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[picodrive.git] / platform / gp2x / mp3.c
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1#include <stdio.h>
2#include <string.h>
3
4#include "../../Pico/sound/mix.h"
5#include "code940/940shared.h"
6#include "helix/pub/mp3dec.h"
7
8static short mp3_out_buffer[2*1152];
9static HMP3Decoder mp3dec = 0;
10static int mp3_buffer_offs = 0;
11
12extern _940_ctl_t *shared_ctl;
13extern unsigned char *mp3_mem;
14extern int PsndRate;
15
16
17static int try_get_header(unsigned char *buff, MP3FrameInfo *fi)
18{
19 int ret, offs1, offs = 0;
20
21 while (1)
22 {
23 offs1 = MP3FindSyncWord(buff + offs, 2048 - offs);
24 if (offs1 < 0) return -2;
25 offs += offs1;
26 if (2048 - offs < 4) return -3;
27
28 // printf("trying header %08x\n", *(int *)(buff + offs));
29
30 ret = MP3GetNextFrameInfo(mp3dec, fi, buff + offs);
31 if (ret == 0 && fi->bitrate != 0) break;
32 offs++;
33 }
34
35 return ret;
36}
37
38int mp3_get_bitrate(FILE *f, int len)
39{
40 unsigned char buff[2048];
41 MP3FrameInfo fi;
42 int ret;
43
44 memset(buff, 0, 2048);
45
46 if (!mp3dec) mp3dec = MP3InitDecoder();
47
48 fseek(f, 0, SEEK_SET);
49 ret = fread(buff, 1, 2048, f);
50 fseek(f, 0, SEEK_SET);
51 if (ret <= 0) return -1;
52
53 ret = try_get_header(buff, &fi);
54 if (ret != 0 || fi.bitrate == 0) {
55 // try to read somewhere around the middle
56 fseek(f, len>>1, SEEK_SET);
57 fread(buff, 1, 2048, f);
58 fseek(f, 0, SEEK_SET);
59 ret = try_get_header(buff, &fi);
60 }
61 if (ret != 0) return ret;
62
63 // printf("bitrate: %i\n", fi.bitrate / 1000);
64
65 return fi.bitrate / 1000;
66}
67
68
69static void mp3_decode(void)
70{
71 // tried copying this to cached mem, no improvement noticed
72 int mp3_offs = shared_ctl->mp3_offs;
73 unsigned char *readPtr = mp3_mem + mp3_offs;
74 int bytesLeft = shared_ctl->mp3_len - mp3_offs;
75 int offset; // frame offset from readPtr
76 int err;
77
78 if (bytesLeft <= 0) return; // EOF, nothing to do
79
80 offset = MP3FindSyncWord(readPtr, bytesLeft);
81 if (offset < 0) {
82 shared_ctl->mp3_offs = shared_ctl->mp3_len;
83 return; // EOF
84 }
85 readPtr += offset;
86 bytesLeft -= offset;
87
88 err = MP3Decode(mp3dec, &readPtr, &bytesLeft, mp3_out_buffer, 0);
89 if (err) {
90 if (err == ERR_MP3_INDATA_UNDERFLOW) {
91 shared_ctl->mp3_offs = shared_ctl->mp3_len; // EOF
92 return;
93 } else if (err <= -6 && err >= -12) {
94 // ERR_MP3_INVALID_FRAMEHEADER, ERR_MP3_INVALID_*
95 // just try to skip the offending frame..
96 readPtr++;
97 }
98 shared_ctl->mp3_errors++;
99 shared_ctl->mp3_lasterr = err;
100 }
101 shared_ctl->mp3_offs = readPtr - mp3_mem;
102}
103
104
105void mp3_update_local(int *buffer, int length, int stereo)
106{
107 int length_mp3, shr = 0;
108 void (*mix_samples)(int *dest_buf, short *mp3_buf, int count) = mix_16h_to_32;
109
110 length_mp3 = length;
111 if (PsndRate == 22050) { mix_samples = mix_16h_to_32_s1; length_mp3 <<= 1; shr = 1; }
112 else if (PsndRate == 11025) { mix_samples = mix_16h_to_32_s2; length_mp3 <<= 2; shr = 2; }
113
114 if (1152 - mp3_buffer_offs >= length_mp3) {
115 mix_samples(buffer, mp3_out_buffer + mp3_buffer_offs*2, length<<1);
116
117 mp3_buffer_offs += length_mp3;
118 } else {
119 int left = 1152 - mp3_buffer_offs;
120
121 mix_samples(buffer, mp3_out_buffer + mp3_buffer_offs*2, (left>>shr)<<1);
122 mp3_decode();
123 mp3_buffer_offs = length_mp3 - left;
124 mix_samples(buffer + ((left>>shr)<<1), mp3_out_buffer, (mp3_buffer_offs>>shr)<<1);
125 }
126}
127
128
129void mp3_start_local(void)
130{
131 mp3_buffer_offs = 0;
132 mp3_decode();
133}
134