HLS recommended segment size is 10 seconds. Is that for VOD only or for live IPTV as well?

HLS segment size is 10 seconds. Is that for VOD only or for live IPTV service as well?

(or is there a different recommended segemnt size for HTTP live streaming)

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>HLS segment size is 10 seconds.


Where did you find that spec? Citation?


>is that for VOD only or for live IPTV service as well? (or is there a different recommended segment size for HTTP live streaming)


From TN2224:


Workflow/Overview/Segment the media

HTTP Live Streaming sends audio and video as a series of small files, typically of less than 10 seconds duration, called media segment files. An index file, or media playlist, gives the clients the URLs of the media segment files.


For video on demand from prerecorded media, Apple provides a free tool to make media segment files and media playlists from MPEG-4 video or QuickTime movies with H.264 video compression, or audio files with AAC or MP3 compression. The media playlists and media segment files can be used for video on demand or streaming radio, for example.

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Can you do instant channel change with 10 sec long segments? or much shorter ones needed for Live streaming?

I don't think it's 10 seconds.


Keyframe rate should be an even interval of the segment size. W/the recommended keyframe interval of three seconds, that makes for a 9 second segment.


'instant channel change' is actually a delayed stream, where the next/other channel is buffered/delayed so as to give the user the perception of no delay when moving to another channel. Segments are still used normally, I believe.

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@KMT, do you know why apple recommends that we inject keyframes within the segment? why not just the first frame of a segment is keyframe and no other keyrames within the segment? what is the purpose of the keyframes inside the segment? I cannot see any purpose really

Apple no longer recommends 10 seconds. The current recommendation is 6 seconds for target duration.

See TN2224 on best practices - https://developer.apple.com/library/content/technotes/tn2224/_index.html

And the HLS Authoring Specification - https://developer.apple.com/library/content/documentation/General/Reference/HLSAuthoringSpec/Requirements.html