Bug 228215

Summary:	MP3 decoder ignoring XIPH header related to encoder delay and padding information
Product:	WebKit	Reporter:	Jean-Yves Avenard [:jya] <jean-yves.avenard>
Component:	Web Audio	Assignee:	Nobody <webkit-unassigned>
Status:	RESOLVED FIXED
Severity:	Normal	CC:	cdumez, webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified

Description Jean-Yves Avenard [:jya] 2021-07-22 19:57:02 PDT

Consider the following case:

STR:

1- Open https://jyavenard.github.io/htmltests/tests/webaudio/decodeAudioData.html
2- Select half-a-second-48000.mp3 at the bottom of the list
3- Click on play

Safari will show 26496 frames 0.552s.

This file is exactly .5s long and made of 24000 frames.

It contains a XIPH header that provides the encoder delay and padding information.

Chrome and Firefox properly parse those MP3 which results in a continuous audio stream when looping. On Safari you can here the incorrectly generated blank frames.

The ability the produce frame-exact content is important for web audio applications. 

WebKit uses ExtAudioFileRead to demux and decode this file and it returns too many frames.

Comment 1 Radar WebKit Bug Importer 2021-07-22 19:57:24 PDT

<rdar://problem/80998793>

Comment 2 Jean-Yves Avenard [:jya] 2021-08-18 15:29:15 PDT

this got fixed on macOS Monterey.