recenter_nonneg(v + 1, MAX_PROB - 1 - m); + } +} + +static int decode_term_subexp(vp9_reader *r, int k, int num_syms) { + int i = 0, mk = 0, word; + while (1) { + const int b = i ? k + i - 1 : k; + const int a = 1 << b; + if (num_syms <= mk + 3 * a) { + word = decode_uniform(r, num_syms - mk) + mk; + break; + } else { + if (vp9_read_bit(r)) { + i++; + mk += a; + } else { + word = vp9_read_literal(r, b) + mk; + break; + } + } + } + return word; +} + +void vp9_diff_update_prob(vp9_reader *r, vp9_prob* p) { + int delp = decode_term_subexp(r, SUBEXP_PARAM, 255); + *p = (vp9_prob)inv_remap_prob(delp, *p); +} |