How does adaptive bitrate streaming affect live streaming latency?

Live streaming is a popular way to deliver video content to your audience, but it also comes with some challenges. One of them is latency, which is the delay between the moment the video is captured and the moment it is played back by the viewer. Latency can affect the quality and interactivity of your live stream, especially if you are using a CDN (content delivery network) to distribute your video. In this article, we will explain what CDN live streaming latency is, what causes it, and how adaptive bitrate streaming (ABR) can help you reduce it.

1 What is CDN live streaming latency?

A CDN is a network of servers that cache and deliver your video content to viewers around the world. By using a CDN, you can improve the speed, scalability, and reliability of your live stream. However, a CDN also introduces some latency, which is the time it takes for your video to travel from the source to the CDN edge server and then to the viewer's device. CDN live streaming latency can vary depending on the distance, bandwidth, and congestion of the network.

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Susan Pinckney
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When going live, you want the benefits that a CDN offers, but you never want to increase latency. Low latency is one of the most important elements in the live streaming experience. Both the host and the viewer want the feeling of instant gratification that comes with timely communication. It's what gives a live stream the feeling of being truly live, fresh and interactive.

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2 What causes CDN live streaming latency?

Live streaming latency can be caused by a variety of factors, such as encoding and transcoding, packaging and segmentation, and delivery and buffering. Encoding and transcoding involve converting your raw video into different formats and resolutions for various devices, which can add latency depending on the complexity and quality of the video. Packaging and segmentation involves dividing your video into small chunks that can be streamed over HTTP, with latency depending on the size and duration of the chunks. Finally, delivery and buffering involves transferring the video chunks from the CDN edge server to the viewer's device and storing them in a buffer before playing them, with latency depending on the network conditions and buffer size.

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Mo Asady

CTO at Convirza
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The choice of video encoding and transcoding hardware can have major impact on latency. There are three types of transcodes: - Software transcodes, these are normal servers typically that uses CPU power to transcode a video stream or VOD asset. - Specialized hardware transcodes, that uses purpose built hardware boards to transcode. - GPU transcodes, which are typically the fastest as they can handle multiple concurrent streams with high efficiency. The closer these machines are to the source stream, the faster the transcoding as that eliminates any delay caused by transferring the original stream in its native high nitrate format between data centers.

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3 How does ABR affect CDN live streaming latency?

Adaptive Bitrate (ABR) is a technique that allows your video to adjust to the viewer's bandwidth and device capabilities by switching between different formats and resolutions. This can improve the quality and continuity of your live stream, but it can also affect latency. ABR can reduce latency by reducing the encoding and transcoding time, as well as the packaging and segmentation time, by using lower resolution and bitrate formats for viewers with lower bandwidth. It can also reduce the delivery and buffering time. However, ABR can increase latency by using higher resolution and bitrate formats for viewers with higher bandwidth, which can increase the encoding and transcoding time, as well as the packaging and segmentation time, and the delivery and buffering time.

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4 How can you optimize CDN live streaming latency with ABR?

In order to optimize CDN live streaming latency with ABR, you need to balance quality and latency. To do this, you should carefully select encoding and transcoding settings, such as frame rate, resolution, and bitrate. While this can reduce the encoding and transcoding time and latency, it may also affect the quality of your video. Additionally, you should consider packaging and segmentation settings, such as smaller and shorter chunks. This can reduce the packaging and segmentation time and latency, but may also affect the smoothness of your video. Lastly, you should choose delivery and buffering settings that have a low buffer size. This can reduce the delivery and buffering time and latency, but may also affect the resilience of your video.

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5 What are some best practices for CDN live streaming latency with ABR?

To reduce latency when using a CDN for live streaming with ABR, it is important to test your live stream on different devices and platforms with tools such as Speedtest or Streamtest. This will help you adjust settings accordingly. Additionally, you should monitor your live stream performance with analytics tools like Google Analytics or Mux to track metrics and identify any issues or bottlenecks. Furthermore, it is important to choose a reliable CDN provider that offers low latency, high availability, and global coverage for your live stream. The CDN should also support ABR protocols such as HLS or DASH, which can enable dynamic switching between formats and resolutions.

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How does adaptive bitrate streaming affect live streaming latency?

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1 What is CDN live streaming latency?

2 What causes CDN live streaming latency?

3 How does ABR affect CDN live streaming latency?

4 How can you optimize CDN live streaming latency with ABR?

5 What are some best practices for CDN live streaming latency with ABR?

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