From f70d0b19af49396750f10a179b7db5dd2d06fa94 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wtaymans@redhat.com>
Date: Tue, 29 Sep 2020 12:00:46 +0200
Subject: [PATCH] channelmix: add option to NORMALIZE volumes

Normalize the complete matrix with the same coefficient
---
 spa/plugins/audioconvert/channelmix-ops.c | 13 +++++++++----
 spa/plugins/audioconvert/channelmix-ops.h |  1 +
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/spa/plugins/audioconvert/channelmix-ops.c b/spa/plugins/audioconvert/channelmix-ops.c
index 7cd91bc28..51f843c4e 100644
--- a/spa/plugins/audioconvert/channelmix-ops.c
+++ b/spa/plugins/audioconvert/channelmix-ops.c
@@ -166,6 +166,7 @@ static int make_matrix(struct channelmix *mix)
 	float clev = SQRT1_2;
 	float slev = SQRT1_2;
 	float llev = 0.5f;
+	float maxsum = 0.0f;
 
 	spa_log_debug(mix->log, "src-mask:%08"PRIx64" dst-mask:%08"PRIx64,
 			src_mask, dst_mask);
@@ -355,7 +356,7 @@ static int make_matrix(struct channelmix *mix)
 		}
 	}
 done:
-	for (ic = 0, i = 0; i < NUM_CHAN; i++) {
+	for (jc = 0, ic = 0, i = 0; i < NUM_CHAN; i++) {
 		float sum = 0.0f;
 		if ((dst_mask & (1UL << (i + 2))) == 0)
 			continue;
@@ -365,11 +366,15 @@ done:
 			mix->matrix_orig[ic][jc++] = matrix[i][j];
 			sum += fabs(matrix[i][j]);
 		}
-		if (sum > 1.0f)
-			for (j = 0; j < jc; j++)
-		                mix->matrix_orig[ic][j] /= sum;
+		maxsum = SPA_MAX(maxsum, sum);
 		ic++;
 	}
+	if (SPA_FLAG_IS_SET(mix->options, CHANNELMIX_OPTION_NORMALIZE) &&
+	    maxsum > 1.0f) {
+		for (i = 0; i < ic; i++)
+			for (j = 0; j < jc; j++)
+		                mix->matrix_orig[i][j] /= maxsum;
+	}
 	return 0;
 }
 
diff --git a/spa/plugins/audioconvert/channelmix-ops.h b/spa/plugins/audioconvert/channelmix-ops.h
index 4aac05540..a89e66a50 100644
--- a/spa/plugins/audioconvert/channelmix-ops.h
+++ b/spa/plugins/audioconvert/channelmix-ops.h
@@ -47,6 +47,7 @@ struct channelmix {
 	uint64_t dst_mask;
 	uint32_t cpu_flags;
 #define CHANNELMIX_OPTION_MIX_LFE	(1<<0)		/**< mix LFE */
+#define CHANNELMIX_OPTION_NORMALIZE	(1<<1)		/**< normalize volumes */
 	uint32_t options;
 
 	struct spa_log *log;