From 5bec891d41ff8b67d77eb57fe86c4bea6158f378 Mon Sep 17 00:00:00 2001
From: Boris Grozev <boris@jitsi.org>
Date: Wed, 1 Oct 2014 14:24:37 +0300
Subject: [PATCH] Adds an option to enable adaptive-last-n.

---
 config.js                     |  1 +
 libs/colibri/colibri.focus.js | 20 ++++++++++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/config.js b/config.js
index 7c5946894..31b02ea22 100644
--- a/config.js
+++ b/config.js
@@ -20,6 +20,7 @@ var config = {
     enableRtpStats: true, // Enables RTP stats processing
     openSctp: true, // Toggle to enable/disable SCTP channels
     channelLastN: -1, // The default value of the channel attribute last-n.
+    adaptiveLastN: false,
     useRtcpMux: true,
     useBundle: true,
     enableRecording: false,
diff --git a/libs/colibri/colibri.focus.js b/libs/colibri/colibri.focus.js
index 4e40ffe32..38b9fd810 100644
--- a/libs/colibri/colibri.focus.js
+++ b/libs/colibri/colibri.focus.js
@@ -292,8 +292,14 @@ ColibriFocus.prototype._makeConference = function (errorCallback) {
         else
         {
             elemName = 'channel';
-            if (('video' === name) && (self.channelLastN >= 0))
-                elemAttrs['last-n'] = self.channelLastN;
+            if ('video' === name) {
+                if (self.channelLastN >= 0) {
+                    elemAttrs['last-n'] = self.channelLastN;
+                }
+                if (config.adaptiveLastN) {
+                    elemAttrs['adaptive-last-n'] = 'true';
+                }
+            }
         }
 
         elem.c('content', { name: name });
@@ -834,8 +840,14 @@ ColibriFocus.prototype.addNewParticipant = function (peer) {
         else
         {
             elemName = 'channel';
-            if (('video' === name) && (self.channelLastN >= 0))
-                elemAttrs['last-n'] = self.channelLastN;
+            if ('video' === name) {
+                if (self.channelLastN >= 0) {
+                    elemAttrs['last-n'] = self.channelLastN;
+                }
+                if (config.adaptiveLastN) {
+                    elemAttrs['adaptive-last-n'] = 'true';
+                }
+            }
         }
 
         elem.c('content', { name: name });