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Re: The future and direction of web audio

From: Chris Rogers <crogers@google.com>
Date: Wed, 13 Jul 2011 12:12:54 -0700
Message-ID: <CA+EzO0kTbpemPBz_q9aRguXAT-=WZVhW9JxjyoeGkkCZ_582Eg@mail.gmail.com>
To: Jussi Kalliokoski <jussi.kalliokoski@gmail.com>
Cc: public-audio@w3.org
On Tue, Jul 12, 2011 at 10:27 PM, Jussi Kalliokoski <
jussi.kalliokoski@gmail.com> wrote:

> Hello guys,
>
> Hope you're all having a nice summer! (Get well, Al!) I feel a bit like a
> broken record for going on with this again, but bare with me.
>
> I think there's an important point we need to think about when we're
> designing this API. If we do this wrong, so many people are going to be
> really mad at us. Audio APIs have the problem that if you can't do much with
> the core, you can't do much with the rest either. That's why I've been
> touting "freedom, freedom..." for some time now. At first, I think it's of
> utmost importance that we stop premature optimization with this API, it is
> going to shoot us in our backs, there's no question of it. So next time
> we're suggesting taking away a freedom  such as the programmer being able
> to decide the sample rate  think of the justifications. If it's
> performance, think again, not good enough, not future-proof. Computers are
> going to get faster, that's inevitable. (Once the graphene sheets hit the
> market, the processing power of consumer computers is forecast to be
> 300-3000x the current) Twenty years from now, if people are still using this
> API, they won't be damning it because it isn't fast enough, but because they
> can't do what they want with it.
>
> I'm not saying we shouldn't keep performance in mind, it's an important
> thing, but I think no compromises should be made in the name of performance.
> Same goes a bit for implementation difficulty, but of course, some of us are
> going to be the ones writing the implementations as well, so I understand
> you guys disagreeing on such points. This means I have nothing against the
> idea of pre-defined standard purpose processing nodes, to serve as the basis
> for games, etc, and to provide extra performance, they're not hurting any
> freedoms I'm seeing. However, Chris mentioned earlier something about adding
> a reasonable maximum value for the sample rate and unless there's a good
> reason for it, I'm not convinced that such a thing should exist.
>

Concerning sample-rates, the range I'm thinking could be quite large such as
11KHz to 384KHz, but at some point when you're writing code in C or C++
which can crash, lock up the machine, or have security issues then you have
to protect against wild values such as 10000000KHz and so on.  Believe me,
we're very conscious of such possibilities as browser implementors.

If you look at the WebGL specification, there all all kinds of limits, see:

    const GLenum MAX_VERTEX_ATTRIBS               = 0x8869;
    const GLenum MAX_VERTEX_UNIFORM_VECTORS       = 0x8DFB;
    const GLenum MAX_VARYING_VECTORS              = 0x8DFC;
    const GLenum MAX_COMBINED_TEXTURE_IMAGE_UNITS = 0x8B4D;
    const GLenum MAX_VERTEX_TEXTURE_IMAGE_UNITS   = 0x8B4C;
    const GLenum MAX_TEXTURE_IMAGE_UNITS          = 0x8872;
    const GLenum MAX_FRAGMENT_UNIFORM_VECTORS     = 0x8DFD;

These values can vary depending on implementation (but must support at least
a certain amount) and can be accessed something like this:

glContext.getParameter(glContext.MAX_TEXTURE_SIZE);

The good news is that the limits on sample-rate can be quite huge to allow
for just about any conceivable application, and this range could be extended
as necessary in the future (without changing API).  I'm not suggesting an
API which locks us into anything, but individual implementations will have
limits.  We can use WebGL as a guide for how such limits are handled.

Chris
Received on Wednesday, 13 July 2011 19:13:18 UTC

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