ref: 6a0f3c931e3a04b11086258bb4e58e2c0358727b
dir: /winamp/AACINFO.C/
/*
* FAAC - Freeware Advanced Audio Decoder
* Copyright (C) 2001 Menno Bakker
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: AACINFO.C,v 1.1 2001/08/03 11:47:03 menno Exp $
*/
#include <windows.h>
#include "aacinfo.h"
#define ADIF_MAX_SIZE 30 /* Should be enough */
#define ADTS_MAX_SIZE 10 /* Should be enough */
const int sample_rates[] = {96000,88200,64000,48000,44100,32000,24000,22050,16000,12000,11025,8000};
static int read_ADIF_header(HANDLE file, FAACAACInfo *info)
{
unsigned long tmp;
int bitstream;
unsigned char buffer[ADIF_MAX_SIZE];
int skip_size = 0;
int sf_idx;
/* Get ADIF header data */
info->headertype = 1;
ReadFile(file, buffer, ADIF_MAX_SIZE, &tmp, 0);
/* copyright string */
if(buffer[4] & 128)
skip_size += 9; /* skip 9 bytes */
bitstream = buffer[4 + skip_size] & 16;
info->bitrate = ((unsigned int)(buffer[4 + skip_size] & 0x0F)<<19)|
((unsigned int)buffer[5 + skip_size]<<11)|
((unsigned int)buffer[6 + skip_size]<<3)|
((unsigned int)buffer[7 + skip_size] & 0xE0);
if (bitstream == 0) {
info->object_type = ((buffer[9 + skip_size]&0x01)<<1)|((buffer[10 + skip_size]&0x80)>>7);
sf_idx = (buffer[10 + skip_size]&0x78)>>3;
info->channels = ((buffer[10 + skip_size]&0x07)<<1)|((buffer[11 + skip_size]&0x80)>>7);
} else {
info->object_type = (buffer[7 + skip_size] & 0x18)>>3;
sf_idx = ((buffer[7 + skip_size] & 0x07)<<1)|((buffer[8 + skip_size] & 0x80)>>7);
info->channels = (buffer[8 + skip_size]&0x78)>>3;
}
info->sampling_rate = sample_rates[sf_idx];
return 0;
}
static int read_ADTS_header(HANDLE file, FAACAACInfo *info, int *seek_table,
int tagsize)
{
/* Get ADTS header data */
unsigned char buffer[ADTS_MAX_SIZE];
int frames, t_framelength = 0, frame_length, sr_idx, ID;
int second = 0, pos;
float frames_per_sec = 0;
unsigned long bytes;
info->headertype = 2;
/* Seek to the first frame */
SetFilePointer(file, tagsize, NULL, FILE_BEGIN);
/* Read all frames to ensure correct time and bitrate */
for(frames=0; /* */; frames++)
{
/* 12 bit SYNCWORD */
ReadFile(file, buffer, ADTS_MAX_SIZE, &bytes, 0);
if(bytes != ADTS_MAX_SIZE)
{
/* Bail out if no syncword found */
break;
}
if (!((buffer[0] == 0xFF)&&((buffer[1] & 0xF6) == 0xF0)))
break;
pos = SetFilePointer(file, 0, NULL, FILE_CURRENT) - ADTS_MAX_SIZE;
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;
frame_length = (((unsigned int)buffer[4]) << 5) |
((unsigned int)buffer[5] >> 3);
} 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;
if (frames > second*frames_per_sec)
{
seek_table[second] = pos;
second++;
}
SetFilePointer(file, frame_length - ADTS_MAX_SIZE, NULL, FILE_CURRENT);
}
info->sampling_rate = sample_rates[sr_idx];
info->bitrate = (int)(((t_framelength / frames) * (info->sampling_rate/1024.0)) +0.5)*8;
info->length = (int)((float)(frames/frames_per_sec))*1000;
return 0;
}
static int f_id3v2_tag(HANDLE file)
{
unsigned char buffer[10];
unsigned long tmp;
ReadFile(file, buffer, 10, &tmp, 0);
if (StringComp(buffer, "ID3", 3) == 0) {
unsigned long tagsize;
/* high bit is not used */
tagsize = (buffer[6] << 21) | (buffer[7] << 14) |
(buffer[8] << 7) | (buffer[9] << 0);
tagsize += 10;
SetFilePointer(file, tagsize, NULL, FILE_BEGIN);
return tagsize;
} else {
SetFilePointer(file, 0, NULL, FILE_BEGIN);
return 0;
}
}
int get_AAC_format(char *filename, FAACAACInfo *info, int *seek_table)
{
unsigned int tagsize;
HANDLE file;
unsigned long file_len;
unsigned char adxx_id[5];
unsigned long tmp;
if(StringComp(filename, "http://", 7) == 0)
{
info->version = 2;
info->length = 0;
info->bitrate = 128000;
info->sampling_rate = 44100;
info->channels = 2;
info->headertype = 0;
info->object_type = 1;
return 0;
}
file = CreateFile(filename, GENERIC_READ,
FILE_SHARE_READ | FILE_SHARE_WRITE, 0,
OPEN_EXISTING, FILE_FLAG_SEQUENTIAL_SCAN, 0);
if (file == INVALID_HANDLE_VALUE)
return -1;
file_len = GetFileSize(file, NULL);
tagsize = f_id3v2_tag(file); /* Skip the tag, if it's there */
file_len -= tagsize;
ReadFile(file, adxx_id, 4, &tmp, 0);
SetFilePointer(file, tagsize, NULL, FILE_BEGIN);
adxx_id[5-1] = 0;
info->length = 0;
if(StringComp(adxx_id, "ADIF", 4) == 0)
{
read_ADIF_header(file, info);
}
else
{
if ((adxx_id[0] == 0xFF)&&((adxx_id[1] & 0xF6) == 0xF0))
{
// SetFilePointer(file, tagsize, NULL, FILE_BEGIN);
read_ADTS_header(file, info, seek_table, tagsize);
}
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;
}
}
if (info->length == 0)
info->length = (int)((file_len/(((info->bitrate*8)/1024)*16))*1000);
CloseHandle(file);
return 0;
}
int StringComp(char const *str1, char const *str2, unsigned long len)
{
signed int c1 = 0, c2 = 0;
while (len--) {
c1 = *str1++;
c2 = *str2++;
if (c1 == 0 || c1 != c2)
break;
}
return c1 - c2;
}