diff options
Diffstat (limited to 'Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst')
| -rw-r--r-- | Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst b/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst new file mode 100644 index 000000000000..ea754f4f5532 --- /dev/null +++ b/Documentation/media/uapi/v4l/vidioc-enum-freq-bands.rst @@ -0,0 +1,190 @@ +.. -*- coding: utf-8; mode: rst -*- + +.. _VIDIOC_ENUM_FREQ_BANDS: + +**************************** +ioctl VIDIOC_ENUM_FREQ_BANDS +**************************** + +Name +==== + +VIDIOC_ENUM_FREQ_BANDS - Enumerate supported frequency bands + + +Synopsis +======== + +.. cpp:function:: int ioctl( int fd, int request, struct v4l2_frequency_band *argp ) + + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`open() <func-open>`. + +``request`` + VIDIOC_ENUM_FREQ_BANDS + +``argp`` + + +Description +=========== + +Enumerates the frequency bands that a tuner or modulator supports. To do +this applications initialize the ``tuner``, ``type`` and ``index`` +fields, and zero out the ``reserved`` array of a struct +:ref:`v4l2_frequency_band <v4l2-frequency-band>` and call the +:ref:`VIDIOC_ENUM_FREQ_BANDS` ioctl with a pointer to this structure. + +This ioctl is supported if the ``V4L2_TUNER_CAP_FREQ_BANDS`` capability +of the corresponding tuner/modulator is set. + + +.. _v4l2-frequency-band: + +.. flat-table:: struct v4l2_frequency_band + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 1 1 + + + - .. row 1 + + - __u32 + + - ``tuner`` + + - The tuner or modulator index number. This is the same value as in + the struct :ref:`v4l2_input <v4l2-input>` ``tuner`` field and + the struct :ref:`v4l2_tuner <v4l2-tuner>` ``index`` field, or + the struct :ref:`v4l2_output <v4l2-output>` ``modulator`` field + and the struct :ref:`v4l2_modulator <v4l2-modulator>` ``index`` + field. + + - .. row 2 + + - __u32 + + - ``type`` + + - The tuner type. This is the same value as in the struct + :ref:`v4l2_tuner <v4l2-tuner>` ``type`` field. The type must be + set to ``V4L2_TUNER_RADIO`` for ``/dev/radioX`` device nodes, and + to ``V4L2_TUNER_ANALOG_TV`` for all others. Set this field to + ``V4L2_TUNER_RADIO`` for modulators (currently only radio + modulators are supported). See :ref:`v4l2-tuner-type` + + - .. row 3 + + - __u32 + + - ``index`` + + - Identifies the frequency band, set by the application. + + - .. row 4 + + - __u32 + + - ``capability`` + + - :cspan:`2` The tuner/modulator capability flags for this + frequency band, see :ref:`tuner-capability`. The + ``V4L2_TUNER_CAP_LOW`` or ``V4L2_TUNER_CAP_1HZ`` capability must + be the same for all frequency bands of the selected + tuner/modulator. So either all bands have that capability set, or + none of them have that capability. + + - .. row 5 + + - __u32 + + - ``rangelow`` + + - :cspan:`2` The lowest tunable frequency in units of 62.5 kHz, or + if the ``capability`` flag ``V4L2_TUNER_CAP_LOW`` is set, in units + of 62.5 Hz, for this frequency band. A 1 Hz unit is used when the + ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is set. + + - .. row 6 + + - __u32 + + - ``rangehigh`` + + - :cspan:`2` The highest tunable frequency in units of 62.5 kHz, + or if the ``capability`` flag ``V4L2_TUNER_CAP_LOW`` is set, in + units of 62.5 Hz, for this frequency band. A 1 Hz unit is used + when the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is set. + + - .. row 7 + + - __u32 + + - ``modulation`` + + - :cspan:`2` The supported modulation systems of this frequency + band. See :ref:`band-modulation`. Note that currently only one + modulation system per frequency band is supported. More work will + need to be done if multiple modulation systems are possible. + Contact the linux-media mailing list + (`https://linuxtv.org/lists.php <https://linuxtv.org/lists.php>`__) + if you need that functionality. + + - .. row 8 + + - __u32 + + - ``reserved``\ [9] + + - Reserved for future extensions. Applications and drivers must set + the array to zero. + + + +.. _band-modulation: + +.. flat-table:: Band Modulation Systems + :header-rows: 0 + :stub-columns: 0 + :widths: 3 1 4 + + + - .. row 1 + + - ``V4L2_BAND_MODULATION_VSB`` + + - 0x02 + + - Vestigial Sideband modulation, used for analog TV. + + - .. row 2 + + - ``V4L2_BAND_MODULATION_FM`` + + - 0x04 + + - Frequency Modulation, commonly used for analog radio. + + - .. row 3 + + - ``V4L2_BAND_MODULATION_AM`` + + - 0x08 + + - Amplitude Modulation, commonly used for analog radio. + + +Return Value +============ + +On success 0 is returned, on error -1 and the ``errno`` variable is set +appropriately. The generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. + +EINVAL + The ``tuner`` or ``index`` is out of bounds or the ``type`` field is + wrong. |