Input Devices
*************

Input devices are configured elements in FFmpeg which enable accessing the data coming from a multimedia device attached to your system.

When you configure your FFmpeg build, all the supported input devices are enabled by default. You can list all available ones using the configure option "--list-indevs".

You can disable all the input devices using the configure option "--disable-indevs", and selectively enable an input device using the option "--enable-indev=INDEV", or you can disable a particular input device using the option "--disable-indev=INDEV".

The option "-devices" of the ff* tools will display the list of supported input devices.

A description of the currently available input devices follows.

alsa
====

ALSA (Advanced Linux Sound Architecture) input device.

To enable this input device during configuration you need libasound installed on your system.

This device allows capturing from an ALSA device. The name of the device to capture has to be an ALSA card identifier.

An ALSA identifier has the syntax:

     hw:CARD[,DEV[,SUBDEV]]

where the DEV and SUBDEV components are optional.

The three arguments (in order: CARD,DEV,SUBDEV) specify card number or identifier, device number and subdevice number (-1 means any).

To see the list of cards currently recognized by your system check the files /proc/asound/cards and /proc/asound/devices.

For example to capture with ffmpeg from an ALSA device with card id 0, you may run the command:

     ffmpeg -f alsa -i hw:0 alsaout.wav

For more information see: http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html

Options
-------

sample_rate
     Set the sample rate in Hz. Default is 48000.

channels
     Set the number of channels. Default is 2.

avfoundation
============

AVFoundation input device.

AVFoundation is the currently recommended framework by Apple for streamgrabbing on OSX >= 10.7 as well as on iOS. The older QTKit framework has been marked deprecated since OSX version 10.7.

The input filename has to be given in the following syntax:

     -i "[[VIDEO]:[AUDIO]]"

The first entry selects the video input while the latter selects the audio input. The stream has to be specified by the device name or the device index as shown by the device list. Alternatively, the video and/or audio input device can be chosen by index using the

-video_device_index <INDEX>

and/or

-audio_device_index <INDEX>

, overriding any device name or index given in the input filename.

All available devices can be enumerated by using -list_devices true, listing all device names and corresponding indices.

There are two device name aliases:

default
     Select the AVFoundation default device of the corresponding type.

none
     Do not record the corresponding media type. This is equivalent to specifying an empty device name or index.

Options
-------

AVFoundation supports the following options:

-list_devices <TRUE|FALSE>
     If set to true, a list of all available input devices is given showing all device names and indices.

-video_device_index <INDEX>
     Specify the video device by its index. Overrides anything given in the input filename.

-audio_device_index <INDEX>
     Specify the audio device by its index. Overrides anything given in the input filename.

-pixel_format <FORMAT>
     Request the video device to use a specific pixel format. If the specified format is not supported, a list of available formats is given and the first one in this list is used instead. Available pixel formats are: monob, rgb555be, rgb555le, rgb565be, rgb565le, rgb24, bgr24, 0rgb, bgr0, 0bgr, rgb0, bgr48be, uyvy422, yuva444p, yuva444p16le, yuv444p, yuv422p16, yuv422p10, yuv444p10, yuv420p, nv12, yuyv422, gray

-framerate
     Set the grabbing frame rate. Default is ntsc, corresponding to a frame rate of 30000/1001.

-video_size
     Set the video frame size.

-capture_cursor
     Capture the mouse pointer. Default is 0.

-capture_mouse_clicks
     Capture the screen mouse clicks. Default is 0.

Examples
--------

  * Print the list of AVFoundation supported devices and exit:

          $ ffmpeg -f avfoundation -list_devices true -i ""

  * Record video from video device 0 and audio from audio device 0 into out.avi:

          $ ffmpeg -f avfoundation -i "0:0" out.avi

  * Record video from video device 2 and audio from audio device 1 into out.avi:

          $ ffmpeg -f avfoundation -video_device_index 2 -i ":1" out.avi

  * Record video from the system default video device using the pixel format bgr0 and do not record any audio into out.avi:

          $ ffmpeg -f avfoundation -pixel_format bgr0 -i "default:none" out.avi

bktr
====

BSD video input device.

