WFDB_wfdbgetstart
Keywords: wfdb_tools

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WFDB_wfdbgetstart

Usage: | `PLENGTH = WFDB_wfdbgetstart(SIG_NUM);` |
Input: | `SIG_NUM`: signal number (note: the first signal is signal number 0, etc.) |
Output: | `PLENGTH`: prolog length, in bytes |

This function gets the number of bytes in the prolog of the signal file that contains the specified input signal, as recorded in the header file. Note that `WFDB_wfdbgetstart` does not determine the length of the prolog by inspection of the signal file; it merely reports what has been determined by other means and recorded in the '.hea' file. Since the prolog is not readable using the WFDB library, and since functions such as `WFDB_isigopen` and `WFDB_isigsettime` take the prolog into account when calculating byte offsets for `WFDB_getframe` and `WFDB_getvec`, `WFDB_wfdbgetstart` is useful primarily for programs that need to rewrite existing '.hea' files, where it is necessary to preserve the previously recorded byte offsets.