platform/common/mp3_helix.c

   1 /*
   2  * Some mp3 related code for Sega/Mega CD.
   3  * Uses the Helix Fixed-point MP3 decoder
   4  * (C) notaz, 2007-2009
   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
  13 #include <pico/pico_int.h>
  14 #include <pico/sound/mix.h>
  15 #include "helix/pub/mp3dec.h"
  16 #include "mp3.h"
  17 #include "lprintf.h"
  18
  19 static HMP3Decoder mp3dec;
  20 static unsigned char mp3_input_buffer[2 * 1024];
  21
  22 #ifdef __GP2X__
  23 #define mp3_update mp3_update_local
  24 #define mp3_start_play mp3_start_play_local
  25 #endif
  26
  27 int mp3dec_decode(FILE *f, int *file_pos, int file_len)
  28 {
  29         unsigned char *readPtr;
  30         int bytesLeft;
  31         int offset; // mp3 frame offset from readPtr
  32         int had_err;
  33         int err = 0;
  34
  35         do
  36         {
  37                 if (*file_pos >= file_len)
  38                         return 1; /* EOF, nothing to do */
  39
  40                 fseek(f, *file_pos, SEEK_SET);
  41                 bytesLeft = fread(mp3_input_buffer, 1, sizeof(mp3_input_buffer), f);
  42
  43                 offset = mp3_find_sync_word(mp3_input_buffer, bytesLeft);
  44                 if (offset < 0) {
  45                         lprintf("find_sync_word (%i/%i) err %i\n",
  46                                 *file_pos, file_len, offset);
  47                         *file_pos = file_len;
  48                         return 1; // EOF
  49                 }
  50                 readPtr = mp3_input_buffer + offset;
  51                 bytesLeft -= offset;
  52
  53                 had_err = err;
  54                 err = MP3Decode(mp3dec, &readPtr, &bytesLeft, cdda_out_buffer, 0);
  55                 if (err) {
  56                         if (err == ERR_MP3_MAINDATA_UNDERFLOW && !had_err) {
  57                                 // just need another frame
  58                                 *file_pos += readPtr - mp3_input_buffer;
  59                                 continue;
  60                         }
  61                         if (err == ERR_MP3_INDATA_UNDERFLOW && !had_err) {
  62                                 if (offset == 0)
  63                                         // something's really wrong here, frame had to fit
  64                                         *file_pos = file_len;
  65                                 else
  66                                         *file_pos += offset;
  67                                 continue;
  68                         }
  69                         if (-12 <= err && err <= -6) {
  70                                 // ERR_MP3_INVALID_FRAMEHEADER, ERR_MP3_INVALID_*
  71                                 // just try to skip the offending frame..
  72                                 *file_pos += offset + 1;
  73                                 continue;
  74                         }
  75                         lprintf("MP3Decode err (%i/%i) %i\n",
  76                                 *file_pos, file_len, err);
  77                         *file_pos = file_len;
  78                         return 1;
  79                 }
  80                 *file_pos += readPtr - mp3_input_buffer;
  81         }
  82         while (0);
  83
  84         return 0;
  85 }
  86
  87 int mp3dec_start(void)
  88 {
  89         // must re-init decoder for new track
  90         if (mp3dec)
  91                 MP3FreeDecoder(mp3dec);
  92         mp3dec = MP3InitDecoder();
  93
  94         return (mp3dec == 0) ? -1 : 0;
  95 }