Documentation:Modules/v4l2

??	VLC uses this protocol (or access module) to read data from a device or network.

Module: v4l2
Type	Access Demux
First VLC version	0.9.0
Last VLC version	-
Operating system(s)	Linux
Description	Video for Linux 2 input
Shortcut(s)	-

Options

• v4l2-caching <integer> : Caching in ms

Video input

• v4l2-dev <string> : Primary device name default value: "/dev/video0"
• v4l2-standard <integer> : Video standard default value: 0
• v4l2-chroma <string> : Force use of a specific video chroma (Use MJPG here to use a webcam's MJPEG stream) default value: ""
• v4l2-input <integer> : Card input to use for video default value: 0
• v4l2-audio-input <integer> : Card input to use for audio default value: 0
• v4l2-io <integer> : IO method default value: 0
• v4l2-width <integer> : Prefered video width (if non zero) default value: 0
• v4l2-height <integer> : Prefered video height (if non zero) default value: 0
• v4l2-fps <float> : Frames per second (if non zero) default value: 0

Audio input

These options do not apply to audio streams in compressed data.

• v4l2-adev <string> : Audio input device default value: ""
• v4l2-audio-method <integer> : Allowed audio input methods (bitmask: 1 for OSS, 2 for ALSA) default value: 3
• v4l2-stereo : Capture audio in stereo default value: enabled
• v4l2-samplerate <integer> : Audio input sample rate in Hz default value: 48000

Tuner

• v4l2-tuner <integer> : Tuner to use default value: 0
• v4l2-tuner-frequency <integer> : Tuner frequency in Hz or MHz depending on the underlying v4l2 driver default value: -1
• v4l2-tuner-audio-mode <integer> : Tuner audio mode default value: -1

Controls

These controls will be used only if they are supported by the v4l2 driver.

• v4l2-controls-reset : Reset all the v4l2 controls default value: disabled
• v4l2-brightness <integer> : Brightness default value: -1
• v4l2-contrast <integer> : Contrast default value: -1
• v4l2-saturation <integer> : Saturation default value: -1
• v4l2-hue <integer> : Hue default value: -1
• v4l2-black-level <integer> : Black level default value: -1
• v4l2-auto-white-balance <integer> : Auto white balance default value: -1
• v4l2-do-white-balance <integer> : Do white balance default value: -1
• v4l2-red-balance <integer> : Red balance default value: -1
• v4l2-blue-balance <integer> : Blue balance default value: -1
• v4l2-gamma <integer> : Gamma default value: -1
• v4l2-exposure <integer> : Exposure default value: -1
• v4l2-autogain <integer> : Auto gain default value: -1
• v4l2-gain <integer> : Gain default value: -1
• v4l2-hflip <integer> : Flip the image horizontaly default value: -1
• v4l2-vflip <integer> : Flip the image verticaly default value: -1
• v4l2-hcenter <integer> : Horizontal center default value: -1
• v4l2-vcenter <integer> : Vertical center default value: -1
• v4l2-audio-volume <integer> : Audio volume default value: -1
• v4l2-audio-balance <integer> : Audio balance default value: -1
• v4l2-audio-mute : Audio mute default value: disabled
• v4l2-audio-bass <integer> : Audio bass default value: -1
• v4l2-audio-treble <integer> : Audio treble default value: -1
• v4l2-audio-loudness <integer> : Audio loudness default value: -1
• v4l2-set-ctrls <string> : Set any other control listed in the debug output using a comma seperated list in curly braces such as {video_bitrate=6000000,audio_crc=0,stream_type=3} default value: ""

Example

Open a video device with default settings:

% vlc v4l2:///dev/video0:width=640:height=480

Get information about a video device's capabilities:

% vlc -vvv --color v4l2:///dev/video0 --run-time 1 vlc://quit -I dummy -V dummy -A dummy

Command line for Hauppauge PVR 250 to get France 2 (at ECP) and encode as MPEG2 and stream using UDP multicast:

% vlc -I dummy -vvv 'v4l2c://:audio-method=0:controls-reset:set-ctrls={video_bitrate_mode=1,video_bitrate=4000000,video_peak_bitrate=4000000}:width=720:height=576:tuner=0:tuner-frequency=478550'  --sout "#std{access=udp{ttl=12},mux=ts,url=239.255.1.1}"

Note: v4l2c is an alias used to force VLC to use the v4l2 module in it's Access variant without probing the Access Demux version first (the c stands for compressed).

Source code

• modules/access/v4l2/v4l2.c

See also

• Documentation:Modules/v4l
• Documentation:Modules/dshow

This page is part of official VLC media player Documentation (User Guide • Streaming HowTo • Hacker Guide • Modules)
Please read the Documentation Editing Guidelines before you edit the documentation

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.