See also: IRC log
<trackbot> Date: 12 September 2012
wtf, zakim
sigh
<scribe> Meeting: W3C Audio Working Group Meeting
<chris> conference code?
<jussi> chris: 26631
<chris> jussi: thanks
-> Agenda is http://lists.w3.org/Archives/Public/public-audio/2012JulSep/0740.html
<ChrisWilson> "the conference is restricted at this time"??
Chris, the code is 26631
<ChrisWilson> mute jussi
<joe> I cannot connect
joe, the code is 26631 today
<joe> thx]
<joe> sorry, now Zakim is not even answering the regular number
Olivier: should we rename notegrainon to startgrain?
<joe> Is there an alternate Zakim number, cannot reach 617 761 6200
cwilso: sounds consistent
crogers: we could overload start
… depending on number of arguments
… but the name would always be start
<jussi> +1
cwilso: sounds better
<tross> +1
<ChrisWilson> +1
<joe> +1
joe, did you manage to connect or are you on IRC only?
<joe> irc only, Zakim appears to be down to my phone
<joe> "non-working number" recording
sorry to hear, will be taking notes
<joe> np, let's go w irc
<scribe> ACTION: ot to add overloading of start to bugzilla [recorded in http://www.w3.org/2012/09/12-audio-minutes.html#action01]
<trackbot> Created ACTION-49 - Add overloading of start to bugzilla [on Olivier Thereaux - due 2012-09-19].
Olivier: crogers, any idea when the changes could get into the spec
crogers: busy with implementation at the moment, but will try to get changes there in next week or two
Olivier: sounds good.
[skipping loop start/stop points for now]
https://www.w3.org/Bugs/Public/show_bug.cgi?id=17326
Olivier: do we need more knowledge/understanding to go forward?
crogers: think we have a good understanding
… problem is when you have a delay in a feedback loop and do block processing, the block size is the minimum delay
… we've defined that value to be 128 sample frames
… depending on sample rate, this value defines a time in seconds
… no restriction on delay time when handled in seconds
… think we've decided not to throw exception
… and silently clamp to the minimum
Olivier: what do people (here) think of the proposal?
[no objection]
<joe> it seems fine
thanks joe
Olivier: does this need to be added to the spec?
crogers: I think so
... ROC was also asking what if you have several such delay
nodes
… may not need to all be clamped
… opinion that we should not require optimisation, each node would be taken separately and be clamped if they are in a feedback loop
Olivier: are there cases where it would be difficult to detect a feedback loop?
crogers: not a problem, seeing our implementation
… but I think Marcus was worried about question of minimum delay in samples or seconds
<joe> q
Proposed resolution: no exception if delay too low in feedback loop, clamp silently to minimum
crogers: the problem is solved if we define the minimum in terms of sample frames
… uniformly 128 sample frames
Olivier: seem to recall the indecision was because this would induce differences between devices with different sample rates
crogers: probably won't get to a
conclusion without Marcus and Robert in the discussion
... setting the limit in sample frames will make
implementations easier
... you will hear differences when you are running at different
sample rates anyway
(joe, will ack you in a sec, write your question on IRC?)
Olivier: are there any precedent?
crogers: think most such systems do it by the sample block size
Olivier: would either make it easier to test?
<joe> (ot, I am on the call live now)
(joe, oh!)
crogers: not a problem if tests are run in a consistent environment
joe: perhaps we could incorporate
caveat on ability to perform certain tasks with feedback
loops
... IOW, leave support for feedback loop out
crogers: seems important to have though, fairly basic feature of modular systems
… ok with not talking about hard limits
crogers: I think we can define it at least in terms of sample frames
… and browser can get equivalent implementations that way
Olivier: so proposal would be to keep the clamping, but implementations can choose their minimum
joe: essentially, yes
… for v1, seems wise
Call for review -> http://lists.w3.org/Archives/Public/public-audio/2012JulSep/0665.html
any objection to publishing as a WD with view to be a Note?
crogers: sounds good to me
… important to get this out
Resolved: publish webaudio-usecases as WD
-> Proposed: https://www.w3.org/Bugs/Public/show_bug.cgi?id=17390#c6
joe: proposal is to augment current capability with loop mode enumeration
… additional behaviour would be to loop through range specified, until the stop time
… could have additional loop modes in the future
crogers: why can't we just have a loop start and end which, if 0, will loop the whole sample
joe: was the original proposal
… would be ok with it, but this proposal is a little cleaner and extensible
crogers: wondering if we could just overload start and end and add loop mode later - would that be dangerous
… if we are able to add loop mode at a later time, would that get rid of danger?
joe: think so. may end up with having to support an odd legacy behavior
… what if today someone uses start and end to specify a loop mode
… what happens when we add the loop mode parameter
crogers: we still have the loop attribute, right?
joe: yes
Olivier: would one proposal make it easier for the generic case of full loop
joe: both solutions would be quite simple for that case
crogers: what if we remove the mode of "loop entire sample"
… that's specified by having the parameters being the whole thing
joe: in which case we don't need the loop mode
crogers: yes, we could add loop
modes (start/end and backwards) later
... which is why I suggest having loop start and end be 0
<jussi> maybe use infinite?
crogers: what if the loop end is beyond the size of the sample
joe: I have clamping in proposal
crogers: what if the new buffer is shorter
joe: if you set start and end points that are invalid, clamped values are used in the playback
… this clamping does not affect visible/readable values of loop start and end
crogers: edge case if both are
invalid, what would it sound like
... like starting simple
jussi: what if the loop end is at infinity? would that be better than 0?
crogers: unsigned long, so there is no infinity
… brings up next question of looping at sub-sample values
crogers: wondering if it's worth adding
joe: not sure it's worth it
crogers: probably not worth if
the likes of soundfont do not do it
... it is possible, but not too fond of it
joe: would favor going to a float now if we suspect we may have sub-sample looping
crogers: then should we go with infinity?
<jussi> nope
joe: would prefer 0 and 0 myself
crogers: do you feel strongly about infinity
jussi: no
Resolution: make loop start and end be floats, and 0 and 0 are default
crogers: rounded if fractional?
joe: yes
Thierry: the charter has been updated with small suggestions
… should be vetted soon
Thierry: registration for TPAC is ongoing, you have a few more weeks
<jussi> Cheers!
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