Initial revision

1 files changed, 691 insertions, 0 deletions

diff --git a/core/multimedia/opieplayer/libmpeg3/audio/ac3.c b/core/multimedia/opieplayer/libmpeg3/audio/ac3.c
new file mode 100644
index 0000000..7a3b664
--- a/dev/null
+++ b/core/multimedia/opieplayer/libmpeg3/audio/ac3.c
@@ -0,0 +1,691 @@
+/* 
+ *
+         *ac3.c Copyright (C) Aaron Holtzman - May 1999
+ *
+ *
+ *  This file is part of libmpeg3
+         *
+ *  libmpeg3 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.
+ *   
+ *  libmpeg3 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 "mpeg3audio.h"
+#include "../libmpeg3.h"
+#include "../mpeg3protos.h"
+
+#include <math.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#define MPEG3AC3_MAGIC_NUMBER 0xdeadbeef
+
+
+int mpeg3_ac3_samplerates[] = { 48000, 44100, 32000 };
+
+struct mpeg3_framesize_s
+{
+        unsigned short bit_rate;
+        unsigned short frm_size[3];
+};
+
+struct mpeg3_framesize_s framesize_codes[] = 
+{
+      { 32  ,{64   ,69   ,96   } },
+      { 32  ,{64   ,70   ,96   } },
+      { 40  ,{80   ,87   ,120  } },
+      { 40  ,{80   ,88   ,120  } },
+      { 48  ,{96   ,104  ,144  } },
+      { 48  ,{96   ,105  ,144  } },
+      { 56  ,{112  ,121  ,168  } },
+      { 56  ,{112  ,122  ,168  } },
+      { 64  ,{128  ,139  ,192  } },
+      { 64  ,{128  ,140  ,192  } },
+      { 80  ,{160  ,174  ,240  } },
+      { 80  ,{160  ,175  ,240  } },
+      { 96  ,{192  ,208  ,288  } },
+      { 96  ,{192  ,209  ,288  } },
+      { 112 ,{224  ,243  ,336  } },
+      { 112 ,{224  ,244  ,336  } },
+      { 128 ,{256  ,278  ,384  } },
+      { 128 ,{256  ,279  ,384  } },
+      { 160 ,{320  ,348  ,480  } },
+      { 160 ,{320  ,349  ,480  } },
+      { 192 ,{384  ,417  ,576  } },
+      { 192 ,{384  ,418  ,576  } },
+      { 224 ,{448  ,487  ,672  } },
+      { 224 ,{448  ,488  ,672  } },
+      { 256 ,{512  ,557  ,768  } },
+      { 256 ,{512  ,558  ,768  } },
+      { 320 ,{640  ,696  ,960  } },
+      { 320 ,{640  ,697  ,960  } },
+      { 384 ,{768  ,835  ,1152 } },
+      { 384 ,{768  ,836  ,1152 } },
+      { 448 ,{896  ,975  ,1344 } },
+      { 448 ,{896  ,976  ,1344 } },
+      { 512 ,{1024 ,1114 ,1536 } },
+      { 512 ,{1024 ,1115 ,1536 } },
+      { 576 ,{1152 ,1253 ,1728 } },
+      { 576 ,{1152 ,1254 ,1728 } },
+      { 640 ,{1280 ,1393 ,1920 } },
+      { 640 ,{1280 ,1394 ,1920 } }
+};
+
+/* Audio channel modes */
+short mpeg3_ac3_acmodes[] = {2, 1, 2, 3, 3, 4, 4, 5};
+
+/* Rematrix tables */
+struct rematrix_band_s
+{
+        int start;
+        int end;
+};
+
+struct rematrix_band_s mpeg3_rematrix_band[] = 
+{ 
+        {13, 24}, 
+        {25, 36}, 
+        {37, 60}, 
+        {61, 252}
+};
+
+int mpeg3_min(int x, int y)
+{
+        return (x < y) ? x : y;
+}
+
+int mpeg3_max(int x, int y)
+{
+        return (x > y) ? x : y;
+}
+
+int mpeg3audio_read_ac3_header(mpeg3audio_t *audio)
+{
+        unsigned int code, crc;
+        unsigned int i;
+        mpeg3_ac3bsi_t *bsi = &(audio->ac3_bsi);
+
+/* Get the sync code */
+        code = mpeg3bits_getbits(audio->astream, 16);
+        while(!mpeg3bits_eof(audio->astream) && code != MPEG3_AC3_START_CODE)
+        {
+                code <<= 8;
+                code &= 0xffff;
+                code |= mpeg3bits_getbits(audio->astream, 8);
+        }
+
+        if(mpeg3bits_eof(audio->astream)) return 1;
+
+/* Get crc1 - we don't actually use this data though */
+/* The crc can be the same as the sync code or come after a sync code repeated twice */
+        crc = mpeg3bits_getbits(audio->astream, 16);
+
+/* Got the sync code.  Read the entire frame into a buffer if possible. */
