Network Working Group P. Jones
Request for Comments: 4102 Cisco Systems, Inc.
Category: Standards Track June 2005
Registration of the text/red MIME Sub-Type
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document defines the text/red MIME sub-type. "Red" is short for
redundant. The actual RTP packetization for this MIME type is
specified in RFC 2198.
1. Introduction
Text is an important component of any multimedia communication
system. Like audio, the transport of text can benefit from the use
of redundancy in order to improve reliability and end-user
experience.
RFC 2198 [1] defines an RTP [2] payload format for redundant audio
data. The format defined in that document is quite suitable for
providing redundancy for text, as well as audio.
RFC 4103 [8] specifies one usage of RFC 2198 and the text/red MIME
type for the transport of redundant text data.
This memo provides the MIME sub-type registration information for
text/red. While this document focuses on the use of this MIME sub-
type in SDP [5], the application of this MIME sub-type is not
restricted to SDP.
2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [3].
3. IANA Considerations
One new MIME sub-type has been registered by the IANA, as described
below:
MIME media type name: text
MIME subtype name: RED
Required parameters:
rate: the RTP clock rate of the payload carried within the RTP
packet. Typically, this rate is 1000, but other rates MAY be
specified. This parameter MUST be set equal to the clock rate of
the text payload format carried as the primary encoding.
pt: a comma-separated ordered list of RTP payload types
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