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asterisk/codecs/mp3/src/dec8.c
Mark Spencer 0d803132c1 Version 0.1.7 from FTP 
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@243 65c4cc65-6c06-0410-ace0-fbb531ad65f3
2001-03-20 20:11:20 +00:00

340 lines
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/*____________________________________________________________________________
FreeAmp - The Free MP3 Player
MP3 Decoder originally Copyright (C) 1995-1997 Xing Technology
Corp. http://www.xingtech.com
Portions Copyright (C) 1998-1999 EMusic.com
This program 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 of the License, or
(at your option) any later version.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
$Id$
____________________________________________________________________________*/
/**** dec8.c ***************************************************
ANSI C
MPEG audio decoder Layer II only mpeg1 and mpeg2
output sample type and sample rate conversion
decode mpeg to 8000Ks mono
output 16 bit linear, 8 bit linear, or u-law
mod 6/29/95 bugfix in u-law table
mod 11/15/95 for Layer I
mod 1/7/97 minor mods for warnings
******************************************************************/
/*****************************************************************
MPEG audio software decoder portable ANSI c.
Decodes all Layer II to 8000Ks mono pcm.
Output selectable: 16 bit linear, 8 bit linear, u-law.
-------------------------------------
int audio_decode8_init(MPEG_HEAD *h, int framebytes_arg,
int reduction_code, int transform_code, int convert_code,
int freq_limit)
initilize decoder:
return 0 = fail, not 0 = success
MPEG_HEAD *h input, mpeg header info (returned by call to head_info)
framebytes input, mpeg frame size (returned by call to head_info)
reduction_code input, ignored
transform_code input, ignored
convert_code input, set convert_code = 4*bit_code + chan_code
bit_code: 1 = 16 bit linear pcm
2 = 8 bit (unsigned) linear pcm
3 = u-law (8 bits unsigned)
chan_code: 0 = convert two chan to mono
1 = convert two chan to mono
2 = convert two chan to left chan
3 = convert two chan to right chan
freq_limit input, ignored
---------------------------------
void audio_decode8_info( DEC_INFO *info)
information return:
Call after audio_decode8_init. See mhead.h for
information returned in DEC_INFO structure.
---------------------------------
IN_OUT audio_decode8(unsigned char *bs, void *pcmbuf)
decode one mpeg audio frame:
bs input, mpeg bitstream, must start with
sync word. Caution: may read up to 3 bytes
beyond end of frame.
pcmbuf output, pcm samples.
IN_OUT structure returns:
Number bytes conceptually removed from mpeg bitstream.
Returns 0 if sync loss.
Number bytes of pcm output. This may vary from frame
to frame.
*****************************************************************/
#include <stdlib.h>
#include <stdio.h>
#include <float.h>
#include <string.h>
#include <math.h>
#include "L3.h"
#include "mhead.h" /* mpeg header structure */
/*------------------------------------------*/
static int output_code;
static int convert(void *mv, unsigned char *pcm);
static int convert_8bit(void *mv, unsigned char *pcm);
static int convert_u(void *mv, unsigned char *pcm);
static CVT_FUNCTION_8 cvt_table[3] =
{
convert,
convert_8bit,
convert_u,
};
void mpeg8_init(MPEG8 *m)
{
memset(&m->dec, 0, sizeof(m->dec));
m->dec.ncnt = 8 * 288;
m->dec.ncnt1 = 8 * 287;
m->dec.nlast = 287;
m->dec.ndeci = 11;
m->dec.kdeci = 8 * 288;
m->dec.first_pass = 1;
}
/*====================================================================*/
IN_OUT audio_decode8(MPEG8 *m, unsigned char *bs, signed short *pcmbuf)
{
IN_OUT x;
x = audio_decode(&m->cupper, bs, m->dec.pcm);
if (x.in_bytes <= 0)
return x;
x.out_bytes = m->dec.convert_routine(m, (void *) pcmbuf);
return x;
}
/*--------------8Ks 16 bit pcm --------------------------------*/
static int convert(void *mv, unsigned char y0[])
{
MPEG8 *m = mv;
int i, k;
long alpha;
short *y;
y = (short *) y0;
k = 0;
if (m->dec.kdeci < m->dec.ncnt)
{
alpha = m->dec.kdeci & 7;
y[k++] = (short) (m->dec.xsave + ((alpha * (m->dec.pcm[0] - m->dec.xsave)) >> 3));
m->dec.kdeci += m->dec.ndeci;
}
