From: Andre Noll <maan@systemlinux.org>
Date: Fri, 18 Jun 2010 08:40:06 +0000 (+0200)
Subject: dccp_send: Add command line options for FEC parameters.
X-Git-Tag: v0.4.3~13^2~1
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=04cc3ada65d336e2b50eea2f942d585198f63f23

dccp_send: Add command line options for FEC parameters.

ATM, these are hardcoded as MPS/3/4. This patch allows to impose
an upper bound on the slice size and to change the number of (data)
slices of a FEC group.
---

diff --git a/dccp_send.c b/dccp_send.c
index 9a2f6caf..6cfdfbbe 100644
--- a/dccp_send.c
+++ b/dccp_send.c
@@ -97,6 +97,8 @@ static int dccp_init_fec(struct sender_client *sc)
 	}
 	PARA_INFO_LOG("current MPS = %d bytes\n", mps);
 	assert(mps > 0);
+	if (conf.dccp_max_slice_size_arg > 0)
+		mps = PARA_MIN(mps, conf.dccp_max_slice_size_arg);
 	return mps;
 }
 
@@ -139,8 +141,8 @@ static void dccp_post_select(fd_set *rfds, __a_unused fd_set *wfds)
 	}
 	dfc = para_calloc(sizeof(*dfc));
 	sc->private_data = dfc;
-	dfc->fcp.slices_per_group	= 4;
-	dfc->fcp.data_slices_per_group	= 3;
+	dfc->fcp.data_slices_per_group	= conf.dccp_data_slices_per_group_arg;
+	dfc->fcp.slices_per_group	= conf.dccp_slices_per_group_arg;
 	dfc->fcp.init_fec		= dccp_init_fec;
 	dfc->fcp.send_fec		= dccp_send_fec;
 	dfc->fc = vss_add_fec_client(sc, &dfc->fcp);
@@ -210,7 +212,7 @@ static char *dccp_info(void)
  */
 void dccp_send_init(struct sender *s)
 {
-	int ret;
+	int ret, k, n;
 
 	s->info = dccp_info;
 	s->send = NULL;
@@ -225,6 +227,15 @@ void dccp_send_init(struct sender *s)
 	s->client_cmds[SENDER_ADD] = NULL;
 	s->client_cmds[SENDER_DELETE] = NULL;
 
+	k = conf.dccp_data_slices_per_group_arg;
+	n = conf.dccp_slices_per_group_arg;
+
+	if (k <= 0 || n <= 0 || k >= n) {
+		PARA_WARNING_LOG("invalid FEC parameters, using defaults\n");
+		conf.dccp_data_slices_per_group_arg = 3;
+		conf.dccp_slices_per_group_arg = 4;
+	}
+
 	init_sender_status(dss, conf.dccp_access_arg, conf.dccp_access_given,
 		conf.dccp_port_arg, conf.dccp_max_clients_arg,
 		conf.dccp_default_deny_given);
diff --git a/ggo/server.m4 b/ggo/server.m4
index 4be4e2c9..af5d8f63 100644
--- a/ggo/server.m4
+++ b/ggo/server.m4
@@ -238,6 +238,53 @@ details="
 	See http_max_clients for details.
 "
 
+option "dccp_max_slice_size" -
+#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+"Upper bound for the FEC slice size"
+int typestr = "size"
+default = "0"
+details = "
+	If this value is non-positive (the default) the dccp sender
+	uses the maximum packet size (MPS) of the connection as the
+	slice size. The MPS is a network parameter and depends on
+	the path maximum transmission unit (path MTU) of an incoming
+	connection, i.e. on the largest packet size that can be
+	transmitted without causing fragmentation.
+
+	This option allows to use a value less than the MPS in order
+	to fine-tune application performance. Values greater than
+	the MPS of an incoming connection can not be set.
+"
+
+option "dccp_data_slices_per_group" -
+#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+"The number of non-redundant slices per FEC group"
+int typestr = "num"
+default = "3"
+details = "
+	This determines the number of slices in each FEC group that are
+	necessary to decode the group. The given number must be smaller
+	than the value of the dccp_slices_per_group option below.
+
+	Note that the duration of a FEC group is proportional to the
+	product dccp_max_slice_size * dccp_data_slices_per_group.
+"
+
+option "dccp_slices_per_group" -
+#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+"The total number of slices per FEC group"
+int typestr = "num"
+default = "4"
+details = "
+	This value must be larger than the value given for above
+	dccp_data_slices_per_group above. The difference being the
+	number of redundant slices per group, i.e.  the number of
+	data packets that may be lost without causing interruptions
+	of the resulting audio stream.
+
+	Increase this value if for lossy networks.
+"
+
 ####################
 section "udp sender"
 ####################