path: root/Documentation/userspace-api/media/v4l/v4l2.rst

.. Permission is granted to copy, distribute and/or modify this
.. document under the terms of the GNU Free Documentation License,
.. Version 1.1 or any later version published by the Free Software
.. Foundation, with no Invariant Sections, no Front-Cover Texts
.. and no Back-Cover Texts. A copy of the license is included at
.. Documentation/userspace-api/media/fdl-appendix.rst.
..
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections

.. 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**

.. only:: html

   .. class:: toc-title

        Table of Contents

.. toctree::
    :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.

- 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.

- 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@xs4all.nl>

  - 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.