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Starred by 29 users

Issue metadata

Status: Fixed
Closed: Aug 2017
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 2
Type: Launch-OWP
Launch-Accessibility: ----
Launch-Exp-Leadership: ----
Launch-Leadership: ----
Launch-Legal: ----
Launch-M-Approved: ----
Launch-M-Target: 62-Dev , 62-Beta , 62-Stable-Exp , 62-Stable
Launch-Privacy: ----
Launch-Security: ----
Launch-Test: ----
Launch-UI: ----
Rollout-Type: ----

Blocked on:
issue 624037

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API for customizing live MediaSource seekable range

Project Member Reported by, Jun 27 2016

Issue description

Change description:
Let MediaSource apps more effectively customize the HTMLMediaElement.seekable range logic by providing (or removing) a single seekable range that is union'ed with the current buffered ranges' to result in a single seekable range which fits both.

Without such support, apps need to fake a finite media duration to obtain reasonable seekable range results when nothing is buffered, and similarly apps need to fake a finite media duration to allow seeking beyond the current buffered ranges' end (perhaps to return to the live edge of the stream).

Previous discussion on this was done in  bug 461733  and  bug 546712 .
The MediaSource Spec [0] now includes a change [1] that supports this behavior. To keep the spec change simpler and less-breaking, existing HTMLMediaElement behavior for seekable is retained until/unless the new {set,clear}LiveSeekableRanges API is used on the MediaSource attached to that HTMLMediaElement, or if the media duration is finite, then the new API's logic is ignored.


Changes to API surface:
MediaSource.setLiveSeekableRange [2]
MediaSource.clearLiveSeekableRange [3]
HTMLMediaElement.seekable when attached to MediaSource with duration of positive infinity [4]


Public standards discussion:

Support in other browsers:
Internet Explorer: Planned (MSFT co-editor of MSE spec approved the change)
Firefox: Unknown
Safari: Unknown
 Issue 546712  has been merged into this issue.
 Issue 461733  has been merged into this issue.
Labels: MSE-compat MSEscrubbed
Blocking: 624037
Project Member

Comment 5 by, Jun 28 2016

The following revision refers to this bug:

commit b2f2d65c0068345ba8d5ee9462bab35463c94475
Author: wolenetz <>
Date: Tue Jun 28 20:18:53 2016

MSE: Experimental support for customizing live seekable range

Adds {set,clear}LiveSeekableRange methods to MediaSource IDL, with
implementations corresponding to the recent MSE spec addition of these
methods [1]. These methods are behind the MediaSourceExperimental
RuntimeEnabled flag until intent to ship is approved in a later
Intent to implement thread is at [2].


BUG= 623698 
TEST=passes upstream w3c/wpt mediasource-liveseekable.html test in PR at,

Cr-Commit-Position: refs/heads/master@{#402519}


Labels: -Pri-3 Pri-2

Comment 7 by, Nov 11 2016


Comment 8 by, Nov 11 2016

Labels: M-62
Intent to ship [a] (M-62) has received its third LGTM. I'll put together a CL that moves this API from behind the MediaSourceExperimental RuntimeEnabled flag to be always-enabled.

Labels: Launch-M-Target-62-Dev Launch-M-Target-62-Beta Launch-M-Target-62-Stable-Exp Launch-M-Target-62-Stable
Always-on CL is out for review at
Project Member

Comment 12 by, Aug 10 2017

The following revision refers to this bug:

commit 5b985d6eadf58cd435e304c86cf34320e46c0bc9
Author: Matt Wolenetz <>
Date: Thu Aug 10 05:13:06 2017

MSE: Ship MediaSource.{set,clear}LiveSeekableRange

Moves this portion of the MSE API from behind the RuntimeEnabled flag

BUG= 623698 

Intent to ship:

https: //!topic/blink-dev/-LTXhyDzS_E
Change-Id: I094c4f27b678949060354bcb8bc6a1315c4d441e
Reviewed-by: Chrome Cunningham <>
Reviewed-by: Rick Byers <>
Commit-Queue: Matthew Wolenetz <>
Cr-Commit-Position: refs/heads/master@{#493246}

Status: Fixed (was: Assigned)
I've updated the chromestatus entry ( to indicate this is "on by default" as of M62 (and Opera 49). Note that it is not behind any runtime flag (risk was deemed very low).
CC+=crouleau@ -- Caleb, w.r.t. test: we have some basic layout tests that have been testing this for about a year now with no known issues. Perhaps sync with dahlke@ to see if there's anything more "meaty" to test here (I think Jon was working on related controls work for live streams).
cc+ crouleau@ for realz -- see #14.
Blocking: -624037
Blockedon: 624037

Comment 18 Deleted

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