88.2 and 96 kHz should work from CVBR mode 5 or 6 upwards, and 24 (or even 32) bits should work in any case. Do you have a short 24-bit WAV file for me which doesn't work, to identify the issue?

#define EXHALE_APP_WCHAR  (defined (_MSC_VER) || defined (__MINGW32__))

Update (preset 3)...

C.R.Helmrich, can you clarify exactly what you are seeing in the fb2k metadata writing that is corrupted, per this note?
...
the files are still playing fine with no issues, at least using kode54's fdk-aac decoder.

[...] not on Linux yet [...]

Since both platforms use UTF-8 as their default 8 bit encoding

One more thing I noticed: when using exhale for converting to USAC directly during CD ripping, foobar2000 1.5.4 fails just after completing each track rip. Strange. Can anyone confirm this?

Converting: "cdda://00BF3150" / index: 1
Audio CD extraction setup: drive: "ATAPI - iHBS112   2", sample offset: 6, security: standard
Destination: "F:\DAE\Warren G - Regulate - USAC\01. Warren G, Nate Dogg - Regulate.m4a"
CLI encoder: exhale.exe
Destination file: F:\DAE\Warren G - Regulate - USAC\01. Warren G, Nate Dogg - Regulate.m4a
Encoder stream format: 44100Hz / 2ch / 16bps
Command line: "C:\Program Files\exhale\exhale.exe" 3 "01. Warren G, Nate Dogg - Regulate.m4a"
Working folder: F:\DAE\Warren G - Regulate - USAC\
Encoder process still running, waiting...
Encoder process terminated cleanly.
Object "mdat" at 44560
Media data is truncated, the file may not be playable completely.
Writing tags to encoded file failed: invalid or incomplete data
An error occurred while finalizing the encoding process (invalid or incomplete data) : "F:\DAE\Warren G - Regulate - USAC\01. Warren G, Nate Dogg - Regulate.m4a"
Conversion failed: invalid or incomplete data
Converting: "cdda://00BF3150" / index: 2
Audio CD extraction setup: drive: "ATAPI - iHBS112   2", sample offset: 6, security: standard
Destination: "F:\DAE\Warren G - Regulate - USAC\02. Warren G - Do You See.m4a"
CLI encoder: exhale.exe
Destination file: F:\DAE\Warren G - Regulate - USAC\02. Warren G - Do You See.m4a
Encoder stream format: 44100Hz / 2ch / 16bps
Command line: "C:\Program Files\exhale\exhale.exe" 3 "02. Warren G - Do You See.m4a"
Working folder: F:\DAE\Warren G - Regulate - USAC\
Encoder process still running, waiting...
Encoder process terminated cleanly.
Object "mdat" at 42860
Media data is truncated, the file may not be playable completely.
Writing tags to encoded file failed: invalid or incomplete data
An error occurred while finalizing the encoding process (invalid or incomplete data) : "F:\DAE\Warren G - Regulate - USAC\02. Warren G - Do You See.m4a"
Conversion failed: invalid or incomplete data
Converting: "cdda://00BF3150" / index: 3

etc.

D:\temp\aac\exhale\test>"c:\Program Files\exhale\exhale.exe" 5 .\Ťęşť_ʄīŀė.wav .\┴ǝsʇ‾ɟᴉlǝ˙m4a

  ---------------------------------------------------------------------
 | exhale - ecodis extended high-efficiency and low-complexity encoder |
 |                                                                     |
 | version 1.0.4 (x64, built on Jun 13 2020) - written by C.R.Helmrich |
  ---------------------------------------------------------------------

 Encoding 44-kHz 2-channel 16-bit WAVE to low-complexity xHE-AAC at 128 kbit/s

 Progress: --------------------------------- Done, actual average 139.8 kbit/s

 Input statistics: Mobile loudness -23.68 LUFS, sample peak level -6.17 dBFS

I have downloaded one 24/88.2 file from this site.
- FLAC -> USAC direct conversion with foobar (v1.5.5 beta 1) to 24/88.2 or 24/44.1 is Ok.

Quote from: kode54 on 2020-06-12 23:45:33

Since both platforms use UTF-8 as their default 8 bit encoding

There is no encoding used at all. It's just raw bytes.

Does that mean on-the-fly downsampling while encoding works now with exhale?

I've tested various combinations on the same (previous) file at 96, 64, 48, 44, 32Khz etc. with the three resamplers installed in my foobar, everything went Ok.

But... 
From preset 3 or 4, there's a problem with 22.5 and 24Khz files. And perhaps with 16Khz ones at preset 5 and above.

Files are encoded with commit 7d9e0db9, I discovered that preset 1 can now encode 44.1 files. Cool!

I'll look into making exhale supported out of the box in near future so no manual settings are needed.

I wonder how long it would take ffmpeg to support xHE-AAC decoding.

Can you please correct the wiki entry, since it's not a foobar2000 problem? Thanks. I'll look into making exhale supported out of the box in near future so no manual settings are needed.