private/ima_adpcm.h
/*
* SpanDSP - a series of DSP components for telephony
*
* private/ima_adpcm.c - Conversion routines between linear 16 bit PCM data
* and IMA/DVI/Intel ADPCM format.
*
* Written by Steve Underwood <steveu@coppice.org>
*
* Copyright (C) 2004 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.
*
* Based on a bit from here, a bit from there, eye of toad,
* ear of bat, etc - plus, of course, my own 2 cents.
*/
#if !defined(_SPANDSP_PRIVATE_IMA_ADPCM_H_)
#define _SPANDSP_PRIVATE_IMA_ADPCM_H_
/*!
IMA (DVI/Intel) ADPCM conversion state descriptor. This defines the state of
a single working instance of the IMA ADPCM converter. This is used for
either linear to ADPCM or ADPCM to linear conversion.
*/
struct ima_adpcm_state_s
{
int variant;
/*! \brief The size of a chunk, in samples. */
int chunk_size;
/*! \brief The last state of the ADPCM algorithm. */
int last;
/*! \brief Current index into the step size table. */
int step_index;
/*! \brief The current IMA code byte in progress. */
uint16_t ima_byte;
int bits;
};
#endif
/*- End of file ------------------------------------------------------------*/
ima_adpcm_state_s
Definition private/ima_adpcm.h:39
ima_adpcm_state_s::step_index
int step_index
Current index into the step size table.
Definition private/ima_adpcm.h:46
ima_adpcm_state_s::last
int last
The last state of the ADPCM algorithm.
Definition private/ima_adpcm.h:44
ima_adpcm_state_s::ima_byte
uint16_t ima_byte
The current IMA code byte in progress.
Definition private/ima_adpcm.h:48
ima_adpcm_state_s::chunk_size
int chunk_size
The size of a chunk, in samples.
Definition private/ima_adpcm.h:42