Streaming video is growing the last few years at very high rates. If you are just starting with streaming, this streaming video basics article will help you understand the technology and the various streaming protocols used today.
Streaming video basics:Introduction
Streaming video is a way of transmitting video (and audio) through networks. The main features of streaming compared to other forms of video or videoconferencing are:
- One-way communication system.
Video is transmitted from one end and there are multiple recipients at the other end to receive it. These viewers cannot send their video and audio back to the sender.
- Almost live
Streaming video has a longer delay than conferencing and is not (usually) suitable for interactive video conferencing. The video that you receive when you are a viewer attending a live streaming event usually has a delay between 10 and 20 seconds. This is because of the encoding and decoding process, and also the transmission time. However recently there have been attempts to reduce streaming systems delays to a minimum and make them suitable for interactive conferencing.
- Video for the masses
Streaming video is suitable for mass audiences. If you want to broadcast an event or a training to a large number of viewers, streaming video technologies are more efficient and cost-effective, as they can easily scale from tens to hundreds to even thousands of viewers. Video conferencing or UC systems would not be able to cope with such numbers.
Streaming Video can be divided into two main categories: Live Streaming and Video-On-Demand Streaming.
Streaming Video Basics: Streaming video formats and technologies
Continuing with the Streaming Video Basics article, we will now see the streaming video technologies have been created by several IT giants. Here is a list of the main technologies and their creators along with brief descriptions:
The Real Time Messaging Protocol is a protocol for streaming video that was created by Adobe. An Adobe Flash-capable player is needed for playback. It has been a popular format for a long time and it is still used a lot in the industry. It does not have the new features and improvements that HTTP-based protocols such as HLS and MPEG-DASH offer but it is still popular due to the fact that it servers well as an “intermediate” format mostly between an encoder and a streaming server or in general in re-streaming cases.
HLS – HTTP Live Streaming
The HLS format is suitable for streaming to desktop browsers but also to iOS devices. The latest Android devices also support HLS after they recently stopped supporting Flash. You can also stream to Quicktime player and some set-top boxes. The HLS streaming video protocol is based on HTTP and delivers video in chunks of data.
HLS supports Adaptive Bit Rate for your streaming video which means that your device can intelligently choose the most appropriate stream based on your bandwidth and other device capabilities.
HDS – HTTP Dynamic Streaming
HDS is another Adobe technology which unlike RTMP is HTTP-based. It also uses media chunks and a manifest file. The HDS protocol enables standards-based mp4 media delivery for on-demand and live applications using adaptive bit rate.
It can support up to 1080p quality with bit rates starting from 700 kbps up to more than 6 Mbps. The H.264 and VP6 video codecs can be used. On audio, it supports AAC and MP3 codecs.
Same as other HTTP-based protocols, it supports the use of existing caching infrastructures such as HTTP cache proxies and standard HTTP servers to deliver content on a large scale.
HDS requires Adobe Flash Player or Adobe Air.
Microsoft Smooth Streaming
Microsoft created MSS. The protocol supports Windows desktop PCs, Windows Phone devices and other devices.
The protocol supports live and on-demand digital media. It provides a means of delivering media from encoders to servers for live streaming and from servers to clients for on-demand content.
In addition, it supports media from servers to servers. The MSS protocol allows standard HTTP Cache Proxies to respond to requests on behalf of the server and therefore increases the number of clients that a single server can serve. It uses HTTP as its underlying transport.
Creator: MPEG Group
MPEG DASH is a relatively new and promising technology that was created to bridge the wars between proprietary formats that each of the big players were creating. It is an international standard and it is gaining a lot of traction in the industry. Similar to Adobe HDS, Apple HLS and Microsoft Smooth Streaming, MPEG-DASH is a technology that is HTTP-based and uses data chunks for delivery.
Dionissis Zervas, UC Engineer
CVE, PCVE, CCNA, MCSE
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