Options
-------

framerate
     Set the frame rate.

video_size
     Set the video frame size. Default is vga.

standard

     Available values are:

     pal

     ntsc

     secam

     paln

     palm

     ntscj

decklink
========

The decklink input device provides capture capabilities for Blackmagic DeckLink devices.

To enable this input device, you need the Blackmagic DeckLink SDK and you need to configure with the appropriate --extra-cflags and --extra-ldflags. On Windows, you need to run the IDL files through widl.

DeckLink is very picky about the formats it supports. Pixel format is uyvy422 or v210, framerate and video size must be determined for your device with -list_formats 1. Audio sample rate is always 48 kHz and the number of channels can be 2, 8 or 16.

Options
-------

list_devices
     If set to true, print a list of devices and exit. Defaults to false.

list_formats
     If set to true, print a list of supported formats and exit. Defaults to false.

bm_v210
     If set to 1, video is captured in 10 bit v210 instead of uyvy422. Not all Blackmagic devices support this option.

Examples
--------

  * List input devices:

          ffmpeg -f decklink -list_devices 1 -i dummy

  * List supported formats:

          ffmpeg -f decklink -list_formats 1 -i 'Intensity Pro'

  * Capture video clip at 1080i50 (format 11):

          ffmpeg -f decklink -i 'Intensity Pro@11' -acodec copy -vcodec copy output.avi

  * Capture video clip at 1080i50 10 bit:

          ffmpeg -bm_v210 1 -f decklink -i 'UltraStudio Mini Recorder@11' -acodec copy -vcodec copy output.avi

dshow
=====

Windows DirectShow input device.

DirectShow support is enabled when FFmpeg is built with the mingw-w64 project. Currently only audio and video devices are supported.

Multiple devices may be opened as separate inputs, but they may also be opened on the same input, which should improve synchronism between them.

The input name should be in the format:

     TYPE=NAME[:TYPE=NAME]

where TYPE can be either AUDIO or VIDEO, and NAME is the device's name or alternative name..

Options
-------

If no options are specified, the device's defaults are used. If the device does not support the requested options, it will fail to open.

video_size
     Set the video size in the captured video.

framerate
     Set the frame rate in the captured video.

sample_rate
     Set the sample rate (in Hz) of the captured audio.

sample_size
     Set the sample size (in bits) of the captured audio.

channels
     Set the number of channels in the captured audio.

list_devices
     If set to true, print a list of devices and exit.

list_options
     If set to true, print a list of selected device's options and exit.

video_device_number
     Set video device number for devices with the same name (starts at 0, defaults to 0).

audio_device_number
     Set audio device number for devices with the same name (starts at 0, defaults to 0).

pixel_format
     Select pixel format to be used by DirectShow. This may only be set when the video codec is not set or set to rawvideo.

audio_buffer_size
     Set audio device buffer size in milliseconds (which can directly impact latency, depending on the device). Defaults to using the audio device's default buffer size (typically some multiple of 500ms). Setting this value too low can degrade performance. See also http://msdn.microsoft.com/en-us/library/windows/desktop/dd377582(v=vs.85).aspx

video_pin_name
     Select video capture pin to use by name or alternative name.

audio_pin_name
     Select audio capture pin to use by name or alternative name.

crossbar_video_input_pin_number
     Select video input pin number for crossbar device. This will be routed to the crossbar device's Video Decoder output pin. Note that changing this value can affect future invocations (sets a new default) until system reboot occurs.

crossbar_audio_input_pin_number
     Select audio input pin number for crossbar device. This will be routed to the crossbar device's Audio Decoder output pin. Note that changing this value can affect future invocations (sets a new default) until system reboot occurs.

