doc-rst: linux_tv: don't simplify VIDIOC_G_foo references
As VIDIOC_G_foo is the reference used for VIDIOC_S_foo and VIDIOC_TRY_foo, we need to explicitly name the reference, as otherwise, it will mention the three ioctls altogether, with is not what we want. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Mauro Carvalho Chehab
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2212ff259f
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4e03cb760d
@ -16,7 +16,7 @@ applications and automatically regain control of the device at a later
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time.
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Since these features cannot be implemented entirely in user space V4L2
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defines the :ref:`VIDIOC_G_PRIORITY` and
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defines the :ref:`VIDIOC_G_PRIORITY <VIDIOC_G_PRIORITY>` and
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:ref:`VIDIOC_S_PRIORITY <VIDIOC_G_PRIORITY>` ioctls to request and
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query the access priority associate with a file descriptor. Opening a
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device assigns a medium priority, compatible with earlier versions of
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@ -33,11 +33,11 @@ The struct :ref:`v4l2_audio <v4l2-audio>` returned by the
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:ref:`VIDIOC_ENUMAUDIO` ioctl also contains signal
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:status information applicable when the current audio input is queried.
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The :ref:`VIDIOC_G_AUDIO` and
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The :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` and
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:ref:`VIDIOC_G_AUDOUT <VIDIOC_G_AUDIOout>` ioctls report the current
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audio input and output, respectively. Note that, unlike
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:ref:`VIDIOC_G_INPUT` and
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:ref:`VIDIOC_G_OUTPUT` these ioctls return a
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:ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` and
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:ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` these ioctls return a
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structure as :ref:`VIDIOC_ENUMAUDIO` and
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:ref:`VIDIOC_ENUMAUDOUT <VIDIOC_ENUMAUDIOout>` do, not just an index.
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@ -364,7 +364,7 @@ Control IDs
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Applications can enumerate the available controls with the
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:ref:`VIDIOC_QUERYCTRL` and
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:ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>` ioctls, get and set a
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control value with the :ref:`VIDIOC_G_CTRL` and
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control value with the :ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` and
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:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls. Drivers must implement
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``VIDIOC_QUERYCTRL``, ``VIDIOC_G_CTRL`` and ``VIDIOC_S_CTRL`` when the
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device has one or more controls, ``VIDIOC_QUERYMENU`` when it has one or
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@ -15,7 +15,7 @@ offset into a video signal.
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Applications can use the following API to select an area in the video
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signal, query the default area and the hardware limits. *Despite their
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name, the :ref:`VIDIOC_CROPCAP`,
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:ref:`VIDIOC_G_CROP` and
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:ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and
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:ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` ioctls apply to input as well
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as output devices.*
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@ -23,7 +23,7 @@ Scaling requires a source and a target. On a video capture or overlay
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device the source is the video signal, and the cropping ioctls determine
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the area actually sampled. The target are images read by the application
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or overlaid onto the graphics screen. Their size (and position for an
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overlay) is negotiated with the :ref:`VIDIOC_G_FMT`
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overlay) is negotiated with the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`
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and :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctls.
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On a video output device the source are the images passed in by the
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@ -65,7 +65,7 @@ To query the current image format applications set the ``type`` field of
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a struct :ref:`v4l2_format <v4l2-format>` to
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``V4L2_BUF_TYPE_VIDEO_CAPTURE`` or
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``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE`` and call the
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:ref:`VIDIOC_G_FMT` ioctl with a pointer to this
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:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctl with a pointer to this
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structure. Drivers fill the struct
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:ref:`v4l2_pix_format <v4l2-pix-format>` ``pix`` or the struct
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:ref:`v4l2_pix_format_mplane <v4l2-pix-format-mplane>` ``pix_mp``
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@ -75,9 +75,9 @@ To request different parameters applications set the ``type`` field of a
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struct :ref:`v4l2_format <v4l2-format>` as above and initialize all
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fields of the struct :ref:`v4l2_pix_format <v4l2-pix-format>`
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``vbi`` member of the ``fmt`` union, or better just modify the results
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of :ref:`VIDIOC_G_FMT`, and call the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`
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of :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`, and call the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`
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ioctl with a pointer to this structure. Drivers may adjust the
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parameters and finally return the actual parameters as :ref:`VIDIOC_G_FMT`
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parameters and finally return the actual parameters as :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`
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does.
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Like :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` the :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` ioctl
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@ -87,10 +87,10 @@ possibly time consuming hardware preparations.
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The contents of struct :ref:`v4l2_pix_format <v4l2-pix-format>` and
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struct :ref:`v4l2_pix_format_mplane <v4l2-pix-format-mplane>` are
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discussed in :ref:`pixfmt`. See also the specification of the
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:ref:`VIDIOC_G_FMT`, :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` and :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` ioctls for
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details. Video capture devices must implement both the :ref:`VIDIOC_G_FMT`
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:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`, :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` and :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` ioctls for
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details. Video capture devices must implement both the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`
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and :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl, even if :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ignores all
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requests and always returns default parameters as :ref:`VIDIOC_G_FMT` does.
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requests and always returns default parameters as :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` does.
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:ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` is optional.
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@ -36,7 +36,7 @@ Contrary to the *Video Overlay* interface the framebuffer is normally
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implemented on the TV card and not the graphics card. On Linux it is
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accessible as a framebuffer device (``/dev/fbN``). Given a V4L2 device,
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applications can find the corresponding framebuffer device by calling
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the :ref:`VIDIOC_G_FBUF` ioctl. It returns, amongst
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the :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>` ioctl. It returns, amongst
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other information, the physical address of the framebuffer in the
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``base`` field of struct :ref:`v4l2_framebuffer <v4l2-framebuffer>`.
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The framebuffer device ioctl ``FBIOGET_FSCREENINFO`` returns the same
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@ -115,7 +115,7 @@ clipping/blending method to be used for the overlay. To get the current
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parameters applications set the ``type`` field of a struct
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:ref:`v4l2_format <v4l2-format>` to
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``V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY`` and call the
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:ref:`VIDIOC_G_FMT` ioctl. The driver fills the
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:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctl. The driver fills the
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:c:type:`struct v4l2_window` substructure named ``win``. It is not
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possible to retrieve a previously programmed clipping list or bitmap.
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@ -124,7 +124,7 @@ struct :ref:`v4l2_format <v4l2-format>` to
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``V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY``, initialize the ``win``
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substructure and call the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl.
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The driver adjusts the parameters against hardware limits and returns
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the actual parameters as :ref:`VIDIOC_G_FMT` does. Like :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`,
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the actual parameters as :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` does. Like :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`,
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the :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` ioctl can be used to learn
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about driver capabilities without actually changing driver state. Unlike
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:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` this also works after the overlay has been enabled.
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@ -62,7 +62,7 @@ defaults. An example is given in :ref:`crop`.
