/* * PicoDrive * (C) notaz, 2010,2013 * * This work is licensed under the terms of MAME license. * See COPYING file in the top-level directory. */ #include #include #include #include #include "mp3.h" static FILE *mp3_current_file; static int mp3_file_len, mp3_file_pos; static int cdda_out_pos; static int decoder_active; unsigned short mpeg1_l3_bitrates[16] = { 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 }; static int try_get_bitrate(unsigned char *buf, int buf_size) { int offs1, offs = 0; int ret; while (1) { offs1 = mp3_find_sync_word(buf + offs, buf_size - offs); if (offs1 < 0) return -2; offs += offs1; if (buf_size - offs < 4) return -3; // printf("trying header %08x\n", *(int *)(buf + offs)); ret = mpeg1_l3_bitrates[buf[offs + 2] >> 4]; if (ret > 0) return ret; } return -2; } int mp3_get_bitrate(void *f_, int len) { unsigned char buf[2048]; FILE *f = f_; int retval = -1; int ret; memset(buf, 0, sizeof(buf)); fseek(f, 0, SEEK_SET); ret = fread(buf, 1, sizeof(buf), f); if (ret != sizeof(buf)) goto out; ret = try_get_bitrate(buf, sizeof(buf)); if (ret <= 0) { // try to read somewhere around the middle fseek(f, len / 2, SEEK_SET); ret = fread(buf, 1, sizeof(buf), f); if (ret == sizeof(buf)) ret = try_get_bitrate(buf, sizeof(buf)); } if (ret > 0) retval = ret; //printf("bitrate: %i\n", retval); out: fseek(f, 0, SEEK_SET); return retval; } void mp3_start_play(void *f_, int pos1024) { unsigned char buf[2048]; FILE *f = f_; int ret; mp3_file_len = mp3_file_pos = 0; mp3_current_file = NULL; cdda_out_pos = 0; decoder_active = 0; if (!(PicoIn.opt & POPT_EN_MCD_CDDA) || f == NULL) // cdda disabled or no file? return; fseek(f, 0, SEEK_END); mp3_file_len = ftell(f); // search for first sync word, skipping stuff like ID3 tags while (mp3_file_pos < 128*1024) { int offs, bytes; fseek(f, mp3_file_pos, SEEK_SET); bytes = fread(buf, 1, sizeof(buf), f); if (bytes < 4) break; offs = mp3_find_sync_word(buf, bytes); if (offs >= 0) { mp3_file_pos += offs; break; } mp3_file_pos += bytes - 3; } // seek.. if (pos1024 != 0) { unsigned long long pos64 = mp3_file_len - mp3_file_pos; pos64 *= pos1024; mp3_file_pos += pos64 >> 10; } ret = mp3dec_start(f, mp3_file_pos); if (ret != 0) { return; } mp3_current_file = f; decoder_active = 1; mp3dec_decode(mp3_current_file, &mp3_file_pos, mp3_file_len); } void mp3_update(int *buffer, int length, int stereo) { int length_mp3, shr = 0; void (*mix_samples)(int *dest_buf, short *mp3_buf, int count) = mix_16h_to_32; if (mp3_current_file == NULL || mp3_file_pos >= mp3_file_len) return; /* no file / EOF */ if (!decoder_active) return; length_mp3 = length; if (PicoIn.sndRate <= 11025 + 100) { mix_samples = mix_16h_to_32_s2; length_mp3 <<= 2; shr = 2; } else if (PicoIn.sndRate <= 22050 + 100) { mix_samples = mix_16h_to_32_s1; length_mp3 <<= 1; shr = 1; } if (1152 - cdda_out_pos >= length_mp3) { mix_samples(buffer, cdda_out_buffer + cdda_out_pos * 2, length * 2); cdda_out_pos += length_mp3; } else { int ret, left = 1152 - cdda_out_pos; if (left > 0) mix_samples(buffer, cdda_out_buffer + cdda_out_pos * 2, (left >> shr) * 2); ret = mp3dec_decode(mp3_current_file, &mp3_file_pos, mp3_file_len); if (ret == 0) { cdda_out_pos = length_mp3 - left; mix_samples(buffer + (left >> shr) * 2, cdda_out_buffer, (cdda_out_pos >> shr) * 2); } else cdda_out_pos = 0; } }