| .. -*- coding: utf-8; mode: rst -*- |
| |
| .. _VIDIOC_G_TUNER: |
| |
| ************************************ |
| ioctl VIDIOC_G_TUNER, VIDIOC_S_TUNER |
| ************************************ |
| |
| Name |
| ==== |
| |
| VIDIOC_G_TUNER - VIDIOC_S_TUNER - Get or set tuner attributes |
| |
| |
| Synopsis |
| ======== |
| |
| .. c:function:: int ioctl( int fd, VIDIOC_G_TUNER, struct v4l2_tuner *argp ) |
| :name: VIDIOC_G_TUNER |
| |
| .. c:function:: int ioctl( int fd, VIDIOC_S_TUNER, const struct v4l2_tuner *argp ) |
| :name: VIDIOC_S_TUNER |
| |
| |
| Arguments |
| ========= |
| |
| ``fd`` |
| File descriptor returned by :ref:`open() <func-open>`. |
| |
| ``argp`` |
| |
| |
| Description |
| =========== |
| |
| To query the attributes of a tuner applications initialize the ``index`` |
| field and zero out the ``reserved`` array of a struct |
| :c:type:`v4l2_tuner` and call the ``VIDIOC_G_TUNER`` 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 tuners applications shall begin at index zero, |
| incrementing by one until the driver returns ``EINVAL``. |
| |
| Tuners have two writable properties, the audio mode and the radio |
| frequency. To change the audio mode, applications initialize the |
| ``index``, ``audmode`` and ``reserved`` fields and call the |
| ``VIDIOC_S_TUNER`` ioctl. This will *not* change the current tuner, |
| which is determined by the current video input. Drivers may choose a |
| different audio mode if the requested mode is invalid or unsupported. |
| Since this is a write-only ioctl, it does not return the actually |
| selected audio mode. |
| |
| :ref:`SDR <sdr>` specific tuner types are ``V4L2_TUNER_SDR`` and |
| ``V4L2_TUNER_RF``. For SDR devices ``audmode`` field must be initialized |
| to zero. The term 'tuner' means SDR receiver in this context. |
| |
| To change the radio frequency the |
| :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>` ioctl is available. |
| |
| |
| .. tabularcolumns:: |p{1.3cm}|p{3.0cm}|p{6.6cm}|p{6.6cm}| |
| |
| .. c:type:: v4l2_tuner |
| |
| .. cssclass:: longtable |
| |
| .. flat-table:: struct v4l2_tuner |
| :header-rows: 0 |
| :stub-columns: 0 |
| |
| * - __u32 |
| - ``index`` |
| - :cspan:`1` Identifies the tuner, set by the application. |
| * - __u8 |
| - ``name``\ [32] |
| - :cspan:`1` |
| |
| Name of the tuner, a NUL-terminated ASCII string. |
| |
| This information is intended for the user. |
| * - __u32 |
| - ``type`` |
| - :cspan:`1` Type of the tuner, see :c:type:`v4l2_tuner_type`. |
| * - __u32 |
| - ``capability`` |
| - :cspan:`1` |
| |
| Tuner capability flags, see :ref:`tuner-capability`. Audio flags |
| indicate the ability to decode audio subprograms. They will *not* |
| change, for example with the current video standard. |
| |
| When the structure refers to a radio tuner the |
| ``V4L2_TUNER_CAP_LANG1``, ``V4L2_TUNER_CAP_LANG2`` and |
| ``V4L2_TUNER_CAP_NORM`` flags can't be used. |
| |
| If multiple frequency bands are supported, then ``capability`` is |
| the union of all ``capability`` fields of each struct |
| :c:type:`v4l2_frequency_band`. |
| * - __u32 |
| - ``rangelow`` |
| - :cspan:`1` 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. If multiple frequency bands are |
| supported, then ``rangelow`` is the lowest frequency of all the |
| frequency bands. |
| * - __u32 |
| - ``rangehigh`` |
| - :cspan:`1` 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. If multiple |
| frequency bands are supported, then ``rangehigh`` is the highest |
| frequency of all the frequency bands. |
| * - __u32 |
| - ``rxsubchans`` |
| - :cspan:`1` |
| |
| Some tuners or audio decoders can determine the received audio |
