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Re: Byte Stream Format specs

From: Cyril Concolato <cyril.concolato@telecom-paristech.fr>
Date: Mon, 20 Oct 2014 12:45:34 +0200
Message-ID: <5444E7CE.5080409@telecom-paristech.fr>
To: public-html-media@w3.org
Le 20/10/2014 06:28, Silvia Pfeiffer a écrit :
> Hi all,
>
> As a Web Developer, it's very nice to have the byte stream format
> registry http://www.w3.org/2013/12/byte-stream-format-registry/ ,
> which defines MIME types and other useful information.
>
> The first thing I'm going to do when loading segments for media
> resources is to load an initialization segment. This usually happens
> with an XHR and a byte range.
Small comments here:
- For live profiles of DASH, that is not the case. You'd have separate 
initialization segment files.
- Then, for DASH on-demand profiles, you don't necessarily have to make 
a single XHR. You can keep making multiple XHR, until you get track 
information. Of course, having the IS size from the beginning would 
reduce the number of requests and latency.

>
> Would it be possible to make a recommendation for each one of the
> registered byte stream formats of how large a byte range one should
> request to ascertain retrieving the Initialization Segment for
> different formats? That would be really useful to developers.
For the ISOBMFF, the size depends almost linearly on the number of 
tracks in the IS. Also the size is theoretically unlimited because you 
may have unlimited textual information (copyright, user information ...) 
or other boxes. In practice, you can check some files here: 
http://download.tsi.telecom-paristech.fr/gpac/DASH_CONFORMANCE/TelecomParisTech/, 
you'll see that the IS rarely exceed 1 or 2 KB. But I'm not sure this 
should be a recommendation.

HTH,
Cyril

-- 
Cyril Concolato
Multimedia Group / Telecom ParisTech
http://concolato.wp.mines-telecom.fr/
@cconcolato
Received on Monday, 20 October 2014 10:46:01 UTC

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