/*** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding** Copyright (C) 2003 M. Bakker, Ahead Software AG, http://www.nero.com**  ** This program is free software; you can redistribute it and/or modify** it under the terms of the GNU General Public License as published by** the Free Software Foundation; either version 2 of the License, or** (at your option) any later version.** ** This program is distributed in the hope that it will be useful,** but WITHOUT ANY WARRANTY; without even the implied warranty of** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the** GNU General Public License for more details.** ** You should have received a copy of the GNU General Public License** along with this program; if not, write to the Free Software ** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.**** Any non-GPL usage of this software or parts of this software is strictly** forbidden.**** Commercial non-GPL licensing of this software is possible.** For more info contact Ahead Software through Mpeg4AAClicense@nero.com.**** $Id: aacinfo.c,v 1.5 2003/07/29 08:20:14 menno Exp $**/#define WIN32_LEAN_AND_MEAN#include <windows.h>#include <malloc.h>#include <stdlib.h>#include <stdio.h>#include "aacinfo.h"#include "utils.h"#define ADIF_MAX_SIZE 30 /* Should be enough */#define ADTS_MAX_SIZE 10 /* Should be enough */static int sample_rates[] = {96000,88200,64000,48000,44100,32000,24000,22050,16000,12000,11025,8000};static int read_ADIF_header(FILE *file, faadAACInfo *info){    int bitstream;    unsigned char buffer[ADIF_MAX_SIZE];    int skip_size = 0;    int sf_idx;    /* Get ADIF header data */    info->headertype = 1;    if (fread(buffer, 1, ADIF_MAX_SIZE, file) != ADIF_MAX_SIZE)        return -1;    /* copyright string */    if(buffer[0] & 0x80)        skip_size += 9; /* skip 9 bytes */    bitstream = buffer[0 + skip_size] & 0x10;    info->bitrate = ((unsigned int)(buffer[0 + skip_size] & 0x0F)<<19)|        ((unsigned int)buffer[1 + skip_size]<<11)|        ((unsigned int)buffer[2 + skip_size]<<3)|        ((unsigned int)buffer[3 + skip_size] & 0xE0);    if (bitstream == 0)    {        info->object_type =  ((buffer[6 + skip_size]&0x01)<<1)|((buffer[7 + skip_size]&0x80)>>7);        sf_idx = (buffer[7 + skip_size]&0x78)>>3;    } else {        info->object_type = (buffer[4 + skip_size] & 0x18)>>3;        sf_idx = ((buffer[4 + skip_size] & 0x07)<<1)|((buffer[5 + skip_size] & 0x80)>>7);    }    info->sampling_rate = sample_rates[sf_idx];    return 0;}static int read_ADTS_header(FILE *file, faadAACInfo *info){    /* Get ADTS header data */    unsigned char buffer[ADTS_MAX_SIZE];    int frames, t_framelength = 0, frame_length, sr_idx = 0, ID;    int second = 0, pos;    float frames_per_sec = 0;    unsigned long bytes;    unsigned long *tmp_seek_table = NULL;    info->headertype = 2;    /* Read all frames to ensure correct time and bitrate */    for (frames = 0; /* */; frames++)    {        bytes = fread(buffer, 1, ADTS_MAX_SIZE, file);        if (bytes != ADTS_MAX_SIZE)            break;        /* check syncword */        if (!((buffer[0] == 0xFF)&&((buffer[1] & 0xF6) == 0xF0)))            break;        if (!frames)        {            /* fixed ADTS header is the same for every frame, so we read it only once */            /* Syncword found, proceed to read in the fixed ADTS header */            ID = buffer[1] & 0x08;            info->object_type = (buffer[2]&0xC0)>>6;            sr_idx = (buffer[2]&0x3C)>>2;            info->channels = ((buffer[2]&0x01)<<2)|((buffer[3]&0xC0)>>6);            frames_per_sec = sample_rates[sr_idx] / 1024.f;        }        /* ...and the variable ADTS header */        if (ID == 0)        {            info->version = 4;        } else { /* MPEG-2 */            info->version = 2;        }        frame_length = ((((unsigned int)buffer[3] & 0x3)) << 11)            | (((unsigned int)buffer[4]) << 3) | (buffer[5] >> 5);        t_framelength += frame_length;        pos = ftell(file) - ADTS_MAX_SIZE;        fseek(file, frame_length - ADTS_MAX_SIZE, SEEK_CUR);    }    if (frames > 0)    {        float sec_per_frame, bytes_per_frame;        info->sampling_rate = sample_rates[sr_idx];        sec_per_frame = (float)info->sampling_rate/1024.0;        bytes_per_frame = (float)t_framelength / (float)frames;        info->bitrate = 8 * (int)floor(bytes_per_frame * sec_per_frame);        info->length = (int)floor((float)frames/frames_per_sec)*1000;    } else {        info->sampling_rate = 4;        info->bitrate = 128000;        info->length = 0;        info->channels = 0;    }    return 0;}int get_AAC_format(char *filename, faadAACInfo *info){    unsigned long tagsize;    FILE *file;    char buffer[10];    unsigned long file_len;    unsigned char adxx_id[5];    unsigned long tmp;    memset(info, 0, sizeof(faadAACInfo));    file = fopen(filename, "rb");    if(file == NULL)        return -1;    fseek(file, 0, SEEK_END);    file_len = ftell(file);    fseek(file, 0, SEEK_SET);    /* Skip the tag, if it's there */    tmp = fread(buffer, 10, 1, file);    if (StringComp(buffer, "ID3", 3) == 0)    {        /* high bit is not used */        tagsize = (buffer[6] << 21) | (buffer[7] << 14) |            (buffer[8] <<  7) | (buffer[9] <<  0);        fseek(file, tagsize, SEEK_CUR);        tagsize += 10;    } else {        tagsize = 0;        fseek(file, 0, SEEK_SET);    }    if (file_len)        file_len -= tagsize;    tmp = fread(adxx_id, 2, 1, file);    adxx_id[5-1] = 0;    info->length = 0;    /* Determine the header type of the file, check the first two bytes */    if (StringComp(adxx_id, "AD", 2) == 0)    {        /* We think its an ADIF header, but check the rest just to make sure */        tmp = fread(adxx_id + 2, 2, 1, file);        if (StringComp(adxx_id, "ADIF", 4) == 0)        {            read_ADIF_header(file, info);            info->length = (int)((float)file_len*8000.0/((float)info->bitrate));        }    } else {        /* No ADIF, check for ADTS header */        if ((adxx_id[0] == 0xFF)&&((adxx_id[1] & 0xF6) == 0xF0))        {            /* ADTS  header located */            fseek(file, tagsize, SEEK_SET);            read_ADTS_header(file, info);        } else {            /* Unknown/headerless AAC file, assume format: */            info->version = 2;            info->bitrate = 128000;            info->sampling_rate = 44100;            info->channels = 2;            info->headertype = 0;            info->object_type = 1;        }    }    fclose(file);    return 0;}