1 /* Copyright (c) 2022 Amazon
2 Written by Jan Buethe */
3 /*
4 Redistribution and use in source and binary forms, with or without
5 modification, are permitted provided that the following conditions
6 are met:
7
8 - Redistributions of source code must retain the above copyright
9 notice, this list of conditions and the following disclaimer.
10
11 - Redistributions in binary form must reproduce the above copyright
12 notice, this list of conditions and the following disclaimer in the
13 documentation and/or other materials provided with the distribution.
14
15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
18 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
19 OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
20 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
22 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
23 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
24 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include <string.h>
29
30 #ifdef HAVE_CONFIG_H
31 #include "config.h"
32 #endif
33
34 #include "os_support.h"
35 #include "dred_decoder.h"
36 #include "dred_coding.h"
37 #include "celt/entdec.h"
38 #include "celt/laplace.h"
39 #include "dred_rdovae_stats_data.h"
40 #include "dred_rdovae_constants.h"
41
dred_decode_latents(ec_dec * dec,float * x,const opus_uint8 * scale,const opus_uint8 * r,const opus_uint8 * p0,int dim)42 static void dred_decode_latents(ec_dec *dec, float *x, const opus_uint8 *scale, const opus_uint8 *r, const opus_uint8 *p0, int dim) {
43 int i;
44 for (i=0;i<dim;i++) {
45 int q;
46 if (r[i] == 0 || p0[i] == 255) q = 0;
47 else q = ec_laplace_decode_p0(dec, p0[i]<<7, r[i]<<7);
48 x[i] = q*256.f/(scale[i] == 0 ? 1 : scale[i]);
49 }
50 }
51
dred_ec_decode(OpusDRED * dec,const opus_uint8 * bytes,int num_bytes,int min_feature_frames,int dred_frame_offset)52 int dred_ec_decode(OpusDRED *dec, const opus_uint8 *bytes, int num_bytes, int min_feature_frames, int dred_frame_offset)
53 {
54 ec_dec ec;
55 int q_level;
56 int i;
57 int offset;
58 int q0;
59 int dQ;
60 int qmax;
61 int state_qoffset;
62 int extra_offset;
63
64 /* since features are decoded in quadruples, it makes no sense to go with an uneven number of redundancy frames */
65 celt_assert(DRED_NUM_REDUNDANCY_FRAMES % 2 == 0);
66
67 /* decode initial state and initialize RDOVAE decoder */
68 ec_dec_init(&ec, (unsigned char*)bytes, num_bytes);
69 q0 = ec_dec_uint(&ec, 16);
70 dQ = ec_dec_uint(&ec, 8);
71 if (ec_dec_uint(&ec, 2)) extra_offset = 32*ec_dec_uint(&ec, 256);
72 else extra_offset = 0;
73 /* Compute total offset, including DRED position in a multiframe packet. */
74 dec->dred_offset = 16 - ec_dec_uint(&ec, 32) - extra_offset + dred_frame_offset;
75 /*printf("%d %d %d\n", dred_offset, q0, dQ);*/
76 qmax = 15;
77 if (q0 < 14 && dQ > 0) {
78 int nvals;
79 int ft;
80 int s;
81 /* The distribution for the dQmax symbol is split evenly between zero
82 (which implies qmax == 15) and larger values, with the probability of
83 all larger values being uniform.
84 This is equivalent to coding 1 bit to decide if the maximum is less than
85 15 followed by a uint to decide the actual value if it is less than
86 15, but combined into a single symbol. */
87 nvals = 15 - (q0 + 1);
88 ft = 2*nvals;
89 s = ec_decode(&ec, ft);
90 if (s >= nvals) {
91 qmax = q0 + (s - nvals) + 1;
92 ec_dec_update(&ec, s, s + 1, ft);
93 }
94 else {
95 ec_dec_update(&ec, 0, nvals, ft);
96 }
97 }
98 state_qoffset = q0*DRED_STATE_DIM;
99 dred_decode_latents(
100 &ec,
101 dec->state,
102 dred_state_quant_scales_q8 + state_qoffset,
103 dred_state_r_q8 + state_qoffset,
104 dred_state_p0_q8 + state_qoffset,
105 DRED_STATE_DIM);
106
107 /* decode newest to oldest and store oldest to newest */
108 for (i = 0; i < IMIN(DRED_NUM_REDUNDANCY_FRAMES, (min_feature_frames+1)/2); i += 2)
109 {
110 /* FIXME: Figure out how to avoid missing a last frame that would take up < 8 bits. */
111 if (8*num_bytes - ec_tell(&ec) <= 7)
112 break;
113 q_level = compute_quantizer(q0, dQ, qmax, i/2);
114 offset = q_level*DRED_LATENT_DIM;
115 dred_decode_latents(
116 &ec,
117 &dec->latents[(i/2)*DRED_LATENT_DIM],
118 dred_latent_quant_scales_q8 + offset,
119 dred_latent_r_q8 + offset,
120 dred_latent_p0_q8 + offset,
121 DRED_LATENT_DIM
122 );
123
124 offset = 2 * i * DRED_NUM_FEATURES;
125 }
126 dec->process_stage = 1;
127 dec->nb_latents = i/2;
128 return i/2;
129 }
130