HLS Library

Introduction

HLS was developed by Apple and earned its widespread popularity due to a relative simplicity and most of all because of the usage of the HTTP as a transport protocol. This simple decision allowed streaming reception in every location where the web is available. However, HLS has its own limitations and the biggest drawback is the protocol’s one-way direction: there is no method specified to publish a stream to HLS server. Despite of that for now HLS is among the most used streaming protocols and supported natively on many platforms.

Transport stream (TS) is not a streaming protocol but a media format most suitable for streaming or media transmission systems. HLS as well as other protocols, most notably MPEG-DASH utilizes TS for media data segments. In addition to that TS itself can be used for direct streaming via multicast or even via pushing it by HTTP server (so-called TS over HTTP).

The wide popularity of HLS and TS guarantees wide compatibility for new software products using them.

Client

VASTreaming HLS library can work as a client to receive a stream from a server and play it on an end user’s device. The necessary UI controls are provided on all supported platforms, developers can easily integrate them in client-oriented apps.

Compared to a standard implementation of HLS protocol on some platforms (most notably Android and Windows), VASTreaming HLS library provides the following advanced features which usually work flawlessly only on iOS or macOS:

• Parsing of master index and multiple playlists with flexible selection of played streams
• Supported multiple renditions
• Supported I-frame streams for bandwidth-wise fast forward and rewind
• In addition to closed captions supported WebVTT subtitles
• Supported Live, Event and VOD content

Server

VASTreaming HLS library allows creating HLS server to distribute streams to connected clients. Another protocols (such as RTMP or RTSP) can be used to ingest the live stream. Based on the server hardware configuration, it can serve from hundreds to tens of thousands of simultaneous connections.

Advanced HLS server features:

• Flexible configuration of output stream allowing multiple renditions and variant streams
• Supported I-frame streams for bandwidth-wise fast forward and rewind
• In addition to closed captions supported WebVTT subtitles
• Supported Live, Event and VOD content

VASTreaming HLS server fully supports latest LL-HLS (low latency HLS) protocol revision allowing to reduce latency to 1-2 seconds range compared to standard 10-15 seconds.

Server-oriented functions can be a good base for development of new server-side applications unfolding new possibilities for video content providers.

Features

VASTreaming HLS library supports the following codecs:

• H.264, MPEG-1, MPEG-2, MPEG-4 video
• AAC, MPEG-1, MPEG-2, AC-3, DTS audio

The library is pretty flexible and extendable to add any new codec support upon a customer request.

For customer needs, any video or audio streaming custom features could be easily implemented with this library, including such serious options as the protocol extensions.

Platforms

VASTreaming HLS library is available for Android, iOS, Windows, Linux and macOS. The library exists in the following languages/frameworks:

• C# code for Xamarin (Android, iOS and UWP supported, Tizen coming soon)
• C# code for .NET Framework, .NET Standard, .NET Core and .NET 5+ (Windows, Linux and macOS supported)
• C++ code for Visual Studio (Windows supported)

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