[foms] WebM Manifest

Steve Lhomme slhomme at matroska.org
Thu Mar 17 05:08:37 PDT 2011

On Thu, Mar 17, 2011 at 10:14 AM, Philip Jägenstedt <philipj at opera.com> wrote:
> On Wed, 16 Mar 2011 17:03:13 +0100, Mark Watson <watsonm at netflix.com>
> wrote:
>> Hi Philip,
>> A couple of comments below...
>> On Mar 15, 2011, at 2:01 AM, Philip Jägenstedt wrote:
>>> On Mon, 14 Mar 2011 22:56:23 +0100, Frank Galligan
>>> <fgalligan at google.com>
>>> wrote:
>>>> If the Web and TV IG choose the DASH manifest as the baseline manifest
>>>> format for adaptive streaming, would all of you be OK with implementing
>>>> it
>>>> in your products?
>>> In short, no.
>>> I've previously glanced over the DASH spec and have done so again today,
>>> and I am not very enthusiastic about it at all.
>>> Since the spec is written for a non-browser context, it fails to make
>>> any
>>> use of existing browser infrastructure. Everything is done
>>> declaratively,
>>> whereas in a browser context one can leave many things to be dealt with
>>> using scripts. I think we should aim for a solution that doesn't
>>> strictly
>>> require fetching a manifest file over HTTP repeatedly, we could just as
>>> well build a solution using WebSockets, just to name one possibility.
>> This was deliberate as it was recognized that HTML/Javascript
>> environments were not the only ones where adaptive streaming would be
>> needed. We wanted to have a solution which was independent of the
>> presentation framework and I think it would be valuable for the industry
>> to have such a single solution, rather the multiple solutions for
>> different environments.
> Would it be an acceptable outcome if one can deliver to browsers using a
> DASH manifest with some JavaScript glue to parse the manifest and map that
> to the lower level APIs that browsers provide?

That would be really odd. First because it would be fixed to a set of
APIs, so would not be able to use newer technologies for adaptive
streaming in the future. It may also mean adapting and changing the
manifest if a bug is found in a specific browser version.

IMO the information about the stream options and the way they are
processed should be completely decorrelated.

Steve Lhomme
Matroska association Chairman

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