366 lines
9.5 KiB
C
366 lines
9.5 KiB
C
/*
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** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
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** Copyright (C) 2003 M. Bakker, Ahead Software AG, http://www.nero.com
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**
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** This program is free software; you can redistribute it and/or modify
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** it under the terms of the GNU General Public License as published by
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** the Free Software Foundation; either version 2 of the License, or
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** (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program; if not, write to the Free Software
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** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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**
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** Any non-GPL usage of this software or parts of this software is strictly
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** forbidden.
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**
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** Commercial non-GPL licensing of this software is possible.
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** For more info contact Ahead Software through Mpeg4AAClicense@nero.com.
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**
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** $Id$
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**/
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#ifdef _WIN32
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#define WIN32_LEAN_AND_MEAN
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#include <windows.h>
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#endif
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#include <stdlib.h>
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#include <string.h>
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//#include "filestream.h"
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#include "aacinfo.h"
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#define ADIF_MAX_SIZE 30 /* Should be enough */
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#define ADTS_MAX_SIZE 10 /* Should be enough */
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static int sample_rates[] = {96000,88200,64000,48000,44100,32000,24000,22050,16000,12000,11025,8000};
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static int read_ADIF_header(FILE *file, faadAACInfo *info)
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{
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int bitstream;
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unsigned char buffer[ADIF_MAX_SIZE];
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int skip_size = 0;
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int sf_idx;
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/* Get ADIF header data */
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info->headertype = 1;
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if(fread(buffer, 1, ADIF_MAX_SIZE, file) < 0)
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return -1;
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/* copyright string */
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if(buffer[0] & 0x80)
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skip_size += 9; /* skip 9 bytes */
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bitstream = buffer[0 + skip_size] & 0x10;
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info->bitrate = ((unsigned int)(buffer[0 + skip_size] & 0x0F)<<19)|
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((unsigned int)buffer[1 + skip_size]<<11)|
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((unsigned int)buffer[2 + skip_size]<<3)|
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((unsigned int)buffer[3 + skip_size] & 0xE0);
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if (bitstream == 0)
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{
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info->object_type = ((buffer[6 + skip_size]&0x01)<<1)|((buffer[7 + skip_size]&0x80)>>7);
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sf_idx = (buffer[7 + skip_size]&0x78)>>3;
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} else {
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info->object_type = (buffer[4 + skip_size] & 0x18)>>3;
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sf_idx = ((buffer[4 + skip_size] & 0x07)<<1)|((buffer[5 + skip_size] & 0x80)>>7);
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}
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info->sampling_rate = sample_rates[sf_idx];
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return 0;
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}
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static int read_ADTS_header(FILE *file, faadAACInfo *info,
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unsigned long **seek_table, int *seek_table_len,
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int tagsize, int no_seek_table)
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{
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/* Get ADTS header data */
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unsigned char buffer[ADTS_MAX_SIZE];
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int frames, framesinsec=0, t_framelength = 0, frame_length, sr_idx, ID;
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int second = 0, pos;
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int i;
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float frames_per_sec = 0;
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unsigned long bytes;
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unsigned long *tmp_seek_table = NULL;
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info->headertype = 2;
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/* Read all frames to ensure correct time and bitrate */
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for(frames=0; /* */; frames++, framesinsec++)
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{
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/* If streaming, only go until we hit 5 seconds worth */
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/* if(file->http)
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{
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if(frames >= 43 * 5)
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{
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break;
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}
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}
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*/
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pos = ftell(file);//tell_filestream(file);
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/* 12 bit SYNCWORD */
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bytes = fread(buffer, 1, ADTS_MAX_SIZE, file);
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if(bytes != ADTS_MAX_SIZE)
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{
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/* Bail out if no syncword found */
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break;
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}
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/* check syncword */
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if (!((buffer[0] == 0xFF)&&((buffer[1] & 0xF6) == 0xF0)))
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break;
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if(!frames)
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{
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/* fixed ADTS header is the same for every frame, so we read it only once */
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/* Syncword found, proceed to read in the fixed ADTS header */
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ID = buffer[1] & 0x08;
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info->object_type = (buffer[2]&0xC0)>>6;
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sr_idx = (buffer[2]&0x3C)>>2;
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info->channels = ((buffer[2]&0x01)<<2)|((buffer[3]&0xC0)>>6);
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frames_per_sec = sample_rates[sr_idx] / 1024.f;
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}
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/* ...and the variable ADTS header */
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if (ID == 0) {
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info->version = 4;
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} else { /* MPEG-2 */
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info->version = 2;
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}
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frame_length = ((((unsigned int)buffer[3] & 0x3)) << 11)
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| (((unsigned int)buffer[4]) << 3) | (buffer[5] >> 5);
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t_framelength += frame_length;
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// if(!file->http)
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{
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if(framesinsec == 43)
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framesinsec = 0;
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if(framesinsec == 0 && seek_table_len)
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{
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tmp_seek_table = (unsigned long *) realloc(tmp_seek_table, (second + 1) * sizeof(unsigned long));
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tmp_seek_table[second] = pos;
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}
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if(framesinsec == 0)
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second++;
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}
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/* NOTE: While simply skipping ahead by reading may seem to be more work than seeking,
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it is actually much faster, and keeps compatibility with streaming */
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//F THAT
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fseek(file, frame_length - ADTS_MAX_SIZE, SEEK_CUR);
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/* for(i=0; i < frame_length - ADTS_MAX_SIZE; i++)
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{
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if(read_byte_filestream(file) < 0)
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break;
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}
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*/
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}
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if(seek_table_len)
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{
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*seek_table_len = second;
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*seek_table = tmp_seek_table;
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}
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info->sampling_rate = sample_rates[sr_idx];
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info->bitrate = (int)(((t_framelength / frames) * (info->sampling_rate/1024.0)) +0.5)*8;
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/* if(file->http)
