From 4468c75adbefed247ae592e42549da544f468277 Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jean-marc.valin@octasic.com>
Date: Thu, 8 Jul 2010 13:40:07 -0400
Subject: draft update, instructions

---
 doc/draft-valin-codec-prototype.xml | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

(limited to 'doc')

diff --git a/doc/draft-valin-codec-prototype.xml b/doc/draft-valin-codec-prototype.xml
index 8ebda971..4a16a228 100644
--- a/doc/draft-valin-codec-prototype.xml
+++ b/doc/draft-valin-codec-prototype.xml
@@ -2,7 +2,7 @@
 <!DOCTYPE rfc SYSTEM 'rfc2629.dtd'>
 <?rfc toc="yes" symrefs="yes" ?>
 
-<rfc ipr="trust200902" category="std" docName="draft-valin-codec-prototype-00">
+<rfc ipr="trust200902" category="std" docName="draft-valin-codec-prototype-01">
 
 <front>
 <title abbrev="Codec Prototype">Prototype for IETF Interactive Audio Codec</title>
@@ -39,7 +39,7 @@
 </author>
 
 
-<date day="5" month="July" year="2010" />
+<date day="8" month="July" year="2010" />
 
 <area>General</area>
 
@@ -107,6 +107,17 @@ of the (now expired) <xref target="CELT">CELT Internet-Draft</xref>.
 The main changes
 include better support for 20 ms frames as well as the ability to encode 
 only the higher bands using a range coder partially filled by the SILK layer.</t>
+
+<t>
+In addition to their frame size, the SILK and CELT codecs require
+a look-ahead of 5.2 ms and 2.5 ms, respectively. SILK's look-ahead is due to
+noise shaping estimation (5 ms) and the internal resampling (0.2 ms), while
+CELT's look-ahead is due to the overlapping MDCT windows. To compensate for the
+difference, the CELT encoder input is delayed by 2.7 ms. This ensures that low
+frequencies and high frequencies arrive at the same time.
+</t>
+
+
 <section title="Source Code">
 <t>
 The source code is currently available in a
@@ -284,7 +295,10 @@ in encoders are typically rarer, the same applies to the encoder. Malicious
 audio stream must not cause the encoder to misbehave because this would
 allow an attacker to attack transcoding gateways.
 </t>
-
+<t>
+In its current version, this prototype codec likely does NOT meet these
+security considerations, so it should be used with caution.
+</t>
 </section> 
 
 
@@ -294,12 +308,12 @@ This document has no actions for IANA.
 </t>
 </section>
 
-<!--
 <section anchor="Acknowledgments" title="Acknowledgments">
 <t>
+Thanks to all other developers, including Soeren Skak Jensen, Gregory Maxwell, 
+Christopher Montgomery, Karsten Vandborg Soerensen, and Timothy Terriberry.
 </t>
 </section> 
--->
 
 </middle>
 
-- 
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