HTTP Live Streaming (HLS) is an adaptive streaming protocol developed by Apple for delivering media content over the internet. To create an HLS stream, certain audio and video formats are required for compatibility with the protocol. Here are the audio and video formats required for HLS:
1. Audio Formats: HLS requires audio to be encoded in either AAC-LC (Advanced Audio Coding Low Complexity) or MP3 (MPEG-1 Audio Layer III) format. However, AAC-LC is recommended because it provides better audio quality at lower bitrates.
2. Video Formats: HLS requires video to be encoded in either H.264 (also known as AVC, Advanced Video Coding) or HEVC (also known as H.265, High-Efficiency Video Coding) format. H.264 is the most widely used video codec for HLS, but HEVC provides better video quality at lower bitrates and is recommended for higher resolution and frame rate streams.
In addition to these audio and video formats, HLS also requires that the media files be segmented into small chunks of equal duration, typically between 2 and 10 seconds. These segments are then delivered to the client using a manifest file (usually an m3u8 file) that contains information about the segments and their URLs.
Overall, HLS is compatible with a wide range of devices and platforms, including iOS and Android devices, web browsers, and streaming media players. By following the recommended audio and video formats, it ensures that the media streams can be played seamlessly across all these platforms.
ENCODING HLS STREAMS
To encode an HLS stream, you need to follow these general steps:
1. Prepare your source media: Before encoding, you need to have your source media in a compatible format (see previous answer for required formats), and you need to segment it into small chunks of equal duration.
2. Choose an encoding software: There are several encoding software tools available such as FFmpeg, Elemental Live, Wowza Streaming Engine, and more. Choose one that fits your needs and supports HLS output.
3. Configure the encoding software: Configure the encoding software by specifying the input format, segment duration, output format (HLS), and other settings.
4. Set up a web server: Set up a web server for hosting your HLS manifest file and media segments. You can use a dedicated web server or a cloud-based one.
5. Encode the media: Use the encoding software to transcode the media into the required HLS format and segment it into small chunks. The software will create an HLS manifest file (.m3u8) that includes information about the segments and their URLs.
6. Upload the output files to the web server: After encoding, upload the manifest file and media segments to the web server.
7. Test the HLS stream: Test the HLS stream on different devices and streaming players to ensure it’s playable and doesn’t have any issues.
Overall, encoding an HLS stream requires specialized software and knowledge of encoding settings and web servers. It’s recommended to follow best practices and reference the documentation provided by your encoding software and web server provider.
How To Create an HLS Stream
To create an HLS stream, you need specialized software called an encoder, which can take your source media and transcode it into the required HLS format. There are several encoding software options available, offering various features and pricing models. Some of the popular encoding software tools for creating HLS streams include:
HLS SOFTWARE & HARDWARE
1. FFmpeg: FFmpeg is a free open-source software that can convert audio and video files into different formats, including HLS output.
2. Elemental Live: Elemental Live is a hardware and software solution that supports real-time video transcoding and streaming with features like ad insertion, scalable live streaming, and more.
3. Wowza Streaming Engine: Wowza is a software-based media server that provides live and on-demand streaming with features like transcoding, live stream recording, and more.
4. Adobe Media Encoder: Adobe Media Encoder is a media processing software that can ingest and output audio and video files in different formats, including HLS.
5. Telestream Vantage: Telestream Vantage is a transcoding software that provides multiplatform content creation and delivery, including support for HLS output.
These tools can help you transcode and segment your media files into the required HLS format and generate the necessary HLS manifest file (.m3u8) that contains information about the segments and their URLs. However, the specific software you choose may depend on your budget, workflow, and other requirements, so it’s important to research and evaluate your options carefully.
HLS SYNTAX
Here are ten examples of the correct syntax for an HLS stream using M3U8 playlist format:
1. #EXTM3U – declares the file as an M3U8 playlist file.
2. #EXT-X-VERSION:3 – specifies the version of the HLS protocol used.
3. #EXT-X-TARGETDURATION:10 – sets the maximum duration of each segment to 10 seconds.
4. #EXT-X-MEDIA-SEQUENCE:0 – indicates the starting number of media segments.
5. #EXT-X-PLAYLIST-TYPE:VOD – specifies that the playlist represents a video-on-demand stream.
6. #EXT-X-ALLOW-CACHE:YES – allows the client to cache the media segments.
7. #EXT-X-DISCONTINUITY – indicates a discontinuity in the media stream, such as a change from one bitrate to another.
8. #EXT-X-STREAM-INF:BANDWIDTH=2000000 – specifies the bitrate and resolution of the video stream.
9. #EXT-X-ENDLIST – indicates that no more segments will be added to the playlist (for live streams, this should be omitted)
10. #EXT-X-MAP:URI=”init.mp4″ – specifies a separate initialization segment for the media stream.
Note that some of these tags are optional, and the syntax may vary depending on the media server and player used. It’s always a good idea to test your playlist with different players and devices to make sure it works well.
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