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To query the current image format applications set the ``type`` field of
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a struct :ref:`v4l2_format <v4l2-format>` to
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``V4L2_BUF_TYPE_VIDEO_OUTPUT`` or ``V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE``
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and call the :ref:`VIDIOC_G_FMT` ioctl with a pointer
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and call the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctl with a pointer
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to this structure. Drivers fill the struct
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:ref:`v4l2_pix_format <v4l2-pix-format>` ``pix`` or the struct
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:ref:`v4l2_pix_format_mplane <v4l2-pix-format-mplane>` ``pix_mp``
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@ -72,9 +72,9 @@ To request different parameters applications set the ``type`` field of a
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struct :ref:`v4l2_format <v4l2-format>` as above and initialize all
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fields of the struct :ref:`v4l2_pix_format <v4l2-pix-format>`
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``vbi`` member of the ``fmt`` union, or better just modify the results
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of :ref:`VIDIOC_G_FMT`, and call the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`
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of :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`, and call the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`
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ioctl with a pointer to this structure. Drivers may adjust the
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parameters and finally return the actual parameters as :ref:`VIDIOC_G_FMT`
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parameters and finally return the actual parameters as :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`
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does.
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Like :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` the :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` ioctl
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@ -84,10 +84,10 @@ possibly time consuming hardware preparations.
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The contents of struct :ref:`v4l2_pix_format <v4l2-pix-format>` and
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struct :ref:`v4l2_pix_format_mplane <v4l2-pix-format-mplane>` are
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discussed in :ref:`pixfmt`. See also the specification of the
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:ref:`VIDIOC_G_FMT`, :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` and :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` ioctls for
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details. Video output devices must implement both the :ref:`VIDIOC_G_FMT`
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:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`, :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` and :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` ioctls for
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details. Video output devices must implement both the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`
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and :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl, even if :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ignores all
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requests and always returns default parameters as :ref:`VIDIOC_G_FMT` does.
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requests and always returns default parameters as :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` does.
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:ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` is optional.
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@ -63,7 +63,7 @@ Setup
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Before overlay can commence applications must program the driver with
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frame buffer parameters, namely the address and size of the frame buffer
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and the image format, for example RGB 5:6:5. The
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:ref:`VIDIOC_G_FBUF` and
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:ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>` and
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:ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>` ioctls are available to get and
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set these parameters, respectively. The :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>` ioctl is
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privileged because it allows to set up DMA into physical memory,
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@ -77,7 +77,7 @@ Some devices add the video overlay to the output signal of the graphics
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card. In this case the frame buffer is not modified by the video device,
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and the frame buffer address and pixel format are not needed by the
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driver. The :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>` ioctl is not privileged. An application
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can check for this type of device by calling the :ref:`VIDIOC_G_FBUF`
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can check for this type of device by calling the :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>`
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ioctl.
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A driver may support any (or none) of five clipping/blending methods:
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@ -121,7 +121,7 @@ its position over the graphics surface and the clipping to be applied.
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To get the current parameters applications set the ``type`` field of a
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struct :ref:`v4l2_format <v4l2-format>` to
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``V4L2_BUF_TYPE_VIDEO_OVERLAY`` and call the
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:ref:`VIDIOC_G_FMT` ioctl. The driver fills the
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:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctl. The driver fills the
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:c:type:`struct v4l2_window` substructure named ``win``. It is not
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possible to retrieve a previously programmed clipping list or bitmap.
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@ -130,7 +130,7 @@ struct :ref:`v4l2_format <v4l2-format>` to
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``V4L2_BUF_TYPE_VIDEO_OVERLAY``, initialize the ``win`` substructure and
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call the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. The driver
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adjusts the parameters against hardware limits and returns the actual
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parameters as :ref:`VIDIOC_G_FMT` does. Like :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`, the
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parameters as :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` does. Like :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`, the
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:ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` ioctl can be used to learn
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about driver capabilities without actually changing driver state. Unlike
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:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` this also works after the overlay has been enabled.
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@ -179,7 +179,7 @@ struct v4l2_window
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``struct v4l2_clip * clips``
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When chroma-keying has *not* been negotiated and
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:ref:`VIDIOC_G_FBUF` indicated this capability,
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:ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>` indicated this capability,
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applications can set this field to point to an array of clipping
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rectangles.
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@ -204,7 +204,7 @@ are undefined.
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``void * bitmap``
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When chroma-keying has *not* been negotiated and
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:ref:`VIDIOC_G_FBUF` indicated this capability,
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:ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>` indicated this capability,
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applications can set this field to point to a clipping bit mask.
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It must be of the same size as the window, ``w.width`` and ``w.height``.
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@ -47,8 +47,8 @@ discussed in :ref:`tuner`) with index number zero to select the radio
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frequency and to determine if a monaural or FM stereo program is
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received/emitted. Drivers switch automatically between AM and FM
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depending on the selected frequency. The
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:ref:`VIDIOC_G_TUNER` or
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:ref:`VIDIOC_G_MODULATOR` ioctl reports the
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:ref:`VIDIOC_G_TUNER <VIDIOC_G_TUNER>` or
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:ref:`VIDIOC_G_MODULATOR <VIDIOC_G_MODULATOR>` ioctl reports the
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supported frequency range.
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@ -71,7 +71,7 @@ parameters and then checking if the actual parameters are suitable.
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To query the current raw VBI capture parameters applications set the
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``type`` field of a struct :ref:`v4l2_format <v4l2-format>` to
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``V4L2_BUF_TYPE_VBI_CAPTURE`` or ``V4L2_BUF_TYPE_VBI_OUTPUT``, and call
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the :ref:`VIDIOC_G_FMT` ioctl with a pointer to this
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the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctl with a pointer to this
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structure. Drivers fill the struct
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:ref:`v4l2_vbi_format <v4l2-vbi-format>` ``vbi`` member of the
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``fmt`` union.
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@ -80,7 +80,7 @@ To request different parameters applications set the ``type`` field of a
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struct :ref:`v4l2_format <v4l2-format>` as above and initialize all
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fields of the struct :ref:`v4l2_vbi_format <v4l2-vbi-format>`
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``vbi`` member of the ``fmt`` union, or better just modify the results
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of :ref:`VIDIOC_G_FMT`, and call the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`
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of :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`, and call the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`
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ioctl with a pointer to this structure. Drivers return an EINVAL error
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code only when the given parameters are ambiguous, otherwise they modify
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the parameters according to the hardware capabilities and return the
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@ -94,9 +94,9 @@ expect other resource allocation points which may return EBUSY, at the
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:ref:`VIDIOC_STREAMON` ioctl and the first read(),
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write() and select() call.
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VBI devices must implement both the :ref:`VIDIOC_G_FMT` and
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VBI devices must implement both the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and
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:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl, even if :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ignores all requests
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and always returns default parameters as :ref:`VIDIOC_G_FMT` does.
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and always returns default parameters as :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` does.
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:ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` is optional.
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@ -57,7 +57,7 @@ Sliced VBI Format Negotiation
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To find out which data services are supported by the hardware
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applications can call the
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:ref:`VIDIOC_G_SLICED_VBI_CAP` ioctl.
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:ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLICED_VBI_CAP>` ioctl.
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All drivers implementing the sliced VBI interface must support this
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ioctl. The results may differ from those of the
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:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl when the number of VBI
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@ -70,7 +70,7 @@ To determine the currently selected services applications set the
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``type`` field of struct :ref:`v4l2_format <v4l2-format>` to
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``V4L2_BUF_TYPE_SLICED_VBI_CAPTURE`` or
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``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT``, and the
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:ref:`VIDIOC_G_FMT` ioctl fills the ``fmt.sliced``
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:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctl fills the ``fmt.sliced``
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member, a struct
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:ref:`v4l2_sliced_vbi_format <v4l2-sliced-vbi-format>`.
