media/v4l/v4l2.rst

.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. c:namespace:: V4L
.. include:: <isonum.txt>

.. _v4l2spec:

############################
Part I - Video for Linux API
############################

This part describes the Video for Linux API version 2 (V4L2 API) specification.

**Revision 4.5**

.. toctree::
    :caption: Table of Contents
    :numbered:
    :maxdepth: 5

    common
    pixfmt
    io
    devices
    libv4l
    compat
    user-func
    common-defs
    videodev
    capture-example
    v4l2grab-example
    biblio


**********************
Revision and Copyright
**********************

Authors, in alphabetical order:

- Ailus, Sakari <sakari.ailus@iki.fi>

  - Subdev selections API.

- Carvalho Chehab, Mauro <mchehab+samsung@kernel.org>

  - Documented libv4l, designed and added v4l2grab example, Remote Controller chapter.

- Dirks, Bill

  - Original author of the V4L2 API and documentation.

- Figa, Tomasz <tfiga@chromium.org>

  - Documented the memory-to-memory decoder interface.
  - Documented the memory-to-memory encoder interface.

- H Schimek, Michael <mschimek@gmx.at>

  - Original author of the V4L2 API and documentation.

- Karicheri, Muralidharan <m-karicheri2@ti.com>

  - Documented the Digital Video timings API.

- Osciak, Pawel <posciak@chromium.org>

  - Documented the memory-to-memory decoder interface.
  - Documented the memory-to-memory encoder interface.

- Osciak, Pawel <pawel@osciak.com>

  - Designed and documented the multi-planar API.

- Palosaari, Antti <crope@iki.fi>

  - SDR API.

- Ribalda, Ricardo

  - Introduce HSV formats and other minor changes.

- Rubli, Martin

  - Designed and documented the VIDIOC_ENUM_FRAMESIZES and VIDIOC_ENUM_FRAMEINTERVALS ioctls.

- Walls, Andy <awalls@md.metrocast.net>

  - Documented the fielded V4L2_MPEG_STREAM_VBI_FMT_IVTV MPEG stream embedded, sliced VBI data format in this specification.

- Verkuil, Hans <hverkuil@kernel.org>

  - Designed and documented the VIDIOC_LOG_STATUS ioctl, the extended control ioctls, major parts of the sliced VBI API, the MPEG encoder and decoder APIs and the DV Timings API.

**Copyright** |copy| 1999-2018: Bill Dirks, Michael H. Schimek, Hans Verkuil, Martin Rubli, Andy Walls, Muralidharan Karicheri, Mauro Carvalho Chehab, Pawel Osciak, Sakari Ailus & Antti Palosaari, Tomasz Figa

Except when explicitly stated as GPL, programming examples within this
part can be used and distributed without restrictions.

****************
Revision History
****************

:revision: 4.10 / 2016-07-15 (*rr*)

Introduce HSV formats.


:revision: 4.5 / 2015-10-29 (*rr*)

Extend VIDIOC_G_EXT_CTRLS;. Replace ctrl_class with a new union with
ctrl_class and which. Which is used to select the current value of the
control or the default value.


:revision: 4.4 / 2015-05-26 (*ap*)

Renamed V4L2_TUNER_ADC to V4L2_TUNER_SDR. Added
V4L2_CID_RF_TUNER_RF_GAIN control. Added transmitter support for
Software Defined Radio (SDR) Interface.


:revision: 4.1 / 2015-02-13 (*mcc*)

Fix documentation for media controller device nodes and add support for
DVB device nodes. Add support for Tuner sub-device.


:revision: 3.19 / 2014-12-05 (*hv*)

Rewrote Colorspace chapter, added new enum
:c:type:`v4l2_ycbcr_encoding` and enum
:c:type:`v4l2_quantization` fields to struct
:c:type:`v4l2_pix_format`, struct
:c:type:`v4l2_pix_format_mplane` and struct
:c:type:`v4l2_mbus_framefmt`.


:revision: 3.17 / 2014-08-04 (*lp, hv*)

Extended struct :c:type:`v4l2_pix_format`. Added
format flags. Added compound control types and VIDIOC_QUERY_EXT_CTRL.


:revision: 3.15 / 2014-02-03 (*hv, ap*)

Update several sections of "Common API Elements": "Opening and Closing
Devices" "Querying Capabilities", "Application Priority", "Video Inputs
and Outputs", "Audio Inputs and Outputs" "Tuners and Modulators", "Video
Standards" and "Digital Video (DV) Timings". Added SDR API.


