summaryrefslogtreecommitdiffstats
path: root/apps/codecs/demac/libdemac/decoder.c
blob: 326e893ec4f0613d9e4600d50ce4db13374d66e6 (plain)
1
2
3
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
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
/*

libdemac - A Monkey's Audio decoder

$Id$

Copyright (C) Dave Chapman 2007

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA

*/

#include <inttypes.h>
#include <string.h>

#include "demac.h"
#include "predictor.h"
#include "entropy.h"
#include "filter.h"

/* Statically allocate the filter buffers */

static int16_t filterbuf32[(32*3 + HISTORY_SIZE) * 2]     /* 4480 bytes */
               IBSS_ATTR __attribute__((aligned(16)));
static int16_t filterbuf256[(256*3 + HISTORY_SIZE) * 2]   /* 5120 bytes */
               IBSS_ATTR __attribute__((aligned(16)));

/* This is only needed for "insane" files, and no Rockbox targets can
   hope to decode them in realtime anyway. */
static int16_t filterbuf1280[(1280*3 + HISTORY_SIZE) * 2] /* 17408 bytes */
               __attribute__((aligned(16)));

void init_frame_decoder(struct ape_ctx_t* ape_ctx,
                        unsigned char* inbuffer, int* firstbyte,
                        int* bytesconsumed)
{
    init_entropy_decoder(ape_ctx, inbuffer, firstbyte, bytesconsumed);
    //printf("CRC=0x%08x\n",ape_ctx->CRC);
    //printf("Flags=0x%08x\n",ape_ctx->frameflags);

    init_predictor_decoder(&ape_ctx->predictor);

    switch (ape_ctx->compressiontype)
    {
        case 2000:
            init_filter_16_11(filterbuf32);
            break;

        case 3000:
            init_filter_64_11(filterbuf256);
            break;

        case 4000:
            init_filter_256_13(filterbuf256);
            init_filter_32_10(filterbuf32);
            break;

        case 5000:
            init_filter_1280_15(filterbuf1280);
            init_filter_256_13(filterbuf256);
            init_filter_16_11(filterbuf32);
    }
}

int decode_chunk(struct ape_ctx_t* ape_ctx,
                 unsigned char* inbuffer, int* firstbyte,
                 int* bytesconsumed,
                 int32_t* decoded0, int32_t* decoded1, 
                 int count)
{
    int res;
    int32_t left, right;
#ifdef ROCKBOX
    int scale = (APE_OUTPUT_DEPTH - ape_ctx->bps);
    #define SCALE(x) ((x) << scale)
#else
    #define SCALE(x) (x)
#endif

    if ((ape_ctx->channels==1) || (ape_ctx->frameflags & APE_FRAMECODE_PSEUDO_STEREO)) {
        if (ape_ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
            res = entropy_decode(ape_ctx, inbuffer, firstbyte, bytesconsumed, decoded0, decoded1, count);
            /* We are pure silence, so we're done. */
            return 0;
        } else {
            res = entropy_decode(ape_ctx, inbuffer, firstbyte, bytesconsumed, decoded0, NULL, count);
        }
    
        switch (ape_ctx->compressiontype)
        {
            case 2000:
                apply_filter_16_11(ape_ctx->fileversion,decoded0,NULL,count);
                break;
    
            case 3000:
                apply_filter_64_11(ape_ctx->fileversion,decoded0,NULL,count);
                break;
    
            case 4000:
                apply_filter_32_10(ape_ctx->fileversion,decoded0,NULL,count);
                apply_filter_256_13(ape_ctx->fileversion,decoded0,NULL,count);
                break;
    
            case 5000:
                apply_filter_16_11(ape_ctx->fileversion,decoded0,NULL,count);
                apply_filter_256_13(ape_ctx->fileversion,decoded0,NULL,count);
                apply_filter_1280_15(ape_ctx->fileversion,decoded0,NULL,count);
        }

        /* Now apply the predictor decoding */
        predictor_decode_mono(&ape_ctx->predictor,decoded0,count);

        if (ape_ctx->channels==2) {
            /* Pseudo-stereo - just copy left channel to right channel */
            while (count--)
            {
                left = *decoded0;
                *(decoded1++) = *(decoded0++) = SCALE(left);
            }
        } else {
            /* Mono - do nothing unless it's 8-bit audio */
            if (ape_ctx->bps == 8) {
                /* TODO: Handle 8-bit streams */
            }
        }
    } else { /* Stereo */
        if (ape_ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
            /* We are pure silence, so we're done. */
            return 0;
        }
    
        res = entropy_decode(ape_ctx, inbuffer, firstbyte, bytesconsumed, decoded0, decoded1, count);

        /* Apply filters - compression type 1000 doesn't have any */
        switch (ape_ctx->compressiontype)
        {
            case 2000:
                apply_filter_16_11(ape_ctx->fileversion,decoded0,decoded1,count);
                break;
    
            case 3000:
                apply_filter_64_11(ape_ctx->fileversion,decoded0,decoded1,count);
                break;
    
            case 4000:
                apply_filter_32_10(ape_ctx->fileversion,decoded0,decoded1,count);
                apply_filter_256_13(ape_ctx->fileversion,decoded0,decoded1,count);
                break;
    
            case 5000:
                apply_filter_16_11(ape_ctx->fileversion,decoded0,decoded1,count);
                apply_filter_256_13(ape_ctx->fileversion,decoded0,decoded1,count);
                apply_filter_1280_15(ape_ctx->fileversion,decoded0,decoded1,count);
        }

        /* Now apply the predictor decoding */
        predictor_decode_stereo(&ape_ctx->predictor,decoded0,decoded1,count);

        if (ape_ctx->bps == 8) {
            /* TODO: Handle 8-bit streams */
        } else {
            /* Decorrelate and scale to output depth */
            while (count--)
            {
                left = *decoded1 - (*decoded0 / 2);
                right = left + *decoded0;

                *(decoded0++) = SCALE(left);
                *(decoded1++) = SCALE(right);
            }
        }
    }

    return res;
}