Prevents SPDIF/HDMI digital audio playback devices from sleeping. Uses WASAPI, requires Windows 7+.

To enable autorun, copy soundkeeper.exe into the startup directory (to open it, press Win+R, enter shell:startup, press Enter). To close the program, just mute the Sound Keeper in the Volume Mixer or kill the soundkeeper.exe process.

Download: soundkeeper.7z (23KB). Source code →

Features

• Sound Keeper is fully automatic and doesn't require any user interaction.
• Sound Keeper can keep sound on many sound outputs simultaneously (e.g. SPDIF and HDMI).
• Sound Keeper detects new sound outputs on the fly (e.g. when you connected a TV via HDMI).

Settings

• Default behavior can be changed by changing file name of the Sound Keeper executable.
• Primary audio output is used by default. Add All to executable file name to enable Sound Keeper on all outputs.
• Inaudible stream is used by default. Add Zero to executable file name to use stream of digital zeroes (like it was in v1.0.0).

If the default inaudible stream doesn't help, try the new Sine stream type. It generates a sine wave, and can be customized. There are two parameters: F (frequency) and A (amplitude). The value goes right after the parameter character. For example, add SineF10A5 to executable file name to generate 10Hz sine wave with 5% amplitude. Low frequencies (below 20Hz) and high frequencies (above 20000Hz) with low amplitude (up to 10%) are inaudible.

What's new in v1.3.1

• A potential deadlock when audio devices are being added or removed has been fixed.
• Fluctuate treats non-PCM output formats (like Dolby Atmos) as 24-bit instead of 16-bit.
• Frequency parameter F is limited by half of current sample rate to avoid generation of unexpected noise.
• More detailed logs in debug build. Debug output is flushed immediately, so it can be redirected to a file.

What's new in v1.3.0

• Fluctuate is 1 fluctuation per second by default. Frequency can be changed using the F parameter.
• Periodic playing of a sound (parameters L and W) with optional fading (parameter T).
• New White, Brown, and Pink noise signal types.
• Self kill command is added. Run soundkeeper kill to stop running Sound Keeper instance.
• Analog switch was added. It works as the opposite of Digital.
• Ignores remote desktop audio device (this feature can be disabled using the Remote switch).
• New OpenOnly mode that just opens audio output, but doesn't stream anything.
• New NoSleep switch which disables PC sleep detection (Windows 7-10).
• Work as a dummy when no suitable devices found.
• Sound Keeper shouldn't prevent PC from automatic going into sleep mode on Windows 10.
• The program is not confused anymore when PC auto sleep is disabled on Windows 10.
• The workaround that allowed PC to auto sleep had to be disabled on Windows 11.

Sound Keeper vs. SPDIF Keep Alive vs. SPDIF-KA

	Sound Keeper v1.0	SPDIF Keep Alive v1.2	SPDIF-KA v1.4
Fully automatic:	Yes	No	No
Multiple outputs:	Yes	No	No
GUI:	No	Yes	Yes
Requires .NET:	No	Yes	Yes
Executable size:	17KB	668KB	163KB
CPU usage (on Intel Core i5 4460):	0.004%	0.06%	0.06%
RAM usage (Private Working Set):	1636KB	13704KB	10600KB

Known issue: streaming audio prevents automatic sleep mode

When a program streams any audio (even silence), the system don't go into sleep mode automatically. Sound Keeper uses the NtPowerInformation(SystemPowerInformation, ...) function to retrieve time when system is going to sleep, and disables itself right before this time. On Windows 7, it works perfectly. Windows 10 waits for 2 minutes more after any sound was streamed, so the PC goes into sleep mode after 2 minutes when Sound Keeper disabled itself. For some reason, Windows 11 always reports that the system is going to sleep in 0 seconds. So, the workaround had to be disabled on this OS until a better solution is found. You can try to use the powercfg to workaround this issue at the system level. Details →