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diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-tuner.rst b/Documentation/userspace-api/media/v4l/vidioc-g-tuner.rst new file mode 100644 index 000000000..b0522f1ff --- /dev/null +++ b/Documentation/userspace-api/media/v4l/vidioc-g-tuner.rst @@ -0,0 +1,464 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later +.. c:namespace:: V4L + +.. _VIDIOC_G_TUNER: + +************************************ +ioctl VIDIOC_G_TUNER, VIDIOC_S_TUNER +************************************ + +Name +==== + +VIDIOC_G_TUNER - VIDIOC_S_TUNER - Get or set tuner attributes + +Synopsis +======== + +.. c:macro:: VIDIOC_G_TUNER + +``int ioctl(int fd, VIDIOC_G_TUNER, struct v4l2_tuner *argp)`` + +.. c:macro:: VIDIOC_S_TUNER + +``int ioctl(int fd, VIDIOC_S_TUNER, const struct v4l2_tuner *argp)`` + +Arguments +========= + +``fd`` + File descriptor returned by :c:func:`open()`. + +``argp`` + Pointer to struct :c:type:`v4l2_tuner`. + +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{7.0cm}|p{5.8cm}| + +.. 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{8.5cm}| + +.. 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{7.0cm}|p{2.2cm}|p{8.1cm}| + +.. _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{8.5cm}| + +.. _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{8.5cm}| + +.. _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 + + \scriptsize + +.. tabularcolumns:: |p{1.5cm}|p{1.5cm}|p{2.9cm}|p{2.9cm}|p{2.9cm}|p{2.9cm}| + +.. _tuner-matrix: + +.. flat-table:: Tuner Audio Matrix + :header-rows: 2 + :stub-columns: 0 + :widths: 7 7 14 14 14 14 + + * - + - :cspan:`4` 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 + + \normalsize + +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. |