+        if(audio->avg_framesize > 0)
+        {
+                if(mpeg3bits_read_buffer(audio->astream, audio->ac3_buffer, audio->framesize - 4))
+                        return 1;
+                        mpeg3bits_use_ptr(audio->astream, audio->ac3_buffer);
+        }
+
+/* Get the sampling rate code */
+        audio->sampling_frequency_code  = mpeg3bits_getbits(audio->astream, 2);
+
+/* Get the frame size code */
+        audio->ac3_framesize_code = mpeg3bits_getbits(audio->astream, 6);
+
+        audio->bitrate = framesize_codes[audio->ac3_framesize_code].bit_rate;
+        audio->avg_framesize = audio->framesize = 2 * framesize_codes[audio->ac3_framesize_code].frm_size[audio->sampling_frequency_code];
+
+/* Check the AC-3 version number */
+        bsi->bsid = mpeg3bits_getbits(audio->astream, 5);
+
+/* Get the audio service provided by the steram */
+        bsi->bsmod = mpeg3bits_getbits(audio->astream, 3);
+
+/* Get the audio coding mode (ie how many channels)*/
+        bsi->acmod = mpeg3bits_getbits(audio->astream, 3);
+        
+/* Predecode the number of full bandwidth channels as we use this
+ * number a lot */
+        bsi->nfchans = mpeg3_ac3_acmodes[bsi->acmod];
+        audio->channels = bsi->nfchans;
+
+/* If it is in use, get the centre channel mix level */
+        if((bsi->acmod & 0x1) && (bsi->acmod != 0x1))
+                bsi->cmixlev = mpeg3bits_getbits(audio->astream, 2);
+
+/* If it is in use, get the surround channel mix level */
+        if(bsi->acmod & 0x4)
+                bsi->surmixlev = mpeg3bits_getbits(audio->astream, 2);
+
+/* Get the dolby surround mode if in 2/0 mode */
+        if(bsi->acmod == 0x2)
+                bsi->dsurmod= mpeg3bits_getbits(audio->astream, 2);
+
+/* Is the low frequency effects channel on? */
+        bsi->lfeon = mpeg3bits_getbits(audio->astream, 1);
+
+/* Get the dialogue normalization level */
+        bsi->dialnorm = mpeg3bits_getbits(audio->astream, 5);
+
+/* Does compression gain exist? */
+        bsi->compre = mpeg3bits_getbits(audio->astream, 1);
+        if (bsi->compre)
+        {
+/* Get compression gain */
+                bsi->compr = mpeg3bits_getbits(audio->astream, 8);
+        }
+
+/* Does language code exist? */
+        bsi->langcode = mpeg3bits_getbits(audio->astream, 1);
+        if (bsi->langcode)
+        {
+/* Get langauge code */
+                bsi->langcod = mpeg3bits_getbits(audio->astream, 8);
+        }
+
+/* Does audio production info exist? */
+        bsi->audprodie = mpeg3bits_getbits(audio->astream, 1);
+        if (bsi->audprodie)
+        {
+/* Get mix level */
+                bsi->mixlevel = mpeg3bits_getbits(audio->astream, 5);
+
+/* Get room type */
+                bsi->roomtyp = mpeg3bits_getbits(audio->astream, 2);
+        }
+
+/* If we're in dual mono mode then get some extra info */
+        if (bsi->acmod == 0)
+        {
+/* Get the dialogue normalization level two */
+                bsi->dialnorm2 = mpeg3bits_getbits(audio->astream, 5);
+
+/* Does compression gain two exist? */
+                bsi->compr2e = mpeg3bits_getbits(audio->astream, 1);
+                if (bsi->compr2e)
+                {
+/* Get compression gain two */
+                        bsi->compr2 = mpeg3bits_getbits(audio->astream, 8);
+                }
+
+/* Does language code two exist? */
+                bsi->langcod2e = mpeg3bits_getbits(audio->astream, 1);
+                if (bsi->langcod2e)
+                {
+/* Get langauge code two */
+                        bsi->langcod2 = mpeg3bits_getbits(audio->astream, 8);
+                }
+
