Symptoms
Consider the following scenario:
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You develop an application that uses the midiInGetNumDevs function to retrieve the number of connected MIDI input devices.
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You run the application on a Windows 8-based computer.
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You insert a universal serial bus (USB) MIDI device, and then you let the application call the midiInGetNumDevs function.
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You remove the USB MIDI device.
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You let the application call the midiInGetNumDevs function again.
In this scenario, the midiInGetNumDevs function returns the previous number of connected MIDI input devices. Note The following functions may also behave incorrectly in Windows 8:
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midiInGetDevCaps
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midiInGetNumDevs
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midiInMessage
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midiInOpen
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midiInPrepareHeader
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midiInReset
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midiInStart
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midiInStop
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midiInUnprepareHeader
Cause
This issue occurs because disconnected devices are incorrectly enumerated when the functions are called.
Resolution
Update information
To resolve this issue, install update rollup 2862768. For more information about how to obtain this update rollup package, click the following article number to view the article in the Microsoft Knowledge Base:
2862768 Windows RT, Windows 8, and Windows Server 2012 update rollup: August 2013
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
More Information
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates
