QuickTimeTcl Commands - seqgrabber manual page

Boolean that defaults to 0. If 1, then no video grabber is created, only an audio grabber. A widget with -audioonly set shall not be mapped on the display. It is typically used for recording sound only. A minimal recording session reads:

seqgrabber .sg -audioonly 1 -file prat.mov
.sg start
.sg audiosettings
.sg record 
...
.sg stop

Note that, unlike the video grabber, it is necessary to explicitly start the audio grabber.

Command-Line Name: -file

Database Name: file

Database Class: File

Specifies the file path to a file to save any recording results to.

Command-Line Name: -framerate

Database Name: frameRate

Database Class: FrameRate

Specifies the desired framerate when recording. It defaults to 0.0 which I believe means max frame rate.

Command-Line Name: -height

Database Name: height

Database Class: Height

Specifies a desired height for the sequence grabber widget. If this option isn't specified, the sequence grabber's height is computed from the width option and the physical size of the video source in pixel coordinates. The ratio of height to width is kept identical to the corresponding ratio of the video source. If an explicit nonzero value of the width option is lacking, the height is found from the size option and the ratio of the video source height and width. If height is put equal to 0 it is disregarded. Both height and width cannot be set simultaneously. Any combination of the options cannot result in a widget size larger than the physical size of the video source in pixel coordinates. The framerate typically decreases with the size of the widget.

Command-Line Name: -overlayimage

Database Name: overlayImage

Database Class: OverlayImage

(Unimplemented on Windows.) Specifies an existing photo (created via image create photo) that should be displayed on top of the grabbed video sequence or still image. It is usually a small image that is shown in one of the corners, which for the moment defaults to the north east corner. Typically it contains large portions that are transparent. This option cannot be set or changed when the seqgrabber has been mapped on the display.

Command-Line Name: -playduringrecord

Database Name: playDuringRecord

Database Class: PlayDuringRecord

Boolean. Defaults to 1. Specifies if previewing shall be on if recording. Sometimes better performance is achieved if not.

Command-Line Name: -quality

Database Name: quality

Database Class: Quality

Specifies the desired playback quality of the video: fast, normal or high. It defaults to normal. The result can depend on the implementation of the drivers for the specific video source. Note that some (mine at least) fails when qulity is set to high, and just givs a white background.

Command-Line Name: -showfps

Database Name: showFPS

Database Class: ShowFPS

Boolean. Defaults to 0. If 1 a running counter and an estimated frames-per-second figure is drawn in the preview window.

Command-Line Name: -size

Database Name: size

Database Class: Size

Sets the wanted size of the grabbed video in terms of fractions of the physical size of the video source in pixel coordinates. It can be any of three values, full, half, or quarter. It defaults to half. If any of the height or width options has been set they override the size of the size option. Performance may be better if the size option is used instead of the height or width options. The framerate typically decreases with the size of the widget.

Command-Line Name: -videocompressor

Database Name: videoCompressor

Database Class: VideoCompressor

Sets the compressor type when recording video. The compressor is named by a four character text string. See ::quicktimetcl::info for how to find the available components on your system. As a shortcut, use the videosettings, set the wanted compressor there, save, and use cget -videcompressor to get the four character code.

Command-Line Name: -volume

Database Name: volume

Database Class: Volume

Sets the recording volume. It is a number between +1.0 and -1.0. Negative numbers means that sound is off, an is used to toggle on-off.

Command-Line Name: -width

Database Name: width

Database Class: Width

Specifies a desired width for the sequence grabber widget. If this option isn't specified, the sequence grabber's width is computed from the height option and the physical size of the video source in pixel coordinates. The ratio of height to width is kept identical to the corresponding ratio of the video source. If an explicit nonzero value of the height option is lacking, the width is found from the size option and the ratio of the video source height and width. If width is put equal to 0 it is disregarded. Both height and width cannot be set simultaneously. Any combination of the options cannot result in a widget size larger than the physical size of the video source in pixel coordinates. The framerate typically decreases with the size of the widget.