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@ -432,7 +432,7 @@ the :ref:`VIDIOC_QBUF` ioctl must return an EINVAL
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error code when applications violate this rule. They must also return an
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EINVAL error code when applications pass an incorrect field or line
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number, or a combination of ``field``, ``line`` and ``id`` which has not
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been negotiated with the :ref:`VIDIOC_G_FMT` or
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been negotiated with the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` or
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:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. When the line numbers are
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unknown the driver must pass the packets in transmitted order. The
|
||||
driver can insert empty packets with ``id`` set to zero anywhere in the
|
||||
|
||||
@ -204,7 +204,7 @@ introduction.
|
||||
|
||||
- ``-``
|
||||
|
||||
- Applications can call the :ref:`VIDIOC_G_CROP`
|
||||
- Applications can call the :ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>`
|
||||
ioctl to determine if the device supports capturing a subsection
|
||||
of the full picture ("cropping" in V4L2). If not, the ioctl
|
||||
returns the EINVAL error code. For more information on cropping
|
||||
@ -248,7 +248,7 @@ introduction.
|
||||
The ``audios`` field was replaced by ``capabilities`` flag
|
||||
``V4L2_CAP_AUDIO``, indicating *if* the device has any audio inputs or
|
||||
outputs. To determine their number applications can enumerate audio
|
||||
inputs with the :ref:`VIDIOC_G_AUDIO` ioctl. The
|
||||
inputs with the :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` ioctl. The
|
||||
audio ioctls are described in :ref:`audio`.
|
||||
|
||||
The ``maxwidth``, ``maxheight``, ``minwidth`` and ``minheight`` fields
|
||||
@ -265,7 +265,7 @@ V4L provides the ``VIDIOCGCHAN`` and ``VIDIOCSCHAN`` ioctl using struct
|
||||
:c:type:`struct video_channel` to enumerate the video inputs of a V4L
|
||||
device. The equivalent V4L2 ioctls are
|
||||
:ref:`VIDIOC_ENUMINPUT`,
|
||||
:ref:`VIDIOC_G_INPUT` and
|
||||
:ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` and
|
||||
:ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` using struct
|
||||
:ref:`v4l2_input <v4l2-input>` as discussed in :ref:`video`.
|
||||
|
||||
@ -328,7 +328,7 @@ Tuning
|
||||
The V4L ``VIDIOCGTUNER`` and ``VIDIOCSTUNER`` ioctl and struct
|
||||
:c:type:`struct video_tuner` can be used to enumerate the tuners of a
|
||||
V4L TV or radio device. The equivalent V4L2 ioctls are
|
||||
:ref:`VIDIOC_G_TUNER` and
|
||||
:ref:`VIDIOC_G_TUNER <VIDIOC_G_TUNER>` and
|
||||
:ref:`VIDIOC_S_TUNER <VIDIOC_G_TUNER>` using struct
|
||||
:ref:`v4l2_tuner <v4l2-tuner>`. Tuners are covered in :ref:`tuner`.
|
||||
|
||||
@ -360,7 +360,7 @@ the struct :ref:`v4l2_tuner <v4l2-tuner>` ``capability`` field.
|
||||
|
||||
The ``VIDIOCGFREQ`` and ``VIDIOCSFREQ`` ioctl to change the tuner
|
||||
frequency where renamed to
|
||||
:ref:`VIDIOC_G_FREQUENCY` and
|
||||
:ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQUENCY>` and
|
||||
:ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>`. They take a pointer
|
||||
to a struct :ref:`v4l2_frequency <v4l2-frequency>` instead of an
|
||||
unsigned long integer.
|
||||
@ -375,7 +375,7 @@ V4L2 has no equivalent of the ``VIDIOCGPICT`` and ``VIDIOCSPICT`` ioctl
|
||||
and struct :c:type:`struct video_picture`. The following fields where
|
||||
replaced by V4L2 controls accessible with the
|
||||
:ref:`VIDIOC_QUERYCTRL`,
|
||||
:ref:`VIDIOC_G_CTRL` and
|
||||
:ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` and
|
||||
:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls:
|
||||
|
||||
|
||||
@ -554,7 +554,7 @@ Audio
|
||||
The ``VIDIOCGAUDIO`` and ``VIDIOCSAUDIO`` ioctl and struct
|
||||
:c:type:`struct video_audio` are used to enumerate the audio inputs
|
||||
of a V4L device. The equivalent V4L2 ioctls are
|
||||
:ref:`VIDIOC_G_AUDIO` and
|
||||
:ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` and
|
||||
:ref:`VIDIOC_S_AUDIO <VIDIOC_G_AUDIO>` using struct
|
||||
:ref:`v4l2_audio <v4l2-audio>` as discussed in :ref:`audio`.
|
||||
|
||||
@ -577,7 +577,7 @@ stereo input, regardless if the source is a tuner.
|
||||
|
||||
The following fields where replaced by V4L2 controls accessible with the
|
||||
:ref:`VIDIOC_QUERYCTRL`,
|
||||
:ref:`VIDIOC_G_CTRL` and
|
||||
:ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` and
|
||||
:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls:
|
||||
|
||||
|
||||
@ -638,7 +638,7 @@ Frame Buffer Overlay
|
||||
====================
|
||||
|
||||
The V4L2 ioctls equivalent to ``VIDIOCGFBUF`` and ``VIDIOCSFBUF`` are
|
||||
:ref:`VIDIOC_G_FBUF` and
|
||||
:ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>` and
|
||||
:ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>`. The ``base`` field of struct
|
||||
:c:type:`struct video_buffer` remained unchanged, except V4L2 defines
|
||||
a flag to indicate non-destructive overlays instead of a ``NULL``
|
||||
@ -650,7 +650,7 @@ list of RGB formats and their respective color depths.
|
||||
|
||||
Instead of the special ioctls ``VIDIOCGWIN`` and ``VIDIOCSWIN`` V4L2
|
||||
uses the general-purpose data format negotiation ioctls
|
||||
:ref:`VIDIOC_G_FMT` and
|
||||
:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and
|
||||
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`. They take a pointer to a struct
|
||||
:ref:`v4l2_format <v4l2-format>` as argument. Here the ``win`` member
|
||||
of the ``fmt`` union is used, a struct
|
||||
@ -687,7 +687,7 @@ Cropping
|
||||
To capture only a subsection of the full picture V4L defines the
|
||||
``VIDIOCGCAPTURE`` and ``VIDIOCSCAPTURE`` ioctls using struct
|
||||
:c:type:`struct video_capture`. The equivalent V4L2 ioctls are
|
||||
:ref:`VIDIOC_G_CROP` and
|
||||
:ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and
|
||||
:ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` using struct
|
||||
:ref:`v4l2_crop <v4l2-crop>`, and the related
|
||||
:ref:`VIDIOC_CROPCAP` ioctl. This is a rather
|
||||
@ -726,7 +726,7 @@ functions.
