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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.

ValueMeaningMeaning
digitalvideoaudio algorithmaudio quality algorithm algorithmaudio streamcountnumber indexstill algorithmstill quality algorithm algorithmvideo algorithmvideo quality algorithm algorithmvideo sourcevideo stream
vcraudio source countaudio source number indexvideo source countvideo source number index

 

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

ValueMeaning
audio algorithmSpecifies the command should retrieve audio algorithm names.
audio quality algorithm algorithmSpecifies 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 countReturns the total number of audio inputs.
audio source number indexReturns the type of audio input of source index.
audio streamSpecifies 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.
countReturns the number of options of the specified type.
number indexReturns 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 algorithmSpecifies the command should retrieve still algorithm names.
still quality algorithm algorithmSpecifies 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 algorithmSpecifies the command should retrieve video algorithm names.
video quality algorithm algorithmSpecifies 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 sourceSpecifies 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 countReturns total number of video inputs.
video source number indexReturns the type of video input of source index.
video streamSpecifies 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

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

See also

MCI
MCI Command Strings

 

 

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