| subprograms by analyzing audio carriers, pilot tones or other |
| indicators. To pass this information drivers set flags defined in |
| :ref:`tuner-rxsubchans` in this field. For example: |
| * - |
| - |
| - ``V4L2_TUNER_SUB_MONO`` |
| - receiving mono audio |
| * - |
| - |
| - ``STEREO | SAP`` |
| - receiving stereo audio and a secondary audio program |
| * - |
| - |
| - ``MONO | STEREO`` |
| - receiving mono or stereo audio, the hardware cannot distinguish |
| * - |
| - |
| - ``LANG1 | LANG2`` |
| - receiving bilingual audio |
| * - |
| - |
| - ``MONO | STEREO | LANG1 | LANG2`` |
| - receiving mono, stereo or bilingual audio |
| * - |
| - |
| - :cspan:`1` |
| |
| When the ``V4L2_TUNER_CAP_STEREO``, ``_LANG1``, ``_LANG2`` or |
| ``_SAP`` flag is cleared in the ``capability`` field, the |
| corresponding ``V4L2_TUNER_SUB_`` flag must not be set here. |
| |
| This field is valid only if this is the tuner of the current video |
| input, or when the structure refers to a radio tuner. |
| * - __u32 |
| - ``audmode`` |
| - :cspan:`1` |
| |
| The selected audio mode, see :ref:`tuner-audmode` for valid |
| values. The audio mode does not affect audio subprogram detection, |
| and like a :ref:`control` it does not automatically |
| change unless the requested mode is invalid or unsupported. See |
| :ref:`tuner-matrix` for possible results when the selected and |
| received audio programs do not match. |
| |
| Currently this is the only field of struct |
| struct :c:type:`v4l2_tuner` applications can change. |
| * - __u32 |
| - ``signal`` |
| - :cspan:`1` The signal strength if known. |
| |
| Ranging from 0 to 65535. Higher values indicate a better signal. |
| * - __s32 |
| - ``afc`` |
| - :cspan:`1` Automatic frequency control. |
| |
| When the ``afc`` value is negative, the frequency is too |
| low, when positive too high. |
| * - __u32 |
| - ``reserved``\ [4] |
| - :cspan:`1` Reserved for future extensions. |
| |
| Drivers and applications must set the array to zero. |
| |
| |
| |
| .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| |
| |
| .. c:type:: v4l2_tuner_type |
| |
| .. flat-table:: enum v4l2_tuner_type |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 3 1 6 |
| |
| * - ``V4L2_TUNER_RADIO`` |
| - 1 |
| - Tuner supports radio |
| * - ``V4L2_TUNER_ANALOG_TV`` |
| - 2 |
| - Tuner supports analog TV |
| * - ``V4L2_TUNER_SDR`` |
| - 4 |
| - Tuner controls the A/D and/or D/A block of a |
| Software Digital Radio (SDR) |
| * - ``V4L2_TUNER_RF`` |
| - 5 |
| - Tuner controls the RF part of a Software Digital Radio (SDR) |
| |
| |
| .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| |
| |
| .. _tuner-capability: |
| |
| .. cssclass:: longtable |
| |
| .. flat-table:: Tuner and Modulator Capability Flags |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 3 1 4 |
| |
| * - ``V4L2_TUNER_CAP_LOW`` |
| - 0x0001 |
| - When set, tuning frequencies are expressed in units of 62.5 Hz |
| instead of 62.5 kHz. |
| * - ``V4L2_TUNER_CAP_NORM`` |
| - 0x0002 |
| - This is a multi-standard tuner; the video standard can or must be |
| switched. (B/G PAL tuners for example are typically not considered |
| multi-standard because the video standard is automatically |
| determined from the frequency band.) The set of supported video |
| standards is available from the struct |
| :c:type:`v4l2_input` pointing to this tuner, see the |
| description of ioctl :ref:`VIDIOC_ENUMINPUT` |
| for details. Only ``V4L2_TUNER_ANALOG_TV`` tuners can have this |
| capability. |
| * - ``V4L2_TUNER_CAP_HWSEEK_BOUNDED`` |
| - 0x0004 |
| - If set, then this tuner supports the hardware seek functionality |