|
||||
|
||||
To select an image format and size, V4L provides the ``VIDIOCSPICT`` and
|
||||
``VIDIOCSWIN`` ioctls. V4L2 uses the general-purpose data format
|
||||
negotiation ioctls :ref:`VIDIOC_G_FMT` and
|
||||
negotiation ioctls :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and
|
||||
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`. They take a pointer to a struct
|
||||
:ref:`v4l2_format <v4l2-format>` as argument, here the struct
|
||||
:ref:`v4l2_pix_format <v4l2-pix-format>` named ``pix`` of its
|
||||
|
||||
@ -29,7 +29,7 @@ device applications use the
|
||||
DV timings for the device applications use the
|
||||
:ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get
|
||||
current DV timings they use the
|
||||
:ref:`VIDIOC_G_DV_TIMINGS` ioctl. To detect
|
||||
:ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. To detect
|
||||
the DV timings as seen by the video receiver applications use the
|
||||
:ref:`VIDIOC_QUERY_DV_TIMINGS` ioctl.
|
||||
|
||||
|
||||
@ -39,11 +39,11 @@ The Extended Control API
|
||||
========================
|
||||
|
||||
Three new ioctls are available:
|
||||
:ref:`VIDIOC_G_EXT_CTRLS`,
|
||||
:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`,
|
||||
:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and
|
||||
:ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`. These ioctls act
|
||||
on arrays of controls (as opposed to the
|
||||
:ref:`VIDIOC_G_CTRL` and
|
||||
:ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` and
|
||||
:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls that act on a single
|
||||
control). This is needed since it is often required to atomically change
|
||||
several controls at once.
|
||||
|
||||
@ -23,7 +23,7 @@ current selection.
|
||||
|
||||
A single mechanism exists to negotiate all data formats using the
|
||||
aggregate struct :ref:`v4l2_format <v4l2-format>` and the
|
||||
:ref:`VIDIOC_G_FMT` and
|
||||
:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and
|
||||
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctls. Additionally the
|
||||
:ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` ioctl can be used to examine
|
||||
what the hardware *could* do, without actually selecting a new data
|
||||
@ -64,7 +64,7 @@ earlier versions of V4L2. Switching the logical stream or returning into
|
||||
*may* support a switch using :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`.
|
||||
|
||||
All drivers exchanging data with applications must support the
|
||||
:ref:`VIDIOC_G_FMT` and :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. Implementation of the
|
||||
:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. Implementation of the
|
||||
:ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` is highly recommended but optional.
|
||||
|
||||
|
||||
|
||||
@ -85,7 +85,7 @@ enough. Again, the behavior when the driver runs out of free buffers
|
||||
depends on the discarding policy.
|
||||
|
||||
Applications can get and set the number of buffers used internally by
|
||||
the driver with the :ref:`VIDIOC_G_PARM` and
|
||||
the driver with the :ref:`VIDIOC_G_PARM <VIDIOC_G_PARM>` and
|
||||
:ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` ioctls. They are optional,
|
||||
however. The discarding policy is not reported and cannot be changed.
|
||||
For minimum requirements see :ref:`devices`.
|
||||
|
||||
@ -40,7 +40,7 @@ enumerable.
|
||||
:c:type:`struct video_standard` and the color subcarrier fields were
|
||||
renamed. The :ref:`VIDIOC_QUERYSTD` ioctl was
|
||||
renamed to :ref:`VIDIOC_ENUMSTD`,
|
||||
:ref:`VIDIOC_G_INPUT` to
|
||||
:ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` to
|
||||
:ref:`VIDIOC_ENUMINPUT`. A first draft of the
|
||||
Codec API was released.
|
||||
|
||||
@ -52,7 +52,7 @@ material changes to struct :ref:`v4l2_capability <v4l2-capability>`.
|
||||
1998-11-14: ``V4L2_PIX_FMT_RGB24`` changed to ``V4L2_PIX_FMT_BGR24``,
|
||||
and ``V4L2_PIX_FMT_RGB32`` changed to ``V4L2_PIX_FMT_BGR32``. Audio
|
||||
controls are now accessible with the
|
||||
:ref:`VIDIOC_G_CTRL` and
|
||||
:ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` and
|
||||
:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls under names starting
|
||||
with ``V4L2_CID_AUDIO``. The ``V4L2_MAJOR`` define was removed from
|
||||
``videodev.h`` since it was only used once in the ``videodev`` kernel
|
||||
@ -142,7 +142,7 @@ common Linux driver API conventions.
|
||||
int a = V4L2_XXX; err = ioctl(fd, VIDIOC_XXX, &a);
|
||||
|
||||
4. All the different get- and set-format commands were swept into one
|
||||
:ref:`VIDIOC_G_FMT` and
|
||||
:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and
|
||||
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl taking a union and a
|
||||
type field selecting the union member as parameter. Purpose is to
|
||||
simplify the API by eliminating several ioctls and to allow new and
|
||||
@ -246,13 +246,13 @@ correctly through the backward compatibility layer. [Solution?]
|
||||
2001-04-13: Big endian 16-bit RGB formats were added.
|
||||
|
||||
2001-09-17: New YUV formats and the
|
||||
:ref:`VIDIOC_G_FREQUENCY` and
|
||||
:ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQUENCY>` and
|
||||
:ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>` ioctls were added.
|
||||
(The old ``VIDIOC_G_FREQ`` and ``VIDIOC_S_FREQ`` ioctls did not take
|
||||
multiple tuners into account.)
|
||||
|
||||
2000-09-18: ``V4L2_BUF_TYPE_VBI`` was added. This may *break
|
||||
compatibility* as the :ref:`VIDIOC_G_FMT` and
|
||||
compatibility* as the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and
|
||||
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctls may fail now if the struct
|
||||
:c:type:`struct v4l2_fmt` ``type`` field does not contain
|
||||
``V4L2_BUF_TYPE_VBI``. In the documentation of the struct
|
||||
@ -401,7 +401,7 @@ This unnamed version was finally merged into Linux 2.5.46.
|
||||
supported standards with an ioctl applications can now refer to
|
||||
standards by :ref:`v4l2_std_id <v4l2-std-id>` and symbols
|
||||
defined in the ``videodev2.h`` header file. For details see
|
||||
:ref:`standard`. The :ref:`VIDIOC_G_STD` and
|
||||
:ref:`standard`. The :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and
|
||||
:ref:`VIDIOC_S_STD <VIDIOC_G_STD>` now take a pointer to this
|
||||
type as argument. :ref:`VIDIOC_QUERYSTD` was
|
||||
added to autodetect the received standard, if the hardware has this
|
||||
@ -716,14 +716,14 @@ V4L2 2003-06-19
|
||||
|
||||
3. The audio input and output interface was found to be incomplete.
|
||||
|
||||
Previously the :ref:`VIDIOC_G_AUDIO` ioctl would
|
||||
Previously the :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` ioctl would
|
||||
enumerate the available audio inputs. An ioctl to determine the
|
||||
current audio input, if more than one combines with the current video
|
||||
input, did not exist. So ``VIDIOC_G_AUDIO`` was renamed to
|
||||
``VIDIOC_G_AUDIO_OLD``, this ioctl was removed on Kernel 2.6.39. The
|
||||
:ref:`VIDIOC_ENUMAUDIO` ioctl was added to
|
||||
enumerate audio inputs, while
|
||||
:ref:`VIDIOC_G_AUDIO` now reports the current
|
||||
:ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` now reports the current
|
||||
audio input.
|
||||
|
||||
The same changes were made to
|
||||
@ -940,7 +940,7 @@ V4L2 in Linux 2.6.17
|
||||
2. A new ``V4L2_TUNER_MODE_LANG1_LANG2`` was defined to record both
|
||||
languages of a bilingual program. The use of
|
||||
``V4L2_TUNER_MODE_STEREO`` for this purpose is deprecated now. See
|
||||
the :ref:`VIDIOC_G_TUNER` section for details.
