---
name: "pcap_set_tstamp_precision"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/pcap_set_tstamp_precision"
---

# pcap\_set\_tstamp\_precision(3)

set the time stamp precision returned in captures

## NAME

pcap\_set\_tstamp\_precision - set the time stamp precision returned in captures

## SYNOPSIS

```
#include <pcap/pcap.h>
```

**int pcap\_set\_tstamp\_precision(pcap\_t \*p, int tstamp\_precision);**

## DESCRIPTION

**pcap\_set\_tstamp\_precision**() sets the precision of the time stamp desired for packets captured on the pcap descriptor to the type specified by *tstamp\_precision*. It must be called on a pcap descriptor created by [**pcap\_create**(3)](/pcap_create/3.md) that has not yet been activated by [**pcap\_activate**(3)](/pcap_activate/3.md). Two time stamp precisions are supported, microseconds and nanoseconds. One can use options **PCAP\_TSTAMP\_PRECISION\_MICRO** and **PCAP\_TSTAMP\_PRECISION\_NANO** to request desired precision. By default, time stamps are in microseconds.

## RETURN VALUE

**pcap\_set\_tstamp\_precision**() returns **0** on success if the specified time stamp precision is expected to be supported by the capture device, **PCAP\_ERROR\_TSTAMP\_PRECISION\_NOTSUP** if the capture device does not support the requested time stamp precision, **PCAP\_ERROR\_ACTIVATED** if called on a capture handle that has been activated.

## BACKWARD COMPATIBILITY

This function became available in libpcap release 1.5.1.  In previous releases, time stamps from a capture device or savefile are always given in seconds and microseconds.

## SEE ALSO

[**pcap**(3)](/pcap/3.md), [**pcap\_get\_tstamp\_precision**(3)](/pcap_get_tstamp_precision/3.md), [**pcap-tstamp**(7)](/pcap-tstamp/7.md)