show_video_device_dialog
     If set to true, before capture starts, popup a display dialog to the end user, allowing them to change video filter properties and configurations manually. Note that for crossbar devices, adjusting values in this dialog may be needed at times to toggle between PAL (25 fps) and NTSC (29.97) input frame rates, sizes, interlacing, etc.  Changing these values can enable different scan rates/frame rates and avoiding green bars at the bottom, flickering scan lines, etc. Note that with some devices, changing these properties can also affect future invocations (sets new defaults) until system reboot occurs.

show_audio_device_dialog
     If set to true, before capture starts, popup a display dialog to the end user, allowing them to change audio filter properties and configurations manually.

show_video_crossbar_connection_dialog
     If set to true, before capture starts, popup a display dialog to the end user, allowing them to manually modify crossbar pin routings, when it opens a video device.

show_audio_crossbar_connection_dialog
     If set to true, before capture starts, popup a display dialog to the end user, allowing them to manually modify crossbar pin routings, when it opens an audio device.

show_analog_tv_tuner_dialog
     If set to true, before capture starts, popup a display dialog to the end user, allowing them to manually modify TV channels and frequencies.

show_analog_tv_tuner_audio_dialog
     If set to true, before capture starts, popup a display dialog to the end user, allowing them to manually modify TV audio (like mono vs. stereo, Language A,B or C).

audio_device_load
     Load an audio capture filter device from file instead of searching it by name. It may load additional parameters too, if the filter supports the serialization of its properties to. To use this an audio capture source has to be specified, but it can be anything even fake one.

audio_device_save
     Save the currently used audio capture filter device and its parameters (if the filter supports it) to a file. If a file with the same name exists it will be overwritten.

video_device_load
     Load a video capture filter device from file instead of searching it by name. It may load additional parameters too, if the filter supports the serialization of its properties to. To use this a video capture source has to be specified, but it can be anything even fake one.

video_device_save
     Save the currently used video capture filter device and its parameters (if the filter supports it) to a file. If a file with the same name exists it will be overwritten.

Examples
--------

  * Print the list of DirectShow supported devices and exit:

          $ ffmpeg -list_devices true -f dshow -i dummy

  * Open video device CAMERA:

          $ ffmpeg -f dshow -i video="Camera"

  * Open second video device with name CAMERA:

          $ ffmpeg -f dshow -video_device_number 1 -i video="Camera"

  * Open video device CAMERA and audio device MICROPHONE:

          $ ffmpeg -f dshow -i video="Camera":audio="Microphone"

  * Print the list of supported options in selected device and exit:

          $ ffmpeg -list_options true -f dshow -i video="Camera"

  * Specify pin names to capture by name or alternative name, specify alternative device name:

          $ ffmpeg -f dshow -audio_pin_name "Audio Out" -video_pin_name 2 -i video=video="@device_pnp_\\?\pci#ven_1a0a&dev_6200&subsys_62021461&rev_01#4&e2c7dd6&0&00e1#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\{ca465100-deb0-4d59-818f-8c477184adf6}":audio="Microphone"

  * Configure a crossbar device, specifying crossbar pins, allow user to adjust video capture properties at startup:

          $ ffmpeg -f dshow -show_video_device_dialog true -crossbar_video_input_pin_number 0
               -crossbar_audio_input_pin_number 3 -i video="AVerMedia BDA Analog Capture":audio="AVerMedia BDA Analog Capture"

dv1394
======

Linux DV 1394 input device.

Options
-------

framerate
     Set the frame rate. Default is 25.

standard

     Available values are:

     pal

     ntsc

     Default value is ntsc.

fbdev
=====

Linux framebuffer input device.

The Linux framebuffer is a graphic hardware-independent abstraction layer to show graphics on a computer monitor, typically on the console. It is accessed through a file device node, usually /dev/fb0.

For more detailed information read the file Documentation/fb/framebuffer.txt included in the Linux source tree.

See also http://linux-fbdev.sourceforge.net/, and fbset(1).

