AudioBufferSourceNode.playbackRate should be specified as k-rate and not a-rate

[olivierthereaux]

Originally reported on W3C Bugzilla ISSUE-21592 Fri, 05 Apr 2013 15:26:40 GMT
Reported by paul@paul.cx
Assigned to

Quote from the spec:

playbackRate

The speed at which to render the audio stream. The default
playbackRate.value is 1. This parameter is a-rate

WebKit implements this property as being k-rate, and I believe this is in fact just a typo in the spec.

[karlt]

Gecko also implements this as k-rate. Creating an efficient quality resampler with a different rate on each sample could be difficult, and there is no need for per-sample changes.

[joeberkovitz]

It is not necessarily true that there is no need for per-sample changes. Consider the need to modulate the frequency of a sampled instrument recording, e.g. apply musical vibrato.

[billhofmann]

What is the decision here? Does it require further discussion?

[joeberkovitz]

I don't know, but it looks like k-rate is what everyone has implemented. I am finding that k-rate is sufficient for most frequency modulation in Noteflight. I think we should go with k-rate and leave fancier per-sample modulation to the realm of custom synthesis.

[padenot]

Yes, I think we can just close this. k-rate has been how it's done for ages now.