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Re: Squid experts

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Fri, 7 Nov 2008 21:58:49 +1100
Message-ID: <2c0e02830811070258m437e49f3qb4fef09770188802@mail.gmail.com>
To: olivier.aubert@liris.cnrs.fr
Cc: public-media-fragment@w3.org

On Fri, Nov 7, 2008 at 8:53 PM, Olivier Aubert
<olivier.aubert@liris.cnrs.fr> wrote:
> Hello all
>> I think we are theorizing a lot and are not actually looking at
>> concrete codecs. We should start getting our hands dirty. ;-) By which
>> I mean: start classifying the different codecs according to the
>> criteria that you have listed above and find out for which we are
>> actually able to do fragments and what types of fragments.
> It is not only a matter of codec, but also a problem of container
> format. Ogg was conceived to be streamed, and each Ogg page contains the
> time offset of the contained data. MPEG TS/PS is also conceived to be
> streamed. But AVI causes more trouble, because its index (the definition
> of the location of data, i.e. basically the source of time to byte
> mapping) is located at the end of the file.
> IMO, the simplest approach wrt. caches is not to try to put too much
> intelligence in them, and consider that they simply store chunks of
> data. Players on the client side are perfectly able to do byte-based
> HTTP Range requests, just like they would do a lseek() when accessing a
> local movie file. The http access module of VLC optimizes this, for
> instance.
> Cheers,
> Olivier

I couldn't agree more - on all accounts.

What I meant with codecs is both, codecs and encapsulation formats (I
think Davy understood that).

As for caches - only dealing with byte ranges requires a
4-way-handshake (or two roundtrips), which is not regarded as optimal
(though I still believe it's the only realistic means forward). We are
now discussing the possibilities of introduction of more intelligent
proxies and a new time range parameter to get that down to a
2-way-handshake (or one roundtrip).

Received on Friday, 7 November 2008 10:59:30 UTC

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