Sound is distorted on WASAPI only

[dbregman]

On Windows 11, using wasapi we observed that sounds play back with some distortion.

Spectrogram comparison made by my colleague: Top image is playback with dsound, bottom is with wasapi. You can see some clear dark bands in the bottom image which I think means frequencies getting removed.

Backend was changed using alsoft.ini. On my machine the sound is correct with all backends except wasapi.

Console log in with ALSOFT_LOGLEVEL=3:

[ALSOFT] (II) Initializing library v1.24.3-dc7d7054 master [ALSOFT] (II) Supported backends: wasapi, dsound, winmm, jack, null, wave [ALSOFT] (II) Loading config C:\Users\Dave\AppData\Roaming\alsoft.ini... [ALSOFT] (II) setting 'drivers' = 'wasapi,winmm,jack,dsound,wave,null' [ALSOFT] (II) setting 'decoder/hq-mode' = 'true' [ALSOFT] (II) Got binary: C:\myth2, Myth II 1.8.5.exe [ALSOFT] (II) Loading config C:\myth2\alsoft.ini... [ALSOFT] (II) Vendor ID: "AuthenticAMD" [ALSOFT] (II) Name: "AMD Ryzen 7 PRO 5875U with Radeon Graphics" [ALSOFT] (II) Extensions: +SSE +SSE2 +SSE3 +SSE4.1 [ALSOFT] (II) Found option drivers = "wasapi,winmm,jack,dsound,wave,null" [ALSOFT] (II) Starting watcher thread [ALSOFT] (II) Initialized backend "wasapi" [ALSOFT] (II) Added "wasapi" for playback [ALSOFT] (II) Added "wasapi" for capture [ALSOFT] (II) Got device "Speakers (Realtek(R) Audio)", "{1521687A-A2FA-435F-8636-13820691DFC5}", "{0.0.0.00000000}.{1521687a-a2fa-435f-8636-13820691dfc5}" [ALSOFT] (II) Got device "1 - DELL S2722QC (AMD High Definition Audio Device)", "{4D442B3F-F140-4E56-979C-0EF9A23D4E95}", "{0.0.0.00000000}.{4d442b3f-f140-4e56-979c-0ef9a23d4e95}" [ALSOFT] (II) Got device "Realtek HD Audio 2nd output (Realtek(R) Audio)", "{A31D68DB-866A-4CF0-889F-2A2D94B13797}", "{0.0.0.00000000}.{a31d68db-866a-4cf0-889f-2a2d94b13797}" [ALSOFT] (II) Got device "Microphone Array (Realtek(R) Audio)", "{18801BEE-F487-4B09-B019-84DB62FECA4E}", "{0.0.1.00000000}.{18801bee-f487-4b09-b019-84db62feca4e}" [ALSOFT] (II) Got device "Stereo Mix (Realtek(R) Audio)", "{95A92A4C-D024-4A68-8A24-B47675B301F5}", "{0.0.1.00000000}.{95a92a4c-d024-4a68-8a24-b47675b301f5}" [ALSOFT] (II) Watcher thread started [ALSOFT] (II) Opening playback device "OpenAL Soft" [ALSOFT] (II) Created device 0xa6b9e80, "OpenAL Soft on Realtek HD Audio 2nd output (Realtek(R) Audio)" [ALSOFT] (II) Pre-reset: Stereo, Float32, 48000hz, 960 / 2880 buffer [ALSOFT] (II) Device mix format: FormatTag = 0xfffe Channels = 2 SamplesPerSec = 48000 AvgBytesPerSec = 384000 BlockAlign = 8 BitsPerSample = 32 Size = 22 Samples = 32 ChannelMask = 0x3 SubFormat = {00000003-0000-0010-8000-00aa00389b71} [ALSOFT] (II) Requesting playback format: FormatTag = 0xfffe Channels = 2 SamplesPerSec = 48000 AvgBytesPerSec = 384000 BlockAlign = 8 BitsPerSample = 32 Size = 22 Samples = 32 ChannelMask = 0x3 SubFormat = {00000003-0000-0010-8000-00aa00389b71} [ALSOFT] (II) Post-reset: Stereo, Float32, 48000hz, 512 / 2880 buffer [ALSOFT] (II) Searching C:\myth2 for *.mhr [ALSOFT] (II) Adding built-in entry "!1_Built-In HRTF" [ALSOFT] (II) Loading !1_Built-In HRTF... [ALSOFT] (II) Detected data set format v3 [ALSOFT] (II) Loaded HRTF Built-In HRTF for sample rate 48000hz, 64-sample filter [ALSOFT] (II) 1st order + Full HRTF rendering enabled, using "Built-In HRTF" [ALSOFT] (II) Channel config, Main: 4, Real: 2 [ALSOFT] (II) Allocating 6 channels, 24576 bytes [ALSOFT] (II) Min delay: 7.75, max delay: 33.50, FIR length: 64 [ALSOFT] (II) New max delay: 25.75, FIR length: 90 [ALSOFT] (II) Max sources: 256 (255 + 1), effect slots: 64, sends: 4 [ALSOFT] (II) Dithering disabled [ALSOFT] (II) Output limiter disabled [ALSOFT] (II) Fixed device latency: 0ns [ALSOFT] (II) Post-start: Stereo, Float32, 48000hz, 512 / 2880 buffer [ALSOFT] (II) Increasing allocated voices to 256 [ALSOFT] (II) Created context 0xa6d5150 [ALSOFT] (II) Increasing allocated context properties to 2 [ALSOFT] (II) Increasing allocated voice properties to 32