Part I. Video for Linux Two API Specification
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# Part I. Video for Linux Two API Specification

## Revision 4.4

### Michael H Schimek

`<mschimek@gmx.at>`

### Bill Dirks

Original author of the V4L2 API and documentation.

### Hans Verkuil

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.

`<hverkuil@xs4all.nl>`

### Martin Rubli

Designed and documented the VIDIOC_ENUM_FRAMESIZES and VIDIOC_ENUM_FRAMEINTERVALS ioctls.

### Andy Walls

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

`<awalls@md.metrocast.net>`

### Mauro Carvalho Chehab

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

`<m.chehab@samsung.com>`

### Muralidharan Karicheri

Documented the Digital Video timings API.

`<m-karicheri2@ti.com>`

### Pawel Osciak

Designed and documented the multi-planar API.

`<pawel AT osciak.com>`

### Sakari Ailus

Subdev selections API.

`<sakari.ailus@iki.fi>`

### Antti Palosaari

SDR API.

`<crope@iki.fi>`

Copyright © 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015 Bill Dirks, Michael H. Schimek, Hans Verkuil, Martin Rubli, Andy Walls, Muralidharan Karicheri, Mauro Carvalho Chehab, Pawel Osciak

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

Revision History
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 v4l2_ycbcr_encoding and enum v4l2_quantization fields to struct v4l2_pix_format, struct v4l2_pix_format_mplane and struct v4l2_mbus_framefmt.
Revision 3.17 | 2014-08-04 | lp, hv
Extended struct 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 JPEG compression control class.
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 multi-planar API.
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.

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