linux/Documentation/media/uapi/dvb/dmx-fopen.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_fopen:
=======================
Digital TV demux open()
=======================
Name
----
Digital TV demux open()
Synopsis
--------
.. c:function:: int open(const char *deviceName, int flags)
:name: dvb-dmx-open
Arguments
---------
``name``
Name of specific Digital TV demux device.
``flags``
A bit-wise OR of the following flags:
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-
- ``O_RDONLY``
- read-only access
-
- ``O_RDWR``
- read/write access
-
- ``O_NONBLOCK``
- open in non-blocking mode
(blocking mode is the default)
Description
-----------
This system call, used with a device name of ``/dev/dvb/adapter?/demux?``,
allocates a new filter and returns a handle which can be used for
subsequent control of that filter. This call has to be made for each
filter to be used, i.e. every returned file descriptor is a reference to
a single filter. ``/dev/dvb/adapter?/dvr?`` is a logical device to be used
for retrieving Transport Streams for digital video recording. When
reading from this device a transport stream containing the packets from
all PES filters set in the corresponding demux device
(``/dev/dvb/adapter?/demux?``) having the output set to ``DMX_OUT_TS_TAP``.
A recorded Transport Stream is replayed by writing to this device.
The significance of blocking or non-blocking mode is described in the
documentation for functions where there is a difference. It does not
affect the semantics of the ``open()`` call itself. A device opened
in blocking mode can later be put into non-blocking mode (and vice versa)
using the ``F_SETFL`` command of the fcntl system call.
Return Value
------------
On success 0 is returned.
On error -1 is returned, and the ``errno`` variable is set
appropriately.
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- - ``EMFILE``
- “Too many open files”, i.e. no more filters available.
The generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.