MCI_GETDEVCAPS command

Artikkel
12/11/2020

The MCI_GETDEVCAPS command retrieves static information about a device. All devices recognize this command. The parameters and flags available for this command depend on the selected device. Information is returned in the dwReturn member of the structure identified by lpCapsParms.

To send this command, call the mciSendCommand function with the following parameters.

MCIERROR mciSendCommand(
  MCIDEVICEID wDeviceID, 
  MCI_GETDEVCAPS, 
  DWORD dwFlags, 
  (DWORD) (LPMCI_GETDEVCAPS_PARMS) lpCapsParms
);

Parameters

wDeviceID: Device identifier of the MCI device that is to receive the command message.
dwFlags: MCI_NOTIFY, MCI_WAIT, or, for digital-video and VCR devices, MCI_TEST. For information about these flags, see The Wait, Notify, and Test Flags.
lpCapsParms: Pointer to an MCI_GETDEVCAPS_PARMS structure.

Return Value

Returns zero if successful or an error otherwise.

Remarks

The following additional standard and command-specific flags apply to all devices supporting MCI_GETDEVCAPS:

MCI_GETDEVCAPS_COMPOUND_DEVICE: The dwReturn member is set to TRUE if the device uses data storage that must be explicitly opened and closed; it is set to FALSE otherwise.
MCI_GETDEVCAPS_DEVICE_TYPE: The dwReturn member is set to one of the values listed in MCI Device Types.
MCI_GETDEVCAPS_HAS_AUDIO: The dwReturn member is set to TRUE if the device has audio output; it is set to FALSE otherwise.
MCI_GETDEVCAPS_HAS_VIDEO: The dwReturn member is set to TRUE if the device has video output; it is set to FALSE otherwise. For example, the member is set to TRUE for devices that support the videodisc command set.
MCI_GETDEVCAPS_ITEM: Specifies that the dwItem member of the MCI_GETDEVCAPS_PARMS structure contains one of the following constants:
MCI_GETDEVCAPS_CAN_EJECT: The dwReturn member is set to TRUE if the device can eject the media; otherwise, it is set to FALSE.
MCI_GETDEVCAPS_CAN_PLAY: The dwReturn member is set to TRUE if the device can play the media; otherwise, it is set to FALSE. If a device specifies TRUE, it implies the device supports the MCI_PAUSE and MCI_STOP commands as well as the MCI_PLAY command.
MCI_GETDEVCAPS_CAN_RECORD: The dwReturn member is set to TRUE if the device supports recording; otherwise, it is set to FALSE. If a device specifies TRUE, it implies the device supports the MCI_PAUSE and MCI_STOP commands as well as the MCI_RECORD command.
MCI_GETDEVCAPS_CAN_SAVE: The dwReturn member is set to TRUE if the device can save a file; otherwise, it is set to FALSE.
MCI_GETDEVCAPS_USES_FILES: The dwReturn member is set to TRUE if the device requires a filename; it is set to FALSE otherwise. Only compound devices use files.

The following flags can be specified in the dwItem member of MCI_GETDEVCAPS_PARMS for the digitalvideo device type:

MCI_DGV_GETDEVCAPS_CAN_FREEZE: The dwReturn member is set to TRUE if the device can freeze frames; otherwise, it is set to FALSE.
MCI_DGV_GETDEVCAPS_CAN_LOCK: The dwReturn member is set to TRUE if the device can lock; otherwise, it is set to FALSE.
MCI_DGV_GETDEVCAPS_CAN_REVERSE: The dwReturn member is set to TRUE if the device can play in reverse; otherwise, it is set to FALSE.
MCI_DGV_GETDEVCAPS_CAN_STR_IN: The dwReturn member is set to TRUE if the device can stretch input; otherwise, it is set to FALSE.
MCI_DGV_GETDEVCAPS_CAN_STRETCH: The dwReturn member is set to TRUE if the device can stretch an image; otherwise, it is set to FALSE.
MCI_DGV_GETDEVCAPS_CAN_TEST: The dwReturn member is set to TRUE if the device can perform tests; otherwise, it is set to FALSE.
MCI_DGV_GETDEVCAPS_HAS_STILL: The dwReturn member is set to TRUE if the device can display still images; otherwise, it is set to FALSE.
MCI_DGV_GETDEVCAPS_MAX_WINDOWS: The dwReturn member is set to the maximum number of windows that the device can handle simultaneously.
MCI_DGV_GETDEVCAPS_MAXIMUM_RATE: The dwReturn member is set to the maximum play rate for the device, in frames per second.
MCI_DGV_GETDEVCAPS_MINIMUM_RATE: The dwReturn member is set to the minimum play rate for the device, in frames per second.
MCI_DGV_GETDEVCAPS_PALETTES: The dwReturn member is set to TRUE if the device can return a palette handle; otherwise, it is set to FALSE.

