/usr/include/spandsp/lpc10.h is in libspandsp-dev 0.0.6-2+b2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 | /*
* SpanDSP - a series of DSP components for telephony
*
* lpc10.h - LPC10 low bit rate speech codec.
*
* Written by Steve Underwood <steveu@coppice.org>
*
* Copyright (C) 2006 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.
*/
#if !defined(_SPANDSP_LPC10_H_)
#define _SPANDSP_LPC10_H_
/*! \page lpc10_page LPC10 encoding and decoding
\section lpc10_page_sec_1 What does it do?
The LPC10 module implements the US Department of Defense LPC10
codec. This codec produces compressed data at 2400bps. At such
a low rate high fidelity cannot be expected. However, the speech
clarity is quite good, and this codec is unencumbered by patent
or other restrictions.
\section lpc10_page_sec_2 How does it work?
???.
*/
#define LPC10_SAMPLES_PER_FRAME 180
#define LPC10_BITS_IN_COMPRESSED_FRAME 54
/*!
LPC10 codec unpacked frame.
*/
typedef struct
{
/*! Pitch */
int32_t ipitch;
/*! Energy */
int32_t irms;
/*! Reflection coefficients */
int32_t irc[10];
} lpc10_frame_t;
/*!
LPC10 codec encoder state descriptor. This defines the state of
a single working instance of the LPC10 encoder.
*/
typedef struct lpc10_encode_state_s lpc10_encode_state_t;
/*!
LPC10 codec decoder state descriptor. This defines the state of
a single working instance of the LPC10 decoder.
*/
typedef struct lpc10_decode_state_s lpc10_decode_state_t;
#if defined(__cplusplus)
extern "C"
{
#endif
/*! Initialise an LPC10e encode context.
\param s The LPC10e context
\param error_correction ???
\return A pointer to the LPC10e context, or NULL for error. */
SPAN_DECLARE(lpc10_encode_state_t *) lpc10_encode_init(lpc10_encode_state_t *s, int error_correction);
SPAN_DECLARE(int) lpc10_encode_release(lpc10_encode_state_t *s);
SPAN_DECLARE(int) lpc10_encode_free(lpc10_encode_state_t *s);
/*! Encode a buffer of linear PCM data to LPC10e.
\param s The LPC10e context.
\param ima_data The LPC10e data produced.
\param amp The audio sample buffer.
\param len The number of samples in the buffer. This must be a multiple of 180, as
this is the number of samples on a frame.
\return The number of bytes of LPC10e data produced. */
SPAN_DECLARE(int) lpc10_encode(lpc10_encode_state_t *s, uint8_t code[], const int16_t amp[], int len);
/*! Initialise an LPC10e decode context.
\param s The LPC10e context
\param error_correction ???
\return A pointer to the LPC10e context, or NULL for error. */
SPAN_DECLARE(lpc10_decode_state_t *) lpc10_decode_init(lpc10_decode_state_t *st, int error_correction);
SPAN_DECLARE(int) lpc10_decode_release(lpc10_decode_state_t *s);
SPAN_DECLARE(int) lpc10_decode_free(lpc10_decode_state_t *s);
/*! Decode a buffer of LPC10e data to linear PCM.
\param s The LPC10e context.
\param amp The audio sample buffer.
\param code The LPC10e data.
\param len The number of bytes of LPC10e data to be decoded. This must be a multiple of 7,
as each frame is packed into 7 bytes.
\return The number of samples returned. */
SPAN_DECLARE(int) lpc10_decode(lpc10_decode_state_t *s, int16_t amp[], const uint8_t code[], int len);
#if defined(__cplusplus)
}
#endif
#endif
/*- End of include ---------------------------------------------------------*/
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