Synopsis
========
-.. c:function:: int ioctl( int fd, int request, struct v4l2_modulator *argp )
+.. cpp:function:: int ioctl( int fd, int request, struct v4l2_modulator *argp )
-.. c:function:: int ioctl( int fd, int request, const struct v4l2_modulator *argp )
+.. cpp:function:: int ioctl( int fd, int request, const struct v4l2_modulator *argp )
Arguments
=========
To query the attributes of a modulator applications initialize the
``index`` field and zero out the ``reserved`` array of a struct
:ref:`v4l2_modulator <v4l2-modulator>` and call the
-``VIDIOC_G_MODULATOR`` ioctl with a pointer to this structure. Drivers
-fill the rest of the structure or return an EINVAL error code when the
+:ref:`VIDIOC_G_MODULATOR <VIDIOC_G_MODULATOR>` ioctl with a pointer to this structure. Drivers
+fill the rest of the structure or return an ``EINVAL`` error code when the
index is out of bounds. To enumerate all modulators applications shall
begin at index zero, incrementing by one until the driver returns
EINVAL.
Modulators have two writable properties, an audio modulation set and the
radio frequency. To change the modulated audio subprograms, applications
initialize the ``index`` and ``txsubchans`` fields and the ``reserved``
-array and call the ``VIDIOC_S_MODULATOR`` ioctl. Drivers may choose a
+array and call the :ref:`VIDIOC_S_MODULATOR <VIDIOC_G_MODULATOR>` ioctl. Drivers may choose a
different audio modulation if the request cannot be satisfied. However
this is a write-only ioctl, it does not return the actual audio
modulation selected.
- ``name``\ [32]
- Name of the modulator, a NUL-terminated ASCII string. This
- information is intended for the user.
+ information is intended for the user.
- .. row 3
- ``capability``
- Modulator capability flags. No flags are defined for this field,
- the tuner flags in struct :ref:`v4l2_tuner <v4l2-tuner>` are
- used accordingly. The audio flags indicate the ability to encode
- audio subprograms. They will *not* change for example with the
- current video standard.
+ the tuner flags in struct :ref:`v4l2_tuner <v4l2-tuner>` are
+ used accordingly. The audio flags indicate the ability to encode
+ audio subprograms. They will *not* change for example with the
+ current video standard.
- .. row 4
- ``rangelow``
- 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, or if the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is
- set, in units of 1 Hz.
+ ``capability`` flag ``V4L2_TUNER_CAP_LOW`` is set, in units of
+ 62.5 Hz, or if the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is
+ set, in units of 1 Hz.
- .. row 5
- ``rangehigh``
- 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, or if the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is
- set, in units of 1 Hz.
+ ``capability`` flag ``V4L2_TUNER_CAP_LOW`` is set, in units of
+ 62.5 Hz, or if the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is
+ set, in units of 1 Hz.
- .. row 6
- ``txsubchans``
- With this field applications can determine how audio sub-carriers
- shall be modulated. It contains a set of flags as defined in
- :ref:`modulator-txsubchans`. Note the tuner ``rxsubchans`` flags
- are reused, but the semantics are different. Video output devices
- are assumed to have an analog or PCM audio input with 1-3
- channels. The ``txsubchans`` flags select one or more channels for
- modulation, together with some audio subprogram indicator, for
- example a stereo pilot tone.
+ shall be modulated. It contains a set of flags as defined in
+ :ref:`modulator-txsubchans`. Note the tuner ``rxsubchans`` flags
+ are reused, but the semantics are different. Video output devices
+ are assumed to have an analog or PCM audio input with 1-3
+ channels. The ``txsubchans`` flags select one or more channels for
+ modulation, together with some audio subprogram indicator, for
+ example a stereo pilot tone.
- .. row 7
- ``reserved``\ [3]
- Reserved for future extensions. Drivers and applications must set
- the array to zero.
+ the array to zero.
- 0x0001
- Modulate channel 1 as mono audio, when the input has more
- channels, a down-mix of channel 1 and 2. This flag does not
- combine with ``V4L2_TUNER_SUB_STEREO`` or
- ``V4L2_TUNER_SUB_LANG1``.
+ channels, a down-mix of channel 1 and 2. This flag does not
+ combine with ``V4L2_TUNER_SUB_STEREO`` or
+ ``V4L2_TUNER_SUB_LANG1``.
