private/oki_adpcm.h
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/*
* SpanDSP - a series of DSP components for telephony
*
* private/oki_adpcm.h - Conversion routines between linear 16 bit PCM data
* and OKI (Dialogic) ADPCM format.
*
* Written by Steve Underwood <steveu@coppice.org>
*
* Copyright (C) 2001 Steve Underwood
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1,
* as published by the Free Software Foundation.
*
* 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*! \file */
#if !defined(_SPANDSP_PRIVATE_OKI_ADPCM_H_)
#define _SPANDSP_PRIVATE_OKI_ADPCM_H_
/*!
Oki (Dialogic) ADPCM conversion state descriptor. This defines the state of
a single working instance of the Oki ADPCM converter. This is used for
either linear to ADPCM or ADPCM to linear conversion.
*/
struct oki_adpcm_state_s
{
/*! \brief The bit rate - 24000 or 32000. */
int bit_rate;
/*! \brief The last state of the ADPCM algorithm. */
int16_t last;
/*! \brief Current index into the step size table. */
int16_t step_index;
/*! \brief The compressed data byte in progress. */
uint8_t oki_byte;
/*! \brief The signal history for the sample rate converter. */
int16_t history[32];
/*! \brief Pointer into the history buffer. */
int ptr;
/*! \brief Odd/even sample counter. */
int mark;
/*! \brief Phase accumulator for the sample rate converter. */
int phase;
};
#endif
/*- End of file ------------------------------------------------------------*/
oki_adpcm_state_s
Definition private/oki_adpcm.h:38
oki_adpcm_state_s::bit_rate
int bit_rate
The bit rate - 24000 or 32000.
Definition private/oki_adpcm.h:40
oki_adpcm_state_s::phase
int phase
Phase accumulator for the sample rate converter.
Definition private/oki_adpcm.h:54
oki_adpcm_state_s::ptr
int ptr
Pointer into the history buffer.
Definition private/oki_adpcm.h:50
oki_adpcm_state_s::last
int16_t last
The last state of the ADPCM algorithm.
Definition private/oki_adpcm.h:42
oki_adpcm_state_s::oki_byte
uint8_t oki_byte
The compressed data byte in progress.
Definition private/oki_adpcm.h:46
oki_adpcm_state_s::step_index
int16_t step_index
Current index into the step size table.
Definition private/oki_adpcm.h:44
oki_adpcm_state_s::mark
int mark
Odd/even sample counter.
Definition private/oki_adpcm.h:52
oki_adpcm_state_s::history
int16_t history[32]
The signal history for the sample rate converter.
Definition private/oki_adpcm.h:48