61 lines
2.0 KiB
C
61 lines
2.0 KiB
C
/*
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* SpanDSP - a series of DSP components for telephony
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*
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* private/oki_adpcm.h - Conversion routines between linear 16 bit PCM data
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* and OKI (Dialogic) ADPCM format.
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*
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* Written by Steve Underwood <steveu@coppice.org>
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*
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* Copyright (C) 2001 Steve Underwood
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License version 2.1,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id: oki_adpcm.h,v 1.1 2008/11/30 10:17:31 steveu Exp $
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*/
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/*! \file */
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#if !defined(_SPANDSP_PRIVATE_OKI_ADPCM_H_)
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#define _SPANDSP_PRIVATE_OKI_ADPCM_H_
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/*!
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Oki (Dialogic) ADPCM conversion state descriptor. This defines the state of
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a single working instance of the Oki ADPCM converter. This is used for
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either linear to ADPCM or ADPCM to linear conversion.
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*/
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struct oki_adpcm_state_s
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{
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/*! \brief The bit rate - 24000 or 32000. */
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int bit_rate;
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/*! \brief The last state of the ADPCM algorithm. */
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int16_t last;
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/*! \brief Current index into the step size table. */
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int16_t step_index;
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/*! \brief The compressed data byte in progress. */
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uint8_t oki_byte;
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/*! \brief The signal history for the sample rate converter. */
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int16_t history[32];
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/*! \brief Pointer into the history buffer. */
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int ptr;
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/*! \brief Odd/even sample counter. */
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int mark;
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/*! \brief Phase accumulator for the sample rate converter. */
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int phase;
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};
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#endif
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/*- End of file ------------------------------------------------------------*/
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