/* * MP3 decoding using dr_mp3 * (C) kub, 2020 * * This work is licensed under the terms of MAME license. * See COPYING file in the top-level directory. */ #include #include #define DR_MP3_IMPLEMENTATION #include "dr_libs/dr_mp3.h" #include "mp3.h" static drmp3dec mp3dec; static unsigned char mp3_input_buffer[2 * 1024]; int mp3dec_start(FILE *f, int fpos_start) { drmp3dec_init(&mp3dec); return 0; } int mp3dec_decode(FILE *f, int *file_pos, int file_len) { drmp3dec_frame_info info; unsigned char *readPtr; int bytesLeft; int offset; // mp3 frame offset from readPtr int len; int retry = 3; do { if (*file_pos >= file_len) return 1; /* EOF, nothing to do */ fseek(f, *file_pos, SEEK_SET); bytesLeft = fread(mp3_input_buffer, 1, sizeof(mp3_input_buffer), f); offset = mp3_find_sync_word(mp3_input_buffer, bytesLeft); if (offset < 0) { lprintf("find_sync_word (%i/%i) err %i\n", *file_pos, file_len, offset); *file_pos = file_len; return 1; // EOF } *file_pos += offset; readPtr = mp3_input_buffer + offset; bytesLeft -= offset; len = drmp3dec_decode_frame(&mp3dec, readPtr, bytesLeft, cdda_out_buffer, &info); if (len > 0) // retrieved decoded data *file_pos += info.frame_bytes; else if (info.frame_bytes > 0) // no output but input consumed? *file_pos += 1; // try to skip frame else if (offset == 0) // bad frame? *file_pos += 1; // try resyncing // else // truncated frame, try more data } while (len <= 0 && --retry > 0); return len <= 0; }