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Re: Internal loop points (Was: thoughts and questions on the API from a modular synth point of view)

From: Chris Wilson <cwilso@google.com>
Date: Mon, 16 Jul 2012 11:16:08 -0700
Message-ID: <CAJK2wqVpUpwMusa2TVOgyo7vCEP=mpg1otijyjeAxUWm53XaAA@mail.gmail.com>
To: Joseph Berkovitz <joe@noteflight.com>
Cc: Peter van der Noord <peterdunord@gmail.com>, "public-audio@w3.org" <public-audio@w3.org>
Yes - I wasn't intending to mean "in the future" as equivalent to "not in
V1 API".

On Mon, Jul 16, 2012 at 11:12 AM, Joseph Berkovitz <joe@noteflight.com>wrote:

> Chris W,
>
> Just as an FYI we had previously categorized these internal loop points as
> a V1 feature at the face-to-face in January and Chris R has indicated an
> intention to implement them in past conversations.  Not that I speak for
> him -- I am happy to wait for Chris Rogers to return before discussing more.
>
> I have implemented ADSR and ADHSR software samplers in the past and so I
> understand the mechanics well. I was not saying that attack phase was the
> only important phase -- only that it is a unique phase of note production
> in that it requires a special segment of audio separate from the loop that
> underlies decay/hold/sustain/release phases.  The internal loop point
> mechanism is in fact the only feature gap preventing a full ADHSR sampler
> from being created in Web Audio, since all the other aspects are fully
> achievable using time-varying gain and filter parameters.
>
> I have filed this issue in the past as Bug 17390 (and originally it was
> AUDIO_ISSUE_12).
>
> Best,
>
> ...Joe
>
> On Jul 16, 2012, at 1:42 PM, Chris Wilson wrote:
>
> Yup.  To me, that's just a sample-playback synthesizer, but then, I'm not
> in anyone's marketing department.  :)
>
> Chris has said several times that we should look at providing a more
> detailed sample-playback system in the future.  You really need to support
> a release sample portion as well - not just the attack and loop portions
> you mention - and I'd personally say we need to handle multi-sampling
> across pitch also.  Even my now-venerable Kurzweil K2000 (which I purchased
> in 1993) claimed to transition through the multisamples as it portamentoed
> from note to note.  (Can't remember if it claimed to do that for pitch bend
> also.)  That said, the basic AudioBufferSourceNode we have today is very
> useful, and its light weight makes it ideal for gaming purposes, et al.  I
> think we would want to add a more complex sample playback node, not change
> the current one.
>
> -C
>
> On Mon, Jul 16, 2012 at 10:30 AM, Joseph Berkovitz <joe@noteflight.com>wrote:
>
>>
>> Unfortunately, this term got confused with a single-cycle-table-lookup
>> sample playback in the early nineties.  Although wavetable synthesis will
>> frequently pre-compute the waveform from the harmonic series coefficients
>> and play back a looped single cycle sample, that's not the point.
>>
>> If you want to have an oscillator that plays from a buffer, a la a
>> single-cycle sample playback engine, it's quite easy - just create a
>> buffer, put a single cycle in it, and use an AudioBufferSourceNode to loop
>> that cycle.
>>
>>
>> With respect to the term "wavetable", I want to add that this term today
>> is often applied to commercial sampled-instrument engines such as Native
>> Instruments' Kontakt.
>>
>> In these "wavetable" synths, there is far more than a single cycle of a
>> waveform present.  Typically the sample consists of a "leader" capturing
>> the unique sound of the instrument's attack, and then an internal loop that
>> encompasses multiple waveform cycles (how many depends on the nature of the
>> instrument).  These internal loops necessarily have both start and end
>> points internal to the sample, hence the need for such a feature in the Web
>> Audio API. The current "loop-the-entire-sample" flag is not useful at all
>> in these scenarios.
>>
>> ... .  .    .       Joe
>>
>> *Joe Berkovitz*
>> President
>>
>> *Noteflight LLC*
>> 84 Hamilton St, Cambridge, MA 02139
>> phone: +1 978 314 6271
>> www.noteflight.com
>>
>>
>
> ... .  .    .       Joe
>
> *Joe Berkovitz*
> President
>
> *Noteflight LLC*
> 84 Hamilton St, Cambridge, MA 02139
> phone: +1 978 314 6271
> www.noteflight.com
>
>
Received on Monday, 16 July 2012 18:16:37 GMT

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