WVIEW(1)

NAME
wview - WFDB browser for MS Windows

SYNOPSIS
wview
wview record
wview record annotator
wview record annotator start-time
wview [drive:][path]record.hea

DESCRIPTION

Note: wview will soon be retired in favor of gtkwave(1).

This program reads one or more signal files and an annotation file (if one is available), and displays the signals with annotations on a PC running MS Windows 3.1 (or later). To run it, either select the wview icon from the appropriate Start menu or Program Manager group (usually `Applications'), select a WFDB `header' file (a file named with the suffix `.hea') from Windows Explorer or File Manager, or enter one of the wview command lines listed above (under `Synopsis') in the Run... window of the Start menu or the Program Manager's File menu. The first two of these methods work only if wview has been installed as described below, under `Installation'; use the Run... method if you have not performed the full installation procedure. If MS Windows is not running, you may start it and launch wview from the MS-DOS prompt by typing win wview (this command may also include record, annotator and start-time options as shown above). Refer to Microsoft's Windows User's Guide for general information about starting and using MS Windows.

The current version of wview is an alpha release. A few of the controls are not implemented, and appear as inactive (greyed) menu items. In comparison with other available software for viewing annotated WFDB records, wview's capabilities lie somewhere between those of view(1) (for MS-DOS) and wave(1) (for the X Window System). wview can do anything that view can do, and much more, but view is likely to be substantially faster than wview on older PCs that do not have 32-bit CPUs with numeric coprocessors and MS Windows accelerated graphics cards. wview has most of the display capabilities of wave with the exception of `scope' windows, but it lacks wave's capabilities for annotation editing and control of external analysis programs, as well as a variety of less important features.

  Choosing Files to View

The Choose Inputs dialog usually appears when you start wview. It allows you to select a database record to view. If you start wview using a command line, or by selecting a WFDB `header' file from the File Manager, wview opens the record immediately without showing the Choose Inputs dialog. If you supply a record name but omit the annotator name, wview attempts to find the reference (atr) annotations. At any time, you may pop up the Choose Inputs dialog by selecting Open... from the File menu, in order to change the record or annotator names, or the WFDB environment (the WFDB path and the WFDB calibration file).

To select sets of signals and annotations to view, fill in the Record name: field (up to 8 characters), and the Annotator name: field (up to 3 characters). Leave the Annotator name: field empty if the record is unannotated, or if you do not wish to view annotations. Although the WFDB environment may be changed within the Choose Inputs dialog, note that the effects of any such changes are limited to the current session of the WFDB (other WFDB applications and future wview sessions are unaffected).

The WFDB path is a list of directories that are searched when you specify a record or annotator name. The WFDB path is usually initialized by setting the MS-DOS environment variable WFDB before starting MS Windows, using the MS-DOS batch file setwfdb.bat (see setwfdb(1)). If a WFDB `header' file was selected (either from the File Manager or from the command line), the optional drive:path component of the file name, if present, is inserted at the beginning of the WFDB path (but after the current directory, if the WFDB path begins with the current directory or has not been initialized).

The WFDB calibration file is a text file containing information about the relative scales of many different types of signals (see wfdbcal(5)). The WFDB calibration file is usually specified by setting the MS-DOS environment variable WFDBCAL; as for the WFDB path, this is usually performed using setwfdb.bat before starting MS Windows. Do not include a drive specification or path information in the name of the WFDB calibration file unless the file cannot be found in any of the directories named in the WFDB path.

  Browsing a Record

Use the scrollbar at the bottom of the window to move in either direction through the record. If you click on the scrollbar arrows, the display scrolls by 1 second at a time in the indicated direction. Clicking in the rectangles beside the ``thumb'' of the scrollbar scrolls the display by the width of the window. You may also drag the ``thumb'' to move to any desired location.

Keyboard commands can also perform these functions and others:
<left-arrow> | back 1 second
<right-arrow> | forward 1 second
<Page Up> | back 1 screenful
<Page Down> | forward 1 screenful
<Home> | back to beginning
<End> | forward to end
<Enter> | search forward (see below)
<backspace> | search backward (see below)
<up-arrow> | zoom in (increase time scale)
<down-arrow> | zoom out (decrease time scale)
+ | increase signal amplitude
- | decrease signal amplitude

You may also enter a desired time in the Recenter at field of the Find window (accessible from the Edit menu). wview redraws the display centered on the specified time.

