linux/Documentation/media/uapi/dvb/dmx-get-stc.rst
Mauro Carvalho Chehab 883dfe8ae6 media: dvb uAPI docs: minor editorial changes
Do minor editorial changes to improve documentation readability:

- mark literals as such;
- add table markups to hint sizes;
- define what PES means;
- instead of hardcoding devnode numbers to zero (like adapter0/) use a
  question mark, to indicate that multiple devnodes may exist;
- add cross-references where useful.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2017-09-05 06:19:32 -04:00

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.. -*- coding: utf-8; mode: rst -*-
.. _DMX_GET_STC:
===========
DMX_GET_STC
===========
Name
----
DMX_GET_STC
Synopsis
--------
.. c:function:: int ioctl( int fd, DMX_GET_STC, struct dmx_stc *stc)
:name: DMX_GET_STC
Arguments
---------
``fd``
File descriptor returned by :c:func:`open() <dvb-dmx-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.