Difference between revisions of "Media key"

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(Function-key mappings)
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Revision as of 01:59, 30 November 2013

A Media key is a key with a special purpose for a specific type of applications or operating system functions. Normally, these functions are concerned with media playback, but the term has been used for other functions as well.

A media key can be a dedicated key, or another key can act like a media key in conjunction with the Fn key. Some USB keyboards contain also a knob or roller, usually for volume control.

Gallery

Function-key mappings

On many keyboards, media keys are dedicated keys with no other function.

On some keyboard, media key functions are on Function keys when holding a Fn key.

On some Apple keyboards such as the aluminium keyboards, the default behaviour is the reverse: numbered Function keys are available on the media keys when holding down Fn.

On some PC keyboards from Microsoft, the Fn "key" is not a modifier key but a toggle switch.

Keyboard Fn-F1 Fn-F2 Fn-F3 Fn-F4 Fn-F5 Fn-F6 Fn-F7 Fn-F8 Fn-F9 Fn-F10 Fn-F11 Fn-F12 Print Screen Scroll lock Pause (Dedicated keys)
SteelSeries 6GV2 Mute Volume Down Volume Up Play / Pause Previous Track Next Track
Ducky G2Pro/Shine Mute Volume Down Volume Up Play / Pause Stop Previous track Next track Calculator Computer Email Home/Browser
iOne (Func KB-460, QPad MK-50 etc.) Mute Volume Down Volume Up Play / Pause Previous track Next track
CMStorm QuickFire Rapid Play / Pause Stop Previous track Next track Mute Volume Down Volume Up
Max Keyboard Blackbird Mute Volume Down Volume Up Play / Pause Previous Track Next Track
Apple Aluminium Keyboard A1243 Brightness Down Brightness Up Exposé / Mission Control Dashboard / Launchpad Rewind Play/Pause Fast Forward Mute Volume Down Volume Up Eject F13 F14 F15 F16 F17 F18 F19

Protocol

Media keys usually emit distinct codes to the host.

USB

In the USB HID ("Human Interface Device") standard, while most key codes are in the "Keyboard/Keypad" usage page (0x07), most most media keys are in "Consumer" usage page (0x0C). System control keys (Power, Sleep, Wake) are in the "Generic Desktop" usage page (0x01).

The "Consumer Usage Page" has also codes for linear relative values for volume control, bass and treble. While it may appear to be analogue, the knob or roller is usually connected to a rotary encoder. The values are relative to the volume level set by the user in the operating system and application software. If the controls had absolute values, they would have needed to be motorized and under computer control, which is something that the USB HID specification does not support.

The controls in each Usage Page are transmitted in a separate packet. Therefore, media keys may have separate rollover characteristics from regular keys.

PS/2

For PS/2, Microsoft has standardized media key scancodes for Windows.

Some vendors have used their own codes that have been activated first after having received a "magic" code from the host's keyboard driver.

Codes

There are more codes in the USB standard that those below, but not all are supported by major operating systems and apps. [1] [2] [3] [4].

Values are in hexadecimal.

Function USB PS/2 (set 2) OS support
System Page Code Type Make Break Windows Mac X Sun
Power 01 81 One-shot E0 37 E0 F0 37 Windows 95 X
07 66 One-shot Mac X Sun
Sleep 01 82 One-shot E0 3F E0 F0 3F Windows 95
Wake 01 83 One-shot E0 5E E0 F0 5E Windows 95
Media Page Code Type Make Break Windows Mac X Sun
Next Track 0C B5 One-shot E0 4D E0 F0 4D Windows Mac X
Previous Track 0C B5 One-shot E0 15 E0 F0 15 Windows Mac X
Stop 0C B7 One-shot E0 3B E0 F0 3B Windows Mac X
Eject 0C B8 One-shot Mac
Play / Pause 0C CD One-shot E0 34 E0 F0 34 Windows Mac X
Volume (knob) 0C E0 Linear Windows 98
Mute 0C E2 On/off E0 23 E0 F0 23 Windows 98 Mac X
07 7F One-shot Sun
Bass (knob) 0C E3 Linear Windows 2000
Treble (knob) 0C E4 Linear Windows 2000
Bass Boost 0C E5 On/off Windows 98
Loudness 0C E7 On/off Windows 2000
Volume Up 0C E9 Re-trigger E0 32 E0 F0 32 Windows 98 Mac X
07 80 One-shot Sun
Volume Down 0C EA Re-trigger E0 21 E0 F0 21 Windows 98 Mac X
07 81 One-shot Sun
Bass Up 0C 0152 Re-trigger Windows 2000
Bass Down 0C 0153 Re-trigger Windows 2000
Treble Up 0C 0154 Re-trigger Windows 2000
Treble Down 0C 0155 Re-trigger Windows 2000
Launch application Page Code Type Make Break Windows Mac X Sun
Media Player 0C 0183 Selector E0 50 E0 F0 50 Windows
Email 0C 018A Selector E0 48 E0 F0 48 Windows
Calculator 0C 0192 Selector E0 2B E0 F0 2B Windows
My Computer 0C 0194 Selector E0 40 E0 F0 40 Windows
Web browser Page Code Type Make Break Windows Mac X Sun
Search 0C 0221 Selector E0 10 E0 F0 10 Windows
Browser/Home 0C 0223 Selector E0 3A E0 F0 3A Windows
Back 0C 0224 Selector E0 38 E0 F0 38 Windows
Forward 0C 0225 Selector E0 30 E0 F0 30 Windows
Stop 0C 0226 Selector E0 28 E0 F0 28 Windows
Refresh 0C 0227 Selector E0 20 E0 F0 20 Windows
Bookmarks 0C 022A Selector E0 18 E0 F0 18 Windows

References

  1. Universal Serial Bus (USB): HID Usage Tables,10/28/2004,Version 1.12
  2. Windows Platform Design Notes: Keyboard Scan Code Specification, Revision 1.3a; revised March 2000. Retrieved from Archive: Key Support, Keyboard Scan Codes, and Windows on 2013-09-19
  3. USB HID to PS/2 Scan Code Translation Table. Retrieved from Archive: Key Support, Keyboard Scan Codes, and Windows on 2013-09-19
  4. Sun USB media key mappings, extracted from looking at the source code of type5usb.