Adaptive bitrate streaming: How it works and why it's important
Streaming video has become an essential part of our daily lives. Whether we are watching a movie on Netflix or streaming a live event, we expect high-quality video with no buffering or interruptions. However, delivering such a seamless experience to viewers can be challenging, especially when streaming over unreliable networks. This is where adaptive bitrate streaming (ABR) comes in. In this blog post, we’ll discuss what ABR is, how it works, and why it’s important.
What is adaptive bitrate streaming?
Adaptive bitrate streaming is a technique used by video streaming platforms to adjust the quality of video in real-time based on the viewer’s internet connection speed. ABR enables streaming platforms to deliver the best possible video quality without buffering or interruptions, regardless of the viewer’s device or network speed. This is achieved by encoding the video at multiple bitrates and resolutions and delivering the video segments that best match the viewer’s network conditions.
How does adaptive bitrate streaming work?
Adaptive bitrate streaming works by dividing the video content into small segments and encoding each segment at multiple bitrates and resolutions. These segments are then made available to viewers through a manifest file that provides information about the available bitrates and resolutions. When a viewer requests to watch a video, the video player downloads the manifest file and selects the video segment that best matches the viewer’s network conditions. If the network speed is high, the video player selects a higher quality segment, and if the network speed is low, the player selects a lower quality segment. This selection process happens in real-time, ensuring that the viewer always gets the best possible video quality without buffering or interruptions.
Here’s a more in-depth and technical step-by-step explanation of how adaptive bitrate streaming works:
1 . Video encoding
The first step in adaptive bitrate streaming is encoding the video at multiple bitrates and resolutions. This involves compressing the video file into smaller segments, each with a different bitrate and resolution. The video segments are then uploaded to a server or content delivery network (CDN).
2. Manifest file creation
A manifest file is created that contains information about the available video segments and their respective bitrates and resolutions. The manifest file is typically written in XML or JSON format and is uploaded to the server or CDN alongside the video segments.
3. Video playback
When a viewer requests to watch a video, the video player downloads the manifest file and begins playback. The video player uses the manifest file to determine the available bitrates and resolutions and selects the appropriate segment based on the viewer’s network conditions.
4. Bitrate selection
To determine the appropriate bitrate for the viewer’s network conditions, the video player measures the viewer’s network speed and latency. This is typically done by downloading a small test file from the server and measuring the time it takes to download. Based on this information, the video player selects the appropriate bitrate from the available options.
5. Video segment selection
Once the appropriate bitrate is selected, the video player downloads the corresponding video segment. This process is repeated for each segment of the video, with the video player dynamically selecting the appropriate bitrate for each segment based on the viewer’s network conditions.
Why is adaptive bitrate streaming important?
Adaptive bitrate streaming is essential because it ensures that viewers get a high-quality streaming experience regardless of their internet connection speed. This is particularly important in regions with unreliable networks, where viewers may experience buffering or interruptions if the video is delivered at a fixed bitrate. ABR also enables streaming platforms to reduce their storage and bandwidth costs by encoding the video at multiple bitrates and resolutions, as viewers only download the segments that match their network conditions. This reduces the overall bandwidth required to deliver the video content and ensures that viewers get a consistent and reliable streaming experience.
In conclusion, adaptive bitrate streaming is a critical technology for video streaming platforms that want to deliver a high-quality streaming experience to their viewers. By encoding the video at multiple bitrates and resolutions and delivering the best possible video quality in real-time, ABR ensures that viewers get a seamless experience regardless of their device or network speed. With the continued growth of video streaming, ABR is set to become even more important in the years to come.