:revision: 3.14 / 2013-11-25 (*rr*)

Set width and height as unsigned on v4l2_rect.


:revision: 3.11 / 2013-05-26 (*hv*)

Remove obsolete VIDIOC_DBG_G_CHIP_IDENT ioctl.


:revision: 3.10 / 2013-03-25 (*hv*)

Remove obsolete and unused DV_PRESET ioctls: VIDIOC_G_DV_PRESET,
VIDIOC_S_DV_PRESET, VIDIOC_QUERY_DV_PRESET and
VIDIOC_ENUM_DV_PRESET. Remove the related v4l2_input/output
capability flags V4L2_IN_CAP_PRESETS and V4L2_OUT_CAP_PRESETS.
Added VIDIOC_DBG_G_CHIP_INFO.


:revision: 3.9 / 2012-12-03 (*sa, sn*)

Added timestamp types to v4l2_buffer. Added
V4L2_EVENT_CTRL_CH_RANGE control event changes flag.


:revision: 3.6 / 2012-07-02 (*hv*)

Added VIDIOC_ENUM_FREQ_BANDS.


:revision: 3.5 / 2012-05-07 (*sa, sn, hv*)

Added V4L2_CTRL_TYPE_INTEGER_MENU and V4L2 subdev selections API.
Improved the description of V4L2_CID_COLORFX control, added
V4L2_CID_COLORFX_CBCR control. Added camera controls
V4L2_CID_AUTO_EXPOSURE_BIAS,
V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE,
V4L2_CID_IMAGE_STABILIZATION, V4L2_CID_ISO_SENSITIVITY,
V4L2_CID_ISO_SENSITIVITY_AUTO, V4L2_CID_EXPOSURE_METERING,
V4L2_CID_SCENE_MODE, V4L2_CID_3A_LOCK,
V4L2_CID_AUTO_FOCUS_START, V4L2_CID_AUTO_FOCUS_STOP,
V4L2_CID_AUTO_FOCUS_STATUS and V4L2_CID_AUTO_FOCUS_RANGE. Added
VIDIOC_ENUM_DV_TIMINGS, VIDIOC_QUERY_DV_TIMINGS and
VIDIOC_DV_TIMINGS_CAP.


:revision: 3.4 / 2012-01-25 (*sn*)

Added :ref:`JPEG compression control class. <jpeg-controls>`


:revision: 3.3 / 2012-01-11 (*hv*)

Added device_caps field to struct v4l2_capabilities.


:revision: 3.2 / 2011-08-26 (*hv*)

Added V4L2_CTRL_FLAG_VOLATILE.


:revision: 3.1 / 2011-06-27 (*mcc, po, hv*)

Documented that VIDIOC_QUERYCAP now returns a per-subsystem version
instead of a per-driver one. Standardize an error code for invalid
ioctl. Added V4L2_CTRL_TYPE_BITMASK.


:revision: 2.6.39 / 2011-03-01 (*mcc, po*)

Removed VIDIOC_*_OLD from videodev2.h header and update it to reflect
latest changes. Added the :ref:`multi-planar API <planar-apis>`.


:revision: 2.6.37 / 2010-08-06 (*hv*)

Removed obsolete vtx (videotext) API.


:revision: 2.6.33 / 2009-12-03 (*mk*)

Added documentation for the Digital Video timings API.


:revision: 2.6.32 / 2009-08-31 (*mcc*)

Now, revisions will match the kernel version where the V4L2 API changes
will be used by the Linux Kernel. Also added Remote Controller chapter.


:revision: 0.29 / 2009-08-26 (*ev*)

Added documentation for string controls and for FM Transmitter controls.


:revision: 0.28 / 2009-08-26 (*gl*)

Added V4L2_CID_BAND_STOP_FILTER documentation.


:revision: 0.27 / 2009-08-15 (*mcc*)

Added libv4l and Remote Controller documentation; added v4l2grab and
keytable application examples.


:revision: 0.26 / 2009-07-23 (*hv*)

Finalized the RDS capture API. Added modulator and RDS encoder
capabilities. Added support for string controls.


:revision: 0.25 / 2009-01-18 (*hv*)

Added pixel formats VYUY, NV16 and NV61, and changed the debug ioctls
VIDIOC_DBG_G/S_REGISTER and VIDIOC_DBG_G_CHIP_IDENT. Added camera
controls V4L2_CID_ZOOM_ABSOLUTE, V4L2_CID_ZOOM_RELATIVE,
V4L2_CID_ZOOM_CONTINUOUS and V4L2_CID_PRIVACY.


