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Re: Byte Stream Format specs

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Mon, 20 Oct 2014 22:39:23 +1100
Message-ID: <CAHp8n2kyRnNsiv281m=OuPEj4GuSBjBAZrbL7kDoTgxJfgx9tg@mail.gmail.com>
To: Cyril Concolato <cyril.concolato@telecom-paristech.fr>
Cc: "<public-html-media@w3.org>" <public-html-media@w3.org>
On Mon, Oct 20, 2014 at 9:45 PM, Cyril Concolato
<cyril.concolato@telecom-paristech.fr> wrote:
> 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.

Ok, sure.

> Of course, having the IS size from the beginning would reduce
> the number of requests and latency.

That's all I'm trying to figure out here: some hint on what would be sensible.


>> 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.

OK, that's a good start, thanks. Knowing that it depends n the number
of tracks is good information to know, too.

Thanks,
Silvia.
Received on Monday, 20 October 2014 11:40:10 UTC

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