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Re: [css3-speech] voice-balance and azimuth

From: fantasai <fantasai.lists@inkedblade.net>
Date: Thu, 07 Jul 2011 10:43:52 -0700
Message-ID: <4E15F058.6030402@inkedblade.net>
To: www-style@w3.org
On 07/07/2011 02:58 AM, Daniel Weck wrote:
>
> On 6 Jul 2011, at 22:43, fantasai wrote:
>> For example, if I output the same amount of sound from all speakers in
>> the system, on a stereo system this is the same as a center-located
>> voice, but in a surround-sound system, a center-located voice would
>> instead be sound coming out of only the front-center speaker.
>
>
> Ultimately, the mapping between CSS spatial audio positioning and concrete audio channels depends on what speaker system is
> plugged-in, and on how precisely the user-agent can dispatch the audio streams (driver). What matters is the author intent,
> right?
>
> Let's assume that the authored content says "voice-balance: center". The content is played with a Level 3 user agent. A stereo
> audio system is plugged-in, which means that both speakers output the speech synthesis at the same volume level. Now, a
> surround audio system is plugged-in (e.g. "5.1"), and the user-agent is able to interface with it properly (e.g. not just
> left/right distribution, but full 5 channel control...yeah, the bass channel can be ignored for now!). Even though the
> user-agent only understands the Level 3 notation, it is perfectly able to map 'center' to the appropriate audio channel(s).
> Let's now say that the content remains the same, but the user-agent supports the Level 4 syntax. The 'center' keyword retains
> the same semantics (in terms of perceived audio output, not of actual channels to dispatch to), so depending on what audio
> system is plugged-in, the user-agent will be able to distribute the audio streams to the adequate channels.
>
> Am I making sense?

Not really. The point here is not about whether the UA supports Level 3 or Level 4,
but about what Level 3 syntax really means. You can plug Level 3 syntax into a
stereo system or into a surround-sound system: both have to be defined.

The stereo system is a flattening of surround sound. In a stereo system, outputting
equal sound from all speakers is equivalent to outputting sound from the front-center.
However in a surround sound system, these are two different things. Which does the
'center' keyword correspond to? And once you've decided that, what syntax would I use
in Level 4 to get the other behavior?

~fantasai
Received on Thursday, 7 July 2011 17:44:21 GMT

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