To record from the framebuffer device /dev/fb0 with ffmpeg:

     ffmpeg -f fbdev -framerate 10 -i /dev/fb0 out.avi

You can take a single screenshot image with the command:

     ffmpeg -f fbdev -framerate 1 -i /dev/fb0 -frames:v 1 screenshot.jpeg

Options
-------

framerate
     Set the frame rate. Default is 25.

gdigrab
=======

Win32 GDI-based screen capture device.

This device allows you to capture a region of the display on Windows.

There are two options for the input filename:

     desktop

or

     title=WINDOW_TITLE

The first option will capture the entire desktop, or a fixed region of the desktop. The second option will instead capture the contents of a single window, regardless of its position on the screen.

For example, to grab the entire desktop using ffmpeg:

     ffmpeg -f gdigrab -framerate 6 -i desktop out.mpg

Grab a 640x480 region at position 10,20:

     ffmpeg -f gdigrab -framerate 6 -offset_x 10 -offset_y 20 -video_size vga -i desktop out.mpg

Grab the contents of the window named "Calculator"

     ffmpeg -f gdigrab -framerate 6 -i title=Calculator out.mpg

Options
-------

draw_mouse
     Specify whether to draw the mouse pointer. Use the value 0 to not draw the pointer. Default value is 1.

framerate
     Set the grabbing frame rate. Default value is ntsc, corresponding to a frame rate of 30000/1001.

show_region
     Show grabbed region on screen.

     If SHOW_REGION is specified with 1, then the grabbing region will be indicated on screen. With this option, it is easy to know what is being grabbed if only a portion of the screen is grabbed.

     Note that SHOW_REGION is incompatible with grabbing the contents of a single window.

     For example:

          ffmpeg -f gdigrab -show_region 1 -framerate 6 -video_size cif -offset_x 10 -offset_y 20 -i desktop out.mpg

video_size
     Set the video frame size. The default is to capture the full screen if desktop is selected, or the full window size if title=WINDOW_TITLE is selected.

offset_x
     When capturing a region with VIDEO_SIZE, set the distance from the left edge of the screen or desktop.

     Note that the offset calculation is from the top left corner of the primary monitor on Windows. If you have a monitor positioned to the left of your primary monitor, you will need to use a negative OFFSET_X value to move the region to that monitor.

offset_y
     When capturing a region with VIDEO_SIZE, set the distance from the top edge of the screen or desktop.

     Note that the offset calculation is from the top left corner of the primary monitor on Windows. If you have a monitor positioned above your primary monitor, you will need to use a negative OFFSET_Y value to move the region to that monitor.

iec61883
========

FireWire DV/HDV input device using libiec61883.

To enable this input device, you need libiec61883, libraw1394 and libavc1394 installed on your system. Use the configure option --enable-libiec61883 to compile with the device enabled.

The iec61883 capture device supports capturing from a video device connected via IEEE1394 (FireWire), using libiec61883 and the new Linux FireWire stack (juju). This is the default DV/HDV input method in Linux Kernel 2.6.37 and later, since the old FireWire stack was removed.

Specify the FireWire port to be used as input file, or "auto" to choose the first port connected.

Options
-------

dvtype
     Override autodetection of DV/HDV. This should only be used if auto detection does not work, or if usage of a different device type should be prohibited. Treating a DV device as HDV (or vice versa) will not work and result in undefined behavior. The values auto, dv and hdv are supported.

dvbuffer
     Set maximum size of buffer for incoming data, in frames. For DV, this is an exact value. For HDV, it is not frame exact, since HDV does not have a fixed frame size.

dvguid
     Select the capture device by specifying it's GUID. Capturing will only be performed from the specified device and fails if no device with the given GUID is found. This is useful to select the input if multiple devices are connected at the same time. Look at /sys/bus/firewire/devices to find out the GUIDs.

Examples
--------

  * Grab and show the input of a FireWire DV/HDV device.

          ffplay -f iec61883 -i auto

  * Grab and record the input of a FireWire DV/HDV device, using a packet buffer of 100000 packets if the source is HDV.

          ffmpeg -f iec61883 -i auto -hdvbuffer 100000 out.mpg

jack
====

JACK input device.

