Mercurial > hg > audiostuff
comparison spandsp-0.0.6pre17/src/spandsp/private/oki_adpcm.h @ 4:26cd8f1ef0b1
import spandsp-0.0.6pre17
| author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
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| date | Fri, 25 Jun 2010 15:50:58 +0200 |
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| 3:c6c5a16ce2f2 | 4:26cd8f1ef0b1 |
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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 * $Id: oki_adpcm.h,v 1.1 2008/11/30 10:17:31 steveu Exp $ | |
| 27 */ | |
| 28 | |
| 29 /*! \file */ | |
| 30 | |
| 31 #if !defined(_SPANDSP_PRIVATE_OKI_ADPCM_H_) | |
| 32 #define _SPANDSP_PRIVATE_OKI_ADPCM_H_ | |
| 33 | |
| 34 /*! | |
| 35 Oki (Dialogic) ADPCM conversion state descriptor. This defines the state of | |
| 36 a single working instance of the Oki ADPCM converter. This is used for | |
| 37 either linear to ADPCM or ADPCM to linear conversion. | |
| 38 */ | |
| 39 struct oki_adpcm_state_s | |
| 40 { | |
| 41 /*! \brief The bit rate - 24000 or 32000. */ | |
| 42 int bit_rate; | |
| 43 /*! \brief The last state of the ADPCM algorithm. */ | |
| 44 int16_t last; | |
| 45 /*! \brief Current index into the step size table. */ | |
| 46 int16_t step_index; | |
| 47 /*! \brief The compressed data byte in progress. */ | |
| 48 uint8_t oki_byte; | |
| 49 /*! \brief The signal history for the sample rate converter. */ | |
| 50 int16_t history[32]; | |
| 51 /*! \brief Pointer into the history buffer. */ | |
| 52 int ptr; | |
| 53 /*! \brief Odd/even sample counter. */ | |
| 54 int mark; | |
| 55 /*! \brief Phase accumulator for the sample rate converter. */ | |
| 56 int phase; | |
| 57 }; | |
| 58 | |
| 59 #endif | |
| 60 /*- End of file ------------------------------------------------------------*/ |