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Media Source Extensions
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cr-heartbeat-2 Fix heartbeat docs to use base specStatus Mar 10, 2015 CoC Oct 17, 2018 pull request #47 Mar 7, 2016 pull request #47 Mar 7, 2016 Update with labeling and milestone guidance Apr 12, 2016
audio_splice.png Adding more detailed splicing text and fixing various other bugs. Feb 19, 2013
byte-stream-format-registry-cr.html Adding CR drafts of registry files Jul 8, 2014
byte-stream-format-registry-respec.html Various changes for the publication of registries #74 Oct 3, 2016
byte-stream-format-registry.html Fix #144: Fix the links into the main MSE spec from bytestream regist… Aug 10, 2016
index.html Fix #168 - Restrict createObjectURL(MediaSource) further Nov 8, 2016
isobmff-byte-stream-format-cr.html Adding CR drafts of registry files Jul 8, 2014
isobmff-byte-stream-format-respec.html Fixed shortnames Oct 3, 2016
isobmff-byte-stream-format.html Fix #144: Fix the links into the main MSE spec from bytestream regist… Aug 10, 2016
media-source-cr.html [MSE] Updating CR draft with SOTD changes Jul 15, 2014
media-source-fpwd.html Fix image URLs in media-source-fpwd.html May 15, 2013
media-source-lc.html [MSE] Update LC dates. Aug 26, 2013
media-source-pr.html Prepared PR draft Sep 7, 2016
media-source-respec.html SOTD cleanup for upcoming publication Nov 16, 2016
media-source-wd.html For 2013-04-15 updated WD publication. Apr 12, 2013
media-source.html New ED Nov 16, 2016
mp2t-byte-stream-format-respec.html Fixed shortnames Oct 3, 2016
mp2t-byte-stream-format.html Fix #144: Fix the links into the main MSE spec from bytestream regist… Aug 10, 2016
mpeg-audio-byte-stream-format-cr.html Adding CR drafts of registry files Jul 8, 2014
mpeg-audio-byte-stream-format-respec.html Fixed shortnames Oct 3, 2016
mpeg-audio-byte-stream-format.html Fix #144: Fix the links into the main MSE spec from bytestream regist… Aug 10, 2016
mse-1-errata.html Added an errata page Nov 16, 2016
mse.css [MSE] - Update to ReSpec 3.2.6 Dec 2, 2013
pipeline_model.svg Fix #44 May 26, 2016
pipeline_model_description.html Fix #44 May 26, 2016
respec-w3c-common.js pull request #47 Mar 7, 2016
w3c.json Now WICG Oct 17, 2018
webm-byte-stream-format-respec.html Fix #180, include vp09... codecs parameter string (#182) May 22, 2018
webm-byte-stream-format.html Fix #180-timestamp: Regenerated webm bytestream html to update date (#… May 22, 2018

Specification 'media-source'

This is the repository for media-source. You're welcome to contribute! Let's make the Web rock our socks off!

Media Source Extensions:

Media Source Extensions Byte Stream Format Registry:

WebM Byte Stream Format

ISO BMFF Byte Stream Format:

MPEG-2 Transport Streams Byte Stream Format:

MPEG Audio Byte Stream Format:

Issue labeling and milestone guidance


Each bug may have multiple labels.

“needs feedback”:

The issue is pending further clarification from the assignee, likely the original bug filer or another who reported aspects of the issue in the bug’s history. The feedback request needs to be in a comment associated with the addition of this label, along with a request for reassignment back to an editor once feedback is provided.

“needs author input”:

The editors are seeking input from web authors on the issue. For example, whether a requested change is useful or how best to expose information.

“needs follow-up”:

The assignee, likely an editor, needs to investigate more deeply before we can decide if this “needs implementation” or to otherwise move forward. The editors have discussed the issue and do not need to discuss it further until we have the resulting follow-up from the assignee. This includes things like determining external spec dependencies, seeking input from other spec owners and/or WGs, confirming the understanding of the nature of the bug, and beginning to formulate a path to a solution.

This doesn’t necessarily mean follow-up has “Started” or is “In Progress.”

“needs implementation”:

The steps needed to resolve this issue are clearly understood and agreed upon. This likely means drafting and committing a spec change, possibly via a pull request. No further discussion is necessary at this time, though review of the change may still be appropriate. Should that change, this label should be removed.

For a bug to be labeled with this, it needs to be understood well enough and in scope of the marked milestone. Otherwise, “needs follow-up” or punting milestone might be options.

This label does not refer to user agent implementations.


Some external dependency or another GitHub issue identified in comment associated with this label’s addition is (or might be) blocking progress on this bug.

“feature request”:

The issue is related to or requesting a new use case or capability not currently (explicitly) covered by the spec. Depending on the nature and impact of the request and the stage of the spec, it may be assigned to a future milestone.


Resolution of this issue is particularly important for interoperability among user agents. This may include breaking API changes, issues related to media compatibility across user agents, or ambiguous parts of the spec that could lead to different incompatible interpretations. There may be known or probable differing interpretations in implementations of the associated portion of the spec. If the identified issue is not addressed, there is a high likelihood of meaningful interoperability problems. The fix for the issue would need to provide a clear direction to prevent differing interpretations by user agents.

"breaking change"

The issue's resolution might cause re-entry to the current spec phase, for example CR.

“wontfix”, “invalid”, “duplicate”:

Self-explanatory :)

Issues with these labels should always be closed (unless they were re-opened at which time an editor should probably remove these labels if the re-opening is accepted).


For greater detail, see our V1 triage process announcement in the archive.


A bug in version # of the spec. Currently, V1 is the first version of MSE (in CR in Q4 2015).


A bug in version # of the spec, which is an editorial change to improve spec language. These should not be treated as blocking on the WG timeline, so the clock may run out before all are fixed.


Perhaps to be addressed by some later version of the spec; not currently expected to be in scope of specific version of the spec. Typically, this milestone is correlated with issues labeled “feature request”. This is equivalent to Bugzilla’s RESOLVED LATER status. As such and to keep the issue tracker focused, issues with this milestone will generally be closed. When work on a new version of the spec starts, the V.Next issues, including those that are closed, should be reviewed and considered for the new version.

(no milestone):

The issue has not been triaged or the editors are currently discussing.

You can’t perform that action at this time.