Mercurial > hg > audiostuff
comparison spandsp-0.0.6pre17/src/spandsp/lpc10.h @ 4:26cd8f1ef0b1
import spandsp-0.0.6pre17
author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
---|---|
date | Fri, 25 Jun 2010 15:50:58 +0200 |
parents | |
children |
comparison
equal
deleted
inserted
replaced
3:c6c5a16ce2f2 | 4:26cd8f1ef0b1 |
---|---|
1 /* | |
2 * SpanDSP - a series of DSP components for telephony | |
3 * | |
4 * lpc10.h - LPC10 low bit rate speech codec. | |
5 * | |
6 * Written by Steve Underwood <steveu@coppice.org> | |
7 * | |
8 * Copyright (C) 2006 Steve Underwood | |
9 * | |
10 * All rights reserved. | |
11 * | |
12 * This program is free software; you can redistribute it and/or modify | |
13 * it under the terms of the GNU Lesser General Public License version 2.1, | |
14 * as published by the Free Software Foundation. | |
15 * | |
16 * This program is distributed in the hope that it will be useful, | |
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
19 * GNU Lesser General Public License for more details. | |
20 * | |
21 * You should have received a copy of the GNU Lesser General Public | |
22 * License along with this program; if not, write to the Free Software | |
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
24 * | |
25 * $Id: lpc10.h,v 1.22 2009/04/11 18:11:19 steveu Exp $ | |
26 */ | |
27 | |
28 #if !defined(_SPANDSP_LPC10_H_) | |
29 #define _SPANDSP_LPC10_H_ | |
30 | |
31 /*! \page lpc10_page LPC10 encoding and decoding | |
32 \section lpc10_page_sec_1 What does it do? | |
33 The LPC10 module implements the US Department of Defense LPC10 | |
34 codec. This codec produces compressed data at 2400bps. At such | |
35 a low rate high fidelity cannot be expected. However, the speech | |
36 clarity is quite good, and this codec is unencumbered by patent | |
37 or other restrictions. | |
38 | |
39 \section lpc10_page_sec_2 How does it work? | |
40 ???. | |
41 */ | |
42 | |
43 #define LPC10_SAMPLES_PER_FRAME 180 | |
44 #define LPC10_BITS_IN_COMPRESSED_FRAME 54 | |
45 | |
46 /*! | |
47 LPC10 codec unpacked frame. | |
48 */ | |
49 typedef struct | |
50 { | |
51 /*! Pitch */ | |
52 int32_t ipitch; | |
53 /*! Energy */ | |
54 int32_t irms; | |
55 /*! Reflection coefficients */ | |
56 int32_t irc[10]; | |
57 } lpc10_frame_t; | |
58 | |
59 /*! | |
60 LPC10 codec encoder state descriptor. This defines the state of | |
61 a single working instance of the LPC10 encoder. | |
62 */ | |
63 typedef struct lpc10_encode_state_s lpc10_encode_state_t; | |
64 | |
65 /*! | |
66 LPC10 codec decoder state descriptor. This defines the state of | |
67 a single working instance of the LPC10 decoder. | |
68 */ | |
69 typedef struct lpc10_decode_state_s lpc10_decode_state_t; | |
70 | |
71 #if defined(__cplusplus) | |
72 extern "C" | |
73 { | |
74 #endif | |
75 | |
76 /*! Initialise an LPC10e encode context. | |
77 \param s The LPC10e context | |
78 \param error_correction ??? | |
79 \return A pointer to the LPC10e context, or NULL for error. */ | |
80 SPAN_DECLARE(lpc10_encode_state_t *) lpc10_encode_init(lpc10_encode_state_t *s, int error_correction); | |
81 | |
82 SPAN_DECLARE(int) lpc10_encode_release(lpc10_encode_state_t *s); | |
83 | |
84 SPAN_DECLARE(int) lpc10_encode_free(lpc10_encode_state_t *s); | |
85 | |
86 /*! Encode a buffer of linear PCM data to LPC10e. | |
87 \param s The LPC10e context. | |
88 \param ima_data The LPC10e data produced. | |
89 \param amp The audio sample buffer. | |
90 \param len The number of samples in the buffer. This must be a multiple of 180, as | |
91 this is the number of samples on a frame. | |
92 \return The number of bytes of LPC10e data produced. */ | |
93 SPAN_DECLARE(int) lpc10_encode(lpc10_encode_state_t *s, uint8_t code[], const int16_t amp[], int len); | |
94 | |
95 /*! Initialise an LPC10e decode context. | |
96 \param s The LPC10e context | |
97 \param error_correction ??? | |
98 \return A pointer to the LPC10e context, or NULL for error. */ | |
99 SPAN_DECLARE(lpc10_decode_state_t *) lpc10_decode_init(lpc10_decode_state_t *st, int error_correction); | |
100 | |
101 SPAN_DECLARE(int) lpc10_decode_release(lpc10_decode_state_t *s); | |
102 | |
103 SPAN_DECLARE(int) lpc10_decode_free(lpc10_decode_state_t *s); | |
104 | |
105 /*! Decode a buffer of LPC10e data to linear PCM. | |
106 \param s The LPC10e context. | |
107 \param amp The audio sample buffer. | |
108 \param code The LPC10e data. | |
109 \param len The number of bytes of LPC10e data to be decoded. This must be a multiple of 7, | |
110 as each frame is packed into 7 bytes. | |
111 \return The number of samples returned. */ | |
112 SPAN_DECLARE(int) lpc10_decode(lpc10_decode_state_t *s, int16_t amp[], const uint8_t code[], int len); | |
113 | |
114 | |
115 #if defined(__cplusplus) | |
116 } | |
117 #endif | |
118 | |
119 #endif | |
120 /*- End of include ---------------------------------------------------------*/ |