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Bug 17357 - (ConvolverNodeChannels): ConvolverNode channel mapping
Summary: (ConvolverNodeChannels): ConvolverNode channel mapping
Status: CLOSED WONTFIX
Alias: None
Product: AudioWG
Classification: Unclassified
Component: Web Audio API (show other bugs)
Version: unspecified
Hardware: PC All
: P2 normal
Target Milestone: TBD
Assignee: This bug has no owner yet - up for the taking
QA Contact: This bug has no owner yet - up for the taking
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Reported: 2012-06-05 11:47 UTC by Philip Jägenstedt
Modified: 2014-10-28 17:16 UTC (History)
3 users (show)

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Description Philip Jägenstedt 2012-06-05 11:47:05 UTC
Audio-ISSUE-70 (ConvolverNodeChannels): ConvolverNode channel mapping [Web Audio API]

http://www.w3.org/2011/audio/track/issues/70

Raised by: Philip Jägenstedt
On product: Web Audio API

The buffer attribute is defined as "A mono or multi-channel audio buffer containing the impulse response used by the convolver." However, it is not defined at all how the channels in the impulse response should be used, even in the case where it matches the number of channels in the input. Possibly, a mono impulse response should be applied to all channels, but beyond that it's hard to guess.
Comment 1 Chris Rogers 2012-06-14 00:53:57 UTC
This information should now be present:
https://dvcs.w3.org/hg/audio/rev/4df179094971
Comment 2 Marcus Geelnard (Opera) 2012-06-18 10:12:45 UTC
The specification does not say anything about what must happen for other channel configurations than the ones listed.

Also, the wording "common cases for stereo playback where N and M are 1 or 2 and K is 1, 2, or 4" is confusing.

First of all the expression "common cases for stereo" indicates that there may be other (less common) cases, but in fact the API does not support them.

Secondly, taking all permutations of "N and M are 1 or 2 and K is 1, 2, or 4" gives 12 possible combinations (not just the 5 that are required):

N M K
1 1 1
1 1 2
1 1 4
1 2 1
1 2 2
1 2 4
2 1 1
2 1 2
2 1 4
2 2 1
2 2 2
2 2 4

Also, what about cases when AudioDestinationNode has numberOfChannels other than 1 or 2?

Furthermore, it seems odd to let the number of output channels of the AudioNode depend on the number of output channels in the playback system (I take it that means ctx.destination.numberOfChannels).
Comment 3 Olivier Thereaux 2014-10-28 17:13:54 UTC
Web Audio API issues have been migrated to Github. 
See https://github.com/WebAudio/web-audio-api/issues
Comment 4 Olivier Thereaux 2014-10-28 17:16:47 UTC
Closing. See https://github.com/WebAudio/web-audio-api/issues for up to date list of issues for the Web Audio API.