@chapter Input Devices

 @c man begin 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=@var{INDEV}", or you can disable a particular
 input device using the option "--disable-indev=@var{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.
 
 @section 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:
 @example
 hw:@var{CARD}[,@var{DEV}[,@var{SUBDEV}]]
 @end example
 
 where the @var{DEV} and @var{SUBDEV} components are optional.
 
 The three arguments (in order: @var{CARD},@var{DEV},@var{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 @file{/proc/asound/cards} and @file{/proc/asound/devices}.
 

 For example to capture with @command{ffmpeg} from an ALSA device with

 card id 0, you may run the command:
 @example
 ffmpeg -f alsa -i hw:0 alsaout.wav
 @end example
 
 For more information see:
 @url{http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html}
 
 @section bktr
 
 BSD video input device.
 

 @section 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:
 
 @example
 @var{TYPE}=@var{NAME}[:@var{TYPE}=@var{NAME}]
 @end example
 
 where @var{TYPE} can be either @var{audio} or @var{video},
 and @var{NAME} is the device's name.
 
 @subsection 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.
 
 @table @option
 
 @item video_size
 Set the video size in the captured video.
 
 @item framerate

 Set the frame rate in the captured video.

 
 @item sample_rate
 Set the sample rate (in Hz) of the captured audio.
 
 @item sample_size
 Set the sample size (in bits) of the captured audio.
 
 @item channels
 Set the number of channels in the captured audio.
 
 @item list_devices
 If set to @option{true}, print a list of devices and exit.
 
 @item list_options
 If set to @option{true}, print a list of selected device's options
 and exit.
 

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

 @item 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.
 

 @item 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
 @url{http://msdn.microsoft.com/en-us/library/windows/desktop/dd377582(v=vs.85).aspx}
 

 @end table
 
 @subsection Examples
 
 @itemize
 
 @item
 Print the list of DirectShow supported devices and exit:
 @example
 $ ffmpeg -list_devices true -f dshow -i dummy
 @end example
 
 @item
 Open video device @var{Camera}:
 @example
 $ ffmpeg -f dshow -i video="Camera"
 @end example
 
 @item

 Open second video device with name @var{Camera}:
 @example
 $ ffmpeg -f dshow -video_device_number 1 -i video="Camera"
 @end example
 
 @item

 Open video device @var{Camera} and audio device @var{Microphone}:
 @example
 $ ffmpeg -f dshow -i video="Camera":audio="Microphone"
 @end example
 
 @item
 Print the list of supported options in selected device and exit:
 @example
 $ ffmpeg -list_options true -f dshow -i video="Camera"
 @end example
 
 @end itemize
 

 @section dv1394
 
 Linux DV 1394 input device.
 

 @section 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
 @file{/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 @file{/dev/fb0} with

 @command{ffmpeg}:

 @example
 ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi
 @end example
 
 You can take a single screenshot image with the command:
 @example

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

 @end example
 
 See also @url{http://linux-fbdev.sourceforge.net/}, and fbset(1).
 

 @section 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
 @code{--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.
 
 @subsection Options
 
 @table @option
 
 @item 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 @option{auto}, @option{dv} and @option{hdv} are supported.
 
 @item dvbuffer
 Set maxiumum 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.
 

 @item 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.
 

 @end table
 
 @subsection Examples
 
 @itemize
 
 @item
 Grab and show the input of a FireWire DV/HDV device.
 @example
 ffplay -f iec61883 -i auto
 @end example
 
 @item
 Grab and record the input of a FireWire DV/HDV device,
 using a packet buffer of 100000 packets if the source is HDV.
 @example
 ffmpeg -f iec61883 -i auto -hdvbuffer 100000 out.mpg
 @end example
 
 @end itemize
 

 @section 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 @var{client_name}:input_@var{N}, where
 @var{client_name} is the name provided by the application, and @var{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 @command{jack_connect}
 and @command{jack_disconnect} programs, or do it through a graphical interface,
 for example with @command{qjackctl}.

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

 @command{jack_lsp}.

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

 with @command{ffmpeg}.