To enable this input device during configuration you need libjack installed on your system.

A JACK input device creates one or more JACK writable clients, one for each audio channel, with name CLIENT_NAME:input_N, where CLIENT_NAME is the name provided by the application, and N is a number which identifies the channel. Each writable client will send the acquired data to the FFmpeg input device.

Once you have created one or more JACK readable clients, you need to connect them to one or more JACK writable clients.

To connect or disconnect JACK clients you can use the jack_connect and jack_disconnect programs, or do it through a graphical interface, for example with qjackctl.

To list the JACK clients and their properties you can invoke the command jack_lsp.

Follows an example which shows how to capture a JACK readable client with ffmpeg.

     # Create a JACK writable client with name "ffmpeg".
     $ ffmpeg -f jack -i ffmpeg -y out.wav

     # Start the sample jack_metro readable client.
     $ jack_metro -b 120 -d 0.2 -f 4000

     # List the current JACK clients.
     $ jack_lsp -c
     system:capture_1
     system:capture_2
     system:playback_1
     system:playback_2
     ffmpeg:input_1
     metro:120_bpm

     # Connect metro to the ffmpeg writable client.
     $ jack_connect metro:120_bpm ffmpeg:input_1

For more information read: http://jackaudio.org/

Options
-------

channels
     Set the number of channels. Default is 2.

lavfi
=====

Libavfilter input virtual device.

This input device reads data from the open output pads of a libavfilter filtergraph.

For each filtergraph open output, the input device will create a corresponding stream which is mapped to the generated output. Currently only video data is supported. The filtergraph is specified through the option graph.

Options
-------

graph
     Specify the filtergraph to use as input. Each video open output must be labelled by a unique string of the form "outN", where N is a number starting from 0 corresponding to the mapped input stream generated by the device. The first unlabelled output is automatically assigned to the "out0" label, but all the others need to be specified explicitly.

     The suffix "+subcc" can be appended to the output label to create an extra stream with the closed captions packets attached to that output (experimental; only for EIA-608 / CEA-708 for now). The subcc streams are created after all the normal streams, in the order of the corresponding stream. For example, if there is "out19+subcc", "out7+subcc" and up to "out42", the stream #43 is subcc for stream #7 and stream #44 is subcc for stream #19.

     If not specified defaults to the filename specified for the input device.

graph_file
     Set the filename of the filtergraph to be read and sent to the other filters. Syntax of the filtergraph is the same as the one specified by the option GRAPH.

dumpgraph
     Dump graph to stderr.

Examples
--------

  * Create a color video stream and play it back with ffplay:

          ffplay -f lavfi -graph "color=c=pink [out0]" dummy

  * As the previous example, but use filename for specifying the graph description, and omit the "out0" label:

          ffplay -f lavfi color=c=pink

  * Create three different video test filtered sources and play them:

          ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3

  * Read an audio stream from a file using the amovie source and play it back with ffplay:

          ffplay -f lavfi "amovie=test.wav"

  * Read an audio stream and a video stream and play it back with ffplay:

          ffplay -f lavfi "movie=test.avi[out0];amovie=test.wav[out1]"

  * Dump decoded frames to images and closed captions to a file (experimental):

          ffmpeg -f lavfi -i "movie=test.ts[out0+subcc]" -map v frame%08d.png -map s -c copy -f rawvideo subcc.bin

libcdio
=======

Audio-CD input device based on libcdio.

To enable this input device during configuration you need libcdio installed on your system. It requires the configure option --enable-libcdio.

This device allows playing and grabbing from an Audio-CD.

For example to copy with ffmpeg the entire Audio-CD in /dev/sr0, you may run the command:

     ffmpeg -f libcdio -i /dev/sr0 cd.wav

Options
-------

speed
     Set drive reading speed. Default value is 0.

