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Diffstat (limited to 'apps/codecs/demac/libdemac/decoder.c')
-rw-r--r--apps/codecs/demac/libdemac/decoder.c184
1 files changed, 184 insertions, 0 deletions
diff --git a/apps/codecs/demac/libdemac/decoder.c b/apps/codecs/demac/libdemac/decoder.c
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1/*
2
3libdemac - A Monkey's Audio decoder
4
5$Id:$
6
7Copyright (C) Dave Chapman 2007
8
9This program is free software; you can redistribute it and/or modify
10it under the terms of the GNU General Public License as published by
11the Free Software Foundation; either version 2 of the License, or
12(at your option) any later version.
13
14This program is distributed in the hope that it will be useful,
15but WITHOUT ANY WARRANTY; without even the implied warranty of
16MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17GNU General Public License for more details.
18
19You should have received a copy of the GNU General Public License
20along with this program; if not, write to the Free Software
21Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
22
23*/
24
25#include <inttypes.h>
26#include <string.h>
27
28#include "demac.h"
29#include "predictor.h"
30#include "entropy.h"
31#include "filter.h"
32
33/* Statically allocate the filter buffers */
34
35static int16_t filterbuf32[(32*3 + HISTORY_SIZE) * 2] IBSS_ATTR; /* 4480 bytes */
36static int16_t filterbuf256[(256*3 + HISTORY_SIZE) * 2] IBSS_ATTR; /* 5120 bytes */
37
38/* This is only needed for "insane" files, and no Rockbox targets can
39 hope to decode them in realtime anyway. */
40static int16_t filterbuf1280[(1280*3 + HISTORY_SIZE) * 2]; /* 17408 bytes */
41
42void init_frame_decoder(struct ape_ctx_t* ape_ctx,
43 unsigned char* inbuffer, int* firstbyte,
44 int* bytesconsumed)
45{
46 init_entropy_decoder(ape_ctx, inbuffer, firstbyte, bytesconsumed);
47 //printf("CRC=0x%08x\n",ape_ctx->CRC);
48 //printf("Flags=0x%08x\n",ape_ctx->frameflags);
49
50 init_predictor_decoder(ape_ctx);
51
52 switch (ape_ctx->compressiontype)
53 {
54 case 2000:
55 init_filter_16_11(filterbuf32);
56 break;
57
58 case 3000:
59 init_filter_64_11(filterbuf256);
60 break;
61
62 case 4000:
63 init_filter_256_13(filterbuf256);
64 init_filter_32_10(filterbuf32);
65 break;
66
67 case 5000:
68 init_filter_1280_15(filterbuf1280);
69 init_filter_256_13(filterbuf256);
70 init_filter_16_11(filterbuf32);
71 }
72}
73
74int decode_chunk(struct ape_ctx_t* ape_ctx,
75 unsigned char* inbuffer, int* firstbyte,
76 int* bytesconsumed,
77 int32_t* decoded0, int32_t* decoded1,
78 int count)
79{
80 int res;
81 int32_t left, right;
82#ifdef ROCKBOX
83 int scale = (APE_OUTPUT_DEPTH - ape_ctx->bps);
84 #define SCALE(x) ((x) << scale)
85#else
86 #define SCALE(x) (x)
87#endif
88
89 if ((ape_ctx->channels==1) || (ape_ctx->frameflags & APE_FRAMECODE_PSEUDO_STEREO)) {
90 if (ape_ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
91 res = entropy_decode(ape_ctx, inbuffer, firstbyte, bytesconsumed, decoded0, decoded1, count);
92 /* We are pure silence, so we're done. */
93 return 0;
94 } else {
95 res = entropy_decode(ape_ctx, inbuffer, firstbyte, bytesconsumed, decoded0, NULL, count);
96 }
97
98 switch (ape_ctx->compressiontype)
99 {
100 case 2000:
101 apply_filter_16_11(ape_ctx->fileversion,decoded0,NULL,count);
102 break;
103
104 case 3000:
105 apply_filter_64_11(ape_ctx->fileversion,decoded0,NULL,count);
106 break;
107
108 case 4000:
109 apply_filter_32_10(ape_ctx->fileversion,decoded0,NULL,count);
110 apply_filter_256_13(ape_ctx->fileversion,decoded0,NULL,count);
111 break;
112
113 case 5000:
114 apply_filter_16_11(ape_ctx->fileversion,decoded0,NULL,count);
115 apply_filter_256_13(ape_ctx->fileversion,decoded0,NULL,count);
116 apply_filter_1280_15(ape_ctx->fileversion,decoded0,NULL,count);
117 }
118
119 /* Now apply the predictor decoding */
120 predictor_decode_mono(ape_ctx,decoded0,count);
121
122 if (ape_ctx->channels==2) {
123 /* Pseudo-stereo - just copy left channel to right channel */
124 while (count--)
125 {
126 left = *decoded0;
127 *(decoded1++) = *(decoded0++) = SCALE(left);
128 }
129 } else {
130 /* Mono - do nothing unless it's 8-bit audio */
131 if (ape_ctx->bps == 8) {
132 /* TODO: Handle 8-bit streams */
133 }
134 }
135 } else { /* Stereo */
136 if (ape_ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
137 /* We are pure silence, so we're done. */
138 return 0;
139 }
140
141 res = entropy_decode(ape_ctx, inbuffer, firstbyte, bytesconsumed, decoded0, decoded1, count);
142
143 /* Apply filters - compression type 1000 doesn't have any */
144 switch (ape_ctx->compressiontype)
145 {
146 case 2000:
147 apply_filter_16_11(ape_ctx->fileversion,decoded0,decoded1,count);
148 break;
149
150 case 3000:
151 apply_filter_64_11(ape_ctx->fileversion,decoded0,decoded1,count);
152 break;
153
154 case 4000:
155 apply_filter_32_10(ape_ctx->fileversion,decoded0,decoded1,count);
156 apply_filter_256_13(ape_ctx->fileversion,decoded0,decoded1,count);
157 break;
158
159 case 5000:
160 apply_filter_16_11(ape_ctx->fileversion,decoded0,decoded1,count);
161 apply_filter_256_13(ape_ctx->fileversion,decoded0,decoded1,count);
162 apply_filter_1280_15(ape_ctx->fileversion,decoded0,decoded1,count);
163 }
164
165 /* Now apply the predictor decoding */
166 predictor_decode_stereo(ape_ctx,decoded0,decoded1,count);
167
168 if (ape_ctx->bps == 8) {
169 /* TODO: Handle 8-bit streams */
170 } else {
171 /* Decorrelate and scale to output depth */
172 while (count--)
173 {
174 left = *decoded1 - (*decoded0 / 2);
175 right = left + *decoded0;
176
177 *(decoded0++) = SCALE(left);
178 *(decoded1++) = SCALE(right);
179 }
180 }
181 }
182
183 return res;
184}
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