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+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: DTV.dmx
+
+.. _dmx_fopen:
+
+=======================
+Digital TV demux open()
+=======================
+
+Name
+----
+
+Digital TV demux open()
+
+Synopsis
+--------
+
+.. c:function:: int open(const char *deviceName, int flags)
+
+Arguments
+---------
+
+``name``
+  Name of specific Digital TV demux device.
+
+``flags``
+  A bit-wise OR of the following flags:
+
+.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
+
+.. flat-table::
+    :header-rows:  0
+    :stub-columns: 0
+    :widths: 1 16
+
+    -
+       - ``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.
+
+.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
+
+.. flat-table::
+    :header-rows:  0
+    :stub-columns: 0
+    :widths: 1 16
+
+    -  -  ``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.