W3C home > Mailing lists > Public > public-html-media@w3.org > October 2014

Clarification of addSourceBuffer() method

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Mon, 20 Oct 2014 12:27:56 +1100
Message-ID: <CAHp8n2k5a5JarwfgLnJgYEULW1kmJM_B0jc7gpRD46f4qSFM2g@mail.gmail.com>
To: "<public-html-media@w3.org>" <public-html-media@w3.org>
I'm just taking a look at the MSE spec (writing a book chapter about
it, actually).

I'm looking at MediaSource.addSourceBuffer() which to me seems to be
the key method to add chunks of a media resource to a MediaSource
object.

I'm reading the following in the spec:

``
addSourceBuffer

Adds a new SourceBuffer to sourceBuffers.

Implementations must support at least 1 MediaSource object with the
following SourceBuffer configurations. MediaSource objects must
support each of the configurations below, but they are only required
to support one configuration at a time. Supporting multiple
configurations at once or additional configurations is a quality of
implementation issue.

* A single SourceBuffer with 1 audio track and/or 1 video track.

* Two SourceBuffers with one handling a single audio track and the
other handling a single video track.
``

It seems that a SourceBuffer can only have either an interleaved
audio/video track, or just audio or just video. I'm a bit confused
about that, because SourceBuffer clearly talks about multiple audio
and video tracks, and also about text tracks.

Is this text left-over from the early days of the specification? Does
it actually mean that you can either provide tracks in an interleaved
manner or as separate SourceBuffers? OR do you really mean what is
written there? If the latter, how then do you get multiple tracks and
in particular text tracks into MediaSource ?

Thanks for any clarification you can provide!

Cheers,
Silvia.
Received on Monday, 20 October 2014 01:28:43 UTC

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