The times shown in the lower corners of the signal window usually indicate elapsed time from the beginning of the record in hours, minutes, and seconds (hours are omitted if the elapsed time is less than one hour). If the times are shown enclosed in square brackets, they indicate the actual time of day (and possibly the date) when the signals shown were recorded, determined by reference to the base time and date recorded in the header file for the record.

  Options

Use the Options menu to set display and printing options. The View Options... dialog allows you to choose display scales, turn the grid on and off, and select options for annotation and signal display. The Print Options... dialog is very similar, but its options apply to printed output only. (The Print Options... dialog may also be accessed via the Options... button in the Print... dialog, which may be opened from the File menu.)

Select Use default scales and options from View Options... to reset all display options to their initial values. In Print Options..., select Use display scales and options to set the printing options to match those you have chosen for display.

If displayed or printed, the grid marks 200 ms intervals horizontally, and 0.5 mV intervals vertically. (For signals not dimensioned in units of mV, the WFDB calibration file specifies the scaling factor between the physical units of the signal and mV.) At the default scales, the grid intervals should measure 5 mm on your screen or printed output, corresponding to the standard ECG display scales of 25 mm/s and 10 mm/mV. (If this is not the case, click on Calibrate... and follow the instructions on-screen to make appropriate adjustments for your hardware.)

Marker bars, if displayed or printed, show the exact locations of each annotation. Note that policies for placement of ECG annotations may vary between records (for example, in the MIT-BIH Arrhythmia Database, QRS annotations are placed at the R-wave peak, but in the AHA Database, these annotations are placed at the PQ junction).

Normally, wview shows only the mnemonic corresponding to the primary annotation type (the anntyp field) of each annotation. Exceptions include RHYTHM annotations (for which the rhythm, encoded in the aux field of the annotation, is shown); NOISE annotations, for which signal quality data encoded in the subtyp field are shown); and STCH, TCH, and NOTE annotations (for which the contents of the aux field are shown). To make it easier to identify these exceptions, RHYTHM annotations appear below the level of ordinary annotations, and the others appear above the level of ordinary annotations. The representation matches that used in the MIT-BIH Arrhythmia Database Directory and other directories, which contain complete lists of the mnemonics used in each database.

By selecting the appropriate items from View Options... or Print Options..., you can view or print the contents of the optional annotation fields (subtyp, chan, num, and aux, shown from top to bottom in that order if two or more are selected). See the WFDB Programmer's Guide for further information about optional annotation fields.

Signal baselines, if selected, are displayed or printed only for signals for which absolute levels are significant, such as blood pressure. Such signals are referred to as DC-coupled signals, since they must be digitized without being passed through high-pass filters in order to preserve absolute levels. In signals such as ECGs, only variations in level, rather than absolute levels are significant. These AC-coupled signals are high-pass filtered before digitization, in order to remove any DC component, so that the gain can be chosen optimally for the range of variation in the signal. By default, signal names appear at the left margin slightly above each signal; deselect Signal names to suppress this output. The header file for each record specifies signal names, and which signals are DC-coupled; see the WFDB Programmer's Guide for further information.

  Searching for Annotations

Select Find... from the Edit menu to bring up the Find dialog. Enter an annotation mnemonic (e.g., V) in the Search forward or Search backward field. Click on the radio button to the left of the chosen search direction, then click on OK. wview redraws the signals, centered on the next annotation of the specified type that was not visible in the previous screenful. If the search is unsuccessful, the Find window remains visible, so that you can modify the search criteria.

In addition to standard annotation mnemonics (listed in the WFDB Programmer's Guide), you may enter signal quality strings (as displayed by wview for NOISE annotations), or aux strings (as displayed for RHYTHM, ST and T change, and NOTE annotations). In short, you may search for any string that wview uses when drawing annotations. When specifying aux strings, a prefix is sufficient as a search target (for example, ``(S'' matches any annotation with an aux string beginning with these characters, such as ``(SVTA'' or ``(ST0+'').