+/* Does audio production info two exist? */
+                bsi->audprodi2e = mpeg3bits_getbits(audio->astream, 1);
+                if (bsi->audprodi2e)
+                {
+/* Get mix level two */
+                        bsi->mixlevel2 = mpeg3bits_getbits(audio->astream, 5);
+
+/* Get room type two */
+                        bsi->roomtyp2 = mpeg3bits_getbits(audio->astream, 2);
+                }
+        }
+
+/* Get the copyright bit */
+        bsi->copyrightb = mpeg3bits_getbits(audio->astream, 1);
+
+/* Get the original bit */
+        bsi->origbs = mpeg3bits_getbits(audio->astream, 1);
+        
+/* Does timecode one exist? */
+        bsi->timecod1e = mpeg3bits_getbits(audio->astream, 1);
+
+        if(bsi->timecod1e)
+                bsi->timecod1 = mpeg3bits_getbits(audio->astream, 14);
+
+/* Does timecode two exist? */
+        bsi->timecod2e = mpeg3bits_getbits(audio->astream, 1);
+
+        if(bsi->timecod2e)
+                bsi->timecod2 = mpeg3bits_getbits(audio->astream, 14);
+
+/* Does addition info exist? */
+        bsi->addbsie = mpeg3bits_getbits(audio->astream, 1);
+
+        if(bsi->addbsie)
+        {
+/* Get how much info is there */
+                bsi->addbsil = mpeg3bits_getbits(audio->astream, 6);
+
+/* Get the additional info */
+                for(i = 0; i < (bsi->addbsil + 1); i++)
+                        bsi->addbsi[i] = mpeg3bits_getbits(audio->astream, 8);
+        }
+
+        if(mpeg3bits_eof(audio->astream))
+        {
+                mpeg3bits_use_demuxer(audio->astream);
+                return 1;
+        }
+        //return mpeg3bits_error(audio->astream);
+}
+
+int mpeg3audio_read_ac3_audblk(mpeg3audio_t *audio)
+{
+        int i, j;
+        mpeg3_ac3bsi_t *bsi = &(audio->ac3_bsi);
+        mpeg3_ac3audblk_t *audblk = &(audio->ac3_audblk);
+
+        for(i = 0; i < bsi->nfchans; i++)
+        {
+/* Is this channel an interleaved 256 + 256 block ? */
+                audblk->blksw[i] = mpeg3bits_getbits(audio->astream, 1);
+        }
+
+        for(i = 0; i < bsi->nfchans; i++)
+        {
+/* Should we dither this channel? */
+                audblk->dithflag[i] = mpeg3bits_getbits(audio->astream, 1);
+        }
+
+/* Does dynamic range control exist? */
+        audblk->dynrnge = mpeg3bits_getbits(audio->astream, 1);
+        if(audblk->dynrnge)
+        {
+/* Get dynamic range info */
+                audblk->dynrng = mpeg3bits_getbits(audio->astream, 8);
+        }
+
+/* If we're in dual mono mode then get the second channel DR info */
+        if(bsi->acmod == 0)
+        {
+/* Does dynamic range control two exist? */
+                audblk->dynrng2e = mpeg3bits_getbits(audio->astream, 1);
+                if (audblk->dynrng2e)
+                {
+/* Get dynamic range info */
+                        audblk->dynrng2 = mpeg3bits_getbits(audio->astream, 8);
+                }
+        }
+
+/* Does coupling strategy exist? */
+        audblk->cplstre = mpeg3bits_getbits(audio->astream, 1);
+        if(audblk->cplstre)
+        {
+/* Is coupling turned on? */
+                audblk->cplinu = mpeg3bits_getbits(audio->astream, 1);
+                if(audblk->cplinu)
+                {
+                        for(i = 0; i < bsi->nfchans; i++)
+                                audblk->chincpl[i] = mpeg3bits_getbits(audio->astream, 1);
+
+                        if(bsi->acmod == 0x2)
+                                audblk->phsflginu = mpeg3bits_getbits(audio->astream, 1);
+
+                        audblk->cplbegf = mpeg3bits_getbits(audio->astream, 4);
+                        audblk->cplendf = mpeg3bits_getbits(audio->astream, 4);