     The speed is specified CD-ROM speed units. The speed is set through the libcdio cdio_cddap_speed_set function. On many CD-ROM drives, specifying a value too large will result in using the fastest speed.

paranoia_mode
     Set paranoia recovery mode flags. It accepts one of the following values:

     disable

     verify

     overlap

     neverskip

     full

     Default value is disable.

     For more information about the available recovery modes, consult the paranoia project documentation.

libdc1394
=========

IIDC1394 input device, based on libdc1394 and libraw1394.

Requires the configure option --enable-libdc1394.

openal
======

The OpenAL input device provides audio capture on all systems with a working OpenAL 1.1 implementation.

To enable this input device during configuration, you need OpenAL headers and libraries installed on your system, and need to configure FFmpeg with --enable-openal.

OpenAL headers and libraries should be provided as part of your OpenAL implementation, or as an additional download (an SDK). Depending on your installation you may need to specify additional flags via the --extra-cflags and --extra-ldflags for allowing the build system to locate the OpenAL headers and libraries.

An incomplete list of OpenAL implementations follows:

Creative
     The official Windows implementation, providing hardware acceleration with supported devices and software fallback. See http://openal.org/.

OpenAL Soft
     Portable, open source (LGPL) software implementation. Includes backends for the most common sound APIs on the Windows, Linux, Solaris, and BSD operating systems. See http://kcat.strangesoft.net/openal.html.

Apple
     OpenAL is part of Core Audio, the official Mac OS X Audio interface. See http://developer.apple.com/technologies/mac/audio-and-video.html

This device allows one to capture from an audio input device handled through OpenAL.

You need to specify the name of the device to capture in the provided filename. If the empty string is provided, the device will automatically select the default device. You can get the list of the supported devices by using the option LIST_DEVICES.

Options
-------

channels
     Set the number of channels in the captured audio. Only the values 1 (monaural) and 2 (stereo) are currently supported. Defaults to 2.

sample_size
     Set the sample size (in bits) of the captured audio. Only the values 8 and 16 are currently supported. Defaults to 16.

sample_rate
     Set the sample rate (in Hz) of the captured audio. Defaults to 44.1k.

list_devices
     If set to true, print a list of devices and exit. Defaults to false.

Examples
--------

Print the list of OpenAL supported devices and exit:

     $ ffmpeg -list_devices true -f openal -i dummy out.ogg

Capture from the OpenAL device DR-BT101 via PulseAudio:

     $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out.ogg

Capture from the default device (note the empty string '' as filename):

     $ ffmpeg -f openal -i '' out.ogg

Capture from two devices simultaneously, writing to two different files, within the same ffmpeg command:

     $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out1.ogg -f openal -i 'ALSA Default' out2.ogg

Note: not all OpenAL implementations support multiple simultaneous capture - try the latest OpenAL Soft if the above does not work.

oss
===

Open Sound System input device.

The filename to provide to the input device is the device node representing the OSS input device, and is usually set to /dev/dsp.

For example to grab from /dev/dsp using ffmpeg use the command:

     ffmpeg -f oss -i /dev/dsp /tmp/oss.wav

For more information about OSS see: http://manuals.opensound.com/usersguide/dsp.html

Options
-------

sample_rate
     Set the sample rate in Hz. Default is 48000.

channels
     Set the number of channels. Default is 2.

pulse
=====

PulseAudio input device.

To enable this output device you need to configure FFmpeg with --enable-libpulse.

The filename to provide to the input device is a source device or the string "default"

To list the PulseAudio source devices and their properties you can invoke the command pactl list sources.

More information about PulseAudio can be found on http://www.pulseaudio.org.

Options
-------

server
     Connect to a specific PulseAudio server, specified by an IP address. Default server is used when not provided.

name
     Specify the application name PulseAudio will use when showing active clients, by default it is the LIBAVFORMAT_IDENT string.

stream_name
     Specify the stream name PulseAudio will use when showing active streams, by default it is "record".

sample_rate
     Specify the samplerate in Hz, by default 48kHz is used.

channels
     Specify the channels in use, by default 2 (stereo) is set.

frame_size
     Specify the number of bytes per frame, by default it is set to 1024.

fragment_size
     Specify the minimal buffering fragment in PulseAudio, it will affect the audio latency. By default it is unset.

wallclock
     Set the initial PTS using the current time. Default is 1.

