Re: How to play back synthesized 22kHz audio in a glitch-free manner?

On Jun 18, 2013, at 6:55 AM, Joe Berkovitz <joe@noteflight.com> wrote:

> Actually, as co-editor of the use case document I am very interested in understanding why the arbitrary concatenation of buffers is important. When would this technique be used by a game? Is this for stitching together prerecorded backgrounds?
> 

Here's a good example of such a use case: http://labs.echonest.com/Uploader/index.html

The WebAudio app slices an uploaded piece of music into discrete chunks, calculates paths between similar chunks, and "stitches" together an inifintely long rendidion of the song by jumping in the timeline between similar chunks.

This app is currently implements its queueing model by calling setTimeout(n), where n is 10ms before the anticipated end time of the current sample. However, this causes stuttering and gaps whenever the timer is late by more than 10ms. WebKit Nightlies implement JavaScript timer coalescing when pages are not visible, which has lead the Infinite Jukebox page to pause playback when it gets a 'visibilitychange'/'hidden' event.

One solution would be to allocate one AudioBufferSourceNode for each chunk and pre-schedule the startTime of each.  One downside here is the floating-point inaccuracy problems mentioned by Kevin.  Another is the complexity required of the page author managing a large number of nodes and calculating start and end times for each.

An alternate solution would be a hypothetical AudioBufferQueueNode, where AudioBuffers could be appended to the node and discarded after they've played.

-Jer