[Webkit-unassigned] [Bug 190963] New: On mobile Safari, mp3 audio spikes in volume after resuming from paused state

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=190963

            Bug ID: 190963
           Summary: On mobile Safari, mp3 audio spikes in volume after
                    resuming from paused state
           Product: WebKit
           Version: Safari 12
          Hardware: iPhone / iPad
                OS: iOS 11
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Web Audio
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: stoldney.mcstoldneyson at gmail.com

I have a tag that I have loaded an mp3 into. When I play the mp3 when it is in paused state, the volume on iPad spikes much louder for a few seconds before returning to its prior volume level. The issue occurs in this sequence:

var sound = $("#AudioElement")[0];
sound.src = url;
sound.load();

// Later
sound.pause();

// Later
sound.play();

I have reproduced this on iOS 11.2.5, 12.0, and 12.1.

The mp3s are encoded at 64Kbps/44100Hz in CBR formatting.

I think 1 of two things is happening here:

1. The audio when first played is being muted by Safari for some reason, and resuming the audio from paused state causes the volume to spike up to the global volume control for the device. IE, volume is spiking to what its supposed to be before being muted again by Safari.

or 

2. The volume is not being muted by Safari on first play, and the spike in volume is just abnormal.

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