Commit bc31c331 authored by Emmanuel Milou's avatar Emmanuel Milou
Browse files

PCMA codec - Sound quality improved

Bug correction.
Remove alaw header from git repository.
Add GPL license in ulaw.cpp
parent bfd0aef0
......@@ -23,100 +23,98 @@
class Alaw : public AudioCodec {
public:
// 8 PCMA A 8000 1 [RFC3551]
Alaw(int payload=0)
: AudioCodec(payload, "PCMA")
{
//_description = "G711a";
_clockRate = 8000;
_channel = 1;
}
virtual int codecDecode (short *dst, unsigned char *src, unsigned int size)
{
int16* end = dst+size;
while(dst<end)
*dst++ = ALawDecode(*src++);
return size<<1;
}
int ALawDecode(uint8 alaw)
{
alaw ^= 0x55; // A-law has alternate bits inverted for transmission
uint sign = alaw&0x80;
int linear = alaw&0x1f;
linear <<= 4;
linear += 8; // Add a 'half' bit (0x08) to place PCM value in middle of range
alaw &= 0x7f;
if(alaw>=0x20)
{
linear |= 0x100; // Put in MSB
uint shift = (alaw>>4)-1;
linear <<= shift;
}
if(!sign)
return -linear;
else
return linear;
}
virtual int codecEncode (unsigned char *dst, short *src, unsigned int size)
{
size >>= 1;
uint8* end = dst+size;
while(dst<end)
*dst++ = ALawEncode(*src++);
return size;
}
uint8 ALawEncode (int16 pcm16)
{
int p = pcm16;
uint u; // u-law value we are forming
if(p<0)
{
p = ~p;
u = 0x80^0x10^0xff; // Sign bit = 1 (^0x10 because this will get inverted later) ^0xff ^0xff to invert final u-Law code
}
else
{
//+ve value
u = 0x00^0x10^0xff;
}
p += 0x84; // Add uLaw bias
if(p>0x7f00)
p = 0x7f00; // Clip to 15 bits
p >>= 3; // Shift down to 13bit
if(p>=0x100)
// 8 PCMA A 8000 1 [RFC3551]
Alaw(int payload=0)
: AudioCodec(payload, "PCMA")
{
_clockRate = 8000;
_channel = 1;
}
virtual int codecDecode (short *dst, unsigned char *src, unsigned int size)
{
int16* end = dst+size;
while(dst<end)
*dst++ = ALawDecode(*src++);
return size<<1;
}
virtual int codecEncode (unsigned char *dst, short *src, unsigned int size)
{
size >>= 1;
uint8* end = dst+size;
while(dst<end)
*dst++ = ALawEncode(*src++);
return size;
}
int ALawDecode(uint8 alaw)
{
alaw ^= 0x55; // A-law has alternate bits inverted for transmission
uint sign = alaw&0x80;
int linear = alaw&0x1f;
linear <<= 4;
linear += 8; // Add a 'half' bit (0x08) to place PCM value in middle of range
alaw &= 0x7f;
if(alaw>=0x20)
{
linear |= 0x100; // Put in MSB
uint shift = (alaw>>4)-1;
linear <<= shift;
}
if(!sign)
return -linear;
else
return linear;
}
uint8 ALawEncode (int16 pcm16)
{
int p = pcm16;
uint a; // u-law value we are forming
if(p<0)
{
p = ~p;
a = 0x00; // sign = 0
}
else
{
//+ve value
a = 0x80; //sign = 1
}
//calculate segment and interval numbers
p >>= 4;
if(p>=0x20)
{
p >>= 4;
u ^= 0x40;
if(p>=0x100)
{
p >>= 4;
a += 0x40;
}
if(p>=0x40)
{
p >>= 2;
a += 0x20;
}
if(p>=0x20)
{
p >>= 1;
a += 0x10;
}
}
if(p>=0x40)
{
p >>= 2;
u ^= 0x20;
}
if(p>=0x20)
{
p >>= 1;
u ^= 0x10;
}
u ^= p; // u now equal to encoded u-law value (with all bits inverted)
// a&0x70 now holds segment value and 'p' the interval number
a += p; // a now equal to encoded A-law value
return a^0x55; // A-law has alternate bits inverted for transmission
}
return u;
}
};
// the class factories
......
/*
* Copyright (C) 2004-2005-2006 Savoir-Faire Linux inc.
* Author: Yan Morin <yan.morin@savoirfairelinux.com>
* Author: Laurielle Lea <laurielle.lea@savoirfairelinux.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 3 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.
*/
#ifndef __ALAW_H__
#define __ALAW_H__
#include "audiocodec.h"
/**
* Alaw audio codec (payload is 8)
*/
class Alaw : public AudioCodec {
public:
// payload should be 8
Alaw (int payload=8);
~Alaw (void);
int codecDecode (short *, unsigned char *, unsigned int);
int codecEncode (unsigned char *, short *, unsigned int);
void test () ;
};
#endif // __ULAW_H__
/**
* Copyright (C) 2004-2005 Savoir-Faire Linux inc.
* Author: Yan Morin <yan.morin@savoirfairelinux.com>
* Author: Laurielle Lea <laurielle.lea@savoirfairelinux.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 3 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.
**/
#include "common.h"
#include "audiocodec.h"
......@@ -11,7 +33,6 @@ public:
_channel = 1;
}
virtual int codecDecode (short *dst, unsigned char *src, unsigned int size) {
int16* end = dst+size;
while(dst<end)
......
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