.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. c:namespace:: DTV.dmx

.. _DMX_GET_STC:

===========
DMX_GET_STC
===========

Name
----

DMX_GET_STC

Synopsis
--------

.. c:macro:: DMX_GET_STC

``int ioctl(int fd, DMX_GET_STC, struct dmx_stc *stc)``

Arguments
---------

``fd``
    File descriptor returned by :c:func:`open()`.

``stc``
    Pointer to :c:type:`dmx_stc` where the stc data is to be stored.

Description
-----------

This ioctl call returns the current value of the system time counter
(which is driven by a PES filter of type :c:type:`DMX_PES_PCR <dmx_ts_pes>`).
Some hardware supports more than one STC, so you must specify which one by
setting the :c:type:`num <dmx_stc>` field of stc before the ioctl (range 0...n).
The result is returned in form of a ratio with a 64 bit numerator
and a 32 bit denominator, so the real 90kHz STC value is
``stc->stc / stc->base``.

Return Value
------------

On success 0 is returned.

On error -1 is returned, and the ``errno`` variable is set
appropriately.

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       -  ``EINVAL``

       -  Invalid stc number.

The generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.