|
||||
the :ref:`VIDIOC_G_TUNER <VIDIOC_G_TUNER>` section for details.
|
||||
|
||||
|
||||
V4L2 spec erratum 2006-09-23 (Draft 0.15)
|
||||
@ -950,13 +950,13 @@ V4L2 spec erratum 2006-09-23 (Draft 0.15)
|
||||
``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT`` of the sliced VBI interface were
|
||||
not mentioned along with other buffer types.
|
||||
|
||||
2. In :ref:`VIDIOC_G_AUDIO` it was clarified that the struct
|
||||
2. In :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` it was clarified that the struct
|
||||
:ref:`v4l2_audio <v4l2-audio>` ``mode`` field is a flags field.
|
||||
|
||||
3. :ref:`VIDIOC_QUERYCAP` did not mention the sliced VBI and radio
|
||||
capability flags.
|
||||
|
||||
4. In :ref:`VIDIOC_G_FREQUENCY` it was clarified that applications
|
||||
4. In :ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQUENCY>` it was clarified that applications
|
||||
must initialize the tuner ``type`` field of struct
|
||||
:ref:`v4l2_frequency <v4l2-frequency>` before calling
|
||||
:ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>`.
|
||||
@ -976,7 +976,7 @@ V4L2 spec erratum 2006-09-23 (Draft 0.15)
|
||||
V4L2 in Linux 2.6.18
|
||||
====================
|
||||
|
||||
1. New ioctls :ref:`VIDIOC_G_EXT_CTRLS`,
|
||||
1. New ioctls :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`,
|
||||
:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and
|
||||
:ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` were added, a
|
||||
flag to skip unsupported controls with
|
||||
@ -995,7 +995,7 @@ V4L2 in Linux 2.6.19
|
||||
buffer type field was added replacing a reserved field. Note on
|
||||
architectures where the size of enum types differs from int types the
|
||||
size of the structure changed. The
|
||||
:ref:`VIDIOC_G_SLICED_VBI_CAP` ioctl
|
||||
:ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLICED_VBI_CAP>` ioctl
|
||||
was redefined from being read-only to write-read. Applications must
|
||||
initialize the type field and clear the reserved fields now. These
|
||||
changes may *break the compatibility* with older drivers and
|
||||
@ -1034,7 +1034,7 @@ V4L2 in Linux 2.6.22
|
||||
|
||||
2. Three new clipping/blending methods with a global or straight or
|
||||
inverted local alpha value were added to the video overlay interface.
|
||||
See the description of the :ref:`VIDIOC_G_FBUF`
|
||||
See the description of the :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>`
|
||||
and :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>` ioctls for details.
|
||||
|
||||
A new ``global_alpha`` field was added to
|
||||
|
||||
@ -92,7 +92,7 @@ and to enhance the image quality.
|
||||
In most cases, libv4l2 just passes the calls directly through to the
|
||||
v4l2 driver, intercepting the calls to
|
||||
:ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>`,
|
||||
:ref:`VIDIOC_G_FMT`
|
||||
:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`
|
||||
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`
|
||||
:ref:`VIDIOC_ENUM_FRAMESIZES` and
|
||||
:ref:`VIDIOC_ENUM_FRAMEINTERVALS` in
|
||||
|
||||
@ -27,7 +27,7 @@ Compressed Formats
|
||||
|
||||
- 'JPEG'
|
||||
|
||||
- TBD. See also :ref:`VIDIOC_G_JPEGCOMP`,
|
||||
- TBD. See also :ref:`VIDIOC_G_JPEGCOMP <VIDIOC_G_JPEGCOMP>`,
|
||||
:ref:`VIDIOC_S_JPEGCOMP <VIDIOC_G_JPEGCOMP>`.
|
||||
|
||||
- .. _`V4L2-PIX-FMT-MPEG`:
|
||||
|
||||
@ -13,7 +13,7 @@ single-planar API, while the latter is used with the multi-planar
|
||||
version (see :ref:`planar-apis`). Image formats are negotiated with
|
||||
the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. (The explanations here
|
||||
focus on video capturing and output, for overlay frame buffer formats
|
||||
see also :ref:`VIDIOC_G_FBUF`.)
|
||||
see also :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>`.)
|
||||
|
||||
|
||||
.. toctree::
|
||||
|
||||
@ -44,7 +44,7 @@ Calls that distinguish between single and multi-planar APIs
|
||||
together with non-multi-planar ones for devices that handle both
|
||||
single- and multi-planar formats.
|
||||
|
||||
:ref:`VIDIOC_G_FMT`,
|
||||
:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>`,
|
||||
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`,
|
||||
:ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>`
|
||||
New structures for describing multi-planar formats are added: struct
|
||||
|
||||
@ -36,7 +36,7 @@ Composite input may collapse standards, enumerating "PAL-B/G/H/I",
|
||||
"NTSC-M" and "SECAM-D/K". [1]_
|
||||
|
||||
To query and select the standard used by the current video input or
|
||||
output applications call the :ref:`VIDIOC_G_STD` and
|
||||
output applications call the :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and
|
||||
:ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctl, respectively. The
|
||||
*received* standard can be sensed with the
|
||||
:ref:`VIDIOC_QUERYSTD` ioctl. Note that the
|
||||
@ -56,7 +56,7 @@ output device which is:
|
||||
|
||||
Here the driver shall set the ``std`` field of struct
|
||||
:ref:`v4l2_input <v4l2-input>` and struct
|
||||
:ref:`v4l2_output <v4l2-output>` to zero and the :ref:`VIDIOC_G_STD`,
|
||||
:ref:`v4l2_output <v4l2-output>` to zero and the :ref:`VIDIOC_G_STD <VIDIOC_G_STD>`,
|
||||
:ref:`VIDIOC_S_STD <VIDIOC_G_STD>`, :ref:`VIDIOC_QUERYSTD` and :ref:`VIDIOC_ENUMSTD` ioctls
|
||||
shall return the ENOTTY error code or the EINVAL error code.
|
||||
|
||||
|
||||
@ -23,7 +23,7 @@ internally by a driver in read/write mode. For implications see the
|
||||
section discussing the :ref:`read() <func-read>` function.
|
||||
|
||||
To get and set the streaming parameters applications call the
|
||||
:ref:`VIDIOC_G_PARM` and
|
||||
:ref:`VIDIOC_G_PARM <VIDIOC_G_PARM>` and
|
||||
:ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` ioctl, respectively. They take
|
||||
a pointer to a struct :ref:`v4l2_streamparm <v4l2-streamparm>`, which
|
||||
contains a union holding separate parameters for input and output
|
||||
|
||||
@ -22,9 +22,9 @@ Radio input devices have exactly one tuner with index zero, no video
|
||||
inputs.
|
||||
|
||||
To query and change tuner properties applications use the
|
||||
:ref:`VIDIOC_G_TUNER` and
|
||||
:ref:`VIDIOC_G_TUNER <VIDIOC_G_TUNER>` and
|
||||
:ref:`VIDIOC_S_TUNER <VIDIOC_G_TUNER>` ioctls, respectively. The
|
||||
struct :ref:`v4l2_tuner <v4l2-tuner>` returned by :ref:`VIDIOC_G_TUNER`
|
||||
struct :ref:`v4l2_tuner <v4l2-tuner>` returned by :ref:`VIDIOC_G_TUNER <VIDIOC_G_TUNER>`
|
||||
also contains signal status information applicable when the tuner of the
|
||||
current video or radio input is queried. Note that :ref:`VIDIOC_S_TUNER <VIDIOC_G_TUNER>`
|
||||
does not switch the current tuner, when there is more than one at all.
