Why Adaptive Bitrate Streaming & ABR Encoding Provide the Best UX

Video accounted for over 60% of downstream web traffic in 2019. ISPs have seen downstream video traffic grow, since March 2020, by double digits.  Cisco predicts that video data will hit 82% of internet traffic by 2023. 

Bandwidth is growing globally – particularly with the arrival of mobile 5G – and streaming demand is keeping pace. Television and film are becoming stream-first forms of entertainment. Cord shaving and satellite-dish ditching for FAST (Free Ad-supported Streaming TV) and subscription video services have accelerated over the past year with no dissipation in the foreseeable future. How can content providers guarantee the best user experience irrespective of which CTV (Connected TV), STB (Set-top Box), or mobile device consumers have at their disposal?  

The solution is simple and affordable: adaptive bitrate streaming (ABR). Read on to learn more about harnessing the power of ABR.

What is Adaptive Bitrate Streaming? 

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Adaptive bitrate streaming (ABR) is a method of streaming video over HTTP.  The source content is encoded at multiple bitrates (renditions), which are small segments or chunks of the overall video content.  Segment size can vary anywhere from 2-10 seconds.  The streaming client is alerted to the available renditions by a manifest file - .m3u8 playlist for HLS and MPD (Media Presentation Description) for DASH.  The client requests a segment rendition based on the available bandwidth of the end-user device on a scaling ladder, starting with the lowest bitrate.  As bandwidth increases, a higher bitrate segment will be requested, and conversely, as bandwidth decreases, a lower bitrate segment will be requested.  To the end-user, content plays back smoothly without interruption, and bitrate changes may even go unnoticed. 

Progressive video streaming preceded ABR and is essentially a one-size-fits-all form of internet video delivery. It uses HTTP-based technology via servers to push downloads (i.e., streams) to devices – without optimizing the stream for client capability and bandwidth. The client makes an HTTP request, and an HTTP response comes back from the server.  Playback starts only after several seconds of content is stored in the playback buffer.  Content continues to be fetched by the client as bandwidth allows, and smooth, uninterrupted playback is dependent on bandwidth, allowing buffer to outpace playback.  The end-user could only fast forward through the previously fetched content.

Progressive streaming ignored user bandwidth, processing power, frame rate, and resolution. There is only one version of the video file, at whatever quality it is encoded in.  That video file is simply scaled (stretched or squeezed) to fit the output display. For example, if a video is 1280 x 720, it will be stretched to fill a 1920 x 1080 raster.

How ABR Streaming Solved Progressive Streaming Issues

Adaptive bitrate streaming solved all of these progressive streaming issues. It transcodes video content into different streams. Content providers encode multiple versions of the same video at different bitrates and resolutions, each optimized for other devices’ needs. 

Device players automatically adapt to the current operational conditions with respect to the end-user network speed and display capability. This all happens in real-time, facilitating the optimal end-user experience. 

ABR allows content providers to deliver a better Quality of Experience, which naturally leads to a more satisfied audience for their service. It is ABR that allows live television programming to be streamed concurrently to large-screen televisions and mobile phones – with, hopefully, minimal issues. 

The Difference between Adaptive Bitrate and Multi-Bitrate Streaming

Multi-bitrate video streaming is another standard method of streaming. It allows video distributors to create multiple versions of a video stream tailored to different devices, similar to adaptive bitrate videos. However, multi-bitrate streaming does not respond to a user’s changing playback environment. 

Multi-bitrate puts the onus on consumers to manually select which of the streaming options is the highest or most efficient that their devices can handle. This means the player will continue to attempt to play the file, even though conditions may not be the most ideal for that selection.

How Does ABR Streaming Work? 

The process of ABR streaming begins with the transcoding of an original stream.

Transcoding

Transcoding is a critical step in delivering content that can adapt to fit the screen sizes and internet speed of viewers.  This is a multistep process that begins with a compressed and encoded video file. The first step is to decompress and decode the video file. The next is to manipulate the video file. There are two subcategories of transcoding.

  • Transrating: The transcoding process by which the bitrate is manipulated without changing the video format. Transrating might also alter a video’s frame rate or resolution. 
  • Transizing: Altering the resolution or video frame to fit different types of screens. 

The final step is to re-encode and re-compress the new version of the video file created from transrating and transizing. This can be a lossy process that minimally degrades the video quality.  This new file becomes part of a streaming profile.  

Profile Ladder

Streaming profiles are organized into a profile ladder – ranging from the lowest quality to the highest quality. Many broadcasters use a standardized ladder system – Apple and Netflix proposed several popular ones. These profiles represent the entire array of adaptive bitrate streams that will be served to viewers. 

Packaging and Chunking

The power of ABR is to adapt based on multiple playback environment variables. At this point in the process, however, we merely have profiles for a multi-rate stream. 

The streaming profiles are broken down into two- to 10-second video chunks – often referred to as packages. 

The chunks are labeled and organized in a manifest. The player uses the manifest to determine how the video is to be downloaded and rendered.

Multi-Device Delivery

When streaming commences, the user device provides information to the server about its bitrate, screen resolution, hardware capabilities, player type, and other information. The media server then begins delivering the highest quality video stream the device is capable of displaying. 

What makes ABR powerful is that the device and server continue to communicate. As the server delivers more packages to the device, the device provides updated information about its state. Perhaps the bandwidth suddenly switched from LTE to 5G, for example. The server will see this and seamlessly deliver a profile with a higher bitrate still optimized for the exact screen resolution. 

It is the constant feedback and on-the-fly adapting that lets you deliver high-quality ABR video to numerous device types at the same time. 

Why ABR Streaming and ABR Encoding Provide the Best UX 

ABR streaming and encoding are no longer the exceptions with the online viewing experience – they are expected. 

The advantages of ABR streaming are innumerable, but its power comes from what your customers will soon take for granted: 

  • High-quality video
  • Less buffering
  • Low latency for smooth streams
  • Better viewing experience on mobile and connected TV devices
  • Fast startup

The ABR advantage is that the user experience is so fluid and painless, your subscribers won’t notice the technology at all. 

Zype Makes ABR Streaming Painless

Your streaming business depends on a satisfactory user experience. You can’t afford to alienate viewers with buffering, low-quality video, slow loading, and bad latency – not when they have innumerable streaming options available to them. 

Adaptive bitrate streaming is inherently technical, but it’s easily implemented with the right tools. 

Zype offers companies and content creators a full-stack suite of video editing and streaming software, including world-class ABR encoding and streaming capabilities.