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{
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// Since we only use 5 seconds of aac data to get a rough bitrate, we must use a different
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// method of calculating the overall length
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if(filelength_filestream(file))
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{
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info->length = (int)((filelength_filestream(file)/(((info->bitrate*8)/1024)*16))*1000);
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}
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else
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{
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// Since the server didnt tell us how long the file is,
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// we have no way of determining length
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info->length = 0;
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}
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}
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else
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*/ {
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info->length = (int)((float)(frames/frames_per_sec))*1000;
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}
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return 0;
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}
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int get_AAC_format(FILE *file, faadAACInfo *info,
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unsigned long **seek_table, int *seek_table_len,
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int no_seek_table)
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{
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unsigned long tagsize;
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char buffer[10];
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unsigned long file_len;
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unsigned char adxx_id[5];
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unsigned long tmp;
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memset(info, 0, sizeof(faadAACInfo));
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fseek(file, 0, SEEK_END);
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file_len = ftell(file);
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/* Skip the tag, if it's there */
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tmp = fread(buffer, 1, 10, file);
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if (StringComp(buffer, "ID3", 3) == 0)
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{
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unsigned int i;
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/* high bit is not used */
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tagsize = (buffer[6] << 21) | (buffer[7] << 14) |
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(buffer[8] << 7) | (buffer[9] << 0);
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fseek(file, tagsize, SEEK_CUR);
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tagsize += 10;
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}
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else
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{
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tagsize = 0;
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fseek(file, 0, SEEK_SET);
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}
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if(file_len)
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file_len -= tagsize;
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tmp = fread(adxx_id, 1, 2, file);
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//seek_filestream(file, tagsize, FILE_BEGIN);
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adxx_id[5-1] = 0;
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info->length = 0;
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/* Determine the header type of the file, check the first two bytes */
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if(strncasecmp((char *)adxx_id, "AD", 2) == 0)
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{
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/* We think its an ADIF header, but check the rest just to make sure */
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tmp = fread(adxx_id+2, 1, 2, file);
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if(strncasecmp((char *)adxx_id, "ADIF", 4) == 0)
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{
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read_ADIF_header(file, info);
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}
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}
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else
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{
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/* No ADIF, check for ADTS header */
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if ((adxx_id[0] == 0xFF)&&((adxx_id[1] & 0xF6) == 0xF0))
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{
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/* ADTS header located */
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/* Since this routine must work for streams, we can't use the seek function to go backwards, thus
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we have to use a quick hack as seen below to go back where we need to. */
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fseek(file, -2, SEEK_CUR);
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/* if(file->buffer_offset >= 2)
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{
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// simple seeking hack, though not really safe, the probability of it causing a problem is low.
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file->buffer_offset -= 2;
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file->file_offset -= 2;
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}
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*/
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read_ADTS_header(file, info, seek_table, seek_table_len, tagsize,
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no_seek_table);
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}
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else
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{
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/* Unknown/headerless AAC file, assume format: */
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info->version = 2;
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info->bitrate = 128000;
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info->sampling_rate = 44100;
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info->channels = 2;
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info->headertype = 0;
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info->object_type = 1;
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}
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}
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return 0;
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}
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int StringComp(char const *str1, char const *str2, unsigned long len)
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{
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signed int c1 = 0, c2 = 0;
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while (len--) {
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c1 = *str1++;
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c2 = *str2++;
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if (c1 == 0 || c1 != c2)
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break;
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}
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return c1 - c2;
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}
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#ifdef TEST
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/* Program to test aacinfo functionality */
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#include <stdio.h>
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void main(int argc, char *argv[])
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{
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faadAACInfo info;
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unsigned long *seek_table = NULL;
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int seek_table_len = 0;
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char *header, *object;
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if (argc < 2)
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{
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fprintf(stderr, "USAGE: aacinfo aacfile.aac\n");
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return;
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}
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get_AAC_format(argv[1], &info, &seek_table, &seek_table_len, 0);
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fprintf(stdout, "MPEG version: %d\n", info.version);
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fprintf(stdout, "channels: %d\n", info.channels);
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fprintf(stdout, "sampling_rate: %d\n", info.sampling_rate);
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fprintf(stdout, "bitrate: %d\n", info.bitrate);
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fprintf(stdout, "length: %.3f\n", (float)info.length/1000.0);
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switch (info.object_type)
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{
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case 0:
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object = "MAIN";
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break;
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case 1:
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object = "LC";
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break;
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case 2:
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object = "SSR";
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break;
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case 3:
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object = "LTP";
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break;
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}
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fprintf(stdout, "object_type: %s\n", object);
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switch (info.headertype)
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{
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case 0:
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header = "RAW";
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break;
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case 1:
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header = "ADIF";
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break;
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case 2:
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header = "ADTS";
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break;
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}
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fprintf(stdout, "headertype: %s\n", header);
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}
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#endif |