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1 | // Some mp3 related code for Sega/Mega CD |
2 | // (c) Copyright 2007, Grazvydas "notaz" Ignotas |
3 | |
abe0ea43 |
4 | #include <stdio.h> |
5 | #include <string.h> |
6 | |
7 | #include "../../Pico/sound/mix.h" |
8 | #include "code940/940shared.h" |
9 | #include "helix/pub/mp3dec.h" |
10 | |
11 | static short mp3_out_buffer[2*1152]; |
12 | static HMP3Decoder mp3dec = 0; |
13 | static int mp3_buffer_offs = 0; |
14 | |
15 | extern _940_ctl_t *shared_ctl; |
16 | extern unsigned char *mp3_mem; |
17 | extern int PsndRate; |
18 | |
19 | |
20 | static int try_get_header(unsigned char *buff, MP3FrameInfo *fi) |
21 | { |
22 | int ret, offs1, offs = 0; |
23 | |
24 | while (1) |
25 | { |
26 | offs1 = MP3FindSyncWord(buff + offs, 2048 - offs); |
27 | if (offs1 < 0) return -2; |
28 | offs += offs1; |
29 | if (2048 - offs < 4) return -3; |
30 | |
31 | // printf("trying header %08x\n", *(int *)(buff + offs)); |
32 | |
33 | ret = MP3GetNextFrameInfo(mp3dec, fi, buff + offs); |
34 | if (ret == 0 && fi->bitrate != 0) break; |
35 | offs++; |
36 | } |
37 | |
38 | return ret; |
39 | } |
40 | |
41 | int mp3_get_bitrate(FILE *f, int len) |
42 | { |
43 | unsigned char buff[2048]; |
44 | MP3FrameInfo fi; |
45 | int ret; |
46 | |
47 | memset(buff, 0, 2048); |
48 | |
49 | if (!mp3dec) mp3dec = MP3InitDecoder(); |
50 | |
51 | fseek(f, 0, SEEK_SET); |
52 | ret = fread(buff, 1, 2048, f); |
53 | fseek(f, 0, SEEK_SET); |
54 | if (ret <= 0) return -1; |
55 | |
56 | ret = try_get_header(buff, &fi); |
57 | if (ret != 0 || fi.bitrate == 0) { |
58 | // try to read somewhere around the middle |
59 | fseek(f, len>>1, SEEK_SET); |
60 | fread(buff, 1, 2048, f); |
61 | fseek(f, 0, SEEK_SET); |
62 | ret = try_get_header(buff, &fi); |
63 | } |
64 | if (ret != 0) return ret; |
65 | |
66 | // printf("bitrate: %i\n", fi.bitrate / 1000); |
67 | |
68 | return fi.bitrate / 1000; |
69 | } |
70 | |
71 | |
72 | static void mp3_decode(void) |
73 | { |
74 | // tried copying this to cached mem, no improvement noticed |
75 | int mp3_offs = shared_ctl->mp3_offs; |
76 | unsigned char *readPtr = mp3_mem + mp3_offs; |
77 | int bytesLeft = shared_ctl->mp3_len - mp3_offs; |
78 | int offset; // frame offset from readPtr |
79 | int err; |
80 | |
81 | if (bytesLeft <= 0) return; // EOF, nothing to do |
82 | |
83 | offset = MP3FindSyncWord(readPtr, bytesLeft); |
84 | if (offset < 0) { |
85 | shared_ctl->mp3_offs = shared_ctl->mp3_len; |
86 | return; // EOF |
87 | } |
88 | readPtr += offset; |
89 | bytesLeft -= offset; |
90 | |
91 | err = MP3Decode(mp3dec, &readPtr, &bytesLeft, mp3_out_buffer, 0); |
92 | if (err) { |
93 | if (err == ERR_MP3_INDATA_UNDERFLOW) { |
94 | shared_ctl->mp3_offs = shared_ctl->mp3_len; // EOF |
95 | return; |
96 | } else if (err <= -6 && err >= -12) { |
97 | // ERR_MP3_INVALID_FRAMEHEADER, ERR_MP3_INVALID_* |
98 | // just try to skip the offending frame.. |
99 | readPtr++; |
100 | } |
101 | shared_ctl->mp3_errors++; |
102 | shared_ctl->mp3_lasterr = err; |
103 | } |
104 | shared_ctl->mp3_offs = readPtr - mp3_mem; |
105 | } |
106 | |
107 | |
108 | void mp3_update_local(int *buffer, int length, int stereo) |
109 | { |
110 | int length_mp3, shr = 0; |
111 | void (*mix_samples)(int *dest_buf, short *mp3_buf, int count) = mix_16h_to_32; |
112 | |
113 | length_mp3 = length; |
114 | if (PsndRate == 22050) { mix_samples = mix_16h_to_32_s1; length_mp3 <<= 1; shr = 1; } |
115 | else if (PsndRate == 11025) { mix_samples = mix_16h_to_32_s2; length_mp3 <<= 2; shr = 2; } |
116 | |
117 | if (1152 - mp3_buffer_offs >= length_mp3) { |
118 | mix_samples(buffer, mp3_out_buffer + mp3_buffer_offs*2, length<<1); |
119 | |
120 | mp3_buffer_offs += length_mp3; |
121 | } else { |
122 | int left = 1152 - mp3_buffer_offs; |
123 | |
124 | mix_samples(buffer, mp3_out_buffer + mp3_buffer_offs*2, (left>>shr)<<1); |
125 | mp3_decode(); |
126 | mp3_buffer_offs = length_mp3 - left; |
127 | mix_samples(buffer + ((left>>shr)<<1), mp3_out_buffer, (mp3_buffer_offs>>shr)<<1); |
128 | } |
129 | } |
130 | |
131 | |
132 | void mp3_start_local(void) |
133 | { |
134 | mp3_buffer_offs = 0; |
135 | mp3_decode(); |
136 | } |
137 | |