1031851 - createScriptProcessor doesn't work with OfflineAudioContext

Status: NEW

(Core :: Web Audio, defect, P4)

Description

[Justin Dolske [:Dolske]]

Attachment: Testcase

Attached is a simplified testcase.

When using and OfflineAudioContext with createScriptProcessor(), my script's onaudioprocess handler is correctly called and modifies an output buffer. But upon completion, the rendered buffer is empty (all samples are 0).

If you modify the testcase to use a normal live AudioContext instead (look for "Uncomment this"), it generates the expected sound. 

Additionally, I created the OfflineAudioContext with a length of 15,000 samples, and createScriptProcessor() requests a buffer of 1024 samples. I'd expect onaudioprocess to be called 14 times with a 1024-sample buffer, and a 15th time with a 664-sample buffer (15000 - 1024*14 = 664). Instead it's only called 14 times.

Comment 1

[Paul Adenot (:padenot)]

This is workaround-able (because you're offline, so you might as well fill you buffer directly), but it's not great to have difference in rendering between OfflineAudioContext and AudioContext.

Comment 2

[Bulk Bug Changes for mreavy's org]

Mass change P3->P4 to align with new Mozilla triage process.

Comment 3

[eliastik]

Issue still present in 2019 (tested in Firefox 66.0.2).

Comment 4

[roillettri]

In Firefox 68.0a1 the ScriptProcessorNode in OfflineAudioContext seems to be broken entirely.
It has some weird comportments (https://jsfiddle.net/Stepan_Kasyanenko/1ncbnt4f/).