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Re: [mediaqueries4] Media queries for multichannel audio ?

From: Mark Watson <watsonm@netflix.com>
Date: Sat, 23 Mar 2013 17:06:40 +0000
To: Florian Rivoal <florian@rivoal.net>
CC: "www-style@w3.org" <www-style@w3.org>
Message-ID: <C74D431F-E0BE-4672-BE43-C71340A2B1CA@netflix.com>


Sent from my iPhone

On Mar 23, 2013, at 6:20 AM, "Florian Rivoal" <florian@rivoal.net> wrote:

> On Wed, 20 Mar 2013 16:03:48 +0100, Mark Watson <watsonm@netflix.com> wrote:
> 
>> Florian, all,
>> 
>> How do I progress this issue ? Do I need to file a bug ? (where?) Do I need to join the WG ?
> 
> 
> Leaving your other two issues aside for the moment, and focusing on the mutichannel part.
> 
> There is no need to join the WG, raising the issue in this mailing list and following up on conversations (as you are doing) is normally enough. Once we reach sufficient consensus, or at least understand well enough the questions that needs to be answered, we can take it to one of our weekly conference calls to try and decide one way or the other.
> 
> From where I stand, I see a few open questions with your proposal:
> 
> * Should it be number of channels, or number of speakers?
> To answer this questions, we would need a variety of use cases to be described, to be able to judge which one fits best.
> 

It's the number of output channels, because:
- you can't know the number of speakers - the audio output may be a digital one connected to an A/V receiver or other equipment which is then connected to the speakers.
- some systems use audio processing techniques to simulate surround sound without the usual number of speakers - for example soundbars.

Some use-cases, all involving content available in stereo and 5.1,
provided as alternative <source> elements in an HTML media element:
- a PC that supports the 5.1 codec, but is outputing the audio over a stereo analogue output jack
- a PC that is outputing the audio over a 5.1 digital audio output (S/PDIF, HDMI)
- a TV that is outputing the audio over internal stereo speakers, with only a capability for basic downmixing
- a TV that is outputing the audio over a 5.1 capable digital audio output
- a TV with internal signal processing that is capable of simulating surround sound from a 5.1 input through less than 6 speakers

> * If number of speakers, can that be reliably detected?
> I am not an expert on the topic, but it seems to be that the OS (let alone the browser) is not necessarily aware of how many physical speakers there are.
> 
> * It seems to me that your main use case for this media query would not actually be applying different styles based on the situation, but feed that back into javascript, and use it there. If that's the case, I wonder if media queries is the best tool to solve the problem.

It's a resource selection problem, which is done today on the media element using media queries (the media attribute of the <source> element) and could be done in the Media Source case by JavaScript using the mediaMatch() function (ensuring that the script approach matches the declarative approach).

...Mark
> 
> 
> - Florian
> 
Received on Saturday, 23 March 2013 17:07:08 GMT

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