The following flags can be specified in the dwItem member of MCI_GETDEVCAPS_PARMS for the vcr device type:

MCI_GETDEVCAPS_CLOCK_INCREMENT_RATE: The dwReturn member is set to the number of increments per second.
MCI_VCR_GETDEVCAPS_CAN_DETECT_LENGTH: The dwReturn member is set to TRUE if the device is capable of detecting the length of the media; otherwise, it is set to FALSE.
MCI_VCR_GETDEVCAPS_CAN_FREEZE: The dwReturn member is set to TRUE if the device is capable of freezing the output image; otherwise, it is set to FALSE.
MCI_VCR_GETDEVCAPS_CAN_MONITOR_SOURCES: The dwReturn member is set to TRUE if the device is capable of monitoring sources; otherwise, it is set to FALSE.
MCI_VCR_GETDEVCAPS_CAN_PREROLL: The dwReturn member is set to TRUE if the device is capable of preroll; otherwise, it is set to FALSE.
MCI_VCR_GETDEVCAPS_CAN_PREVIEW: The dwReturn member is set to TRUE if the device is capable of previews; otherwise, it is set to FALSE.
MCI_VCR_GETDEVCAPS_CAN_REVERSE: The dwReturn member is set to TRUE if the device is capable of playing in reverse; otherwise, it is set to FALSE.
MCI_VCR_GETDEVCAPS_CAN_TEST: The dwReturn member is set to TRUE if the device is capable of testing; otherwise, it is set to FALSE.
MCI_VCR_GETDEVCAPS_HAS_CLOCK: The dwReturn member is set to TRUE if the device supports an external clock; otherwise, it is set to FALSE.
MCI_VCR_GETDEVCAPS_HAS_TIMECODE: The dwReturn member is set to TRUE if device has timecode capability or if this capability is unknown; otherwise, it is set to FALSE.
MCI_VCR_GETDEVCAPS_NUMBER_OF_MARKS: The dwReturn member is set to the number of marks (99).
MCI_VCR_GETDEVCAPS_SEEK_ACCURACY: The dwReturn member is set to the seek accuracy of the device.

The following flags can be specified in the dwItem member of MCI_GETDEVCAPS_PARMS for the overlay device type:

MCI_OVLY_GETDEVCAPS_CAN_FREEZE: The dwReturn member is set to TRUE if the device can freeze the image; otherwise, it is set to FALSE.
MCI_OVLY_GETDEVCAPS_CAN_STRETCH: The dwReturn member is set to TRUE if the device can stretch the image to fill the frame; otherwise, it is set to FALSE.
MCI_OVLY_GETDEVCAPS_MAX_WINDOWS: The dwReturn member is set to the maximum number of windows that the device can handle simultaneously.

The following flags can be specified in the dwItem member of MCI_GETDEVCAPS_PARMS for the videodisc device type:

MCI_VD_GETDEVCAPS_CAN_REVERSE: The dwReturn member is set to TRUE if the videodisc player can play in reverse; otherwise, it is set to FALSE. Some players can play CLV discs in reverse as well as CAV discs.
MCI_VD_GETDEVCAPS_CAV: When combined with other items, specifies that the return information applies to CAV format videodiscs. This is the default if no videodisc is inserted.
MCI_VD_GETDEVCAPS_CLV: When combined with other items, specifies that the return information applies to CLV format videodiscs.
MCI_VD_GETDEVCAPS_FAST_RATE: The dwReturn member is set to the standard fast play rate in frames per second.
MCI_VD_GETDEVCAPS_NORMAL_RATE: The dwReturn member is set to the normal play rate in frames per second.
MCI_VD_GETDEVCAPS_SLOW_RATE: The dwReturn member is set to the standard slow play rate in frames per second.

The following flags can be specified in the dwItem member of MCI_GETDEVCAPS_PARMS for the waveaudio device type:

MCI_WAVE_GETDEVCAPS_INPUT: The dwReturn member is set to the total number of waveform input (recording) devices.
MCI_WAVE_GETDEVCAPS_OUTPUT: The dwReturn member is set to the total number of waveform output (playback) devices.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Mmsystem.h (include Windows.h)

Del via

MCI_GETDEVCAPS command

Parameters

Return Value

Remarks

Requirements

See also

Tilbakemeldinger

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