September 2008
Intermediate to advanced
550 pages
18h 10m
English
Content preview from VoIP Voice and Fax Signal ProcessingBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
10
PACKETIZATION—RTP, RTCP, AND JITTER BUFFER
In VoIP, voice samples from telephone interfaces are compressed using compression codecs such as G.711, G.729A, G.723.1, and G.722, and are framed as payload. Voice payload size varies with the compression codec, compression rate options, and payload duration. For G.729A, 10 ms is the frame, and for G.723.1,30 ms is the basic frame. Voice payload may use a group of compressed frames up to 80 ms. The compressed payloads are framed as Real-Time Protocol (RTP)/User Protocol Datagram (UDP)/Internet Protocol (IP) packets for sending on the IP network. At the destination, payloads from RTP/UDP/IP are passed through the jitter buffer before decompressing in the decoder. RTP Control Protocol (RTCP), RTCP-Extended Report (XR) packets are used to convey end-to-end voice packet transmission parameters and statistics. In actual implementation, voice payload, RTP, jitter buffer, RTCP, voice quality monitoring, quality of service (QoS) mechanisms, and bandwidth management parameters work in coordination for ensuring better end-to-end packet delivery. This chapter is presented for RTP, RTCP, RTCP-XR, packet impediments, and jitter buffer. More details on voice packet headers of UDP/IP and network interface headers for Ethernet and digital subscriber line (DSL) are presented in Chapter 11.
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.