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- /*
- * PicoDrive
- * (C) notaz, 2010,2013
- *
- * This work is licensed under the terms of MAME license.
- * See COPYING file in the top-level directory.
- */
- #include <stdio.h>
- #include <string.h>
- #include <pico/pico_int.h>
- #include <pico/sound/mix.h>
- #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;
- }
- }
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