===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/sndiod/dev.c,v
retrieving revision 1.29
retrieving revision 1.30
diff -u -r1.29 -r1.30
--- src/usr.bin/sndiod/dev.c	2017/11/03 17:12:59	1.29
+++ src/usr.bin/sndiod/dev.c	2017/11/07 11:41:07	1.30
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dev.c,v 1.29 2017/11/03 17:12:59 ratchov Exp $	*/
+/*	$OpenBSD: dev.c,v 1.30 2017/11/07 11:41:07 ratchov Exp $	*/
 /*
  * Copyright (c) 2008-2012 Alexandre Ratchov <alex@caoua.org>
  *
@@ -1709,7 +1709,20 @@
 			enc_init(&s->sub.enc, &s->par, slot_nch);
 			s->sub.encbuf =
 			    xmalloc(s->round * slot_nch * sizeof(adata_t));
-			enc_sil_do(&s->sub.enc, s->sub.buf.data, s->appbufsz);
+		}
+
+		/*
+		 * cmap_copy() doesn't write samples in all channels,
+	         * for instance when mono->stereo conversion is
+	         * disabled. So we have to prefill cmap_copy() output
+	         * with silence.
+	         */
+		if (s->sub.resampbuf) {
+			memset(s->sub.resampbuf, 0,
+			    d->round * slot_nch * sizeof(adata_t));
+		} else if (s->sub.encbuf) {
+			memset(s->sub.encbuf, 0,
+			    s->round * slot_nch * sizeof(adata_t));
 		} else {
 			memset(s->sub.buf.data, 0,
 			    s->appbufsz * slot_nch * sizeof(adata_t));