Bandwidth measures the speed of a network connection. In the streaming industry, your internet connections bandwidth is typically measured in kilobits or megabits per second. In live streaming, it is critically important to consider the upload speed, rather than the download speed which most broadband suppliers focus on.
Bitrate is a measure of the amount of data per unit of time in a video or audio stream. Typically, this is measured in kilobits, megabits, or gigabits per second. For example, the bitrate of a typical 720p HD video stream may be in the realm of 4 Mbit/s (megabits per second), and a standard audio bitrate is 128 Kbps.
Bonding exists to solve the problem of not having enough bandwidth to stream in acceptable quality. Specifically, it refers to a process of combining multiple cellular and Wi-Fi networks into a single “bonded” connection. This is common for mobile journalists and requires specialized hardware such as Teradek’s Bond.
A codec is an encoding/decoding standard for reducing the file sizes of video, audio, and other media formats. The most common video codec is H.264, and the most common audio codecs are AAC and MP3.
Content Delivery Network (CDN)
A Content Delivery Network, or CDN, is a network of servers designed to increase the speed and reliability of delivering digital content to users. This is done by caching content dynamically at servers located close to the audience. It is especially important for live streaming. Popular CDNs include Facebook Live and YouTube Live, but content specific networks also exist, for example Kaltura for the education sector, or Azure for corporate.
Hardware or software that converts a video signal to an IP stream for transmitting to a Decoder or CDN for delivery.
Video is made up of a consecutive series of still pictures. The speed these pictures are displayed is the frame rate, measured in frames per second (fps). Cinema film typically uses 24 fps, and 25 fps is common on television or the Internet, although fast action can look better at 50 fps.
H.264 is the most common video codec in use today. It’s compatible with essentially every device out there and provides reasonable file sizes for streaming video up to 1080p HD resolutions.
The evolution of H.264, offering higher quality at the same bitrate, or the same quality at half the bitrate. Using the example above, if we are currently transmitting 720p at 4 Mbit/s in H.264, HEVC would stream at 2 Mbits/s without a drop-in quality. Ideal for environments where bandwidth is limited, or data costs are high. A caveat being that not all networks support HEVC streaming.
High Definition (Standard Definition and Ultra HD)
A key part of video quality is the resolution, measured in the horizontal pixels in each video frame. Standard definition is 480 pixels, 720 or 1080 pixels is high definition, with UltraHD at 2160 pixels. For live streaming, 720 is considered to be a good balance between quality and manageable bandwidth.
HTML5 is a markup language widely supported by Internet browsers such as Chrome and Safari. In the streaming industry, HTML5 allows a streaming player to be embedded into your website.
Latency refers to the elapsed time between an event taking place and that event being displayed via live stream to viewers on their screens. Most live streams have a latency of less than or around 30 seconds. Lower latency is possible with specialised settings.
The Real Time Messaging Protocol is the most universally accepted standard for live streaming over the internet. Streaming encoders encode the live video and audio using H.264 compression, this is then packaged and sent to a server using RTMP. Most streaming services such as YouTube and Facebook Live will receive your stream using this standard, to which they’ll then usually re-encode using a more modern HTML5 standard such as HLS or MPEG-Dash for delivery to your audience.
INTRODUCTION TO LIVE STREAMING WEBINAR
Download the slide deck used in the live session here