--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.6pre17/src/spandsp/oki_adpcm.h	Fri Jun 25 15:50:58 2010 +0200
@@ -0,0 +1,104 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * oki_adpcm.h - Conversion routines between linear 16 bit PCM data and
+ *		         OKI (Dialogic) ADPCM format.
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2001 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.
+ *
+ * $Id: oki_adpcm.h,v 1.24 2009/02/10 13:06:47 steveu Exp $
+ */
+
+/*! \file */
+
+#if !defined(_SPANDSP_OKI_ADPCM_H_)
+#define _SPANDSP_OKI_ADPCM_H_
+
+/*! \page okiadpcm_page OKI (Dialogic) ADPCM encoding and decoding
+\section okiadpcm_page_sec_1 What does it do?
+OKI ADPCM is widely used in the CTI industry because it is the principal format
+supported by Dialogic. As the market leader, they tend to define "common
+practice". It offers a good balance of simplicity and quality at rates of
+24kbps or 32kbps. 32kbps is obtained by ADPCM compressing 8k samples/second linear
+PCM. 24kbps is obtained by resampling to 6k samples/second and using the same ADPCM
+compression algorithm on the slower samples.
+
+The algorithms for this ADPCM codec can be found in "PC Telephony - The complete guide
+to designing, building and programming systems using Dialogic and Related Hardware"
+by Bob Edgar. pg 272-276. */
+
+/*!
+    Oki (Dialogic) ADPCM conversion state descriptor. This defines the state of
+    a single working instance of the Oki ADPCM converter. This is used for
+    either linear to ADPCM or ADPCM to linear conversion.
+*/
+typedef struct oki_adpcm_state_s oki_adpcm_state_t;
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/*! Initialise an Oki ADPCM encode or decode context.
+    \param s The Oki ADPCM context.
+    \param bit_rate The required bit rate for the ADPCM data.
+           The valid rates are 24000 and 32000.
+    \return A pointer to the Oki ADPCM context, or NULL for error. */
+SPAN_DECLARE(oki_adpcm_state_t *) oki_adpcm_init(oki_adpcm_state_t *s,
+                                                 int bit_rate);
+
+/*! Release an Oki ADPCM encode or decode context.
+    \param s The Oki ADPCM context.
+    \return 0 for OK. */
+SPAN_DECLARE(int) oki_adpcm_release(oki_adpcm_state_t *s);
+
+/*! Free an Oki ADPCM encode or decode context.
+    \param s The Oki ADPCM context.
+    \return 0 for OK. */
+SPAN_DECLARE(int) oki_adpcm_free(oki_adpcm_state_t *s);
+
+/*! Decode a buffer of Oki ADPCM data to linear PCM.
+    \param s The Oki ADPCM context.
+    \param amp The audio sample buffer.
+    \param oki_data
+    \param oki_bytes
+    \return The number of samples returned. */
+SPAN_DECLARE(int) oki_adpcm_decode(oki_adpcm_state_t *s,
+                                   int16_t amp[],
+                                   const uint8_t oki_data[],
+                                   int oki_bytes);
+
+/*! Encode a buffer of linear PCM data to Oki ADPCM.
+    \param s The Oki ADPCM context.
+    \param oki_data The Oki ADPCM data produced
+    \param amp The audio sample buffer.
+    \param len The number of samples in the buffer.
+    \return The number of bytes of Oki ADPCM data produced. */
+SPAN_DECLARE(int) oki_adpcm_encode(oki_adpcm_state_t *s,
+                                   uint8_t oki_data[],
+                                   const int16_t amp[],
+                                   int len);
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/