capability command

The capability command requests information about a particular capability of a device. All MCI devices recognize this command.

To send this command, call the mciSendString function with the lpszCommand parameter set as follows.

_stprintf_s(
  lpszCommand, 
  TEXT("capability %s %s %s"), 
  lpszDeviceID, 
  lpszRequest, 
  lpszFlags
); 

Parameters

lpszDeviceID

Identifier of an MCI device. This identifier or alias is assigned when the device is opened.

lpszRequest

Flag that identifies a device capability. The following table lists device types that recognize the capability command and the flags used by each type:

Value	Type	Type
cdaudio	can eject can play can record can save compound device	device type has audio has video uses files
digitalvideo	can eject can freeze can lock can play can record can reverse can save can stretch can stretch input can test	compound device device type has audio has still has video maximum play rate minimum play rate uses files uses palettes windows
overlay	can eject can freeze can play can record can save can stretch	compound device device type has audio has video uses files windows
sequencer	can eject can play can record can save compound device	device type has audio has video uses files
vcr	can detect length can eject can freeze can monitor sources can play can preroll can preview can record can reverse can save can test	clock increment rate compound device device type has audio has clock has timecode has video number of marks seek accuracy uses files
videodisc	can eject can play can record can reverse can save CAV CLV compound device	device type fast play rate has audio has video normal play rate slow play rate uses files
waveaudio	can eject can play can record can save compound device device type	has audio has video inputs outputs uses files

The following table lists the flags that can be specified in the lpszRequest parameter and their meanings:

Flags	Meaning
can detect length	Returns TRUE if the device can detect the length of the media.
can eject	Returns TRUE if the device can eject the media.
can freeze	Returns TRUE if the device can freeze data in the frame buffer.
can lock	Returns TRUE if the device can lock data.
can monitor sources	Returns TRUE if the device can pass an input (source) to the monitored output, independent of the current input selection.
can play	Returns TRUE if the device can play.
can preroll	Returns TRUE if the device supports the "preroll" flag with the cue command.
can preview	Returns TRUE if the device supports previews.
can record	Returns TRUE if the device supports recording.
can reverse	Returns TRUE if the device can play in reverse.
can save	Returns TRUE if the device can save data.
can stretch	Returns TRUE if the device can stretch frames to fill a given display rectangle.
can stretch input	Returns TRUE if the device can resize an image in the process of digitizing it into the frame buffer.
can test	Returns TRUE if the device recognizes the test keyword.
cav	When combined with other items, this flag specifies that the return information applies to CAV format videodiscs. This is the default if no videodisc is inserted.
clock increment rate	Returns the number of subdivisions the external clock supports per second. If the external clock is a millisecond clock, the return value is 1000. If the return value is 0, no clock is supported.
clv	When combined with other items, this flag specifies that the return information applies to CLV format videodiscs.
compound device	Returns TRUE if the device supports an element name (filename).
device type	Returns a device type name, which can be one of the following: cdaudio dat digitalvideo other overlay scanner sequencer vcr videodisc waveaudio
fast play rate	Returns the fast play rate in frames per second, or zero if the device cannot play fast.
has audio	Returns TRUE if the device supports audio playback.
has clock	Returns TRUE if the device has a clock.
has still	Returns TRUE if the device treats files with a single image more efficiently than motion video files.
has timecode	Returns TRUE if the device is capable of supporting timecode, or if it is unknown.
has video	Returns TRUE if the device supports video.
inputs	Returns the total number of input devices.
maximum play rate	Returns the maximum play rate, in frames per second, for the device.
minimum play rate	Returns the minimum play rate, in frames per second, for the device.
normal play rate	Returns the normal play rate, in frames per second, for the device.
number of marks	Returns the maximum number of marks that can be used; zero indicates that marks are unsupported.
outputs	Returns the total number of output devices.
seek accuracy	Returns the expected accuracy of a search in frames; 0 indicates that the device is frame accurate, 1 indicates that the device expects to be within one frame of the indicated seek position, and so on.
slow play rate	Returns the slow play rate in frames per second, or zero if the device cannot play slowly.
uses files	Returns TRUE if the data storage used by a compound device is a file.
uses palettes	Returns TRUE if the device uses palettes.
windows	Returns the number of simultaneous display windows the device can support.

lpszFlags

Can be "wait", "notify", or both. For digital-video and VCR devices, "test" can also be specified. For more information about these flags, see The Wait, Notify, and Test Flags.

Return Value

Returns information in the lpszReturnString parameter of the mciSendString function. The information is dependent on the request type.

Examples

The following command returns the device type of the "mysound" device.

capability mysound device type

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]

See also

MCI

MCI Command Strings

cue