Bug 216183 – Improve interpolation algorithm in OscillatorNode

• Status: RESOLVED
• Resolution: FIXED
• Component: Web Audio

[Chris Dumez]

Improve interpolation algorithm in OscillatorNode.

[Chris Dumez]

Created attachment 407985 [details]
Patch

[Chris Dumez]

Created attachment 407989 [details]
Patch

[Geoffrey Garen]

Comment on attachment 407989 [details]
Patch

r=me

[EWS]

Committed r266627: <https://trac.webkit.org/changeset/266627>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 407989 [details].

[Radar WebKit Bug Importer]

<rdar://problem/68358295>

[Eric Carlson]

Comment on attachment 407989 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=407989&action=review

> Source/WebCore/Modules/webaudio/OscillatorNode.cpp:210
> +    // Consider a typical sample rate of 44100 Hz and max periodic wave
> +    // size of 4096. The relationship between |incr| and the frequency
> +    // of the oscillator is |incr| = freq * 4096/44100. Or freq =
> +    // |incr|*44100/4096 = 10.8*|incr|.
> +    //
> +    // For the |incr| thresholds below, this means that we use linear
> +    // interpolation for all freq >= 3.2 Hz, 3-point Lagrange
> +    // for freq >= 1.7 Hz and 5-point Lagrange for every thing else.
> +    //
> +    // We use Lagrange interpolation because it's relatively simple to
> +    // implement and fairly inexpensive, and the interpolator always
> +    // passes through known points.

You should note somewhere that this is based on code in Chrome's oscillator_node.cc

[Chris Dumez]

Comment on attachment 407989 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=407989&action=review

>> Source/WebCore/Modules/webaudio/OscillatorNode.cpp:210
>> +    // passes through known points.
> 
> You should note somewhere that this is based on code in Chrome's oscillator_node.cc

I said in the Changelog: "Align our OscillatorNode implementation with Chromium". How to you suggest I do better?

[Eric Carlson]

Comment on attachment 407989 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=407989&action=review

>>> Source/WebCore/Modules/webaudio/OscillatorNode.cpp:210
>>> +    // passes through known points.
>> 
>> You should note somewhere that this is based on code in Chrome's oscillator_node.cc
> 
> I said in the Changelog: "Align our OscillatorNode implementation with Chromium". How to you suggest I do better?

Some of you other patches have said something like "cherry picked from Chrome ...", but the ChangeLog comment is fine too.

[Chris Dumez]

(In reply to Eric Carlson from comment #8)
> Comment on attachment 407989 [details]
> Patch
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=407989&action=review
> 
> >>> Source/WebCore/Modules/webaudio/OscillatorNode.cpp:210
> >>> +    // passes through known points.
> >> 
> >> You should note somewhere that this is based on code in Chrome's oscillator_node.cc
> > 
> > I said in the Changelog: "Align our OscillatorNode implementation with Chromium". How to you suggest I do better?
> 
> Some of you other patches have said something like "cherry picked from
> Chrome ...", but the ChangeLog comment is fine too.

Ok, I will try and be clearer.