Bug 45077 – Add EqualPowerPanner files

• Status: RESOLVED
• Resolution: FIXED
• Component: New Bugs

[Chris Rogers]

Add EqualPowerPanner files

[Chris Rogers]

Created attachment 66307 [details]
Patch

[Kenneth Russell]

Comment on attachment 66307 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=66307&action=prettypatch

> WebCore/platform/audio/EqualPowerPanner.cpp:85
> +    const double kDezipperK = 0.0005;
This or similar constants are replicated in a few places in the code, for example in the AudioBus (where it's ten times as large). Can this be refactored? Also, what about a FIXME indicating that it's sample rate dependent?

> WebCore/platform/audio/EqualPowerPanner.cpp:98
> +    m_gainR = gainR;
Why does this class not need to expose these gains externally, like the AudioBus does via the lastMixGain outgoing argument in processWithGainFromMonoStereo and processWithGainFrom?

[Chris Rogers]

Created attachment 69518 [details]
Patch

[Chris Rogers]

(In reply to comment #2)
> (From update of attachment 66307 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=66307&action=prettypatch
> 
> > WebCore/platform/audio/EqualPowerPanner.cpp:85
> > +    const double kDezipperK = 0.0005;
> This or similar constants are replicated in a few places in the code, for example in the AudioBus (where it's ten times as large). Can this be refactored? Also, what about a FIXME indicating that it's sample rate dependent?

I've uploaded a patch for AudioUtilities which contains a discreteTimeConstantForSampleRate() function and am now using this.
The actual time-constant value (non sample-rate dependent) is chosen empirically for panning and may be different than volume smoothing.

> 
> > WebCore/platform/audio/EqualPowerPanner.cpp:98
> > +    m_gainR = gainR;
> Why does this class not need to expose these gains externally, like the AudioBus does via the lastMixGain outgoing argument in processWithGainFromMonoStereo and processWithGainFrom?

The smoothing state is best kept inside this class.  The reason they have to be kept externally in the AudioBus case is because many different sources may be summing into the same AudioBus, thus each source must keep track of its own state.  In the case of EqualPowerPanner, there is only a single source, so it makes logical sense to keep the state inside this class.

[Kenneth Russell]

Comment on attachment 69518 [details]
Patch

Looks good to me, but please update the license text before committing.

[Chris Rogers]

Created attachment 69700 [details]
Patch

[Chris Rogers]

Was previously R+, just fixed the license.

[Kenneth Russell]

Comment on attachment 69700 [details]
Patch

Looks good to me.

[WebKit Commit Bot]

Comment on attachment 69700 [details]
Patch

Clearing flags on attachment: 69700

Committed r69089: <http://trac.webkit.org/changeset/69089>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.