SerenityOS/serenity

Intel HDA on QEMU Windows regularly skips ahead in audio

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#18,132 opened on Apr 1, 2023

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bughelp wanted

Description

The exact skipping behaviour observed here is not short stops in audio playback, but the not-playing of certain parts of the audio, which happens semi-regularly. The audio is not "pausing", it is "skipping ahead".

Parameters that, as far as has been tested, do not affect this behaviour:

  • HDA stream buffer size (40 to 400ms tested)
  • QEMU DirectSound timer interrupt (2ms to 40ms tested including the recommended default of 10ms)

As far as known, this issue is specific to QEMU on Windows and the DirectSound audio backend. It is NOT (only) a general issue with DirectSound, as AC'97 does not have this problem under identical backend settings.

Contributor guide

Tech stack
cpp
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
5
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C++ knowledgeAudio driver conceptsQEMU internalsWindows DirectSound
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
10
Research direction
Investigate the Intel HDA audio driver in SerenityOS (likely in Kernel/Sound/). Compare the audio buffer handling with the working AC'97 driver. Also examine the interaction with QEMU's DirectSound backend to identify why skipping occurs specifically with HDA.