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/*
* decode.c
*
* Copyright (C) Aaron Holtzman - May 1999
*
* This file is part of ac3dec, a free Dolby AC-3 stream decoder.
*
* ac3dec 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, or (at your option)
* any later version.
*
* ac3dec 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 GNU Make; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*
*
*/
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/time.h>
#include <inttypes.h>
#include "ac3.h"
#include "ac3_internal.h"
#include "bitstream.h"
#include "imdct.h"
#include "coeff.h"
#include "bit_allocate.h"
#include "parse.h"
#include "stats.h"
#include "rematrix.h"
#include "sanity_check.h"
#include "downmix.h"
#include "debug.h"
//our global config structure
uint32_t error_flag = 0;
static audblk_t audblk;
static ac3_state_t state;
static uint32_t frame_count = 0;
static uint32_t done_banner;
static ac3_frame_t frame;
//the floating point samples for one audblk
static stream_samples_t samples;
//the integer samples for the entire frame (with enough space for 5 ch out)
//if this size change, be sure to change the size when muting
static int16_t s16_samples[5 * 6 * 256];
void
ac3_init(void)
{
imdct_init();
sanity_check_init(&state,&audblk);
frame.audio_data = s16_samples;
}
int ac3_frame_length(uint8_t * buf)
{
int dummy;
return parse_syncinfo (buf, &dummy, &dummy);
}
int ac3_sampling_rate(uint8_t * buf)
{
int dummy, rate;
parse_syncinfo (buf, &rate, &dummy);
return rate;
}
ac3_frame_t*
ac3_decode_frame(uint8_t * buf, int max_num_channels)
{
uint32_t i;
int dummy;
int num_channels;
if (!parse_syncinfo (buf, &frame.sampling_rate, &dummy))
goto error;
dprintf("(decode) begin frame %d\n",frame_count++);
if (parse_bsi (&state, buf))
goto error;
switch (state.acmod) {
case 7 :
case 5 :
/* case 3 : FIXME : implement downmix functions*/
num_channels = (max_num_channels<5) ? max_num_channels : 5;
break;
case 4 :
case 6 :
num_channels = (max_num_channels<4) ? max_num_channels : 4;
break;
default:
num_channels = 2;
}
frame.num_channels = num_channels;
if (!done_banner) {
stats_print_banner (&state);
done_banner = 1;
}
for(i=0; i < 6; i++) {
//Initialize freq/time sample storage
memset(samples,0,sizeof(float) * 256 * (state.nfchans + state.lfeon));
// Extract most of the audblk info from the bitstream
// (minus the mantissas
if (parse_audblk (&state, &audblk))
goto error;
// Figure out how many bits per mantissa
//bit_allocate(&state,&audblk);
// Extract the mantissas from the stream and
// generate floating point frequency coefficients
coeff_unpack(&state,&audblk,samples);
if(error_flag)
goto error;
if(state.acmod == 0x2)
rematrix(&audblk,samples);
// Convert the frequency samples into time samples
imdct(&state,&audblk,samples);
// Downmix into the requested number of channels
// and convert floating point to int16_t
downmix(&state,samples,&s16_samples[i * num_channels * 256],
num_channels);
sanity_check(&state,&audblk);
if(error_flag)
goto error;
}
return &frame;
error:
//mute the frame
memset(s16_samples,0,sizeof(int16_t) * 256 * 2 * 6);
error_flag = 0;
return &frame;
}
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