path: root/ac3dec/decode.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. 
 *
 *------------------------------------------------------------
 *
 *	Thomas Mirlacher <dent@cosy.sbg.ac.at>
 *	added OMS support
 * 11 Jan 2001
 *	Thomas Mirlacher <dent@cosy.sbg.ac.at>
 *	faster error response using jmp functions
 * 
 *  9 Aug 2001      
 *      Matjaz Thaler <matjaz.thaler@rd.iskraemeco.si>
 *      Added support for DVB-s PCI card
 *
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif 

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/time.h>

#ifdef __OMS__
#include <oms/oms.h>
#include <oms/plugin/output_audio.h>
#endif

#include "ac3.h"
#include "ac3_internal.h"
#include "bitstream.h"
#include "downmix.h"
#include "srfft.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 "debug.h"
#ifndef __OMS__
//#include "audio_out.h"
#endif
//our global config structure
ac3_config_t ac3_config;

static audblk_t audblk;
static bsi_t bsi;
static syncinfo_t syncinfo;
#ifndef __OMS__
static uint32_t done_banner;
#endif
static uint32_t is_output_initialized = 0;

//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 int16_t s16_samples[2 * 6 * 256] __attribute__ ((aligned(16)));

// downmix stuff
static float cmixlev_lut[4] = { 0.707, 0.595, 0.500, 0.707 };
static float smixlev_lut[4] = { 0.707, 0.500, 0.0   , 0.500 };
static dm_par_t dm_par;
 
//Storage for the syncframe
#define BUFFER_MAX_SIZE 4096
static uint8_t buffer[BUFFER_MAX_SIZE];
static uint32_t buffer_size = 0;;
// for error handling
jmp_buf error_jmp_mark;

static uint32_t decode_buffer_syncframe (syncinfo_t *syncinfo, uint8_t **start, uint8_t *end)
{
	uint8_t *cur = *start;
	uint16_t syncword = syncinfo->syncword;
	uint32_t ret = 0;

	// Find an ac3 sync frame.
	while (syncword != 0x0b77) {
		if (cur >= end)
			goto done;
		syncword = (syncword << 8) + *cur++;
	}

	//need the next 3 bytes to decide how big the frame is
	while (buffer_size < 3) {
		if(cur >= end)
			goto done;

		buffer[buffer_size++] = *cur++;
	}
	
	parse_syncinfo (syncinfo,buffer);
	stats_print_syncinfo (syncinfo);

	while (buffer_size < syncinfo->frame_size * 2 - 2) {
		if(cur >= end)
			goto done;

		buffer[buffer_size++] = *cur++;
	}

#if 0
	// Check the crc over the entire frame 
	crc_init();
	crc_process_frame (buffer, syncinfo->frame_size * 2 - 2);

	if (!crc_validate()) {
		fprintf(stderr,"** CRC failed - skipping frame **\n");
		goto done;
	}
#endif

	//if we got to this point, we found a valid ac3 frame to decode

	bitstream_init (buffer);
	//get rid of the syncinfo struct as we already parsed it
	bitstream_get (24);

	//reset the syncword for next time
	syncword = 0xffff;
	buffer_size = 0;
	ret = 1;

done:
	syncinfo->syncword = syncword;
	*start = cur;
	return ret;
}


void inline decode_mute (void)
{
	//mute the frame
	memset (s16_samples, 0, sizeof(int16_t) * 256 * 2 * 6);
}


void ac3dec_init (void)
{
// FIXME - don't do that statically here
	ac3_config.num_output_ch = 2;
	ac3_config.flags = 0;

	imdct_init ();
	downmix_init ();
	memset (&syncinfo, 0, sizeof (syncinfo));
	memset (&bsi, 0, sizeof (bsi));
	memset (&audblk, 0, sizeof (audblk));
	sanity_check_init (&syncinfo,&bsi,&audblk);
}

#ifdef __OMS__
size_t ac3dec_decode_data (plugin_output_audio_t *output, uint8_t *data_start, uint8_t *data_end)
#else
size_t ac3dec_decode_data (uint8_t *data_start ,uint8_t *data_end, int ac3reset, int *input_pointer, int *output_pointer, char *ac3_data)
#endif
{
	uint32_t i;
	int datasize;
	char *data;


	if(ac3reset != 0){
	  syncinfo.syncword = 0xffff;
	  buffer_size = 0;
	}
		
	if (setjmp (error_jmp_mark) < 0) {
		ac3dec_init ();
		return 0;
	}

	while (decode_buffer_syncframe (&syncinfo, &data_start, data_end)) {
		parse_bsi (&bsi);

#ifndef __OMS__
		if(!done_banner) {
		  //			stats_print_banner(&syncinfo,&bsi);
			done_banner = 1;
		}
#endif

		// compute downmix parameters
		// downmix to tow channels for now
		dm_par.clev = 0.0; dm_par.slev = 0.0; dm_par.unit = 1.0;
		if (bsi.acmod & 0x1)	// have center
			dm_par.clev = cmixlev_lut[bsi.cmixlev];

		if (bsi.acmod & 0x4)	// have surround channels
			dm_par.slev = smixlev_lut[bsi.surmixlev];

		dm_par.unit /= 1.0 + dm_par.clev + dm_par.slev;
		dm_par.clev *= dm_par.unit;
		dm_par.slev *= dm_par.unit;

		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); 

			// 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 (bsi.acmod == 0x2)
				rematrix (&audblk,samples);

			// Convert the frequency samples into time samples 
			imdct (&bsi,&audblk,samples, &s16_samples[i * 2 * 256], &dm_par);

			// Downmix into the requested number of channels
			// and convert floating point to int16_t
			// downmix(&bsi,samples,&s16_samples[i * 2 * 256]);

			if (sanity_check(&syncinfo,&bsi,&audblk) < 0) {
				HANDLE_ERROR ();
				return 0;
			}

			continue;
		}

		if (!is_output_initialized) {
#ifdef __OMS__
			plugin_output_audio_attr_t attr;
#ifdef __sun__
			attr.format = 16;
#else
			attr.format = AFMT_S16_NE;
#endif
			attr.speed = syncinfo.sampling_rate;
			attr.channels = 2;

			//	output->setup (&attr);
#else
			//			ao_functions->open (16, syncinfo.sampling_rate, 2);
#endif
			is_output_initialized = 1;
		}

#ifdef __OMS__
		output->write (s16_samples, 256 * 6 * 2 * 2);
#else
		//		ao_functions->play(s16_samples, 256 * 6 * 2);
		data = (char *)s16_samples;
		datasize = 0;
		while(datasize < 6144){
		  if(((*input_pointer+1) % AC3_BUFFER_SIZE) != *output_pointer){    // There is room in the sync_buffer
		    ac3_data[*input_pointer]=data[datasize];
		    datasize++;
		    *input_pointer = (*input_pointer+1) % AC3_BUFFER_SIZE;
		  }
		  else{
		    *input_pointer = *output_pointer = 0;
		    break;
		  }
		}

#endif

	}

	decode_mute ();

	return 0;	
}