1.. Permission is granted to copy, distribute and/or modify this
2.. document under the terms of the GNU Free Documentation License,
3.. Version 1.1 or any later version published by the Free Software
4.. Foundation, with no Invariant Sections, no Front-Cover Texts
5.. and no Back-Cover Texts. A copy of the license is included at
6.. Documentation/userspace-api/media/fdl-appendix.rst.
7..
8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
9
10.. _dmx_fwrite:
11
12========================
13Digital TV demux write()
14========================
15
16Name
17----
18
19Digital TV demux write()
20
21
22Synopsis
23--------
24
25.. c:function:: ssize_t write(int fd, const void *buf, size_t count)
26    :name: dvb-dmx-write
27
28Arguments
29---------
30
31``fd``
32  File descriptor returned by a previous call to :c:func:`open() <dvb-ca-open>`.
33
34``buf``
35     Buffer with data to be written
36
37``count``
38    Number of bytes at the buffer
39
40Description
41-----------
42
43This system call is only provided by the logical device
44``/dev/dvb/adapter?/dvr?``, associated with the physical demux device that
45provides the actual DVR functionality. It is used for replay of a
46digitally recorded Transport Stream. Matching filters have to be defined
47in the corresponding physical demux device, ``/dev/dvb/adapter?/demux?``.
48The amount of data to be transferred is implied by count.
49
50
51Return Value
52------------
53
54On success 0 is returned.
55
56On error -1 is returned, and the ``errno`` variable is set
57appropriately.
58
59.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
60
61.. flat-table::
62    :header-rows:  0
63    :stub-columns: 0
64    :widths: 1 16
65
66    -  -  ``EWOULDBLOCK``
67       -  No data was written. This might happen if ``O_NONBLOCK`` was
68	  specified and there is no more buffer space available (if
69	  ``O_NONBLOCK`` is not specified the function will block until buffer
70	  space is available).
71
72    -  -  ``EBUSY``
73       -  This error code indicates that there are conflicting requests. The
74	  corresponding demux device is setup to receive data from the
75	  front- end. Make sure that these filters are stopped and that the
76	  filters with input set to ``DMX_IN_DVR`` are started.
77
78The generic error codes are described at the
79:ref:`Generic Error Codes <gen-errors>` chapter.
80