From 3f99693b6933fb8f098746c48f97ed993ca7fa8c Mon Sep 17 00:00:00 2001
From: Paul Brossier <piem@piem.org>
Date: Mon, 19 Oct 2009 15:00:32 +0200
Subject: [PATCH] src/temporal/filter.c: reset filter memory in filtfilt

---
 src/temporal/filter.c | 33 ++++++++++++---------------------
 src/temporal/filter.h |  3 +++
 2 files changed, 15 insertions(+), 21 deletions(-)

diff --git a/src/temporal/filter.c b/src/temporal/filter.c
index bf8139a3..a94495f9 100644
--- a/src/temporal/filter.c
+++ b/src/temporal/filter.c
@@ -79,35 +79,19 @@ aubio_filter_do (aubio_filter_t * f, fvec_t * in)
   }
 }
 
-/*  
- *
- * despite mirroring, end effects destroy both phse and amplitude. the longer
- * the buffer, the less affected they are.
- *
- * replacing with zeros clicks.
- *
- * seems broken for order > 4 (see biquad_do_filtfilt for audible one) 
- */
+/* The rough way: reset memory of filter between each run to avoid end effects. */
 void aubio_filter_do_filtfilt(aubio_filter_t * f, fvec_t * in, fvec_t * tmp) {
   uint_t j,i=0;
   uint_t length = in->length;
-  //uint_t order = f->order;
-  //lsmp_t mir;
-  /* mirroring */
-  //mir = 2*in->data[i][0];
-  //for (j=1;j<order;j++)
-  //f->x[j] = 0.;//mir - in->data[i][order-j];
   /* apply filtering */
   aubio_filter_do(f,in);
-  /* invert */
+  aubio_filter_do_reset(f);
+  /* mirror */
   for (j = 0; j < length; j++)
     tmp->data[i][length-j-1] = in->data[i][j];
-  /* mirror inverted */
-  //mir = 2*tmp->data[i][0];
-  //for (j=1;j<order;j++)
-  //f->x[j] = 0.;//mir - tmp->data[i][order-j];
-  /* apply filtering on inverted */
+  /* apply filtering on mirrored */
   aubio_filter_do(f,tmp);
+  aubio_filter_do_reset(f);
   /* invert back */
   for (j = 0; j < length; j++)
     in->data[i][j] = tmp->data[i][length-j-1];
@@ -144,6 +128,13 @@ aubio_filter_set_samplerate (aubio_filter_t * f, uint_t samplerate)
   return AUBIO_OK;
 }
 
+void
+aubio_filter_do_reset (aubio_filter_t * f)
+{
+  lvec_zeros(f->x);
+  lvec_zeros(f->y);
+}
+
 aubio_filter_t *
 new_aubio_filter (uint_t order, uint_t channels)
 {
diff --git a/src/temporal/filter.h b/src/temporal/filter.h
index a5e74a70..633ec812 100644
--- a/src/temporal/filter.h
+++ b/src/temporal/filter.h
@@ -140,6 +140,9 @@ uint_t aubio_filter_get_samplerate (aubio_filter_t * f);
 */
 uint_t aubio_filter_set_samplerate (aubio_filter_t * f, uint_t samplerate);
 
+/** reset filter memory */
+void aubio_filter_do_reset (aubio_filter_t * f);
+
 /** create new filter object
 
   This function creates a new ::aubio_filter_t object, given an order 
-- 
2.26.2