1 .. -*- coding: utf-8; mode: rst -*-
3 .. _VIDIOC_S_HW_FREQ_SEEK:
5 ***************************
6 ioctl VIDIOC_S_HW_FREQ_SEEK
7 ***************************
12 VIDIOC_S_HW_FREQ_SEEK - Perform a hardware frequency seek
18 .. cpp:function:: int ioctl( int fd, int request, struct v4l2_hw_freq_seek *argp )
25 File descriptor returned by :ref:`open() <func-open>`.
36 Start a hardware frequency seek from the current frequency. To do this
37 applications initialize the ``tuner``, ``type``, ``seek_upward``,
38 ``wrap_around``, ``spacing``, ``rangelow`` and ``rangehigh`` fields, and
39 zero out the ``reserved`` array of a struct
40 :ref:`v4l2_hw_freq_seek <v4l2-hw-freq-seek>` and call the
41 ``VIDIOC_S_HW_FREQ_SEEK`` ioctl with a pointer to this structure.
43 The ``rangelow`` and ``rangehigh`` fields can be set to a non-zero value
44 to tell the driver to search a specific band. If the struct
45 :ref:`v4l2_tuner <v4l2-tuner>` ``capability`` field has the
46 ``V4L2_TUNER_CAP_HWSEEK_PROG_LIM`` flag set, these values must fall
47 within one of the bands returned by
48 :ref:`VIDIOC_ENUM_FREQ_BANDS`. If the
49 ``V4L2_TUNER_CAP_HWSEEK_PROG_LIM`` flag is not set, then these values
50 must exactly match those of one of the bands returned by
51 :ref:`VIDIOC_ENUM_FREQ_BANDS`. If the
52 current frequency of the tuner does not fall within the selected band it
53 will be clamped to fit in the band before the seek is started.
55 If an error is returned, then the original frequency will be restored.
57 This ioctl is supported if the ``V4L2_CAP_HW_FREQ_SEEK`` capability is
60 If this ioctl is called from a non-blocking filehandle, then ``EAGAIN``
61 error code is returned and no seek takes place.
64 .. _v4l2-hw-freq-seek:
66 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
68 .. flat-table:: struct v4l2_hw_freq_seek
80 - The tuner index number. This is the same value as in the struct
81 :ref:`v4l2_input <v4l2-input>` ``tuner`` field and the struct
82 :ref:`v4l2_tuner <v4l2-tuner>` ``index`` field.
90 - The tuner type. This is the same value as in the struct
91 :ref:`v4l2_tuner <v4l2-tuner>` ``type`` field. See
92 :ref:`v4l2-tuner-type`
100 - If non-zero, seek upward from the current frequency, else seek
109 - If non-zero, wrap around when at the end of the frequency range,
110 else stop seeking. The struct :ref:`v4l2_tuner <v4l2-tuner>`
111 ``capability`` field will tell you what the hardware supports.
119 - If non-zero, defines the hardware seek resolution in Hz. The
120 driver selects the nearest value that is supported by the device.
121 If spacing is zero a reasonable default value is used.
129 - If non-zero, the lowest tunable frequency of the band to search in
130 units of 62.5 kHz, or if the struct
131 :ref:`v4l2_tuner <v4l2-tuner>` ``capability`` field has the
132 ``V4L2_TUNER_CAP_LOW`` flag set, in units of 62.5 Hz or if the
133 struct :ref:`v4l2_tuner <v4l2-tuner>` ``capability`` field has
134 the ``V4L2_TUNER_CAP_1HZ`` flag set, in units of 1 Hz. If
135 ``rangelow`` is zero a reasonable default value is used.
143 - If non-zero, the highest tunable frequency of the band to search
144 in units of 62.5 kHz, or if the struct
145 :ref:`v4l2_tuner <v4l2-tuner>` ``capability`` field has the
146 ``V4L2_TUNER_CAP_LOW`` flag set, in units of 62.5 Hz or if the
147 struct :ref:`v4l2_tuner <v4l2-tuner>` ``capability`` field has
148 the ``V4L2_TUNER_CAP_1HZ`` flag set, in units of 1 Hz. If
149 ``rangehigh`` is zero a reasonable default value is used.
157 - Reserved for future extensions. Applications must set the array to
164 On success 0 is returned, on error -1 and the ``errno`` variable is set
165 appropriately. The generic error codes are described at the
166 :ref:`Generic Error Codes <gen-errors>` chapter.
169 The ``tuner`` index is out of bounds, the ``wrap_around`` value is
170 not supported or one of the values in the ``type``, ``rangelow`` or
171 ``rangehigh`` fields is wrong.
174 Attempted to call ``VIDIOC_S_HW_FREQ_SEEK`` with the filehandle in
178 The hardware seek found no channels.
181 Another hardware seek is already in progress.