 @example

 # 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
 @end example
 
 For more information read:
 @url{http://jackaudio.org/}
 

 @section 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 @option{graph}.
 
 @subsection Options
 
 @table @option
 
 @item graph
 Specify the filtergraph to use as input. Each video open output must be
 labelled by a unique string of the form "out@var{N}", where @var{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.

 
 @item 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 @var{graph}.
 

 @end table
 
 @subsection Examples
 
 @itemize
 @item

 Create a color video stream and play it back with @command{ffplay}:

 @example

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

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

 ffplay -f lavfi color=c=pink

 @end example
 
 @item
 Create three different video test filtered sources and play them:
 @example
 ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3
 @end example

 
 @item
 Read an audio stream from a file using the amovie source and play it

 back with @command{ffplay}:

 @example
 ffplay -f lavfi "amovie=test.wav"
 @end example
 
 @item
 Read an audio stream and a video stream and play it back with

 @command{ffplay}:

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

 @end itemize
 

 @section libdc1394
 
 IIDC1394 input device, based on libdc1394 and libraw1394.
 

 @section 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 @code{--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
 @code{--extra-cflags} and @code{--extra-ldflags} for allowing the build
 system to locate the OpenAL headers and libraries.
 
 An incomplete list of OpenAL implementations follows:
 
 @table @strong
 @item Creative
 The official Windows implementation, providing hardware acceleration
 with supported devices and software fallback.
 See @url{http://openal.org/}.
 @item 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 @url{http://kcat.strangesoft.net/openal.html}.
 @item Apple
 OpenAL is part of Core Audio, the official Mac OS X Audio interface.
 See @url{http://developer.apple.com/technologies/mac/audio-and-video.html}
 @end table
 
 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 @var{list_devices}.
 
 @subsection Options
 
 @table @option
 
 @item channels
 Set the number of channels in the captured audio. Only the values
 @option{1} (monaural) and @option{2} (stereo) are currently supported.
 Defaults to @option{2}.
 
 @item sample_size
 Set the sample size (in bits) of the captured audio. Only the values
 @option{8} and @option{16} are currently supported. Defaults to
 @option{16}.
 
 @item sample_rate
 Set the sample rate (in Hz) of the captured audio.
 Defaults to @option{44.1k}.
 
 @item list_devices
 If set to @option{true}, print a list of devices and exit.
 Defaults to @option{false}.
 
 @end table
 
 @subsection Examples
 
 Print the list of OpenAL supported devices and exit:
 @example
 $ ffmpeg -list_devices true -f openal -i dummy out.ogg
 @end example
 
 Capture from the OpenAL device @file{DR-BT101 via PulseAudio}:
 @example
 $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out.ogg
 @end example
 
 Capture from the default device (note the empty string '' as filename):
 @example
 $ ffmpeg -f openal -i '' out.ogg
 @end example
 
 Capture from two devices simultaneously, writing to two different files,

 within the same @command{ffmpeg} command:

 @example
 $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out1.ogg -f openal -i 'ALSA Default' out2.ogg
 @end example
 Note: not all OpenAL implementations support multiple simultaneous capture -
 try the latest OpenAL Soft if the above does not work.
 

 @section 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

 @file{/dev/dsp}.

 For example to grab from @file{/dev/dsp} using @command{ffmpeg} use the

 command:
 @example
 ffmpeg -f oss -i /dev/dsp /tmp/oss.wav
 @end example
 
 For more information about OSS see:
 @url{http://manuals.opensound.com/usersguide/dsp.html}
 

 @section pulse
 

 PulseAudio input device.

 To enable this output device you need to configure FFmpeg with @code{--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 @command{pactl list sources}.

 More information about PulseAudio can be found on @url{http://www.pulseaudio.org}.
 

 @subsection Options
 @table @option
 @item server

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

 @item name
 Specify the application name PulseAudio will use when showing active clients,
 by default it is the @code{LIBAVFORMAT_IDENT} string.

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

 @item sample_rate

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

 @item channels

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

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

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

 @subsection Examples
 Record a stream from default device:

 @example

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

 @end example
 

 @section 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
 @file{/dev/audio0}.
 

