git-svn-id: http://webrtc.googlecode.com/svn/trunk@4 4adac7df-926f-26a2-2b94-8c16560cd09d

modules/audio_coding/codecs/iLBC/main/source/lpc_encode.c

@@ -0,0 +1,60 @@
+/*
+ *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+/******************************************************************
+
+ iLBC Speech Coder ANSI-C Source Code
+
+ WebRtcIlbcfix_LpcEncode.c
+
+******************************************************************/
+
+#include "defines.h"
+#include "simple_lpc_analysis.h"
+#include "simple_interpolate_lsf.h"
+#include "simple_lsf_quant.h"
+#include "lsf_check.h"
+#include "constants.h"
+
+/*----------------------------------------------------------------*
+ *  lpc encoder
+ *---------------------------------------------------------------*/
+
+void WebRtcIlbcfix_LpcEncode(
+    WebRtc_Word16 *syntdenum,  /* (i/o) synthesis filter coefficients
+                                           before/after encoding */
+    WebRtc_Word16 *weightdenum, /* (i/o) weighting denumerator coefficients
+                                   before/after encoding */
+    WebRtc_Word16 *lsf_index,  /* (o) lsf quantization index */
+    WebRtc_Word16 *data,   /* (i) Speech to do LPC analysis on */
+    iLBC_Enc_Inst_t *iLBCenc_inst
+    /* (i/o) the encoder state structure */
+                              ) {
+  /* Stack based */
+  WebRtc_Word16 lsf[LPC_FILTERORDER * LPC_N_MAX];
+  WebRtc_Word16 lsfdeq[LPC_FILTERORDER * LPC_N_MAX];
+
+  /* Calculate LSF's from the input speech */
+  WebRtcIlbcfix_SimpleLpcAnalysis(lsf, data, iLBCenc_inst);
+
+  /* Quantize the LSF's */
+  WebRtcIlbcfix_SimpleLsfQ(lsfdeq, lsf_index, lsf, iLBCenc_inst->lpc_n);
+
+  /* Stableize the LSF's if needed */
+  WebRtcIlbcfix_LsfCheck(lsfdeq, LPC_FILTERORDER, iLBCenc_inst->lpc_n);
+
+  /* Calculate the synthesis and weighting filter coefficients from
+     the optimal LSF and the dequantized LSF */
+  WebRtcIlbcfix_SimpleInterpolateLsf(syntdenum, weightdenum,
+                                     lsf, lsfdeq, iLBCenc_inst->lsfold,
+                                     iLBCenc_inst->lsfdeqold, LPC_FILTERORDER, iLBCenc_inst);
+
+  return;
+}