[x3d-public] Sound v4 > ListenerPointSource QUESTIONS

[GPU Group]

Q4. or does it mean LPS is implemented with one (or 2 for binaural)
panner node(s), and the panner positions the SAD sound relative to its pose
(with no influence on panner nodes under SAD)?
-Doug

On Thu, Mar 2, 2023 at 5:31 AM GPU Group <gpugroup at gmail.com> wrote:

> Thanks very much Don. Yes it fascinating - great node.
>
> Specs: "If the *dopplerEnabled* field is TRUE, ListenerPointSource
> *children* sources which are moving spatially in the transformation
> hierarchy, relative to the location of the ListenerPointSource node, shall
> apply velocity-induced frequency shifts corresponding to Doppler effect."
> You said LPS has no inputs (children) yet this text talks about its
> children.
> Q1. is it trying to say the source streams / stream sources / SAD
> StreamAudioDestinations?
> Q2. is it saying LPS pose would be used by any panner node under any SAD
> it refers to?
> (PS web audio has deprecated doppler effect).
> Q3. if multiple LPS refer to the same SAD, which LPS pose would panner
> nodes under SAD use?
> Thanks, Doug
>
> On Wed, Mar 1, 2023 at 11:31 PM Brutzman, Donald (Don) (CIV) <
> brutzman at nps.edu> wrote:
>
>> Thanks for asking Doug.  References:
>>
>>
>>
>>    - X3D4 Architecture, Sound Component, 16.4.13 ListenerPointSource
>>    -
>>    https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-DIS/Part01/components/sound.html#ListenerPointSource
>>    - X3D Tooltips, ListenerPointSource
>>    -
>>    https://www.web3d.org/x3d/content/X3dTooltips.html#ListenerPointSource
>>
>>
>>
>> “ListenerPointSource represents the position and orientation of a person
>> listening to virtual sound in the audio scene, and provides single or
>> multiple sound channels as output. Multiple ListenerPointSource nodes can
>> be active for sound processing.”
>>
>>
>>
>> Suggested analogy: a virtual microphone in the virtual environment.  The
>> essential idea is that sound can be recorded as if a listener were at that
>> point.  Thus position and orientation can be placed at a given location
>> (such as a seat in a virtual auditorium) or even be animated to rehearse an
>> audio soundtrack through a virtual environment.
>>
>>
>>
>> Further option: can be user driven at run time.
>>
>>
>>
>>    - *trackCurrentView* field is TRUE then *position* and *orientation* matches
>>    the user's current view.
>>
>>
>>
>> The ListenerPointSource can be an input to other parts of an audio graph,
>> and feeding outputs to external speakers, or whatever.  Note similarity to
>> other sources such as MicrophoneSource and StreamAudioSource - they provide
>> outputs for processing by other audio nodes, and don’t have inputs.
>>
>>
>>
>> Our design intent was to take full advantage of a sound spatialization in
>> a virtual environment so that any point (static or moving or navigating)
>> might be a potential sample point.  Seems pretty powerful, especially as
>> our aural designs become further sophisticated to match or augment our
>> geometric designs.
>>
>>
>>
>> Similarly, just as *Source nodes provide audio signals, the *Destination
>> consume audio signals.  In other words (electrical engineering parlance)
>> they are signal sources and signal sinks.  All variation occurs between
>> those.
>>
>>
>>
>> We followed the example (and insightful design) of Web Audio API
>> Recommendation and stayed relatively silent about monaural, binaural, etc.
>> If a signal source has one or two channels, for example, the audio graph
>> mostly looks the same.  ChannelMerger ChannelSelector and ChannelSplitter
>> lets an author work on individual channels if they want.
>>
>>
>>
>> No doubt you noticed in the Support Levels we did not place any bounds on
>> the number of nodes supported at one time, expecting that implementations
>> and hardware support will vary quite a bit and further improve over time.
>>
>>
>>
>> Hopefully the spec prose is a bit clearer now – we will all learn a lot
>> as we keep building more sophisticated audio graphs and sound environments.
>>
>>
>>
>> All the best, Don
>>
>>
>>
>> *From:* x3d-public <x3d-public-bounces at web3d.org> *On Behalf Of *GPU
>> Group
>> *Sent:* Wednesday, March 1, 2023 11:47 AM
>> *To:* X3D Graphics public mailing list <x3d-public at web3d.org>
>> *Subject:* [x3d-public] Sound v4 > ListenerPointSource QUESTIONS
>>
>>
>>
>> I'm struggling to understand how the LPS ListenerPointSource should work.
>> It seems like a great idea with plenty of possibilities.
>>
>> Guess 1:
>>
>> LP ListenerPoint - would have just the pose of the listener.
>>
>> - that pose would be used in any Panner nodes instead of viewpoint
>>
>> - LP would be a singleton and apply to all contexts
>>
>> - would work under AD AudioDestination
>>
>> Guess 2:
>>
>> Multiple LP - like LP, except each LP could refer to / apply its pose to
>> a specific audio context using keys / IDs.
>>
>> - each AD would have a key/ID (SFString or SFInt32), (ID would be simple
>> number like 0 or 1 or 2, not UUID of mediaStream)
>>
>> - each LP would have a keys/IDs field, (MFString, MFInt32), and could
>> apply its pose to panner nodes under the ADs with a key in its key list, or
>> if key list empty, to all contexts.
>>
>> Guess 3:
>>
>> LPS works with SAD StreamAudioSource, with each SAD converting its output
>> to a bufferable stream like HTML MediaStream. The program would hold a list
>> of Streams with key/ID: list (Stream,key)
>>
>> Each LPS would have a keys/IDs field, and merge all the streams its
>> interested in.
>>
>> The LPS pose would not affect Panner nodes under SADs.
>>
>> Rather it would take each stream as positionless and add its own pose
>> with an internal panner node.
>>
>> And have a built in AD to deliver its output to the scene
>>
>> (when I implemented Sound and SpatialSound, I included an AD node if and
>> only if it had no audio parent)
>>
>> Guess 4:
>>
>> Like 3, except LPS pose affects Panner nodes under its SAD list.
>>
>> x But multiple LPS would have conflicting pose claims, the Panner node
>> under SAD wouldn't know which one to use)
>>
>>
>>
>> I've lost the link to a paper that explained it.
>>
>> Q. how is it supposed to work?
>>
>> Thanks, Doug Sanden
>>
>>
>>
>
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