|
||||
@ -59,7 +59,7 @@ functionality. The reason is a limitation with the
|
||||
cannot specify whether the frequency is for a tuner or a modulator.
|
||||
|
||||
To query and change modulator properties applications use the
|
||||
:ref:`VIDIOC_G_MODULATOR` and
|
||||
:ref:`VIDIOC_G_MODULATOR <VIDIOC_G_MODULATOR>` and
|
||||
:ref:`VIDIOC_S_MODULATOR <VIDIOC_G_MODULATOR>` ioctl. Note that
|
||||
:ref:`VIDIOC_S_MODULATOR <VIDIOC_G_MODULATOR>` does not switch the current modulator, when there
|
||||
is more than one at all. The modulator is solely determined by the
|
||||
@ -74,7 +74,7 @@ Radio Frequency
|
||||
===============
|
||||
|
||||
To get and set the tuner or modulator radio frequency applications use
|
||||
the :ref:`VIDIOC_G_FREQUENCY` and
|
||||
the :ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQUENCY>` and
|
||||
:ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>` ioctl which both take
|
||||
a pointer to a struct :ref:`v4l2_frequency <v4l2-frequency>`. These
|
||||
ioctls are used for TV and radio devices alike. Drivers must support
|
||||
|
||||
@ -20,8 +20,8 @@ struct :ref:`v4l2_input <v4l2-input>` returned by the
|
||||
:ref:`VIDIOC_ENUMINPUT` ioctl also contains signal
|
||||
:status information applicable when the current video input is queried.
|
||||
|
||||
The :ref:`VIDIOC_G_INPUT` and
|
||||
:ref:`VIDIOC_G_OUTPUT` ioctls return the index of
|
||||
The :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` and
|
||||
:ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` ioctls return the index of
|
||||
the current video input or output. To select a different input or output
|
||||
applications call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` and
|
||||
:ref:`VIDIOC_S_OUTPUT <VIDIOC_G_OUTPUT>` ioctls. Drivers must
|
||||
|
||||
@ -48,7 +48,7 @@ The ``format`` field specifies the image format that the buffers must be
|
||||
able to handle. The application has to fill in this struct
|
||||
:ref:`v4l2_format <v4l2-format>`. Usually this will be done using the
|
||||
:ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` or
|
||||
:ref:`VIDIOC_G_FMT` ioctls to ensure that the
|
||||
:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctls to ensure that the
|
||||
requested format is supported by the driver. Based on the format's
|
||||
``type`` field the requested buffer size (for single-planar) or plane
|
||||
sizes (for multi-planar formats) will be used for the allocated buffers.
|
||||
|
||||
@ -39,7 +39,7 @@ structure or return an EINVAL error code when the index is out of
|
||||
bounds. To enumerate all audio inputs applications shall begin at index
|
||||
zero, incrementing by one until the driver returns EINVAL.
|
||||
|
||||
See :ref:`VIDIOC_G_AUDIO` for a description of struct
|
||||
See :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` for a description of struct
|
||||
:ref:`v4l2_audio <v4l2-audio>`.
|
||||
|
||||
|
||||
|
||||
@ -42,7 +42,7 @@ zero, incrementing by one until the driver returns EINVAL.
|
||||
Note connectors on a TV card to loop back the received audio signal to a
|
||||
sound card are not audio outputs in this sense.
|
||||
|
||||
See :ref:`VIDIOC_G_AUDIOout` for a description of struct
|
||||
See :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDIOout>` for a description of struct
|
||||
:ref:`v4l2_audioout <v4l2-audioout>`.
|
||||
|
||||
|
||||
|
||||
@ -401,7 +401,7 @@ ENODATA
|
||||
|
||||
.. [1]
|
||||
The supported standards may overlap and we need an unambiguous set to
|
||||
find the current standard returned by :ref:`VIDIOC_G_STD`.
|
||||
find the current standard returned by :ref:`VIDIOC_G_STD <VIDIOC_G_STD>`.
|
||||
|
||||
.. [2]
|
||||
Japan uses a standard similar to M/NTSC (V4L2_STD_NTSC_M_JP).
|
||||
|
||||
@ -36,7 +36,7 @@ Description
|
||||
|
||||
To query the current audio input applications zero out the ``reserved``
|
||||
array of a struct :ref:`v4l2_audio <v4l2-audio>` and call the
|
||||
:ref:`VIDIOC_G_AUDIO` ioctl with a pointer to this structure. Drivers fill
|
||||
:ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` ioctl with a pointer to this structure. Drivers fill
|
||||
the rest of the structure or return an EINVAL error code when the device
|
||||
has no audio inputs, or none which combine with the current video input.
|
||||
|
||||
|
||||
@ -36,7 +36,7 @@ Description
|
||||
|
||||
To query the cropping rectangle size and position applications set the
|
||||
``type`` field of a :c:type:`struct v4l2_crop` structure to the
|
||||
respective buffer (stream) type and call the :ref:`VIDIOC_G_CROP` ioctl
|
||||
respective buffer (stream) type and call the :ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` ioctl
|
||||
with a pointer to this structure. The driver fills the rest of the
|
||||
structure or returns the EINVAL error code if cropping is not supported.
|
||||
|
||||
@ -66,7 +66,7 @@ vertical scaling factor.
|
||||
Finally the driver programs the hardware with the actual cropping and
|
||||
image parameters. :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` is a write-only ioctl, it does not
|
||||
return the actual parameters. To query them applications must call
|
||||
:ref:`VIDIOC_G_CROP` and :ref:`VIDIOC_G_FMT`. When the
|
||||
:ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and :ref:`VIDIOC_G_FMT`. When the
|
||||
parameters are unsuitable the application may modify the cropping or
|
||||
image parameters and repeat the cycle until satisfactory parameters have
|
||||
been negotiated.
|
||||
|
||||
@ -34,7 +34,7 @@ Description
|
||||
|
||||
To get the current value of a control applications initialize the ``id``
|
||||
field of a struct :c:type:`struct v4l2_control` and call the
|
||||
:ref:`VIDIOC_G_CTRL` ioctl with a pointer to this structure. To change the
|
||||
:ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` ioctl with a pointer to this structure. To change the
|
||||
value of a control applications initialize the ``id`` and ``value``
|
||||
fields of a struct :c:type:`struct v4l2_control` and call the
|
||||
:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctl.
|
||||
@ -48,7 +48,7 @@ actual new value. If the ``value`` is inappropriate for the control
|
||||
EINVAL error code is returned as well.
|
||||
|
||||
These ioctls work only with user controls. For other control classes the
|
||||
:ref:`VIDIOC_G_EXT_CTRLS`,
|
||||
:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`,
|
||||
:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` or
|
||||
:ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` must be used.