| where the seek stops when it reaches the end of the frequency |
| range. |
| * - ``V4L2_TUNER_CAP_HWSEEK_WRAP`` |
| - 0x0008 |
| - If set, then this tuner supports the hardware seek functionality |
| where the seek wraps around when it reaches the end of the |
| frequency range. |
| * - ``V4L2_TUNER_CAP_STEREO`` |
| - 0x0010 |
| - Stereo audio reception is supported. |
| * - ``V4L2_TUNER_CAP_LANG1`` |
| - 0x0040 |
| - Reception of the primary language of a bilingual audio program is |
| supported. Bilingual audio is a feature of two-channel systems, |
| transmitting the primary language monaural on the main audio |
| carrier and a secondary language monaural on a second carrier. |
| Only ``V4L2_TUNER_ANALOG_TV`` tuners can have this capability. |
| * - ``V4L2_TUNER_CAP_LANG2`` |
| - 0x0020 |
| - Reception of the secondary language of a bilingual audio program |
| is supported. Only ``V4L2_TUNER_ANALOG_TV`` tuners can have this |
| capability. |
| * - ``V4L2_TUNER_CAP_SAP`` |
| - 0x0020 |
| - Reception of a secondary audio program is supported. This is a |
| feature of the BTSC system which accompanies the NTSC video |
| standard. Two audio carriers are available for mono or stereo |
| transmissions of a primary language, and an independent third |
| carrier for a monaural secondary language. Only |
| ``V4L2_TUNER_ANALOG_TV`` tuners can have this capability. |
| |
| .. note:: |
| |
| The ``V4L2_TUNER_CAP_LANG2`` and ``V4L2_TUNER_CAP_SAP`` |
| flags are synonyms. ``V4L2_TUNER_CAP_SAP`` applies when the tuner |
| supports the ``V4L2_STD_NTSC_M`` video standard. |
| * - ``V4L2_TUNER_CAP_RDS`` |
| - 0x0080 |
| - RDS capture is supported. This capability is only valid for radio |
| tuners. |
| * - ``V4L2_TUNER_CAP_RDS_BLOCK_IO`` |
| - 0x0100 |
| - The RDS data is passed as unparsed RDS blocks. |
| * - ``V4L2_TUNER_CAP_RDS_CONTROLS`` |
| - 0x0200 |
| - The RDS data is parsed by the hardware and set via controls. |
| * - ``V4L2_TUNER_CAP_FREQ_BANDS`` |
| - 0x0400 |
| - The :ref:`VIDIOC_ENUM_FREQ_BANDS` |
| ioctl can be used to enumerate the available frequency bands. |
| * - ``V4L2_TUNER_CAP_HWSEEK_PROG_LIM`` |
| - 0x0800 |
| - The range to search when using the hardware seek functionality is |
| programmable, see |
| :ref:`VIDIOC_S_HW_FREQ_SEEK` for |
| details. |
| * - ``V4L2_TUNER_CAP_1HZ`` |
| - 0x1000 |
| - When set, tuning frequencies are expressed in units of 1 Hz |
| instead of 62.5 kHz. |
| |
| |
| |
| .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| |
| |
| .. _tuner-rxsubchans: |
| |
| .. flat-table:: Tuner Audio Reception Flags |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 3 1 4 |
| |
| * - ``V4L2_TUNER_SUB_MONO`` |
| - 0x0001 |
| - The tuner receives a mono audio signal. |
| * - ``V4L2_TUNER_SUB_STEREO`` |
| - 0x0002 |
| - The tuner receives a stereo audio signal. |
| * - ``V4L2_TUNER_SUB_LANG1`` |
| - 0x0008 |
| - The tuner receives the primary language of a bilingual audio |
| signal. Drivers must clear this flag when the current video |
| standard is ``V4L2_STD_NTSC_M``. |
| * - ``V4L2_TUNER_SUB_LANG2`` |
| - 0x0004 |
| - The tuner receives the secondary language of a bilingual audio |
| signal (or a second audio program). |
| * - ``V4L2_TUNER_SUB_SAP`` |
| - 0x0004 |
| - The tuner receives a Second Audio Program. |
| |
| .. note:: |
| |
| The ``V4L2_TUNER_SUB_LANG2`` and ``V4L2_TUNER_SUB_SAP`` |
| flags are synonyms. The ``V4L2_TUNER_SUB_SAP`` flag applies |
| when the current video standard is ``V4L2_STD_NTSC_M``. |
| * - ``V4L2_TUNER_SUB_RDS`` |
| - 0x0010 |
| - The tuner receives an RDS channel. |
| |
| |
| |
