From eb8b3c2b07a761fdb3fcb6f7e39679ccfba595a6 Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jmvalin@jmvalin.ca>
Date: Mon, 23 Apr 2012 16:24:45 -0400
Subject: [PATCH] Adds note on monic filter
---
silk/fixed/noise_shape_analysis_FIX.c | 3 +++
silk/float/noise_shape_analysis_FLP.c | 3 +++
2 files changed, 6 insertions(+)
diff --git a/silk/fixed/noise_shape_analysis_FIX.c b/silk/fixed/noise_shape_analysis_FIX.c
index 8a3d7ccb3..d8459ae74 100644
--- a/silk/fixed/noise_shape_analysis_FIX.c
+++ b/silk/fixed/noise_shape_analysis_FIX.c
@@ -34,6 +34,9 @@ POSSIBILITY OF SUCH DAMAGE.
/* Compute gain to make warped filter coefficients have a zero mean log frequency response on a */
/* non-warped frequency scale. (So that it can be implemented with a minimum-phase monic filter.) */
+/* Note: A monic filter is one with the first coefficient equal to 1.0. In Silk
+ we omit the first coefficient in an array of coefficients, for monic filters.
+*/
static inline opus_int32 warped_gain( /* gain in Q16*/
const opus_int32 *coefs_Q24,
opus_int lambda_Q16,
diff --git a/silk/float/noise_shape_analysis_FLP.c b/silk/float/noise_shape_analysis_FLP.c
index 0f3a4965f..89c979926 100644
--- a/silk/float/noise_shape_analysis_FLP.c
+++ b/silk/float/noise_shape_analysis_FLP.c
@@ -34,6 +34,9 @@ POSSIBILITY OF SUCH DAMAGE.
/* Compute gain to make warped filter coefficients have a zero mean log frequency response on a */
/* non-warped frequency scale. (So that it can be implemented with a minimum-phase monic filter.) */
+/* Note: A monic filter is one with the first coefficient equal to 1.0. In Silk
+ we omit the first coefficient in an array of coefficients, for monic filters.
+*/
static inline silk_float warped_gain(
const silk_float *coefs,
silk_float lambda,
--
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