- .. row 2
- 0x0002
- Modulate channel 1 and 2 as left and right channel of a stereo
- audio signal. When the input has only one channel or two channels
- and ``V4L2_TUNER_SUB_SAP`` is also set, channel 1 is encoded as
- left and right channel. This flag does not combine with
- ``V4L2_TUNER_SUB_MONO`` or ``V4L2_TUNER_SUB_LANG1``. When the
- driver does not support stereo audio it shall fall back to mono.
+ audio signal. When the input has only one channel or two channels
+ and ``V4L2_TUNER_SUB_SAP`` is also set, channel 1 is encoded as
+ left and right channel. This flag does not combine with
+ ``V4L2_TUNER_SUB_MONO`` or ``V4L2_TUNER_SUB_LANG1``. When the
+ driver does not support stereo audio it shall fall back to mono.
- .. row 3
- 0x0008
- Modulate channel 1 and 2 as primary and secondary language of a
- bilingual audio signal. When the input has only one channel it is
- used for both languages. It is not possible to encode the primary
- or secondary language only. This flag does not combine with
- ``V4L2_TUNER_SUB_MONO``, ``V4L2_TUNER_SUB_STEREO`` or
- ``V4L2_TUNER_SUB_SAP``. If the hardware does not support the
- respective audio matrix, or the current video standard does not
- permit bilingual audio the ``VIDIOC_S_MODULATOR`` ioctl shall
- return an EINVAL error code and the driver shall fall back to mono
- or stereo mode.
+ bilingual audio signal. When the input has only one channel it is
+ used for both languages. It is not possible to encode the primary
+ or secondary language only. This flag does not combine with
+ ``V4L2_TUNER_SUB_MONO``, ``V4L2_TUNER_SUB_STEREO`` or
+ ``V4L2_TUNER_SUB_SAP``. If the hardware does not support the
+ respective audio matrix, or the current video standard does not
+ permit bilingual audio the :ref:`VIDIOC_S_MODULATOR <VIDIOC_G_MODULATOR>` ioctl shall
+ return an ``EINVAL`` error code and the driver shall fall back to mono
+ or stereo mode.
- .. row 4
- 0x0004
- When combined with ``V4L2_TUNER_SUB_MONO`` the first channel is
- encoded as mono audio, the last channel as Second Audio Program.
- When the input has only one channel it is used for both audio
- tracks. When the input has three channels the mono track is a
- down-mix of channel 1 and 2. When combined with
- ``V4L2_TUNER_SUB_STEREO`` channel 1 and 2 are encoded as left and
- right stereo audio, channel 3 as Second Audio Program. When the
- input has only two channels, the first is encoded as left and
- right channel and the second as SAP. When the input has only one
- channel it is used for all audio tracks. It is not possible to
- encode a Second Audio Program only. This flag must combine with
- ``V4L2_TUNER_SUB_MONO`` or ``V4L2_TUNER_SUB_STEREO``. If the
- hardware does not support the respective audio matrix, or the
- current video standard does not permit SAP the
- ``VIDIOC_S_MODULATOR`` ioctl shall return an EINVAL error code and
- driver shall fall back to mono or stereo mode.
+ encoded as mono audio, the last channel as Second Audio Program.
+ When the input has only one channel it is used for both audio
+ tracks. When the input has three channels the mono track is a
+ down-mix of channel 1 and 2. When combined with
+ ``V4L2_TUNER_SUB_STEREO`` channel 1 and 2 are encoded as left and
+ right stereo audio, channel 3 as Second Audio Program. When the
+ input has only two channels, the first is encoded as left and
+ right channel and the second as SAP. When the input has only one
+ channel it is used for all audio tracks. It is not possible to
+ encode a Second Audio Program only. This flag must combine with
+ ``V4L2_TUNER_SUB_MONO`` or ``V4L2_TUNER_SUB_STEREO``. If the
+ hardware does not support the respective audio matrix, or the
+ current video standard does not permit SAP the
+ :ref:`VIDIOC_S_MODULATOR <VIDIOC_G_MODULATOR>` ioctl shall return an ``EINVAL`` error code and
+ driver shall fall back to mono or stereo mode.
- .. row 6
EINVAL
The struct :ref:`v4l2_modulator <v4l2-modulator>` ``index`` is
out of bounds.
-
-
-.. ------------------------------------------------------------------------------
-.. This file was automatically converted from DocBook-XML with the dbxml
-.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
-.. from the linux kernel, refer to:
-..
-.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
-.. ------------------------------------------------------------------------------
projects / cascardo / linux.git / blobdiff