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WFDB 10.2

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Changes in version 10.2.9 (27 October 2002)

Fixed a bug in example 9 in this guide (introduced in version 10.2.0).

Updated ‘lib/wfdbdll.def’ and the ‘Makefile.dos’ files in several directories. These have not been tested in recent years and may need further revisions; feedback is welcome.

Corrected persistent problems with generating PDF versions of the manuals for the desired page size, and added hyperlinks to the PDF version of this guide.

(WFDB library version 10.2.8 was identical to 10.2.7.)

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Changes in version 10.2.7 (14 October 2002)

Added a workaround to wfdb_fclose (in ‘lib/wfdbio.c’) so that closing stdin after using freopen doesn’t trigger a core dump.

If out-of-order annotations were written and automatic annotation sorting was suppressed, the warning produced by oannclose (in ‘lib/annot.c’) once again includes the correct sortann command needed to put the annotations into order. (This feature was broken by a previous revision.)

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Changes in version 10.2.6 (24 June 2002)

The new functions setifreq and getifreq allow an application to choose any convenient sampling frequency for reading input signals. Samples read from signal files using getvec are buffered, resampled, and delivered to the calling application as if the original signals had been sampled at the desired frequency. Times expressed in sample intervals passed to or from other WFDB library functions (getann, putann, mstimstr, timstr, and strtim) are rescaled as needed to match intervals corresponding to the chosen frequency. Thanks to Pat Hamilton for the inspiration!

The WFDB library now records the base time with millisecond precision (previous versions did so with one-second precision), and ‘xform’ provides starting times to the library function setbasetime with millisecond precision. Thanks to Allavatam Venugopal for providing examples that illustrated the need for these features.

Fixed deskewing buffer initialization in getframe, broken by the 10.2.0 update, which introduced an infinite loop when reading a record that requires skew correction starting at sample 0. Thanks to Andrew Walsh for finding an example that triggered this bug.

Fixed rounding errors in adumuv, muvadu, and physadu. Previous versions rounded negative values toward zero; to obtain consistent conversions, however, it is necessary to round all values down (e.g., from -1.5 to -2 rather than up to -1).

Fixed a memory leak in wfdb_fclose (in ‘lib/wfdbio.h’). Thanks to Ion Gaztañaga.

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Changes in version 10.2.5 (10 March 2002)

Additions and fixes in ‘wfdbf.c’ (the Fortran wrappers for the WFDB library).

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Changes in version 10.2.4 (20 December 2001)

Code in ‘wfdbio.c’ that required the use of the string header to identify a header file has been revised so that the standard hea is now usable for this purpose in all cases.

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Changes in version 10.2.3 (14 December 2001)

Portability fixes in ‘wfdblib.h’. (WFDB library version 10.2.2 was identical to 10.2.1.)

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Changes in version 10.2.1 (16 November 2001)

Most users will no longer need to set the WFDB path explicitly, as a result of several minor changes in the default path and in the installer for the WFDB Software Package.

The environment variable WFDBNOSORT was replaced by WFDBANNSORT, and the environment variable WFDBGVMODE was introduced (see section Annotation Order, and see section Multi-Frequency Records, for details).

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Changes in version 10.2.0 (15 October 2001)

There are no longer any fixed limits on the numbers of signals or annotation files that can be opened simultaneously, or on the number of samples per signal per frame. In previous versions of the WFDB library, the symbols WFDB_MAXSIG, WFDB_MAXANN, and WFDB_MAXSPF (all defined in ‘<wfdb/wfdb.h>’) specified limits on these parameters that could be modified only by recompiling the WFDB library. These symbols are still defined for compatibility with older applications that use them (typically to determine the size of static arrays).

Since version 10.1.1, record names may include path information (see the notes for version 10.1.1 below), but if such names are used to generate names of WFDB output files, the user has been required to ensure that the target directory exists. This requirement is eliminated in version 10.2.0. If an output file is specified to be located in a non-existent directory, the WFDB library will attempt to create the directory (including, if necessary, any non-existent parent directories). This feature simplifies the use of record names that include directory information, as is common when reading data from a CDROM or a web server such as PhysioNet. For example, using the WFDB path (‘. http://physionet.org/physiobank/database’), if the current directory, ‘.’, does not contain a subdirectory named ‘mitdb’, the command:

sqrs -r mitdb/100

will read its input from http://physionet.org/physiobank/database/mitdb/, will create a directory named ‘mitdb’ within the current directory, and will write its output annotation file (‘100.qrs’) into this newly-created directory. If we then use the command:

rdann -r mitdb/100 -a qrs

the header file is still read from the remote directory, but the annotation file is read from ‘./mitdb’. (The programs ‘sqrs’ and ‘rdann’ are standard applications that use the WFDB library; see the WFDB Applications Guide for details.)

Also new is the WFDB test suite (located in the ‘checkpkg’ directory of the WFDB source tree, at the same level as the ‘lib’ directory containing the WFDB library sources). This set of programs can be used to help verify that a newly-installed version of the WFDB library behaves properly.

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George B. Moody (george@mit.edu)