spandsp: oki_adpcm.h Source File

spandsp 0.0.6

private/oki_adpcm.h
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1/*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * private/oki_adpcm.h - Conversion routines between linear 16 bit PCM data
5 * and OKI (Dialogic) ADPCM format.
6 *
7 * Written by Steve Underwood <steveu@coppice.org>
8 *
9 * Copyright (C) 2001 Steve Underwood
10 *
11 * All rights reserved.
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU Lesser General Public License version 2.1,
15 * as published by the Free Software Foundation.
16 *
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Lesser General Public License for more details.
21 *
22 * You should have received a copy of the GNU Lesser General Public
23 * License along with this program; if not, write to the Free Software
24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 */
26
27/*! \file */
28
29#if !defined(_SPANDSP_PRIVATE_OKI_ADPCM_H_)
30#define _SPANDSP_PRIVATE_OKI_ADPCM_H_
31
32/*!
33 Oki (Dialogic) ADPCM conversion state descriptor. This defines the state of
34 a single working instance of the Oki ADPCM converter. This is used for
35 either linear to ADPCM or ADPCM to linear conversion.
36*/
37 struct oki_adpcm_state_s
38{
39 /*! \brief The bit rate - 24000 or 32000. */
40 int bit_rate;
41 /*! \brief The last state of the ADPCM algorithm. */
42 int16_t last;
43 /*! \brief Current index into the step size table. */
44 int16_t step_index;
45 /*! \brief The compressed data byte in progress. */
46 uint8_t oki_byte;
47 /*! \brief The signal history for the sample rate converter. */
48 int16_t history[32];
49 /*! \brief Pointer into the history buffer. */
50 int ptr;
51 /*! \brief Odd/even sample counter. */
52 int mark;
53 /*! \brief Phase accumulator for the sample rate converter. */
54 int phase;
55};
56
57#endif
58/*- 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