+                        audblk->ncplsubnd = (audblk->cplendf + 2) - audblk->cplbegf + 1;
+
+/* Calculate the start and end bins of the coupling channel */
+                        audblk->cplstrtmant = (audblk->cplbegf * 12) + 37 ; 
+                        audblk->cplendmant =  ((audblk->cplendf + 3) * 12) + 37;
+
+/* The number of combined subbands is ncplsubnd minus each combined band */
+                        audblk->ncplbnd = audblk->ncplsubnd; 
+
+                        for(i = 1; i < audblk->ncplsubnd; i++)
+                        {
+                                audblk->cplbndstrc[i] = mpeg3bits_getbits(audio->astream, 1);
+                                audblk->ncplbnd -= audblk->cplbndstrc[i];
+                        }
+                }
+        }
+
+        if(audblk->cplinu)
+        {
+        /* Loop through all the channels and get their coupling co-ords */
+                for(i = 0; i < bsi->nfchans; i++)
+                {
+                        if(!audblk->chincpl[i])
+                                continue;
+
+/* Is there new coupling co-ordinate info? */
+                        audblk->cplcoe[i] = mpeg3bits_getbits(audio->astream, 1);
+
+                        if(audblk->cplcoe[i])
+                        {
+                                audblk->mstrcplco[i] = mpeg3bits_getbits(audio->astream, 2); 
+                                for(j = 0; j < audblk->ncplbnd; j++)
+                                {
+                                        audblk->cplcoexp[i][j] = mpeg3bits_getbits(audio->astream, 4); 
+                                        audblk->cplcomant[i][j] = mpeg3bits_getbits(audio->astream, 4); 
+                                }
+                        }
+                }
+
+/* If we're in dual mono mode, there's going to be some phase info */
+                if((bsi->acmod == 0x2) && audblk->phsflginu && 
+                        (audblk->cplcoe[0] || audblk->cplcoe[1]))
+                {
+                        for(j = 0; j < audblk->ncplbnd; j++)
+                        {
+                                audblk->phsflg[j] = mpeg3bits_getbits(audio->astream, 1);
+                        }
+                }
+        }
+
+/* If we're in dual mono mode, there may be a rematrix strategy */
+        if(bsi->acmod == 0x2)
+        {
+                audblk->rematstr = mpeg3bits_getbits(audio->astream, 1);
+                if(audblk->rematstr)
+                {
+                        if (audblk->cplinu == 0) 
+                        { 
+                                for(i = 0; i < 4; i++) 
+                                        audblk->rematflg[i] = mpeg3bits_getbits(audio->astream, 1);
+                        }
+                        if((audblk->cplbegf > 2) && audblk->cplinu) 
+                        {
+                                for(i = 0; i < 4; i++) 
+                                        audblk->rematflg[i] = mpeg3bits_getbits(audio->astream, 1);
+                        }
+                        if((audblk->cplbegf <= 2) && audblk->cplinu) 
+                        { 
+                                for(i = 0; i < 3; i++) 
+                                        audblk->rematflg[i] = mpeg3bits_getbits(audio->astream, 1);
+                        } 
+                        if((audblk->cplbegf == 0) && audblk->cplinu) 
+                                for(i = 0; i < 2; i++) 
+                                        audblk->rematflg[i] = mpeg3bits_getbits(audio->astream, 1);
+
+                }
+        }
+
+        if (audblk->cplinu)
+        {
