| 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 | |
| 14 | #include <pico/pico_int.h> |
| 15 | #include "../libpicofe/lprintf.h" |
| 16 | #include "mp3.h" |
| 17 | |
| 18 | static AVCodecContext *ctx; |
| 19 | |
| 20 | int mp3dec_decode(FILE *f, int *file_pos, int file_len) |
| 21 | { |
| 22 | unsigned char input_buf[2 * 1024]; |
| 23 | int frame_size; |
| 24 | AVPacket avpkt; |
| 25 | int bytes_in; |
| 26 | int bytes_out; |
| 27 | int offset; |
| 28 | int len; |
| 29 | |
| 30 | av_init_packet(&avpkt); |
| 31 | |
| 32 | do |
| 33 | { |
| 34 | if (*file_pos >= file_len) |
| 35 | return 1; // EOF, nothing to do |
| 36 | |
| 37 | fseek(f, *file_pos, SEEK_SET); |
| 38 | bytes_in = fread(input_buf, 1, sizeof(input_buf), f); |
| 39 | |
| 40 | offset = mp3_find_sync_word(input_buf, bytes_in); |
| 41 | if (offset < 0) { |
| 42 | lprintf("find_sync_word (%i/%i) err %i\n", |
| 43 | *file_pos, file_len, offset); |
| 44 | *file_pos = file_len; |
| 45 | return 1; // EOF |
| 46 | } |
| 47 | |
| 48 | // to avoid being flooded with "incorrect frame size" errors, |
| 49 | // we must calculate and pass exact frame size - lame |
| 50 | frame_size = mpeg1_l3_bitrates[input_buf[offset + 2] >> 4]; |
| 51 | frame_size = frame_size * 144000 / 44100; |
| 52 | frame_size += (input_buf[offset + 2] >> 1) & 1; |
| 53 | |
| 54 | if (offset > 0 && bytes_in - offset < frame_size) { |
| 55 | // underflow |
| 56 | *file_pos += offset; |
| 57 | continue; |
| 58 | } |
| 59 | |
| 60 | avpkt.data = input_buf + offset; |
| 61 | avpkt.size = frame_size; |
| 62 | bytes_out = sizeof(cdda_out_buffer); |
| 63 | |
| 64 | len = avcodec_decode_audio3(ctx, cdda_out_buffer, |
| 65 | &bytes_out, &avpkt); |
| 66 | if (len <= 0) { |
| 67 | lprintf("mp3 decode err (%i/%i) %i\n", |
| 68 | *file_pos, file_len, len); |
| 69 | |
| 70 | // attempt to skip the offending frame.. |
| 71 | *file_pos += offset + 1; |
| 72 | continue; |
| 73 | } |
| 74 | |
| 75 | *file_pos += offset + len; |
| 76 | } |
| 77 | while (0); |
| 78 | |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | int mp3dec_start(void) |
| 83 | { |
| 84 | AVCodec *codec; |
| 85 | int ret; |
| 86 | |
| 87 | if (ctx != NULL) |
| 88 | return 0; |
| 89 | |
| 90 | // init decoder |
| 91 | |
| 92 | //avcodec_init(); |
| 93 | avcodec_register_all(); |
| 94 | |
| 95 | // AV_CODEC_ID_MP3 ? |
| 96 | codec = avcodec_find_decoder(CODEC_ID_MP3); |
| 97 | if (codec == NULL) { |
| 98 | lprintf("mp3dec: codec missing\n"); |
| 99 | return -1; |
| 100 | } |
| 101 | |
| 102 | ctx = avcodec_alloc_context(); |
| 103 | if (ctx == NULL) { |
| 104 | lprintf("mp3dec: avcodec_alloc_context failed\n"); |
| 105 | return -1; |
| 106 | } |
| 107 | |
| 108 | ret = avcodec_open(ctx, codec); |
| 109 | if (ret < 0) { |
| 110 | lprintf("mp3dec: avcodec_open failed: %d\n", ret); |
| 111 | av_free(ctx); |
| 112 | ctx = NULL; |
| 113 | return -1; |
| 114 | } |
| 115 | |
| 116 | return 0; |
| 117 | } |