To repeat a search forward, press the <enter> key; to repeat a search backward, press the <backspace> key. If you use these keyboard shortcuts without having defined a search target, <enter> behaves in the same way as <Page Down>, and <backspace> in the same way as <Page Up> (moving to the adjacent screenful in the appropriate direction).

  Printing

You can print the current contents of the main wview window, or any selected segment of the current record, by selecting Print... from the File menu to bring up the Print dialog. Choose the output device from the Printer list. Select the range (time interval) to be printed by choosing either Entire Record, Current Contents of Window (the default), or Segment. If you choose Segment, enter the times of the beginning and end of the desired segment in the From: and To: fields. Press OK to begin printing, or Cancel to return to wview without printing.

  Help

On-line help is available by selecting a topic from the Help menu, or by selecting any control and pressing the F1 key. The Help menu topics include most of the text of this man page.

ENVIRONMENT

WFDB
    The database path: a list of directories that contain database files. An empty component is taken to refer to the current directory. All applications built with the wfdb(3) library search for their database input files in the order specified by WFDB. If WFDB is not set, searches are limited to the builtin WFDB path (see setwfdb(3)). Under MS-DOS/MS-Windows, directory names are separated by semicolons (;), and the format of WFDB is that of the MS-DOS PATH variable (colons may be used following drive specifiers within WFDB in this case).

WFDBCAL
    The name of the WFDB calibration file (see wfdbcal(5)), which must be in a directory named by WFDB (see immediately above). This file is used by wview to determine standard scales for signals other than ECGs. If WFDBCAL is not set, the default WFDB calibration file is used (see setwfdb(3)). If the calibration file is not readable, signals may be drawn at incorrect scales.

After determining appropriate values for these variables, you may wish to add commands for setting them to your autoexec.bat file.

INSTALLATION

The current version of wview requires manual installation of a few files:
wview.exe | wview itself, in Windows executable form
wview.hlp | the compressed MS Windows Help file for wview
wfdb.dll | the WFDB library, compiled as a large model MS Windows DLL
All of these files should be installed in the same directory, which should be somewhere in your PATH; the main MS Windows directory (usually c:\windows) seems to be the most popular choice for commercial MS Windows applications, and is suitable for this purpose. Be certain that you do not overwrite other files of the same names, however (I don't know of any commercial applications that use these file names, but check your system to be safe). At this point, it is possible to start wview using the command-line interface.

To install a wview icon in the Program Manager workspace, select (click once on) a program group (such as `Applications'). Select New... from the Program Manager's File menu, choose Program item from the New Program Object dialog that appears, and click on OK. The Program Item Properties dialog then appears. Enter ``WFDB Browser'' in the Description: field, and the full pathname of wview.exe in the Command line: field, then click on OK. It is now possible to start wview by clicking on its icon.

Finally, open the MS Windows File Manager and choose Associate... from its File menu. Enter ``hea'' in the Files with extension: field, and click on Browse. Find and select wview.exe using the Browse dialog, and click on OK. This procedure makes it possible to start wview simply by double-clicking on any WFDB header (.hea) file.

BUGS

Probably many. Please send your comments, suggestions, and bug reports to the author: George B. Moody
MIT Room E25-505A
Cambridge, MA 02139 USA
Internet: george@mit.edu

A significant known bug is that only one instance of wview may be run at any given time. This is a consequence of using a large memory model DLL (in this case, wfdb.dll) under MS Windows 3.1. Fixing this bug is a very low priority (i.e., not likely to happen soon unless it is fixed by a future version of MS Windows). If you are careful, it is possible to have two or more instances running simultaneously provided that the same record (and annotator, if any) are open in all instances. Exit cleanly by iconifying (closing) all instances first, then quit each instance without reopening the window.

SEE ALSO
pschart(1) (for PostScript), view(1) (for MS-DOS), wave(1) (for X11), gtkwave(1) (for MS-Windows)

AUTHOR
George B. Moody (george@mit.edu)

SOURCES
http://www.physionet.org/physiotools/wfdb/wview/