list command

The list command determines the number and types of video and audio inputs. Digital-video and VCR devices recognize this command.

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

_stprintf_s(
  lpszCommand, 
  TEXT("list %s %s %s"), 
  lpszDeviceID, 
  lpszList, 
  lpszFlags
); 

Parameters

lpszDeviceID

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

lpszList

Flag that identifies the number and types of video and audio inputs. The following table lists device types that recognize the list command and the flags used by each type.

Value	Meaning	Meaning
digitalvideo	audio algorithmaudio quality algorithm algorithmaudio streamcountnumber index	still algorithmstill quality algorithm algorithmvideo algorithmvideo quality algorithm algorithmvideo sourcevideo stream
vcr	audio source countaudio source number index	video source countvideo source number index

The following table lists the flags that can be specified in the lpszList parameter and their meanings.

Value	Meaning
audio algorithm	Specifies the command should retrieve audio algorithm names.
audio quality algorithm algorithm	Specifies the command should retrieve quality levels associated with the specified algorithm. If algorithm is "current", the quality level of the current algorithm is returned.
audio source count	Returns the total number of audio inputs.
audio source number index	Returns the type of audio input of source index.
audio stream	Specifies the command should retrieve the names of the audio streams associated with the workspace. These strings (such as "English" or "German") are embedded in the file and identify the stream.
count	Returns the number of options of the specified type.
number index	Returns a string describing a specific option (as identified by index) of the specified option type. Index must be an integer between 1 and the value returned by "count".
still algorithm	Specifies the command should retrieve still algorithm names.
still quality algorithm algorithm	Specifies the command should retrieve quality levels associated with the specified still algorithm. If algorithm is "current", the quality level of the current algorithm is returned.
video algorithm	Specifies the command should retrieve video algorithm names.
video quality algorithm algorithm	Specifies the command should retrieve quality levels associated with the specified video algorithm. If algorithm is "current", the quality level of the current algorithm is returned.
video source	Specifies the command should return information about the video sources. When used with the "count" flag, it returns the number of video sources. When used with the "number" flag, it returns the type of a video source. MCI defines the following constants for type: "ntsc", "rgb", "pal", "secam", "svideo", and "generic". There might be more than one source of each type returned. The "generic" source type is used when more than one signal is allowed for that connector.
video source count	Returns total number of video inputs.
video source number index	Returns the type of video input of source index.
video stream	Specifies the command should retrieve the names of video streams associated with the workspace. These strings (such as "funny ending" or "sad ending") are embedded in the file and identify the stream.

lpszFlags

Can be "wait", "notify", or "test". For more information about these flags, see The Wait, Notify, and Test Flags.

Return Value

Returns zero if successful or an error otherwise.

Remarks

For VCR devices, either "video source" or "audio source" must be specified with either the "count" or "number" flags. If "count" is specified, the total number of inputs of video or audio is returned. If "number" is specified, the driver returns a type corresponding to the input. The type can be any one of the following: "tuner", "line", "svideo", "aux", or "generic". Typically, you should first query the VCR for the "count" and then use the count as the range for the "number" flag. The "source" numbers start from 1.

Requirements

See also

MCI

MCI Command Strings