Audio quality will degrade over time until it eventually fails

[thisandagain]

Expected behavior

• Should be able to play a long project with audio

Actual behavior

• Audio quality begins to degrade until eventually it "cuts out" and will not resume audio playback until refreshing the page

Steps to reproduce

• Load project https://llk.github.io/scratch-gui/#100736613
• Press green flag
• Sit through the entire animation 🐱
• Press green flag again

Operating system and browser

Mac OS 10.12.2 Chrome Version 56.0.2924.87 (64-bit)

[ed-cooper]

I didn't see anything out of the ordinary when running the project

Windows 10, Chrome 56.0.2924.87 (64-bit)

[ed-cooper]

Actually, I do see what @thisandagain describes, although I can't consistently reproduce it.

However, I only experience any issues if I switch to another tab whilst the project is playing.

So maybe this is a fundamental issue to do with how Chrome handles tabs running in the background?

[towerofnix]

I'm also able to reproduce this, and, as @chooper100 said, only from switching between tabs.

[SillyInventor]

I am able to reproduce this by playing it 3 times in a row. I got degradation by running the program without sound a few times, and then adding in sound. As such I suspect an indirect source. A brief look at the memory usage shows a ~50mb leak every run with or without sound, but more concerning an increasing CPU usage.

Using Ubuntu 16.04, Chrome 56.0.2924.87

[thisandagain]

An event emitter leak would be my first guess, but we'll need to instrument the audio engine to track that down.

[SillyInventor]

Well, after checking the heap, I found there were a lot of gain nodes etc. owned by clones. By eliminating the forever clone loop in sprites 16 and 10 the problem was solved. This may be a result of poor clone disposal.