+/* Get the coupling channel exponent strategy */
+                audblk->cplexpstr = mpeg3bits_getbits(audio->astream, 2);
+
+                if(audblk->cplexpstr == 0) 
+                        audblk->ncplgrps = 0;
+                else
+                        audblk->ncplgrps = (audblk->cplendmant - audblk->cplstrtmant) / 
+                                (3 << (audblk->cplexpstr - 1));
+
+        }
+
+        for(i = 0; i < bsi->nfchans; i++)
+        {
+                audblk->chexpstr[i] = mpeg3bits_getbits(audio->astream, 2);
+        }
+
+/* Get the exponent strategy for lfe channel */
+        if(bsi->lfeon) 
+                audblk->lfeexpstr = mpeg3bits_getbits(audio->astream, 1);
+
+/* Determine the bandwidths of all the fbw channels */
+        for(i = 0; i < bsi->nfchans; i++)
+        { 
+                unsigned short grp_size;
+
+                if(audblk->chexpstr[i] != MPEG3_EXP_REUSE) 
+                { 
+                        if (audblk->cplinu && audblk->chincpl[i]) 
+                        {
+                                audblk->endmant[i] = audblk->cplstrtmant;
+                        }
+                        else
+                        {
+                                audblk->chbwcod[i] = mpeg3bits_getbits(audio->astream, 6); 
+                                audblk->endmant[i] = ((audblk->chbwcod[i] + 12) * 3) + 37;
+                        }
+
+/* Calculate the number of exponent groups to fetch */
+                        grp_size =  3 * (1 << (audblk->chexpstr[i] - 1));
+                        audblk->nchgrps[i] = (audblk->endmant[i] - 1 + (grp_size - 3)) / grp_size;
+                }
+        }
+
+/* Get the coupling exponents if they exist */
+        if(audblk->cplinu && (audblk->cplexpstr != MPEG3_EXP_REUSE))
+        {
+                audblk->cplabsexp = mpeg3bits_getbits(audio->astream, 4);
+                for(i = 0; i< audblk->ncplgrps; i++)
+                        audblk->cplexps[i] = mpeg3bits_getbits(audio->astream, 7);
+        }
+
+/* Get the fwb channel exponents */
+        for(i = 0; i < bsi->nfchans; i++)
+        {
+                if(audblk->chexpstr[i] != MPEG3_EXP_REUSE)
+                {
+                        audblk->exps[i][0] = mpeg3bits_getbits(audio->astream, 4);
+                        for(j = 1; j <= audblk->nchgrps[i]; j++)
+                                audblk->exps[i][j] = mpeg3bits_getbits(audio->astream, 7);
+                        audblk->gainrng[i] = mpeg3bits_getbits(audio->astream, 2);
+                }
+        }
+
+/* Get the lfe channel exponents */
+        if(bsi->lfeon && (audblk->lfeexpstr != MPEG3_EXP_REUSE))
+        {
+                audblk->lfeexps[0] = mpeg3bits_getbits(audio->astream, 4);
+                audblk->lfeexps[1] = mpeg3bits_getbits(audio->astream, 7);
+                audblk->lfeexps[2] = mpeg3bits_getbits(audio->astream, 7);
+        }
+
+/* Get the parametric bit allocation parameters */
+        audblk->baie = mpeg3bits_getbits(audio->astream, 1);
+
+        if(audblk->baie)
+        {
+                audblk->sdcycod = mpeg3bits_getbits(audio->astream, 2);
+                audblk->fdcycod = mpeg3bits_getbits(audio->astream, 2);
+                audblk->sgaincod = mpeg3bits_getbits(audio->astream, 2);
+                audblk->dbpbcod = mpeg3bits_getbits(audio->astream, 2);
+                audblk->floorcod = mpeg3bits_getbits(audio->astream, 3);
+        }
+
+
+/* Get the SNR off set info if it exists */
+        audblk->snroffste = mpeg3bits_getbits(audio->astream, 1);
+
+        if(audblk->snroffste)
+        {
+                audblk->csnroffst = mpeg3bits_getbits(audio->astream, 6);