|
||||
|
||||
|
||||
@ -37,7 +37,7 @@ Description
|
||||
|
||||
To set DV timings for the input or output, applications use the
|
||||
:ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get the current timings,
|
||||
applications use the :ref:`VIDIOC_G_DV_TIMINGS` ioctl. The detailed timing
|
||||
applications use the :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. The detailed timing
|
||||
information is filled in using the structure struct
|
||||
:ref:`v4l2_dv_timings <v4l2-dv-timings>`. These ioctls take a
|
||||
pointer to the struct :ref:`v4l2_dv_timings <v4l2-dv-timings>`
|
||||
|
||||
@ -52,7 +52,7 @@ value, then the EINVAL error code will be returned.
|
||||
|
||||
To get the EDID data the application has to fill in the ``pad``,
|
||||
``start_block``, ``blocks`` and ``edid`` fields, zero the ``reserved``
|
||||
array and call :ref:`VIDIOC_G_EDID`. The current EDID from block
|
||||
array and call :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>`. The current EDID from block
|
||||
``start_block`` and of size ``blocks`` will be placed in the memory
|
||||
``edid`` points to. The ``edid`` pointer must point to memory at least
|
||||
``blocks`` * 128 bytes large (the size of one block is 128 bytes).
|
||||
@ -65,7 +65,7 @@ If blocks have to be retrieved from the sink, then this call will block
|
||||
until they have been read.
|
||||
|
||||
If ``start_block`` and ``blocks`` are both set to 0 when
|
||||
:ref:`VIDIOC_G_EDID` is called, then the driver will set ``blocks`` to the
|
||||
:ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>` is called, then the driver will set ``blocks`` to the
|
||||
total number of available EDID blocks and it will return 0 without
|
||||
copying any data. This is an easy way to discover how many EDID blocks
|
||||
there are. Note that if there are no EDID blocks available at all, then
|
||||
|
||||
@ -31,19 +31,19 @@ Arguments
|
||||
Description
|
||||
===========
|
||||
|
||||
The :ref:`VIDIOC_G_ENC_INDEX` ioctl provides meta data about a compressed
|
||||
The :ref:`VIDIOC_G_ENC_INDEX <VIDIOC_G_ENC_INDEX>` ioctl provides meta data about a compressed
|
||||
video stream the same or another application currently reads from the
|
||||
driver, which is useful for random access into the stream without
|
||||
decoding it.
|
||||
|
||||
To read the data applications must call :ref:`VIDIOC_G_ENC_INDEX` with a
|
||||
To read the data applications must call :ref:`VIDIOC_G_ENC_INDEX <VIDIOC_G_ENC_INDEX>` with a
|
||||
pointer to a struct :ref:`v4l2_enc_idx <v4l2-enc-idx>`. On success
|
||||
the driver fills the ``entry`` array, stores the number of elements
|
||||
written in the ``entries`` field, and initializes the ``entries_cap``
|
||||
field.
|
||||
|
||||
Each element of the ``entry`` array contains meta data about one
|
||||
picture. A :ref:`VIDIOC_G_ENC_INDEX` call reads up to
|
||||
picture. A :ref:`VIDIOC_G_ENC_INDEX <VIDIOC_G_ENC_INDEX>` call reads up to
|
||||
``V4L2_ENC_IDX_ENTRIES`` entries from a driver buffer, which can hold up
|
||||
to ``entries_cap`` entries. This number can be lower or higher than
|
||||
``V4L2_ENC_IDX_ENTRIES``, but not zero. When the application fails to
|
||||
|
||||
@ -48,7 +48,7 @@ by the ``controls`` fields.
|
||||
To get the current value of a set of controls applications initialize
|
||||
the ``id``, ``size`` and ``reserved2`` fields of each struct
|
||||
:ref:`v4l2_ext_control <v4l2-ext-control>` and call the
|
||||
:ref:`VIDIOC_G_EXT_CTRLS` ioctl. String controls controls must also set the
|
||||
:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctl. String controls controls must also set the
|
||||
``string`` field. Controls of compound types
|
||||
(``V4L2_CTRL_FLAG_HAS_PAYLOAD`` is set) must set the ``ptr`` field.
|
||||
|
||||
@ -122,7 +122,7 @@ still cause this situation.
|
||||
- The total size in bytes of the payload of this control. This is
|
||||
normally 0, but for pointer controls this should be set to the
|
||||
size of the memory containing the payload, or that will receive
|
||||
the payload. If :ref:`VIDIOC_G_EXT_CTRLS` finds that this value is
|
||||
the payload. If :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` finds that this value is
|
||||
less than is required to store the payload result, then it is set
|
||||
to a value large enough to store the payload result and ENOSPC is
|
||||
returned. Note that for string controls this ``size`` field should
|
||||
@ -328,7 +328,7 @@ still cause this situation.
|
||||
:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` fails with ``error_idx`` set to ``count``,
|
||||
then you can call :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` to try to discover the
|
||||
actual control that failed the validation step. Unfortunately,
|
||||
there is no ``TRY`` equivalent for :ref:`VIDIOC_G_EXT_CTRLS`.
|
||||
there is no ``TRY`` equivalent for :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`.
|
||||
|
||||
- .. row 6
|
||||
|
||||
@ -367,7 +367,7 @@ still cause this situation.
|
||||
- The class containing user controls. These controls are described
|
||||
in :ref:`control`. All controls that can be set using the
|
||||
:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` and
|
||||
:ref:`VIDIOC_G_CTRL` ioctl belong to this
|
||||
:ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` ioctl belong to this
|
||||
class.
|
||||
|
||||
- .. row 2
|
||||
|
||||
@ -34,7 +34,7 @@ Arguments
|
||||
Description
|
||||
===========
|
||||
|
||||
Applications can use the :ref:`VIDIOC_G_FBUF` and :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>` ioctl
|
||||
Applications can use the :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>` and :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>` ioctl
|
||||
to get and set the framebuffer parameters for a
|
||||
:ref:`Video Overlay <overlay>` or :ref:`Video Output Overlay <osd>`
|
||||
(OSD). The type of overlay is implied by the device type (capture or
|
||||
@ -48,7 +48,7 @@ of a graphics card. A non-destructive overlay blends video images into a
|
||||
VGA signal or graphics into a video signal. *Video Output Overlays* are
|
||||
always non-destructive.
|
||||
|
||||
To get the current parameters applications call the :ref:`VIDIOC_G_FBUF`
|
||||
To get the current parameters applications call the :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>`
|
||||
ioctl with a pointer to a :c:type:`struct v4l2_framebuffer`
|
||||
structure. The driver fills all fields of the structure or returns an
|
||||
EINVAL error code when overlays are not supported.
|
||||
@ -59,13 +59,13 @@ initialize the ``flags`` field of a struct
|
||||
implemented on the TV card all other parameters are determined by the
|
||||
driver. When an application calls :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>` with a pointer to
|
||||
this structure, the driver prepares for the overlay and returns the
|
||||
framebuffer parameters as :ref:`VIDIOC_G_FBUF` does, or it returns an error
|
||||
framebuffer parameters as :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>` does, or it returns an error
|
||||
code.
|
||||
|
||||
To set the parameters for a *non-destructive Video Overlay*,
|
||||
applications must initialize the ``flags`` field, the ``fmt``
|
||||
substructure, and call :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>`. Again the driver prepares for
|
||||
the overlay and returns the framebuffer parameters as :ref:`VIDIOC_G_FBUF`
|
||||
the overlay and returns the framebuffer parameters as :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>`
|
||||
does, or it returns an error code.