:revision: 0.24 / 2008-03-04 (*mhs*)

Added pixel formats Y16 and SBGGR16, new controls and a camera controls
class. Removed VIDIOC_G/S_MPEGCOMP.


:revision: 0.23 / 2007-08-30 (*mhs*)

Fixed a typo in VIDIOC_DBG_G/S_REGISTER. Clarified the byte order of
packed pixel formats.


:revision: 0.22 / 2007-08-29 (*mhs*)

Added the Video Output Overlay interface, new MPEG controls,
V4L2_FIELD_INTERLACED_TB and V4L2_FIELD_INTERLACED_BT,
VIDIOC_DBG_G/S_REGISTER, VIDIOC\_(TRY\_)ENCODER_CMD,
VIDIOC_G_CHIP_IDENT, VIDIOC_G_ENC_INDEX, new pixel formats.
Clarifications in the cropping chapter, about RGB pixel formats, the
mmap(), poll(), select(), read() and write() functions. Typographical
fixes.


:revision: 0.21 / 2006-12-19 (*mhs*)

Fixed a link in the VIDIOC_G_EXT_CTRLS section.


:revision: 0.20 / 2006-11-24 (*mhs*)

Clarified the purpose of the audioset field in struct v4l2_input and
v4l2_output.


:revision: 0.19 / 2006-10-19 (*mhs*)

Documented V4L2_PIX_FMT_RGB444.


:revision: 0.18 / 2006-10-18 (*mhs*)

Added the description of extended controls by Hans Verkuil. Linked
V4L2_PIX_FMT_MPEG to V4L2_CID_MPEG_STREAM_TYPE.


:revision: 0.17 / 2006-10-12 (*mhs*)

Corrected V4L2_PIX_FMT_HM12 description.


:revision: 0.16 / 2006-10-08 (*mhs*)

VIDIOC_ENUM_FRAMESIZES and VIDIOC_ENUM_FRAMEINTERVALS are now part
of the API.


:revision: 0.15 / 2006-09-23 (*mhs*)

Cleaned up the bibliography, added BT.653 and BT.1119.
capture.c/start_capturing() for user pointer I/O did not initialize the
buffer index. Documented the V4L MPEG and MJPEG VID_TYPEs and
V4L2_PIX_FMT_SBGGR8. Updated the list of reserved pixel formats. See
the history chapter for API changes.


:revision: 0.14 / 2006-09-14 (*mr*)

Added VIDIOC_ENUM_FRAMESIZES and VIDIOC_ENUM_FRAMEINTERVALS proposal
for frame format enumeration of digital devices.


:revision: 0.13 / 2006-04-07 (*mhs*)

Corrected the description of struct v4l2_window clips. New V4L2_STD\_
and V4L2_TUNER_MODE_LANG1_LANG2 defines.


:revision: 0.12 / 2006-02-03 (*mhs*)

Corrected the description of struct v4l2_captureparm and
v4l2_outputparm.


:revision: 0.11 / 2006-01-27 (*mhs*)

Improved the description of struct v4l2_tuner.


:revision: 0.10 / 2006-01-10 (*mhs*)

VIDIOC_G_INPUT and VIDIOC_S_PARM clarifications.


:revision: 0.9 / 2005-11-27 (*mhs*)

Improved the 525 line numbering diagram. Hans Verkuil and I rewrote the
sliced VBI section. He also contributed a VIDIOC_LOG_STATUS page.
Fixed VIDIOC_S_STD call in the video standard selection example.
Various updates.


:revision: 0.8 / 2004-10-04 (*mhs*)

Somehow a piece of junk slipped into the capture example, removed.


:revision: 0.7 / 2004-09-19 (*mhs*)

Fixed video standard selection, control enumeration, downscaling and
aspect example. Added read and user pointer i/o to video capture
example.


:revision: 0.6 / 2004-08-01 (*mhs*)

v4l2_buffer changes, added video capture example, various corrections.


:revision: 0.5 / 2003-11-05 (*mhs*)

Pixel format erratum.


:revision: 0.4 / 2003-09-17 (*mhs*)

Corrected source and Makefile to generate a PDF. SGML fixes. Added
latest API changes. Closed gaps in the history chapter.


:revision: 0.3 / 2003-02-05 (*mhs*)

Another draft, more corrections.


:revision: 0.2 / 2003-01-15 (*mhs*)

Second draft, with corrections pointed out by Gerd Knorr.


:revision: 0.1 / 2002-12-01 (*mhs*)

First draft, based on documentation by Bill Dirks and discussions on the
V4L mailing list.