+
+                if(audblk->cplinu)
+                {
+                        audblk->cplfsnroffst = mpeg3bits_getbits(audio->astream, 4);
+                        audblk->cplfgaincod = mpeg3bits_getbits(audio->astream, 3);
+                }
+
+                for(i = 0; i < bsi->nfchans; i++)
+                {
+                        audblk->fsnroffst[i] = mpeg3bits_getbits(audio->astream, 4);
+                        audblk->fgaincod[i] = mpeg3bits_getbits(audio->astream, 3);
+                }
+                if(bsi->lfeon)
+                {
+
+                        audblk->lfefsnroffst = mpeg3bits_getbits(audio->astream, 4);
+                        audblk->lfefgaincod = mpeg3bits_getbits(audio->astream, 3);
+                }
+        }
+
+/* Get coupling leakage info if it exists */
+        if(audblk->cplinu)
+        {
+                        audblk->cplleake = mpeg3bits_getbits(audio->astream, 1);
+                
+                if(audblk->cplleake)
+                {
+                        audblk->cplfleak = mpeg3bits_getbits(audio->astream, 3);
+                        audblk->cplsleak = mpeg3bits_getbits(audio->astream, 3);
+                }
+        }
+        
+/* Get the delta bit alloaction info */
+                audblk->deltbaie = mpeg3bits_getbits(audio->astream, 1);
+
+        if(audblk->deltbaie)
+        {
+                if(audblk->cplinu)
+                        audblk->cpldeltbae = mpeg3bits_getbits(audio->astream, 2);
+
+                for(i = 0; i < bsi->nfchans; i++)
+                        audblk->deltbae[i] = mpeg3bits_getbits(audio->astream, 2);
+
+                if (audblk->cplinu && (audblk->cpldeltbae == DELTA_BIT_NEW))
+                {
+                        audblk->cpldeltnseg = mpeg3bits_getbits(audio->astream, 3);
+                        for(i = 0; i < audblk->cpldeltnseg + 1; i++)
+                        {
+                                audblk->cpldeltoffst[i] = mpeg3bits_getbits(audio->astream, 5);
+                                audblk->cpldeltlen[i] = mpeg3bits_getbits(audio->astream, 4);
+                                audblk->cpldeltba[i] = mpeg3bits_getbits(audio->astream, 3);
+                        }
+                }
+
+                for(i = 0; i < bsi->nfchans; i++)
+                {
+                        if (audblk->deltbae[i] == DELTA_BIT_NEW)
+                        {
+                                audblk->deltnseg[i] = mpeg3bits_getbits(audio->astream, 3);
+                                for(j = 0; j < audblk->deltnseg[i] + 1; j++)
+                                {
+                                        audblk->deltoffst[i][j] = mpeg3bits_getbits(audio->astream, 5);
+                                        audblk->deltlen[i][j] = mpeg3bits_getbits(audio->astream, 4);
+                                        audblk->deltba[i][j] = mpeg3bits_getbits(audio->astream, 3);
+                                }
+                        }
+                }
+        }
+
+/* Check to see if there's any dummy info to get */
+        if((audblk->skiple = mpeg3bits_getbits(audio->astream, 1)))
+        {
+                unsigned int skip_data;
+                audblk->skipl = mpeg3bits_getbits(audio->astream, 9);
+                for(i = 0; i < audblk->skipl ; i++)
+                {
+                        skip_data = mpeg3bits_getbits(audio->astream, 8);
+                }
+        }
+
+        return mpeg3bits_error(audio->astream);
+}
+
+
+/* This routine simply does stereo rematrixing for the 2 channel 
+ * stereo mode */
