What are the benefits and challenges of using HLS for HDR live streaming?

1 What is HLS and how does it work?

HLS is a streaming protocol developed by Apple that uses HTTP to deliver video segments and playlists to clients. HLS works by breaking down the video source into small chunks of different bitrates and resolutions, and creating a manifest file that lists these segments and their metadata. The client requests the manifest file from the server, and then downloads the segments that best suit its network conditions and device capabilities. The client can switch between different segments dynamically, depending on the available bandwidth and user preferences. This allows for adaptive streaming, which improves the user experience and reduces buffering and latency.

2 What are the advantages of HLS for HDR live streaming?

HLS is an advantageous streaming protocol for HDR live streaming. It offers wide compatibility across browsers, devices, and platforms, including iOS, Android, Safari, Chrome, Firefox, Edge, Roku, Apple TV, and Fire TV. This means you can reach a broad range of viewers with your HDR content. Additionally, HLS can adapt the bitrate and resolution of the video segments to the network conditions and device capabilities of the client for consistent playback quality. Moreover, HLS supports encryption and DRM to protect your HDR content from unauthorized access and piracy. You can use AES-128 encryption or FairPlay Streaming (FPS) to encrypt your video segments with HLS key tags specifying the key URL and method. You can also utilize third-party DRM solutions such as Widevine, PlayReady, or ClearKey to control access and distribution of your HDR content.

3 What are the challenges of HLS for HDR live streaming?

HLS has some challenges for HDR live streaming, such as complexity and overhead, fragmentation and compatibility, and quality and performance. For instance, HLS requires more processing power and storage space than other streaming protocols, such as MPEG-DASH or RTMP. This can increase the encoding time, cost, server load, and bandwidth consumption. It also adds some overhead to the HTTP requests and responses, which can affect the latency and efficiency of streaming. Furthermore, HLS has several versions and extensions that support different features, but not all clients and devices support the same version or extension of HLS. This can cause fragmentation and compatibility issues. Additionally, HLS relies on the client to choose the best video segment based on network conditions and device capabilities which can affect the quality and performance of HDR live streaming. This can result in washed out or clipped colors, or reduced contrast and brightness.

4 How to optimize HLS for HDR live streaming?

Optimizing HLS for HDR live streaming requires consideration of several factors. You must encode the HDR video source with a codec that supports HDR, such as HEVC or AV1, and a color space that matches the HDR format, such as BT.2020 or BT.2100. Packaging the HDR video segments with a container format that supports HDR metadata, such as MP4 or TS, is also essential. Additionally, you must create a manifest file that specifies the characteristics and attributes of your HDR video segments, such as bitrate, resolution, and codec. HLS tags can be used to include this information in your manifest file. Furthermore, you must deliver your HLS stream via a CDN (content delivery network) that supports HTTP and HTTPS protocols, and can handle the bandwidth and latency requirements of HDR live streaming. Finally, you must ensure that your clients have a player that supports HLS and HDR and can adapt to network conditions and device capabilities.

5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?