RFC 3558 · PROPOSED STANDARD · 2003

RTP Payload Format for Enhanced Variable Rate Codecs and Selectable Mode Vocoders

Overview

RFC 3558, “RTP Payload Format for Enhanced Variable Rate Codecs and Selectable Mode Vocoders”, is a Proposed Standard document published in July 2003 by A. Li. It has since been updated by RFC 4788. The canonical text is published by the RFC Editor.

Abstract

This document describes the RTP payload format for Enhanced Variable Rate Codec (EVRC) Speech and Selectable Mode Vocoder (SMV) Speech. Two sub-formats are specified for different application scenarios. A bundled/interleaved format is included to reduce the effect of packet loss on speech quality and amortize the overhead of the RTP header over more than one speech frame. A non-bundled format is also supported for conversational applications. [STANDARDS-TRACK]

Abstract as published in the RFC, via rfc-editor.org.

What “Proposed Standard” means

An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.

Read this RFC

The canonical text of RFC 3558 is hosted at rfc-editor.org. Available in TXT,HTML.

Relationships to other RFCs
Updated by
RFC 4788
Other RFCs from 2003

Who Is Online

In total there are 40 users online: 0 registered, 33 guests and 7 bots.

Most users ever online was 5,555 on 17 Jul 2026, 3:23 am.

Bots: AhrefsBot Applebot Bingbot Googlebot Other Bot PetalBot SemrushBot

Users active in the past 15 minutes. Total registered members: 372