Examples
--------

Record a stream from default device:

     ffmpeg -f pulse -i default /tmp/pulse.wav

qtkit
=====

QTKit input device.

The filename passed as input is parsed to contain either a device name or index. The device index can also be given by using -video_device_index. A given device index will override any given device name. If the desired device consists of numbers only, use -video_device_index to identify it. The default device will be chosen if an empty string  or the device name "default" is given. The available devices can be enumerated by using -list_devices.

     ffmpeg -f qtkit -i "0" out.mpg

     ffmpeg -f qtkit -video_device_index 0 -i "" out.mpg

     ffmpeg -f qtkit -i "default" out.mpg

     ffmpeg -f qtkit -list_devices true -i ""

Options
-------

frame_rate
     Set frame rate. Default is 30.

list_devices
     If set to true, print a list of devices and exit. Default is false.

video_device_index
     Select the video device by index for devices with the same name (starts at 0).

sndio
=====

sndio input device.

To enable this input device during configuration you need libsndio installed on your system.

The filename to provide to the input device is the device node representing the sndio input device, and is usually set to /dev/audio0.

For example to grab from /dev/audio0 using ffmpeg use the command:

     ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav

Options
-------

sample_rate
     Set the sample rate in Hz. Default is 48000.

channels
     Set the number of channels. Default is 2.

video4linux2, v4l2
==================

Video4Linux2 input video device.

"v4l2" can be used as alias for "video4linux2".

If FFmpeg is built with v4l-utils support (by using the --enable-libv4l2 configure option), it is possible to use it with the -use_libv4l2 input device option.

The name of the device to grab is a file device node, usually Linux systems tend to automatically create such nodes when the device (e.g. an USB webcam) is plugged into the system, and has a name of the kind /dev/videoN, where N is a number associated to the device.

Video4Linux2 devices usually support a limited set of WIDTHxHEIGHT sizes and frame rates. You can check which are supported using -list_formats all for Video4Linux2 devices. Some devices, like TV cards, support one or more standards. It is possible to list all the supported standards using -list_standards all.

The time base for the timestamps is 1 microsecond. Depending on the kernel version and configuration, the timestamps may be derived from the real time clock (origin at the Unix Epoch) or the monotonic clock (origin usually at boot time, unaffected by NTP or manual changes to the clock). The -timestamps abs or -ts abs option can be used to force conversion into the real time clock.

Some usage examples of the video4linux2 device with ffmpeg and ffplay:

  * List supported formats for a video4linux2 device:

          ffplay -f video4linux2 -list_formats all /dev/video0

  * Grab and show the input of a video4linux2 device:

          ffplay -f video4linux2 -framerate 30 -video_size hd720 /dev/video0

  * Grab and record the input of a video4linux2 device, leave the frame rate and size as previously set:

          ffmpeg -f video4linux2 -input_format mjpeg -i /dev/video0 out.mpeg

For more information about Video4Linux, check http://linuxtv.org/.

Options
-------

standard
     Set the standard. Must be the name of a supported standard. To get a list of the supported standards, use the list_standards option.

channel
     Set the input channel number. Default to -1, which means using the previously selected channel.

video_size
     Set the video frame size. The argument must be a string in the form WIDTHxHEIGHT or a valid size abbreviation.

pixel_format
     Select the pixel format (only valid for raw video input).

input_format
     Set the preferred pixel format (for raw video) or a codec name. This option allows one to select the input format, when several are available.

framerate
     Set the preferred video frame rate.

list_formats
     List available formats (supported pixel formats, codecs, and frame sizes) and exit.

     Available values are:

     all
          Show all available (compressed and non-compressed) formats.

     raw
          Show only raw video (non-compressed) formats.

     compressed
          Show only compressed formats.

list_standards
     List supported standards and exit.