| .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| |
| |
| .. _tuner-audmode: |
| |
| .. flat-table:: Tuner Audio Modes |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 3 1 4 |
| |
| * - ``V4L2_TUNER_MODE_MONO`` |
| - 0 |
| - Play mono audio. When the tuner receives a stereo signal this a |
| down-mix of the left and right channel. When the tuner receives a |
| bilingual or SAP signal this mode selects the primary language. |
| * - ``V4L2_TUNER_MODE_STEREO`` |
| - 1 |
| - Play stereo audio. When the tuner receives bilingual audio it may |
| play different languages on the left and right channel or the |
| primary language is played on both channels. |
| |
| Playing different languages in this mode is deprecated. New |
| drivers should do this only in ``MODE_LANG1_LANG2``. |
| |
| When the tuner receives no stereo signal or does not support |
| stereo reception the driver shall fall back to ``MODE_MONO``. |
| * - ``V4L2_TUNER_MODE_LANG1`` |
| - 3 |
| - Play the primary language, mono or stereo. Only |
| ``V4L2_TUNER_ANALOG_TV`` tuners support this mode. |
| * - ``V4L2_TUNER_MODE_LANG2`` |
| - 2 |
| - Play the secondary language, mono. When the tuner receives no |
| bilingual audio or SAP, or their reception is not supported the |
| driver shall fall back to mono or stereo mode. Only |
| ``V4L2_TUNER_ANALOG_TV`` tuners support this mode. |
| * - ``V4L2_TUNER_MODE_SAP`` |
| - 2 |
| - Play the Second Audio Program. When the tuner receives no |
| bilingual audio or SAP, or their reception is not supported the |
| driver shall fall back to mono or stereo mode. Only |
| ``V4L2_TUNER_ANALOG_TV`` tuners support this mode. |
| |
| .. note:: The ``V4L2_TUNER_MODE_LANG2`` and ``V4L2_TUNER_MODE_SAP`` |
| are synonyms. |
| * - ``V4L2_TUNER_MODE_LANG1_LANG2`` |
| - 4 |
| - Play the primary language on the left channel, the secondary |
| language on the right channel. When the tuner receives no |
| bilingual audio or SAP, it shall fall back to ``MODE_LANG1`` or |
| ``MODE_MONO``. Only ``V4L2_TUNER_ANALOG_TV`` tuners support this |
| mode. |
| |
| .. raw:: latex |
| |
| \begin{adjustbox}{width=\columnwidth} |
| |
| .. _tuner-matrix: |
| |
| .. flat-table:: Tuner Audio Matrix |
| :header-rows: 2 |
| :stub-columns: 0 |
| |
| * - |
| - :cspan:`5` Selected ``V4L2_TUNER_MODE_`` |
| * - Received ``V4L2_TUNER_SUB_`` |
| - ``MONO`` |
| - ``STEREO`` |
| - ``LANG1`` |
| - ``LANG2 = SAP`` |
| - ``LANG1_LANG2``\ [#f1]_ |
| * - ``MONO`` |
| - Mono |
| - Mono/Mono |
| - Mono |
| - Mono |
| - Mono/Mono |
| * - ``MONO | SAP`` |
| - Mono |
| - Mono/Mono |
| - Mono |
| - SAP |
| - Mono/SAP (preferred) or Mono/Mono |
| * - ``STEREO`` |
| - L+R |
| - L/R |
| - Stereo L/R (preferred) or Mono L+R |
| - Stereo L/R (preferred) or Mono L+R |
| - L/R (preferred) or L+R/L+R |
| * - ``STEREO | SAP`` |
| - L+R |
| - L/R |
| - Stereo L/R (preferred) or Mono L+R |
| - SAP |
| - L+R/SAP (preferred) or L/R or L+R/L+R |
| * - ``LANG1 | LANG2`` |
| - Language 1 |
| - Lang1/Lang2 (deprecated [#f2]_) or Lang1/Lang1 |
| - Language 1 |
| - Language 2 |
| - Lang1/Lang2 (preferred) or Lang1/Lang1 |
| |
| .. raw:: latex |
| |
| \end{adjustbox}\newline\newline |
| |
| 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 struct :c:type:`v4l2_tuner` ``index`` is out of |
| bounds. |
| |
| .. [#f1] |
| This mode has been added in Linux 2.6.17 and may not be supported by |
| older drivers. |
| |
| .. [#f2] |
| Playback of both languages in ``MODE_STEREO`` is deprecated. In the |
| future drivers should produce only the primary language in this mode. |
| Applications should request ``MODE_LANG1_LANG2`` to record both |
| languages or a stereo signal. |
