1 /*
2 * Some mp3 related code for Sega/Mega CD.
3 * Uses Libav/FFmpeg libavcodec
4 * (C) notaz, 2013
5 *
6 * This work is licensed under the terms of MAME license.
7 * See COPYING file in the top-level directory.
8 */
9
10 #include <stdio.h>
11 #include <string.h>
12 #include <libavcodec/avcodec.h>
13 #include <dlfcn.h>
14
15 #include <pico/pico_int.h>
16 #include "../libpicofe/lprintf.h"
17 #include "mp3.h"
18
19 #if LIBAVCODEC_VERSION_MAJOR < 55
20 #define AVCodecID CodecID
21 #define AV_CODEC_ID_MP3 CODEC_ID_MP3
22 #endif
23
24 static AVCodecContext *ctx;
25
26 /* avoid compile time linking to libavcodec due to huge list of it's deps..
27 * we also use this old API as newer one is not available on pandora */
28 void (*p_av_init_packet)(AVPacket *pkt);
29 int (*p_avcodec_decode_audio3)(AVCodecContext *avctx, int16_t *samples,
30 int *frame_size_ptr, AVPacket *avpkt);
31
mp3dec_decode(FILE * f,int * file_pos,int file_len)32 int mp3dec_decode(FILE *f, int *file_pos, int file_len)
33 {
34 unsigned char input_buf[2 * 1024];
35 int frame_size;
36 AVPacket avpkt;
37 int bytes_in;
38 int bytes_out;
39 int offset;
40 int len;
41
42 p_av_init_packet(&avpkt);
43
44 do
45 {
46 if (*file_pos >= file_len)
47 return 1; // EOF, nothing to do
48
49 fseek(f, *file_pos, SEEK_SET);
50 bytes_in = fread(input_buf, 1, sizeof(input_buf), f);
51
52 offset = mp3_find_sync_word(input_buf, bytes_in);
53 if (offset < 0) {
54 lprintf("find_sync_word (%i/%i) err %i\n",
55 *file_pos, file_len, offset);
56 *file_pos = file_len;
57 return 1; // EOF
58 }
59
60 // to avoid being flooded with "incorrect frame size" errors,
61 // we must calculate and pass exact frame size - lame
62 frame_size = mpeg1_l3_bitrates[input_buf[offset + 2] >> 4];
63 frame_size = frame_size * 144000 / 44100;
64 frame_size += (input_buf[offset + 2] >> 1) & 1;
65
66 if (offset > 0 && bytes_in - offset < frame_size) {
67 // underflow
68 *file_pos += offset;
69 continue;
70 }
71
72 avpkt.data = input_buf + offset;
73 avpkt.size = frame_size;
74 bytes_out = sizeof(cdda_out_buffer);
75 #if LIBAVCODEC_VERSION_MAJOR < 53
76 // stupidity in v52: enforces this size even when
77 // it doesn't need/use that much at all
78 bytes_out = AVCODEC_MAX_AUDIO_FRAME_SIZE;
79 #endif
80
81 len = p_avcodec_decode_audio3(ctx, cdda_out_buffer,
82 &bytes_out, &avpkt);
83 if (len <= 0) {
84 lprintf("mp3 decode err (%i/%i) %i\n",
85 *file_pos, file_len, len);
86
87 // attempt to skip the offending frame..
88 *file_pos += offset + 1;
89 continue;
90 }
91
92 *file_pos += offset + len;
93 }
94 while (0);
95
96 return 0;
97 }
98
mp3dec_start(FILE * f,int fpos_start)99 int mp3dec_start(FILE *f, int fpos_start)
100 {
101 void (*avcodec_register_all)(void);
102 AVCodec *(*avcodec_find_decoder)(enum AVCodecID id);
103 AVCodecContext *(*avcodec_alloc_context)(void);
104 int (*avcodec_open)(AVCodecContext *avctx, AVCodec *codec);
105 void (*av_free)(void *ptr);
106 AVCodec *codec;
107 void *soh;
108 int ret;
109
110 if (ctx != NULL)
111 return 0;
112
113 // either v52 or v53 should be ok
114 soh = dlopen("libavcodec.so.52", RTLD_NOW);
115 if (soh == NULL)
116 soh = dlopen("libavcodec.so.53", RTLD_NOW);
117 if (soh == NULL) {
118 lprintf("mp3dec: load libavcodec.so: %s\n", dlerror());
119 return -1;
120 }
121
122 avcodec_register_all = dlsym(soh, "avcodec_register_all");
123 avcodec_find_decoder = dlsym(soh, "avcodec_find_decoder");
124 avcodec_alloc_context = dlsym(soh, "avcodec_alloc_context");
125 avcodec_open = dlsym(soh, "avcodec_open");
126 av_free = dlsym(soh, "av_free");
127 p_av_init_packet = dlsym(soh, "av_init_packet");
128 p_avcodec_decode_audio3 = dlsym(soh, "avcodec_decode_audio3");
129
130 if (avcodec_register_all == NULL || avcodec_find_decoder == NULL
131 || avcodec_alloc_context == NULL || avcodec_open == NULL
132 || av_free == NULL
133 || p_av_init_packet == NULL || p_avcodec_decode_audio3 == NULL)
134 {
135 lprintf("mp3dec: missing symbol(s) in libavcodec.so\n");
136 dlclose(soh);
137 return -1;
138 }
139
140 // init decoder
141
142 //avcodec_init();
143 avcodec_register_all();
144
145 codec = avcodec_find_decoder(AV_CODEC_ID_MP3);
146 if (codec == NULL) {
147 lprintf("mp3dec: codec missing\n");
148 return -1;
149 }
150
151 ctx = avcodec_alloc_context();
152 if (ctx == NULL) {
153 lprintf("mp3dec: avcodec_alloc_context failed\n");
154 return -1;
155 }
156
157 ret = avcodec_open(ctx, codec);
158 if (ret < 0) {
159 lprintf("mp3dec: avcodec_open failed: %d\n", ret);
160 av_free(ctx);
161 ctx = NULL;
162 return -1;
163 }
164
165 return 0;
166 }
167