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