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Extend HLS to add the first segment's start time #294

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joeyparrish opened this issue Nov 20, 2017 · 2 comments
Open

Extend HLS to add the first segment's start time #294

joeyparrish opened this issue Nov 20, 2017 · 2 comments
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component: HLS The issue involves HLS output type: enhancement New feature or request
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@joeyparrish
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It is very helpful for web-based players to know the start time of segments, to build an accurate segment index. HLS doesn't provide this information in the playlist, but it should.

I propose to add a new tag for media playlists that indicates the start time of the first segment in the playlist. Start times of other segments can be derived from the existing segment duration tags.

This will cut out expensive operations in Shaka Player and others for any HLS content which is packaged in Shaka Packager. The new tag can then be proposed to Apple for inclusion in a future version of HLS.
shaka-bot pushed a commit to shaka-project/shaka-player that referenced this issue Nov 21, 2017
@joeyparrish
Increase HLS partial segment size
6e626cc 
This increases the amount of data we fetch to get HLS segment start
times.  The presence of a large PSSH box in Widevine-encrypted content
was pushing the "tfdt" box past the 1kB mark, so we will now fetch
2kB.

Issue #1137
References FR in shaka-project/shaka-packager#294

Change-Id: I51a1407c4d992e42d07c3e6c6c501051100d1620
@joeyparrish
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I propose we name the tag "EXT-X-EARLIEST-START-TIME" for now.

@kqyang kqyang added component: HLS The issue involves HLS output type: enhancement New feature or request labels Nov 28, 2017
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kqyang commented Nov 28, 2017

The idea sounds good to me.

I think the tag should be associated with the media segments though. I propose name it EXT-X-SEGMENT-START-TIME and associate it with the next media segment, similar to EXT-X-PROGRAM-DATE-TIME: https://tools.ietf.org/html/draft-pantos-http-live-streaming-23#section-4.3.2.6.

Every media segment can have an EXT-X-SEGMENT-START-TIME defined before it, but it is optional.

@vaage vaage added this to the Backlog milestone Feb 14, 2018
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component: HLS The issue involves HLS output type: enhancement New feature or request
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@joeyparrish @kqyang @vaage