mirror of
https://github.com/alsa-project/alsa-tools.git
synced 2025-11-03 09:01:51 -05:00
150 lines
3.5 KiB
C
150 lines
3.5 KiB
C
/*
|
|
* 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.
|
|
*
|
|
*
|
|
*/
|
|
|
|
#ifdef HAVE_CONFIG_H
|
|
#include "config.h"
|
|
#endif
|
|
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
#include <errno.h>
|
|
#include <string.h>
|
|
#include <sys/time.h>
|
|
#include "ac3.h"
|
|
#include "ac3_internal.h"
|
|
#include "bitstream.h"
|
|
#include "imdct.h"
|
|
#include "exponent.h"
|
|
#include "coeff.h"
|
|
#include "bit_allocate.h"
|
|
#include "parse.h"
|
|
#include "crc.h"
|
|
#include "stats.h"
|
|
#include "rematrix.h"
|
|
#include "sanity_check.h"
|
|
#include "downmix.h"
|
|
#include "debug.h"
|
|
|
|
//our global config structure
|
|
ac3_config_t ac3_config;
|
|
uint_32 error_flag = 0;
|
|
|
|
static audblk_t audblk;
|
|
static bsi_t bsi;
|
|
static syncinfo_t syncinfo;
|
|
static uint_32 frame_count = 0;
|
|
static uint_32 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 2 ch out)
|
|
//if this size change, be sure to change the size when muting
|
|
static sint_16 s16_samples[6 * 6 * 256];
|
|
|
|
void
|
|
ac3_init(ac3_config_t *config)
|
|
{
|
|
memcpy(&ac3_config,config,sizeof(ac3_config_t));
|
|
|
|
bitstream_init(config->fill_buffer_callback);
|
|
imdct_init();
|
|
sanity_check_init(&syncinfo,&bsi,&audblk);
|
|
|
|
frame.audio_data = s16_samples;
|
|
}
|
|
|
|
ac3_frame_t*
|
|
ac3_decode_frame(void)
|
|
{
|
|
uint_32 i;
|
|
|
|
//find a syncframe and parse
|
|
if (parse_syncinfo(&syncinfo) < 0)
|
|
return NULL;
|
|
if(error_flag)
|
|
goto error;
|
|
|
|
dprintf("(decode) begin frame %d\n",frame_count++);
|
|
frame.sampling_rate = syncinfo.sampling_rate;
|
|
|
|
parse_bsi(&bsi);
|
|
|
|
if(!done_banner && !(ac3_config.flags & AC3_QUIET))
|
|
{
|
|
stats_print_banner(&syncinfo,&bsi);
|
|
done_banner = 1;
|
|
}
|
|
|
|
for(i=0; i < 6; i++)
|
|
{
|
|
//Initialize freq/time sample storage
|
|
memset(samples,0,sizeof(float) * 256 * (bsi.nfchans + bsi.lfeon));
|
|
|
|
// Extract most of the audblk info from the bitstream
|
|
// (minus the mantissas
|
|
parse_audblk(&bsi,&audblk);
|
|
|
|
// Take the differential exponent data and turn it into
|
|
// absolute exponents
|
|
exponent_unpack(&bsi,&audblk);
|
|
if(error_flag)
|
|
goto error;
|
|
|
|
// Figure out how many bits per mantissa
|
|
bit_allocate(syncinfo.fscod,&bsi,&audblk);
|
|
|
|
// Extract the mantissas from the stream and
|
|
// generate floating point frequency coefficients
|
|
coeff_unpack(&bsi,&audblk,samples);
|
|
if(error_flag)
|
|
goto error;
|
|
|
|
if(bsi.acmod == 0x2)
|
|
rematrix(&audblk,samples);
|
|
|
|
// Convert the frequency samples into time samples
|
|
imdct(&bsi,&audblk,samples);
|
|
|
|
// Downmix into the requested number of channels
|
|
// and convert floating point to sint_16
|
|
downmix(&bsi,samples,&s16_samples[i * ac3_config.num_output_ch * 256]);
|
|
|
|
sanity_check(&syncinfo,&bsi,&audblk);
|
|
if(error_flag)
|
|
goto error;
|
|
}
|
|
parse_auxdata(&syncinfo);
|
|
|
|
return &frame;
|
|
|
|
error:
|
|
//mute the frame
|
|
memset(s16_samples,0,sizeof(sint_16) * 256 * 2 * 6);
|
|
|
|
error_flag = 0;
|
|
return &frame;
|
|
|
|
}
|