From fd4db8fd4fd2f085874318c54ee4173fde853c22 Mon Sep 17 00:00:00 2001
From: Stefano D'Angelo <stefano.dangelo@orastron.com>
Date: Wed, 15 Mar 2023 17:45:38 +0100
Subject: [PATCH] fix bw_src_int upsampling
---
TODO | 1 +
include/bw_src_int.h | 40 ++++++++++++++++------------------------
2 files changed, 17 insertions(+), 24 deletions(-)
diff --git a/TODO b/TODO
index 93c3a96..1ea9bc7 100644
--- a/TODO
+++ b/TODO
@@ -33,6 +33,7 @@ code:
* web examples: need to export memset?
* bw_satur gain compensation to divide by actual gain (derivative) rather than gain parameter?
* cite papers, thank authors
+* process1 and multi-channel
build system:
* make makefiles handle paths with spaces etc
diff --git a/include/bw_src_int.h b/include/bw_src_int.h
index 51c9c53..f13b88f 100644
--- a/include/bw_src_int.h
+++ b/include/bw_src_int.h
@@ -110,10 +110,6 @@ struct _bw_src_int_state {
float z2;
float z3;
float z4;
- float xz1;
- float xz2;
- float xz3;
- float xz4;
};
static inline void bw_src_int_init(bw_src_int_coeffs *BW_RESTRICT coeffs, int ratio) {
@@ -140,15 +136,11 @@ static inline void bw_src_int_reset_state(const bw_src_int_coeffs *BW_RESTRICT c
state->z4 = state->z3;
state->i = 1;
} else {
- // DF-I
- state->z1 = x0;
- state->z2 = x0;
- state->z3 = x0;
- state->z4 = x0;
- state->xz1 = x0;
- state->xz2 = x0;
- state->xz3 = x0;
- state->xz4 = x0;
+ // TDF-II
+ state->z4 = (coeffs->b4 - coeffs->a4) * x0;
+ state->z3 = (coeffs->b3 - coeffs->a3) * x0 + state->z4;
+ state->z2 = (coeffs->b2 - coeffs->a2) * x0 + state->z3;
+ state->z1 = (coeffs->b1 - coeffs->a1) * x0 + state->z2;
}
}
@@ -171,18 +163,18 @@ static inline int bw_src_int_process(const bw_src_int_coeffs *BW_RESTRICT coeffs
}
} else {
for (int i = 0; i < n_in_samples; i++) {
- // DF-I
- const float v = coeffs->b0 * x[i] + coeffs->b1 * state->xz1 + coeffs->b2 * state->xz2 + coeffs->b3 * state->xz3 + coeffs->b4 * state->xz4;
- state->xz4 = state->xz3;
- state->xz3 = state->xz2;
- state->xz2 = state->xz1;
- state->xz1 = x[i];
+ // TDF-II
+ const float v0 = coeffs->b0 * x[i];
+ const float v1 = coeffs->b1 * x[i];
+ const float v2 = coeffs->b2 * x[i];
+ const float v3 = coeffs->b3 * x[i];
+ const float v4 = coeffs->b4 * x[i];
for (int j = 0; j < coeffs->ratio; j++) {
- y[n] = v - coeffs->a1 * state->z1 - coeffs->a2 * state->z2 - coeffs->a3 * state->z3 - coeffs->a4 * state->z4;
- state->z4 = state->z3;
- state->z3 = state->z2;
- state->z2 = state->z1;
- state->z1 = y[n];
+ y[n] = v0 + state->z1;
+ state->z1 = v1 - coeffs->a1 * y[n] + state->z2;
+ state->z2 = v2 - coeffs->a2 * y[n] + state->z3;
+ state->z3 = v3 - coeffs->a3 * y[n] + state->z4;
+ state->z4 = v4 - coeffs->a4 * y[n];
n++;
}
}