1 files changed, 269 insertions, 0 deletions
diff --git a/ac3dec/decode.c b/ac3dec/decode.c
new file mode 100644
index 0000000..5e7f034
--- /dev/null
+++ b/ac3dec/decode.c
@@ -0,0 +1,269 @@
+/* 
+ *    decode.c
+ *
+ *	Copyright (C) Aaron Holtzman - May 1999
+ *
+ *      Added support for DVB-s PCI card by:
+ *      Matjaz Thaler <matjaz.thaler@rd.iskraemeco.si> - November 2000
+ *
+ *  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 <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.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"
+
+#define AC3_BUFFER_SIZE (6*1024*16)      
+
+//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 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 sint_16 s16_samples[2 * 6 * 256];
+
+
+//Storage for the syncframe
+#define SYNC_BUFFER_MAX_SIZE 4096
+static uint_8 sync_buffer[SYNC_BUFFER_MAX_SIZE];
+static uint_32 sync_buffer_size = 0;;
+
+uint_32
+decode_sync_buffer_syncframe(syncinfo_t *syncinfo, uint_8 **start,uint_8 *end)
+{
+	uint_8 *cur = *start;
+	uint_16 syncword = syncinfo->syncword;
+	uint_32 ret = 0;
+
+	// 
+	// Find an ac3 sync frame.
+	// 
+resync:
+
+	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(sync_buffer_size < 3)
+	{
+		if(cur >= end)
+			goto done;
+
+		sync_buffer[sync_buffer_size++] = *cur++;
+	}
+	
+	parse_syncinfo(syncinfo,sync_buffer);
+	stats_print_syncinfo(syncinfo);
+
+	while(sync_buffer_size < syncinfo->frame_size * 2 - 2)
+	{
+		if(cur >= end)
+			goto done;
+
+		sync_buffer[sync_buffer_size++] = *cur++;
+	}
+	
+	// Check the crc over the entire frame 
+	crc_init();
+	crc_process_frame(sync_buffer,syncinfo->frame_size * 2 - 2);
+
+	if(!crc_validate())
+	{
+		fprintf(stderr,"** CRC failed - skipping frame **\n");
+		syncword = 0xffff;
+		sync_buffer_size = 0;
+		goto resync;
+	}
+	
+	//
+	//if we got to this point, we found a valid ac3 frame to decode
+	//
+
+	bitstream_init(sync_buffer);
+	//get rid of the syncinfo struct as we already parsed it
+	bitstream_get(24);
+
+	//reset the syncword for next time
+	syncword = 0xffff;
+	sync_buffer_size = 0;
+	ret = 1;
+
+done:
+	syncinfo->syncword = syncword;
+	*start = cur;
+	return ret;
+}
+
+void
+decode_mute(void)
+{
+	fprintf(stderr,"muting frame\n");
+	//mute the frame
+	memset(s16_samples,0,sizeof(sint_16) * 256 * 2 * 6);
+	error_flag = 0;
+}
+
+
+void
+ac3_init(ac3_config_t *config)
+{
+	memcpy(&ac3_config,config,sizeof(ac3_config_t));
+
+	imdct_init();
+	sanity_check_init(&syncinfo,&bsi,&audblk);
+
+	//	ac3_output = *foo;
+}
+
+uint_32 ac3_decode_data(uint_8 *data_start,uint_8 *data_end, int ac3reset, int *input_pointer, int *output_pointer, char *ac3_data)
+{
+	uint_32 i;
+	int datasize;
+	char *data;
+
+	if(ac3reset != 0){
+	  syncinfo.syncword = 0xffff;
+	  sync_buffer_size = 0;
+	}
+	
+	while(decode_sync_buffer_syncframe(&syncinfo,&data_start,data_end))
+	{
+		dprintf("(decode) begin frame %d\n",frame_count++);
+
+		if(error_flag)
+		{
+			decode_mute();
+			continue;
+		}
+
+		parse_bsi(&bsi);
+
+		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 * 2 * 256]);
+
+			sanity_check(&syncinfo,&bsi,&audblk);
+			if(error_flag)
+				goto error;
+
+			continue;
+		}
+		
+		parse_auxdata(&syncinfo);
+
+		/*
+		if(!is_output_initialized)
+		{
+			ac3_output.open(16,syncinfo.sampling_rate,2);
+			is_output_initialized = 1;
+		}
+		*/
+		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;
+		  }
+		}
+
+
+		//write(1, s16_samples, 256 * 6 * 2* 2);
+		//ac3_output.play(s16_samples, 256 * 6 * 2);
+error:
+		;
+		//find a new frame
+	}
+
+	return 0;	
+}