Initial revision

CVS patchset: 1
CVS date: 2001/04/18 22:33:39

1 files changed, 314 insertions, 0 deletions

diff --git a/src/libac3/decode.c b/src/libac3/decode.c
new file mode 100644
index 000000000..cca544933
--- /dev/null
+++ b/src/libac3/decode.c
@@ -0,0 +1,314 @@
+/* 
+ *    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 <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/time.h>
+
+#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 "rematrix.h"
+#include "sanity_check.h"
+
+#include "audio_out.h"
+#include "attributes.h"
+
+
+//our global config structure
+ac3_config_t ac3_config;
+#ifdef FAST_ERROR
+jmp_buf error_jmp_mark;
+#else
+uint32_t error_flag = 0;
+#endif
+
+static audblk_t audblk;
+static bsi_t bsi;
+static syncinfo_t syncinfo;
+static uint32_t frame_count = 0;
+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)));
+
+/* output buffer for spdiv output */
+static int16_t s16_samples_out[4 * 6 * 256] __attribute__ ((aligned(16)));
+
+static ao_functions_t ac3_output;
+
+// 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;;
+
+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);
+
+	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()) {
+#ifndef FAST_ERROR
+		error_flag = 1;
+#endif
+		fprintf(stderr,"** CRC failed - skipping frame **\n");
+		goto done;
+	}
+#endif
+
+	//
+	//if we got to this point, we found a valid ac3 frame to decode
+	//
+
+	if ((ac3_config.flags & AO_MODE_AC3) == 0) {
+		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);
+#ifndef FAST_ERROR
+	error_flag = 0;
+#endif
+}
+
+
+void ac3_init(ac3_config_t *config ,ao_functions_t *foo)
+{
+  memcpy(&ac3_config,config,sizeof(ac3_config_t));
+  ac3_output = *foo;
+  
+  imdct_init ();
+  /* downmix_init (); */
+  sanity_check_init (&syncinfo,&bsi,&audblk);
+  memset(s16_samples_out,0,4 * 6 * 256);
+
+}
+
+void ac3_reset () 
+{
+        printf ("ac3_reset\n");
+#ifndef FAST_ERROR
+        error_flag = 0;
+#endif
+
+	frame_count = 0;
+	is_output_initialized = 0;
+	
+	buffer_size = 0;
+	syncinfo.syncword = 0;
+	imdct_init();
+	sanity_check_init(&syncinfo,&bsi,&audblk);
+
+}
+
+size_t ac3_decode_data (uint8_t *data_start, uint8_t *data_end, uint32_t pts_)
+{
+	uint32_t i;
+
+#ifdef FAST_ERROR
+	if (setjmp (error_jmp_mark) < 0) {
+		imdct_init ();
+		sanity_check_init(&syncinfo,&bsi,&audblk);
+		return 0;
+	}
+#endif
+	
+	while (decode_buffer_syncframe (&syncinfo, &data_start, data_end)) {
+
+#ifndef FAST_ERROR
+		if (error_flag)
+			goto error;
+#endif
+
+		if ((ac3_config.flags & AO_MODE_AC3) == 0) {
+		   parse_bsi (&bsi);
+
+		   // compute downmix parameters
+		   // downmix to two 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); 
+#ifndef FAST_ERROR
+			if (error_flag)
+				goto error;
+#endif
+
+			// 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);
+#ifndef FAST_ERROR
+			if (error_flag)
+				goto error;
+#endif
+
+			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)
+				sanity_check_init (&syncinfo,&bsi,&audblk);
+
+			continue;
+		   }
+		}
+		else {
+                   s16_samples_out[0] = 0xf872;  //spdif syncword
+                   s16_samples_out[1] = 0x4e1f;  // .............
+                   s16_samples_out[2] = 0x0001;  // AC3 data
+                   s16_samples_out[3] = syncinfo.frame_size * 16;
+                   s16_samples_out[4] = 0x0b77;  // AC3 syncwork
+
+                   // ac3 seems to be swabbed data
+                   swab(buffer,&s16_samples_out[5],  syncinfo.frame_size * 2 );
+
+		}
+
+		if (!is_output_initialized) {
+			ac3_output.open (16, syncinfo.sampling_rate, 
+					 (ac3_config.flags & AO_MODE_AC3) ? AO_MODE_AC3 : AO_MODE_STEREO);
+			is_output_initialized = 1;
+		}
+
+		if ((ac3_config.flags & AO_MODE_AC3) == 0) {
+			ac3_output.write_audio_data(s16_samples, 256*6, pts_);
+		}
+		else {
+			ac3_output.write_audio_data(s16_samples_out, 6 * 256, pts_);
+		}
+
+		pts_ = 0;
+
+#ifndef FAST_ERROR
+error:
+	    
+		//find a new frame
+		decode_mute (); //RMB CHECK
+#endif
+        }
+#ifdef FAST_ERROR
+	decode_mute ();
+#endif
+
+	return 0;	
+}
+