Allows any input/output stream to underrun/overrun without disturbing

other streams. Beside making aucat usable with slow apps (eg. cdio),
this change will ease turning aucat into an audio server later

if one of the input buffers underruns, then silence is generated in
place of the missing samples. Later, as many samples are dropped in
order to maintain the stream in sync with the rest

if one of the output buffers overruns then newer samples are
discarded. Later silence is generated in order to maintain the
stream in sync with the rest.

ok jakemsr

2 files changed, 56 insertions, 11 deletions

diff --git a/usr.bin/aucat/abuf.h b/usr.bin/aucat/abuf.h
index ed0625a4328..67f8a70830a 100644
--- a/usr.bin/aucat/abuf.h
+++ b/usr.bin/aucat/abuf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: abuf.h,v 1.2 2008/05/25 21:16:37 ratchov Exp $	*/
+/*	$OpenBSD: abuf.h,v 1.3 2008/06/02 17:03:25 ratchov Exp $	*/
 /*
  * Copyright (c) 2008 Alexandre Ratchov <alex@caoua.org>
  *
@@ -29,7 +29,9 @@ struct abuf {
 	int mixvol;		/* input gain */
 	unsigned mixdone;	/* input of mixer */
 	unsigned mixtodo;	/* output of mixer */
+	unsigned mixdrop;	/* frames mix_in() will discard */
 	unsigned subdone;	/* output if sub */
+	unsigned subdrop;	/* silence frames sub_out() will insert */ 
 	LIST_ENTRY(abuf) ient;	/* for mix inputs list */
 	LIST_ENTRY(abuf) oent;	/* for sub outputs list */
 
diff --git a/usr.bin/aucat/aproc.c b/usr.bin/aucat/aproc.c
index 6d3067fb936..fa060326135 100644
--- a/usr.bin/aucat/aproc.c
+++ b/usr.bin/aucat/aproc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: aproc.c,v 1.2 2008/05/25 21:16:37 ratchov Exp $	*/
+/*	$OpenBSD: aproc.c,v 1.3 2008/06/02 17:03:25 ratchov Exp $	*/
 /*
  * Copyright (c) 2008 Alexandre Ratchov <alex@caoua.org>
  *
@@ -332,11 +332,26 @@ int
 mix_in(struct aproc *p, struct abuf *ibuf)
 {
 	struct abuf *i, *inext, *obuf = LIST_FIRST(&p->obuflist);
-	unsigned ocount;
+	unsigned icount, ocount;
 
 	DPRINTFN(4, "mix_in: used = %u, done = %u, zero = %u\n",
 	    ibuf->used, ibuf->mixdone, obuf->mixtodo);
 
+	/* 
+	 * discard data already sent as silence
+	 */
+	if (ibuf->mixdrop > 0) {
+		icount = ibuf->mixdrop;
+		if (icount > ibuf->used)
+			icount = ibuf->used;
+		ibuf->used -= icount;
+		ibuf->start += icount;
+		if (ibuf->start >= ibuf->len)
+			ibuf->start -= ibuf->len;
+		ibuf->mixdrop -= icount;
+		DPRINTF("mix_in: catched xruns, drop = %u\n", ibuf->mixdrop);
+	}
+		
 	if (ibuf->mixdone >= obuf->mixtodo)
 		return 0;
 	mix_badd(ibuf, obuf);
@@ -372,20 +387,22 @@ int
 mix_out(struct aproc *p, struct abuf *obuf)
 {
 	struct abuf *i, *inext;
-	unsigned ocount;
+	unsigned ocount, drop;
 
 	DPRINTFN(4, "mix_out: used = %u, zero = %u\n",
 	    obuf->used, obuf->mixtodo);
 
-	/*
-	 * XXX: should handle underruns here, currently if one input is
-	 * blocked, then the output block can underrun.
-	 */
 	mix_bzero(p);
 	ocount = obuf->mixtodo;
 	for (i = LIST_FIRST(&p->ibuflist); i != LIST_END(&p->ibuflist); i = inext) {
 		inext = LIST_NEXT(i, ient);
-		mix_badd(i, obuf);
+		if (!ABUF_ROK(i) && i->mixdone == 0) {
+			drop = obuf->mixtodo;
+			i->mixdone += drop;
+			i->mixdrop += drop;
+			DPRINTF("mix_out: xrun, drop = %u\n", i->mixdrop);
+		} else
+			mix_badd(i, obuf);
 		if (ocount > i->mixdone)
 			ocount = i->mixdone;
 		if (ABUF_EOF(i)) {
@@ -444,6 +461,7 @@ void
 mix_newin(struct aproc *p, struct abuf *ibuf)
 {
 	ibuf->mixdone = 0;
+	ibuf->mixdrop = 0;
 	ibuf->mixvol = ADATA_UNIT;
 }
 
@@ -506,19 +524,26 @@ int
 sub_in(struct aproc *p, struct abuf *ibuf)
 {
 	struct abuf *i, *inext;
-	unsigned done;
+	unsigned done, drop;
 	int again;
 
 	again = 1;
 	done = ibuf->used;
 	for (i = LIST_FIRST(&p->obuflist); i != LIST_END(&p->obuflist); i = inext) {
 		inext = LIST_NEXT(i, oent);
-		if (ABUF_WOK(i)) {
+		if (!ABUF_WOK(i) && i->subdone == 0) {
+			drop = ibuf->used;
+			i->subdrop += drop;
+			i->subdone += drop;
+			DPRINTF("sub_in: xrun, drop =  %u\n", i->subdrop);
+		} else {
 			sub_bcopy(ibuf, i);
 			abuf_flush(i);
 		}
+#ifdef sub_xrun_disabled		
 		if (!ABUF_WOK(i))
 			again = 0;
+#endif
 		if (done > i->subdone)
 			done = i->subdone;
 	}
@@ -537,8 +562,25 @@ sub_out(struct aproc *p, struct abuf *obuf)
 {
 	struct abuf *ibuf = LIST_FIRST(&p->ibuflist);
 	struct abuf *i, *inext;
+	unsigned char *odata;
+	unsigned ocount;
 	unsigned done;
 
+	/*
+	 * generate silence for dropped samples
+	 */
+	while (obuf->subdrop > 0) {
+		odata = abuf_wgetblk(obuf, &ocount, 0);
+		if (ocount >= obuf->subdrop)
+			ocount = obuf->subdrop;
+		if (ocount == 0)
+			break;
+		memset(odata, 0, ocount);
+		obuf->used += ocount;
+		obuf->subdrop -= ocount;
+		DPRINTF("sub_out: catched, drop = %u\n", obuf->subdrop);
+	}
+
 	if (obuf->subdone >= ibuf->used)
 		return 0;
 
@@ -611,6 +653,7 @@ void
 sub_newout(struct aproc *p, struct abuf *obuf)
 {
 	obuf->subdone = 0;
+	obuf->subdrop = 0;
 }
 
 struct aproc_ops sub_ops = {