m->dec.kdeci -= m->dec.ncnt;
for (; m->dec.kdeci < m->dec.ncnt1; m->dec.kdeci += m->dec.ndeci)
{
i = m->dec.kdeci >> 3;
alpha = m->dec.kdeci & 7;
y[k++] = (short) (m->dec.pcm[i] + ((alpha * (m->dec.pcm[i + 1] - m->dec.pcm[i])) >> 3));
}
m->dec.xsave = m->dec.pcm[m->dec.nlast];
/* printf("\n k out = %4d", k); */
return sizeof(short) * k;
}
/*----------------8Ks 8 bit unsigned pcm ---------------------------*/
static int convert_8bit(void *mv, unsigned char y[])
{
MPEG8 *m = mv;
int i, k;
long alpha;
k = 0;
if (m->dec.kdeci < m->dec.ncnt)
{
alpha = m->dec.kdeci & 7;
y[k++] = (unsigned char) (((m->dec.xsave + ((alpha * (m->dec.pcm[0] - m->dec.xsave)) >> 3)) >> 8) + 128);
m->dec.kdeci += m->dec.ndeci;
}
m->dec.kdeci -= m->dec.ncnt;
for (; m->dec.kdeci < m->dec.ncnt1; m->dec.kdeci += m->dec.ndeci)
{
i = m->dec.kdeci >> 3;
alpha = m->dec.kdeci & 7;
y[k++] = (unsigned char) (((m->dec.pcm[i] + ((alpha * (m->dec.pcm[i + 1] - m->dec.pcm[i])) >> 3)) >> 8) + 128);
}
m->dec.xsave = m->dec.pcm[m->dec.nlast];
/* printf("\n k out = %4d", k); */
return k;
}
/*--------------8Ks u-law --------------------------------*/
static int convert_u(void *mv, unsigned char y[])
{
MPEG8 *m = mv;
int i, k;
long alpha;
unsigned char *look;
look = m->dec.look_u + 4096;
k = 0;
if (m->dec.kdeci < m->dec.ncnt)
{
alpha = m->dec.kdeci & 7;
y[k++] = look[(m->dec.xsave + ((alpha * (m->dec.pcm[0] - m->dec.xsave)) >> 3)) >> 3];
m->dec.kdeci += m->dec.ndeci;
}
m->dec.kdeci -= m->dec.ncnt;
for (; m->dec.kdeci < m->dec.ncnt1; m->dec.kdeci += m->dec.ndeci)
{
i = m->dec.kdeci >> 3;
alpha = m->dec.kdeci & 7;
y[k++] = look[(m->dec.pcm[i] + ((alpha * (m->dec.pcm[i + 1] - m->dec.pcm[i])) >> 3)) >> 3];
}
m->dec.xsave = m->dec.pcm[m->dec.nlast];
/* printf("\n k out = %4d", k); */
return k;
}
/*--------------------------------------------------------------------*/
static int ucomp3(int x) /* re analog devices CCITT G.711 */
{
int s, p, y, t, u, u0, sign;
sign = 0;
if (x < 0)
{
x = -x;
sign = 0x0080;
}
if (x > 8031)
x = 8031;
x += 33;
t = x;
for (s = 0; s < 15; s++)
{
if (t & 0x4000)
break;
t <<= 1;
}
y = x << s;
p = (y >> 10) & 0x0f; /* position */
s = 9 - s; /* segment */
u0 = (((s << 4) | p) & 0x7f) | sign;
u = u0 ^ 0xff;
return u;
}
/*------------------------------------------------------------------*/
static void table_init(MPEG8 *m)
{
int i;
for (i = -4096; i < 4096; i++)
m->dec.look_u[4096 + i] = (unsigned char) (ucomp3(2 * i));
}
/*-------------------------------------------------------------------*/
int audio_decode8_init(MPEG8 *m, MPEG_HEAD * h, int framebytes_arg,
int reduction_code, int transform_code, int convert_code,
int freq_limit)
{
int istat;
int outvals;
static int sr_table[2][4] =
{{22, 24, 16, 0}, {44, 48, 32, 0}};
if (m->dec.first_pass)
{
table_init(m);
m->dec.first_pass = 0;
}
if ((h->sync & 1) == 0)
return 0; // fail mpeg 2.5
output_code = convert_code >> 2;
if (output_code < 1)
output_code = 1; /* 1= 16bit 2 = 8bit 3 = u */
if (output_code > 3)
output_code = 3; /* 1= 16bit 2 = 8bit 3 = u */
convert_code = convert_code & 3;
if (convert_code <= 0)
convert_code = 1; /* always cvt to mono */
reduction_code = 1;
if (h->id)
reduction_code = 2;
/* select convert routine */
m->dec.convert_routine = cvt_table[output_code - 1];
/* init decimation/convert routine */
/*-- MPEG-2 layer III --*/
if ((h->option == 1) && h->id == 0)
outvals = 576 >> reduction_code;
else if (h->option == 3)
outvals = 384 >> reduction_code;
/*-- layer I --*/
else
outvals = 1152 >> reduction_code;
m->dec.ncnt = 8 * outvals;
m->dec.ncnt1 = 8 * (outvals - 1);
m->dec.nlast = outvals - 1;
m->dec.ndeci = sr_table[h->id][h->sr_index] >> reduction_code;
m->dec.kdeci = 8 * outvals;
/* printf("\n outvals %d", outvals); */
freq_limit = 3200;
istat = audio_decode_init(&m->cupper, h, framebytes_arg,
reduction_code, transform_code, convert_code,
freq_limit);
return istat;
}
/*-----------------------------------------------------------------*/
void audio_decode8_info(MPEG8 *m, DEC_INFO * info)
{
audio_decode_info(&m->cupper, info);
info->samprate = 8000;
if (output_code != 1)
info->bits = 8;
if (output_code == 3)
info->type = 10;
}
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