+int mpeg3audio_ac3_rematrix(mpeg3_ac3audblk_t *audblk, 
+                mpeg3ac3_stream_samples_t samples)
+{
+        int num_bands;
+        int start;
+        int end;
+        int i, j;
+        mpeg3_real_t left, right;
+
+        if(audblk->cplinu || audblk->cplbegf > 2)
+                num_bands = 4;
+        else if (audblk->cplbegf > 0)
+                num_bands = 3;
+        else
+                num_bands = 2;
+
+        for(i = 0; i < num_bands; i++)
+        {
+                if(!audblk->rematflg[i])
+                        continue;
+
+                start = mpeg3_rematrix_band[i].start;
+                end = mpeg3_min(mpeg3_rematrix_band[i].end, 12 * audblk->cplbegf + 36);
+        
+                for(j = start; j < end; j++)
+                {
+                        left = samples[0][j] + samples[1][j];
+                        right = samples[0][j] - samples[1][j];
+                        samples[0][j] = left;
+                        samples[1][j] = right;
+                }
+        }
+        return 0;
+}
+
+
+int mpeg3audio_ac3_reset_frame(mpeg3audio_t *audio)
+{
+        memset(&audio->ac3_bit_allocation, 0, sizeof(mpeg3_ac3_bitallocation_t));
+        memset(&audio->ac3_mantissa, 0, sizeof(mpeg3_ac3_mantissa_t));
+        memset(&audio->ac3_audblk, 0, sizeof(mpeg3_ac3audblk_t));
+
+        return 0;
+}
+
+int mpeg3audio_do_ac3(mpeg3audio_t *audio)
+{
+        int result = 0, i;
+
+/* Reset the coefficients and exponents */
+        mpeg3audio_ac3_reset_frame(audio);
+
+        for(i = 0; i < 6 && !result; i++)
+        {
+                memset(audio->ac3_samples, 0, sizeof(mpeg3_real_t) * 256 * (audio->ac3_bsi.nfchans + audio->ac3_bsi.lfeon));
+/* Extract most of the audblk info from the bitstream
+ * (minus the mantissas */
+                result |= mpeg3audio_read_ac3_audblk(audio);
+
+/* Take the differential exponent data and turn it into
+ * absolute exponents */
+                if(!result) result |= mpeg3audio_ac3_exponent_unpack(audio, 
+                                        &(audio->ac3_bsi), 
+                                        &(audio->ac3_audblk));
+
+/* Figure out how many bits per mantissa */
+                if(!result) result |= mpeg3audio_ac3_bit_allocate(audio, 
+                                        audio->sampling_frequency_code, 
+                                        &(audio->ac3_bsi), 
+                                        &(audio->ac3_audblk));
+
+/* Extract the mantissas from the data stream */
+                if(!result) result |= mpeg3audio_ac3_coeff_unpack(audio,
+                                        &(audio->ac3_bsi), 
+                                        &(audio->ac3_audblk),
+                                        audio->ac3_samples);
+
+                if(audio->ac3_bsi.acmod == 0x2)
+                        if(!result) result |= mpeg3audio_ac3_rematrix(&(audio->ac3_audblk), 
+                                        audio->ac3_samples);
+
+/* Convert the frequency data into time samples */
+                if(!result) result |= mpeg3audio_ac3_imdct(audio, 
+                        &(audio->ac3_bsi), 
+                        &(audio->ac3_audblk), 
+                        audio->ac3_samples);
+
+                if(audio->pcm_point / audio->channels >= audio->pcm_allocated - MPEG3AUDIO_PADDING * audio->channels)
+                {
+/* Need more room */
+                        mpeg3audio_replace_buffer(audio, audio->pcm_allocated + MPEG3AUDIO_PADDING * audio->channels);
+                }
+        }
+
+        mpeg3bits_use_demuxer(audio->astream);
+
+        return result;
+}