     Available values are:

     all
          Show all supported standards.

timestamps, ts
     Set type of timestamps for grabbed frames.

     Available values are:

     default
          Use timestamps from the kernel.

     abs
          Use absolute timestamps (wall clock).

     mono2abs
          Force conversion from monotonic to absolute timestamps.

     Default value is default.

use_libv4l2
     Use libv4l2 (v4l-utils) conversion functions. Default is 0.

vfwcap
======

VfW (Video for Windows) capture input device.

The filename passed as input is the capture driver number, ranging from 0 to 9. You may use "list" as filename to print a list of drivers. Any other filename will be interpreted as device number 0.

Options
-------

video_size
     Set the video frame size.

framerate
     Set the grabbing frame rate. Default value is ntsc, corresponding to a frame rate of 30000/1001.

x11grab
=======

X11 video input device.

To enable this input device during configuration you need libxcb installed on your system. It will be automatically detected during configuration.

Alternatively, the configure option --enable-x11grab exists for legacy Xlib users.

This device allows one to capture a region of an X11 display.

The filename passed as input has the syntax:

     [HOSTNAME]:DISPLAY_NUMBER.SCREEN_NUMBER[+X_OFFSET,Y_OFFSET]

HOSTNAME:DISPLAY_NUMBER.SCREEN_NUMBER specifies the X11 display name of the screen to grab from. HOSTNAME can be omitted, and defaults to "localhost". The environment variable DISPLAY contains the default display name.

X_OFFSET and Y_OFFSET specify the offsets of the grabbed area with respect to the top-left border of the X11 screen. They default to 0.

Check the X11 documentation (e.g. man X) for more detailed information.

Use the xdpyinfo program for getting basic information about the properties of your X11 display (e.g. grep for "name" or "dimensions").

For example to grab from :0.0 using ffmpeg:

     ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0 out.mpg

Grab at position 10,20:

     ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0+10,20 out.mpg

Options
-------

draw_mouse
     Specify whether to draw the mouse pointer. A value of 0 specify not to draw the pointer. Default value is 1.

follow_mouse
     Make the grabbed area follow the mouse. The argument can be centered or a number of pixels PIXELS.

     When it is specified with "centered", the grabbing region follows the mouse pointer and keeps the pointer at the center of region; otherwise, the region follows only when the mouse pointer reaches within PIXELS (greater than zero) to the edge of region.

     For example:

          ffmpeg -f x11grab -follow_mouse centered -framerate 25 -video_size cif -i :0.0 out.mpg

     To follow only when the mouse pointer reaches within 100 pixels to edge:

          ffmpeg -f x11grab -follow_mouse 100 -framerate 25 -video_size cif -i :0.0 out.mpg

framerate
     Set the grabbing frame rate. Default value is ntsc, corresponding to a frame rate of 30000/1001.

show_region
     Show grabbed region on screen.

     If SHOW_REGION is specified with 1, then the grabbing region will be indicated on screen. With this option, it is easy to know what is being grabbed if only a portion of the screen is grabbed.

region_border
     Set the region border thickness if -show_region 1 is used. Range is 1 to 128 and default is 3 (XCB-based x11grab only).

     For example:

          ffmpeg -f x11grab -show_region 1 -framerate 25 -video_size cif -i :0.0+10,20 out.mpg

     With FOLLOW_MOUSE:

          ffmpeg -f x11grab -follow_mouse centered -show_region 1 -framerate 25 -video_size cif -i :0.0 out.mpg

video_size
     Set the video frame size. Default value is vga.

use_shm
     Use the MIT-SHM extension for shared memory. Default value is 1. It may be necessary to disable it for remote displays (legacy x11grab only).

GRAB_X GRAB_Y AVOption
----------------------

The syntax is:

     -grab_x X_OFFSET -grab_y Y_OFFSET

Set the grabbing region coordinates. They are expressed as offset from the top left corner of the X11 window. The default value is 0.