media/v4l/vidioc-query-dv-timings.rst

1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
13 VIDIOC_QUERY_DV_TIMINGS - VIDIOC_SUBDEV_QUERY_DV_TIMINGS - Sense the DV preset received by the curr…
38 The hardware may be able to detect the current DV timings automatically,
39 similar to sensing the video standard. To do so, applications call
41 :c:type:`v4l2_dv_timings`. Once the hardware detects
42 the timings, it will fill in the timings structure.
47    timings are detected. Instead, drivers should send the
50    The reason is that new timings usually mean different buffer sizes as
51    well, and you cannot change buffer sizes on the fly. In general,
52    applications that receive the Source Change event will have to call
53    :ref:`VIDIOC_QUERY_DV_TIMINGS`, and if the detected timings are valid they
54    will have to stop streaming, set the new timings, allocate new buffers
57 If the timings could not be detected because there was no signal, then
59 the receiver could not lock to the signal, then ``ENOLCK`` is returned. If
60 the receiver could lock to the signal, but the format is unsupported
61 (e.g. because the pixelclock is out of range of the hardware
62 capabilities), then the driver fills in whatever timings it could find
63 and returns ``ERANGE``. In that case the application can call
64 :ref:`VIDIOC_DV_TIMINGS_CAP` to compare the
65 found timings with the hardware's capabilities in order to give more
66 precise feedback to the user.
71 On success 0 is returned, on error -1 and the ``errno`` variable is set
72 appropriately. The generic error codes are described at the
73 :ref:`Generic Error Codes <gen-errors>` chapter.
82     The signal was unstable and the hardware could not lock on to it.
85     Timings were found, but they are out of range of the hardware