spandsp: ima_adpcm.h Source File

spandsp 0.0.6

private/ima_adpcm.h
1/*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * private/ima_adpcm.c - Conversion routines between linear 16 bit PCM data
5 * and IMA/DVI/Intel ADPCM format.
6 *
7 * Written by Steve Underwood <steveu@coppice.org>
8 *
9 * Copyright (C) 2004 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 * Based on a bit from here, a bit from there, eye of toad,
27 * ear of bat, etc - plus, of course, my own 2 cents.
28 */
29
30#if !defined(_SPANDSP_PRIVATE_IMA_ADPCM_H_)
31#define _SPANDSP_PRIVATE_IMA_ADPCM_H_
32
33/*!
34 IMA (DVI/Intel) ADPCM conversion state descriptor. This defines the state of
35 a single working instance of the IMA ADPCM converter. This is used for
36 either linear to ADPCM or ADPCM to linear conversion.
37*/
38 struct ima_adpcm_state_s
39{
40 int variant;
41 /*! \brief The size of a chunk, in samples. */
42 int chunk_size;
43 /*! \brief The last state of the ADPCM algorithm. */
44 int last;
45 /*! \brief Current index into the step size table. */
46 int step_index;
47 /*! \brief The current IMA code byte in progress. */
48 uint16_t ima_byte;
49 int bits;
50};
51
52#endif
53/*- 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