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

Input devices are configured elements in FFmpeg which allow to access 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 "-formats" of the ff* tools will display the list of supported input devices (amongst the demuxers).

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

bktr
====

BSD video input device.

dshow
=====

Windows DirectShow input device.

DirectShow support is enabled when FFmpeg is built with mingw-w64. 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.

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 framerate 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 same name (starts at 0, defaults to 0).

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

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"

dv1394
======

Linux DV 1394 input device.

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.

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

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

You can take a single screenshot image with the command:

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

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

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/

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.

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

Examples
--------

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

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

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

          ffplay -f lavfi color=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]"

libdc1394
=========

IIDC1394 input device, based on libdc1394 and libraw1394.

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 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

pulse
=====

pulseaudio input device.

To enable this input device during configuration you need libpulse-simple installed in your system.

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

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

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

SERVER AVOption
---------------

The syntax is:

     -server SERVER NAME

Connects to a specific server.

NAME AVOption
-------------

The syntax is:

     -name APPLICATION NAME

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

STREAM_NAME AVOption
--------------------

The syntax is:

     -stream_name STREAM NAME

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

SAMPLE_RATE AVOption
--------------------

The syntax is:

     -sample_rate SAMPLERATE

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

CHANNELS AVOption
-----------------

The syntax is:

     -channels N

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

FRAME_SIZE AVOption
-------------------

The syntax is:

     -frame_size BYTES

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

FRAGMENT_SIZE AVOption
----------------------

The syntax is:

     -fragment_size BYTES

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

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

video4linux2
============

Video4Linux2 input video device.

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 framerates. You can check which are supported using -list_formats all for Video4Linux2 devices.

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

Note that if FFmpeg is build with v4l-utils support ("--enable-libv4l2" option), it will always be used.

     # 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
     framerate and size as previously set.
     ffmpeg -f video4linux2 -input_format mjpeg -i /dev/video0 out.mpeg

"v4l" and "v4l2" can be used as aliases for the respective "video4linux" and "video4linux2".

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.

x11grab
=======

X11 video input device.

This device allows 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 dpyinfo 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 -r 25 -s cif -i :0.0 out.mpg

     # Grab at position 10,20.
     ffmpeg -f x11grab -r 25 -s cif -i :0.0+10,20 out.mpg

FOLLOW_MOUSE AVOption
---------------------

The syntax is:

     -follow_mouse centered|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 -r 25 -s cif -i :0.0 out.mpg

     # Follows only when the mouse pointer reaches within 100 pixels to edge
     ffmpeg -f x11grab -follow_mouse 100 -r 25 -s cif -i :0.0 out.mpg

SHOW_REGION AVOption
--------------------

The syntax is:

     -show_region 1

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

For example:

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

     # With follow_mouse
     ffmpeg -f x11grab -follow_mouse centered -show_region 1  -r 25 -s cif -i :0.0 out.mpg