From f3d6c7a3d174b65e8e9de52d916d421fbd38050d Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jmvalin@jmvalin.ca>
Date: Mon, 30 Jun 2014 14:13:46 -0400
Subject: [PATCH] Update Opus RTP payload
Addresses comments from several months ago
---
doc/draft-ietf-payload-rtp-opus.xml | 31 +++++++++++++++++++----------
1 file changed, 21 insertions(+), 10 deletions(-)
diff --git a/doc/draft-ietf-payload-rtp-opus.xml b/doc/draft-ietf-payload-rtp-opus.xml
index 89a980c6c..558fc9173 100644
--- a/doc/draft-ietf-payload-rtp-opus.xml
+++ b/doc/draft-ietf-payload-rtp-opus.xml
@@ -1,6 +1,7 @@
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd" [
<!ENTITY rfc2119 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml'>
+<!ENTITY rfc3389 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.3389.xml'>
<!ENTITY rfc3550 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.3550.xml'>
<!ENTITY rfc3711 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.3711.xml'>
<!ENTITY rfc3551 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.3551.xml'>
@@ -17,7 +18,7 @@
<!ENTITY nbsp " ">
]>
- <rfc category="std" ipr="trust200902" docName="draft-ietf-payload-rtp-opus-01">
+ <rfc category="std" ipr="trust200902" docName="draft-ietf-payload-rtp-opus-02">
<?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>
<?rfc strict="yes" ?>
@@ -60,17 +61,17 @@
<organization>Mozilla</organization>
<address>
<postal>
- <street>650 Castro Street</street>
- <city>Mountain View</city>
+ <street>2 Harrison Street</street>
+ <city>San Francisco</city>
<region>CA</region>
- <code>94041</code>
+ <code>94105</code>
<country>USA</country>
</postal>
<email>jmvalin@jmvalin.ca</email>
</address>
</author>
- <date day='14' month='January' year='2014' />
+ <date day='30' month='June' year='2014' />
<abstract>
<t>
@@ -189,7 +190,7 @@
The bitrate can be changed dynamically within that range.
All
other parameters being
- equal, higher bitrate results in higher quality.
+ equal, a higher bitrate results in higher quality.
</t>
<section title='Recommended Bitrate' anchor='bitrate_by_bandwidth'>
<t>
@@ -247,14 +248,22 @@
the Opus encoder may be set to use discontinuous
transmission (DTX), where parts of the encoded signal that
correspond to periods of silence in the input speech or audio signal
- are not transmitted to the receiver.
+ are not transmitted to the receiver. A receiver can distinguish
+ between DTX and packet loss by looking for gaps in the sequence
+ number, as described by Section 4.1
+ of <xref target="RFC3551"/>.
</t>
<t>
On the receiving side, the non-transmitted parts will be handled by a
frame loss concealment unit in the Opus decoder which generates a
comfort noise signal to replace the non transmitted parts of the
- speech or audio signal.
+ speech or audio signal. Use of <xref target="RFC3389"/> Comfort
+ Noise (CN) with Opus is discouraged.
+ The transmitter MUST drop whole frames only,
+ based on the size of the last transmitted frame,
+ to ensure successive RTP timestamps differ by a multiple of 120 and
+ to allow the receiver to use whole frames for concealment.
</t>
<t>
@@ -346,8 +355,9 @@
therefore no padding is required. The payload MAY be padded by an
integer number of octets according to <xref target="RFC3550"/>.</t>
- <t>The marker bit (M) of the RTP header is used in accordance with
- Section 4.1 of <xref target="RFC3551"/>.</t>
+ <t>The timestamp, sequence number, and marker bit (M) of the RTP header
+ are used in accordance with Section 4.1
+ of <xref target="RFC3551"/>.</t>
<t>The RTP payload type for Opus has not been assigned statically and is
expected to be assigned dynamically.</t>
@@ -914,6 +924,7 @@
<back>
<references title="Normative References">
&rfc2119;
+ &rfc3389;
&rfc3550;
&rfc3711;
&rfc3551;
--
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