Command-Line Name: -zoom

Database Name: zoom

Database Class: Zoom

The zoom option must be given by a floating point number larger or equal to one (1). The video is zoomed in by this factor but the widget size is kept unchanged. As a result, the video source is clipped. The framerate may increase if the video is zoomed since not the complete video source rectangle needs to be captured.

DESCRIPTION

The sequence grabber widget is a widget for showing and capturing video and audio. Previewing starts automatically when the widget is displayed. It is typically used together with a web camera that has a driver interface to QuickTime. The QuickTime interface is general enough to allow for many types of input devices, such as DV video, for instance. Moreover, it is not limited to a particular hardware port on the computer, such as ADB (serial), USB, or FireWire. The content in the widget is updated "live", but it is possible to just take snapshots. Recording of video and audio to a movie file on disk is also possible. Standard panels for separately setting video and audio parameters are included as commands. Only a single instance of this widget can exist.

WIDGET COMMAND

The seqgrabber command creates a new Tcl command whose name is pathName. This command may be used to invoke various operations on the widget. It has the following general form:

pathName option ?arg arg ...?

Option and the args determine the exact behavior of the command. The following commands are possible for sequence grabber widgets:

pathName audiosettings

Displays the standard QuickTime audio settings panel as a dialog window. The settings are stored internally in QuickTime. It returns 0 if user canceled, 1 if Ok.

pathName cget option

Returns the current value of the configuration option given by option. Option may have any of the values accepted by the seqgrabber command.

pathName configure ?option? ?value option value ...?

Query or modify the configuration options of the widget. If no option is specified, returns a list describing all of the available options for pathName (see Tk_ConfigureInfo for information on the format of this list). If option is specified with no value, then the command returns a list describing the one named option (this list will be identical to the corresponding sublist of the value returned if no option is specified). If one or more option-value pairs are specified, then the command modifies the given widget option(s) to have the given value(s); in this case the command returns an empty string. Option may have any of the values accepted by the seqgrabber command.

pathName image procName imageName

Takes a snapshot asynchronously of the playback video frame and places it in the imageName, which must already exist. Create the imageName with image create photo imageName. The procName must look like:

proc shot {w imageName} {
   ...
}

Note that the image is not written after the pathName image returns, but when the procName is invoked. This is much faster than the picture command. The grabber must be running for this to work.

pathName ispaused

Returns 1 if the preview process is paused, and 0 if it's unpaused. Note that the process may be stopped but still unpaused.

pathName isrunning

Returns 1 if the preview process is neither paused, nor stopped, and 0 else.

pathName pause boolean

Pauses or unpauses the playback in the widget. It doesn't cause any system resources involved to be released so it's a rather "light" task.

pathName picture imageName

Takes a snapshot of the playback video frame and places it in the imageName, which must already exist. Create the imageName with image create photo imageName. See also image

pathName record

Starts recording to the file specified by the file option. A stop or pause command stops the recording.

pathName start

Starts video playback in the widget. The start and stop commands release and allocate system resources. For a short break it is therefore better to use pause. It also resets any paused state to unpause (?).

pathName stop

Stops video playback in the widget. It also stops any recording operations.

pathName videosettings

Displays the standard QuickTime video settings panel as a dialog window. The settings are stored internally in QuickTime. It returns 0 if user canceled, 1 if Ok.

BUGS

It happens that the quality option just stops previewing. Testing on Windows is limited to the emulated 'vdig' (Video Digitizer) component WinVDIG from "http://www.vdig.com". Experience with Connectix QuickCam and Philips ToUcam on Macintosh shows that video drivers are not always as robust as one would wish.

KEYWORDS

Sequence grabber, Movie,QuickTime and tk_getOpenFilePreview

Copyright © 2000-2001 Mats Bengtsson