|
||||
|
||||
For a *destructive Video Overlay* applications must additionally provide
|
||||
|
||||
@ -41,7 +41,7 @@ struct :c:type:`struct v4l2_format` to the respective buffer (stream)
|
||||
type. For example video capture devices use
|
||||
``V4L2_BUF_TYPE_VIDEO_CAPTURE`` or
|
||||
``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE``. When the application calls the
|
||||
:ref:`VIDIOC_G_FMT` ioctl with a pointer to this structure the driver fills
|
||||
:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctl with a pointer to this structure the driver fills
|
||||
the respective member of the ``fmt`` union. In case of video capture
|
||||
devices that is either the struct
|
||||
:ref:`v4l2_pix_format <v4l2-pix-format>` ``pix`` or the struct
|
||||
@ -62,10 +62,10 @@ this is a mechanism to fathom device capabilities and to approach
|
||||
parameters acceptable for both the application and driver. On success
|
||||
the driver may program the hardware, allocate resources and generally
|
||||
prepare for data exchange. Finally the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl returns
|
||||
the current format parameters as :ref:`VIDIOC_G_FMT` does. Very simple,
|
||||
the current format parameters as :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` does. Very simple,
|
||||
inflexible devices may even ignore all input and always return the
|
||||
default parameters. However all V4L2 devices exchanging data with the
|
||||
application must implement the :ref:`VIDIOC_G_FMT` and :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`
|
||||
application must implement the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`
|
||||
ioctl. When the requested buffer type is not supported drivers return an
|
||||
EINVAL error code on a :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` attempt. When I/O is already in
|
||||
progress or the resource is not available for other reasons drivers
|
||||
|
||||
@ -39,7 +39,7 @@ the ``tuner`` field of a struct
|
||||
:ref:`v4l2_frequency <v4l2-frequency>` to the respective tuner or
|
||||
modulator number (only input devices have tuners, only output devices
|
||||
have modulators), zero out the ``reserved`` array and call the
|
||||
:ref:`VIDIOC_G_FREQUENCY` ioctl with a pointer to this structure. The
|
||||
:ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQUENCY>` ioctl with a pointer to this structure. The
|
||||
driver stores the current frequency in the ``frequency`` field.
|
||||
|
||||
To change the current tuner or modulator radio frequency applications
|
||||
|
||||
@ -33,7 +33,7 @@ Description
|
||||
===========
|
||||
|
||||
To query the current video input applications call the
|
||||
:ref:`VIDIOC_G_INPUT` ioctl with a pointer to an integer where the driver
|
||||
:ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer to an integer where the driver
|
||||
stores the number of the input, as in the struct
|
||||
:ref:`v4l2_input <v4l2-input>` ``index`` field. This ioctl will fail
|
||||
only when there are no video inputs, returning EINVAL.
|
||||
|
||||
@ -37,7 +37,7 @@ Description
|
||||
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
|
||||
:ref:`VIDIOC_G_MODULATOR` ioctl with a pointer to this structure. Drivers
|
||||
: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
|
||||
|
||||
@ -33,7 +33,7 @@ Description
|
||||
===========
|
||||
|
||||
To query the current video output applications call the
|
||||
:ref:`VIDIOC_G_OUTPUT` ioctl with a pointer to an integer where the driver
|
||||
:ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a pointer to an integer where the driver
|
||||
stores the number of the output, as in the struct
|
||||
:ref:`v4l2_output <v4l2-output>` ``index`` field. This ioctl will
|
||||
fail only when there are no video outputs, returning the EINVAL error
|
||||
|
||||
@ -44,7 +44,7 @@ internally by a driver in read/write mode. For implications see the
|
||||
section discussing the :ref:`read() <func-read>` function.
|
||||
|
||||
To get and set the streaming parameters applications call the
|
||||
:ref:`VIDIOC_G_PARM` and :ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` ioctl, respectively. They take a
|
||||
:ref:`VIDIOC_G_PARM <VIDIOC_G_PARM>` and :ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` ioctl, respectively. They take a
|
||||
pointer to a struct :c:type:`struct v4l2_streamparm` which contains a
|
||||
union holding separate parameters for input and output devices.
|
||||
|
||||
|
||||
@ -36,7 +36,7 @@ Description
|
||||
===========
|
||||
|
||||
To query the current access priority applications call the
|
||||
:ref:`VIDIOC_G_PRIORITY` ioctl with a pointer to an enum v4l2_priority
|
||||
:ref:`VIDIOC_G_PRIORITY <VIDIOC_G_PRIORITY>` ioctl with a pointer to an enum v4l2_priority
|
||||
variable where the driver stores the current priority.
|
||||
|
||||
To request an access priority applications store the desired priority in
|
||||
|
||||
@ -34,7 +34,7 @@ Description
|
||||
To find out which data services are supported by a sliced VBI capture or
|
||||
output device, applications initialize the ``type`` field of a struct
|
||||
:ref:`v4l2_sliced_vbi_cap <v4l2-sliced-vbi-cap>`, clear the
|
||||
``reserved`` array and call the :ref:`VIDIOC_G_SLICED_VBI_CAP` ioctl. The
|
||||
``reserved`` array and call the :ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLICED_VBI_CAP>` ioctl. The
|
||||
driver fills in the remaining fields or returns an EINVAL error code if
|
||||
the sliced VBI API is unsupported or ``type`` is invalid.
|
||||
|
||||
|
||||
@ -35,15 +35,15 @@ Description
|
||||
===========
|
||||
|
||||
To query and select the current video standard applications use the
|
||||
:ref:`VIDIOC_G_STD` and :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctls which take a pointer to a
|
||||
:ref:`v4l2_std_id <v4l2-std-id>` type as argument. :ref:`VIDIOC_G_STD`
|
||||
:ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctls which take a pointer to a
|
||||
:ref:`v4l2_std_id <v4l2-std-id>` type as argument. :ref:`VIDIOC_G_STD <VIDIOC_G_STD>`
|
||||
can return a single flag or a set of flags as in struct
|
||||
:ref:`v4l2_standard <v4l2-standard>` field ``id``. The flags must be
|
||||
unambiguous such that they appear in only one enumerated
|
||||
:c:type:`struct v4l2_standard` structure.
|
||||
|
||||
:ref:`VIDIOC_S_STD <VIDIOC_G_STD>` accepts one or more flags, being a write-only ioctl it
|
||||
does not return the actual new standard as :ref:`VIDIOC_G_STD` does. When
|
||||
does not return the actual new standard as :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` does. When
|
||||
no flags are given or the current input does not support the requested
|
||||
standard the driver returns an EINVAL error code. When the standard set
|
||||
is ambiguous drivers may return EINVAL or choose any of the requested
|
||||
|
||||
@ -569,7 +569,7 @@ See also the examples in :ref:`control`.
|
||||
:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` you need to
|
||||
set the ``size`` field of struct
|
||||
:ref:`v4l2_ext_control <v4l2-ext-control>` to 9. For
|
||||
:ref:`VIDIOC_G_EXT_CTRLS` you can set
|
||||
:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` you can set
|
||||
the ``size`` field to ``maximum`` + 1. Which character encoding is
|
||||
used will depend on the string control itself and should be part
|
||||
of the control documentation.
|
||||
|
||||
Loading…
Reference in New Issue
Block a user