 For example to grab from @file{/dev/audio0} using @command{ffmpeg} use the

 command:
 @example
 ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav
 @end example
 

 @section 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

 @code{--enable-libv4l2} configure option), it is possible to use it with the
 @code{-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 @file{/dev/video@var{N}}, where @var{N} is a number associated to
 the device.
 

 Video4Linux2 devices usually support a limited set of

 @var{width}x@var{height} sizes and frame rates. You can check which are

 supported using @command{-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 @command{-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
 @option{-timestamps abs} or @option{-ts abs} option can be used to force
 conversion into the real time clock.
 

 Some usage examples of the video4linux2 device with @command{ffmpeg}

 and @command{ffplay}:

 @itemize
 @item
 Grab and show the input of a video4linux2 device:

 @example

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

 @end example

 @item
 Grab and record the input of a video4linux2 device, leave the

 frame rate and size as previously set:

 @example

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

 @end example

 @end itemize

 For more information about Video4Linux, check @url{http://linuxtv.org/}.

 @subsection Options
 
 @table @option
 @item standard
 Set the standard. Must be the name of a supported standard. To get a
 list of the supported standards, use the @option{list_standards}
 option.
 
 @item channel

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

 
 @item video_size
 Set the video frame size. The argument must be a string in the form
 @var{WIDTH}x@var{HEIGHT} or a valid size abbreviation.
 
 @item pixel_format
 Select the pixel format (only valid for raw video input).
 
 @item input_format
 Set the preferred pixel format (for raw video) or a codec name.
 This option allows to select the input format, when several are
 available.
 
 @item framerate

 Set the preferred video frame rate.

 
 @item list_formats
 List available formats (supported pixel formats, codecs, and frame
 sizes) and exit.
 
 Available values are:
 @table @samp
 @item all
 Show all available (compressed and non-compressed) formats.
 
 @item raw
 Show only raw video (non-compressed) formats.
 
 @item compressed
 Show only compressed formats.
 @end table
 
 @item list_standards
 List supported standards and exit.
 
 Available values are:
 @table @samp
 @item all
 Show all supported standards.
 @end table
 
 @item timestamps, ts
 Set type of timestamps for grabbed frames.
 
 Available values are:
 @table @samp
 @item default
 Use timestamps from the kernel.
 
 @item abs
 Use absolute timestamps (wall clock).
 
 @item mono2abs

 Force conversion from monotonic to absolute timestamps.

 @end table
 
 Default value is @code{default}.
 @end table
 

 @section 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.
 

 @section x11grab
 
 X11 video input device.
 
 This device allows to capture a region of an X11 display.
 

 The filename passed as input has the syntax:

 @example
 [@var{hostname}]:@var{display_number}.@var{screen_number}[+@var{x_offset},@var{y_offset}]
 @end example
 
 @var{hostname}:@var{display_number}.@var{screen_number} specifies the

 X11 display name of the screen to grab from. @var{hostname} can be

 omitted, and defaults to "localhost". The environment variable

 @env{DISPLAY} contains the default display name.
 
 @var{x_offset} and @var{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 @command{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 @file{:0.0} using @command{ffmpeg}:

 @example

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

 @end example

 Grab at position @code{10,20}:
 @example

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

 @end example
 

 @subsection Options

 @table @option

 @item draw_mouse
 Specify whether to draw the mouse pointer. A value of @code{0} specify
 not to draw the pointer. Default value is @code{1}.
 

 @item follow_mouse
 Make the grabbed area follow the mouse. The argument can be
 @code{centered} or a number of pixels @var{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 @var{PIXELS} (greater than
 zero) to the edge of region.
 
 For example:
 @example

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

 @end example
 

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

 @example

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

 @end example
 

 @item framerate
 Set the grabbing frame rate. Default value is @code{ntsc},

 corresponding to a frame rate of @code{30000/1001}.

 @item show_region
 Show grabbed region on screen.
 
 If @var{show_region} is specified with @code{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.

 
 For example:
 @example

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

 @end example

 With @var{follow_mouse}:
 @example

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

 @end example

 
 @item video_size
 Set the video frame size. Default value is @code{vga}.

 @end table

 
 @c man end INPUT DEVICES