ref: b2aec36134f39421dc3a434d973409d98bffb3aa
dir: /common/faad/aacinfo.c/
/*
** FAAD - Freeware Advanced Audio Decoder
** Copyright (C) 2002 M. Bakker
**
** 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.
**
** $Id: aacinfo.c,v 1.2 2002/01/24 14:30:08 menno Exp $
**/
#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif
#include <malloc.h>
#include "filestream.h"
#include "aacinfo.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_STREAM *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(read_buffer_filestream(file, buffer, ADIF_MAX_SIZE) < 0)
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_STREAM *file, faadAACInfo *info,
unsigned long **seek_table, int *seek_table_len,
int tagsize, int no_seek_table)
{
/* Get ADTS header data */
unsigned char buffer[ADTS_MAX_SIZE];
int frames, framesinsec=0, t_framelength = 0, frame_length, sr_idx, ID;
int second = 0, pos;
int i;
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++, framesinsec++)
{
/* If streaming, only go until we hit 5 seconds worth */
if(file->http)
{
if(frames >= 43 * 5)
{
break;
}
}
pos = tell_filestream(file);
/* 12 bit SYNCWORD */
bytes = read_buffer_filestream(file, buffer, ADTS_MAX_SIZE);
if(bytes != ADTS_MAX_SIZE)
{
/* Bail out if no syncword found */
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;
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(!file->http)
{
if(framesinsec == 43)
framesinsec = 0;
if(framesinsec == 0 && seek_table_len)
{
tmp_seek_table = (unsigned long *) realloc(tmp_seek_table, (second + 1) * sizeof(unsigned long));
tmp_seek_table[second] = pos;
}
if(framesinsec == 0)
second++;
}
/* NOTE: While simply skipping ahead by reading may seem to be more work than seeking,
it is actually much faster, and keeps compatibility with streaming */
for(i=0; i < frame_length - ADTS_MAX_SIZE; i++)
{
if(read_byte_filestream(file) < 0)
break;
}
}
if(seek_table_len)
{
*seek_table_len = second;
*seek_table = tmp_seek_table;
}
info->sampling_rate = sample_rates[sr_idx];
info->bitrate = (int)(((t_framelength / frames) * (info->sampling_rate/1024.0)) +0.5)*8;
if(file->http)
{
/* Since we only use 5 seconds of aac data to get a rough bitrate, we must use a different
method of calculating the overall length */
if(filelength_filestream(file))
{
info->length = (int)((filelength_filestream(file)/(((info->bitrate*8)/1024)*16))*1000);
}
else
{
/* Since the server didnt tell us how long the file is,
we have no way of determining length */
info->length = 0;
}
}
else
{
info->length = (int)((float)(frames/frames_per_sec))*1000;
}
return 0;
}
int get_AAC_format(char *filename, faadAACInfo *info,
unsigned long **seek_table, int *seek_table_len,
int no_seek_table)
{
unsigned long tagsize;
FILE_STREAM *file;
char buffer[10];
unsigned long file_len;
unsigned char adxx_id[5];
unsigned long tmp;
memset(info, 0, sizeof(faadAACInfo));
file = open_filestream(filename);
if(file == NULL)
return -1;
file_len = filelength_filestream(file);
/* Skip the tag, if it's there */
tmp = read_buffer_filestream(file, buffer, 10);
if (StringComp(buffer, "ID3", 3) == 0)
{
unsigned int i;
/* high bit is not used */
tagsize = (buffer[6] << 21) | (buffer[7] << 14) |
(buffer[8] << 7) | (buffer[9] << 0);
for(i=0; i < tagsize; i++)
if(read_byte_filestream(file) < 0)
return -1;
tagsize += 10;
}
else
{
tagsize = 0;
/* Simple hack to reset to the beginning */
file->buffer_offset = 0;
file->file_offset = 0;
}
if(file_len)
file_len -= tagsize;
tmp = read_buffer_filestream(file, adxx_id, 2);
//seek_filestream(file, tagsize, FILE_BEGIN);
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 = read_buffer_filestream(file, adxx_id + 2, 2);
if(StringComp(adxx_id, "ADIF", 4) == 0)
{
read_ADIF_header(file, info);
}
}
else
{
/* No ADIF, check for ADTS header */
if ((adxx_id[0] == 0xFF)&&((adxx_id[1] & 0xF6) == 0xF0))
{
/* ADTS header located */
/* Since this routine must work for streams, we can't use the seek function to go backwards, thus
we have to use a quick hack as seen below to go back where we need to. */
if(file->buffer_offset >= 2)
{
// simple seeking hack, though not really safe, the probability of it causing a problem is low.
file->buffer_offset -= 2;
file->file_offset -= 2;
}
read_ADTS_header(file, info, seek_table, seek_table_len, tagsize,
no_seek_table);
}
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;
}
}
close_filestream(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;
}
#ifdef TEST
/* Program to test aacinfo functionality */
#include <stdio.h>
void main(int argc, char *argv[])
{
faadAACInfo info;
unsigned long *seek_table = NULL;
int seek_table_len = 0;
char *header, *object;
if (argc < 2)
{
fprintf(stderr, "USAGE: aacinfo aacfile.aac\n");
return;
}
get_AAC_format(argv[1], &info, &seek_table, &seek_table_len, 0);
fprintf(stdout, "MPEG version: %d\n", info.version);
fprintf(stdout, "channels: %d\n", info.channels);
fprintf(stdout, "sampling_rate: %d\n", info.sampling_rate);
fprintf(stdout, "bitrate: %d\n", info.bitrate);
fprintf(stdout, "length: %.3f\n", (float)info.length/1000.0);
switch (info.object_type)
{
case 0:
object = "MAIN";
break;
case 1:
object = "LC";
break;
case 2:
object = "SSR";
break;
case 3:
object = "LTP";
break;
}
fprintf(stdout, "object_type: %s\n", object);
switch (info.headertype)
{
case 0:
header = "RAW";
break;
case 1:
header = "ADIF";
break;
case 2:
header = "ADTS";
break;
}
fprintf(stdout, "headertype: %s\n", header);
}
#endif