doc/indevs.texi - third_party/ffmpeg - Git at Google

 @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 @file{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 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
 @file{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 -vframes 1 -r 1 -i /dev/fb0 screenshot.jpeg
 @end example

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

 @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
 @file{jack_connect} and @file{jack_disconnect} programs, or do it
 through a graphical interface, for example with @file{qjackctl}.

 To list the JACK clients and their properties you can invoke the command
 @file{jack_lsp}.

 Follows an example which shows how to capture a JACK readable client
 with @file{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 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 @file{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 @file{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 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 @file{ffmpeg} use the
 command:
 @example
 ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav
 @end example

 @section video4linux and video4linux2

 Video4Linux and Video4Linux2 input video devices.

 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.

 Video4Linux and Video4Linux2 devices only support a limited set of
 @var{width}x@var{height} sizes and framerates. You can check which are
 supported for example with the command @file{dov4l} for Video4Linux
 devices and the command @file{v4l-info} for Video4Linux2 devices.

 If the size for the device is set to 0x0, the input device will
 try to autodetect the size to use.
 Only for the video4linux2 device, if the frame rate is set to 0/0 the
 input device will use the frame rate value already set in the driver.

 Video4Linux support is deprecated since Linux 2.6.30, and will be
 dropped in later versions.

 Follow some usage examples of the video4linux devices with the ff*
 tools.
 @example
 # Grab and show the input of a video4linux device, frame rate is set
 # to the default of 25/1.
 ffplay -s 320x240 -f video4linux /dev/video0

 # Grab and show the input of a video4linux2 device, autoadjust size.
 ffplay -f video4linux2 /dev/video0

 # Grab and record the input of a video4linux2 device, autoadjust size,
 # frame rate value defaults to 0/0 so it is read from the video4linux2
 # driver.
 ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
 @end example

 @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
 ommitted, 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 @file{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 @file{ffmpeg}:
 @example
 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
 @end example

 @subsection @var{follow_mouse} AVOption

 The syntax is:
 @example
 -follow_mouse centered|@var{PIXELS}
 @end example

 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 -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
 @end example

 @subsection @var{show_region} AVOption

 The syntax is:
 @example
 -show_region 1
 @end example

 If @var{show_region} AVOption is specified with @var{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:
 @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
 @end example

 @c man end INPUT DEVICES
	@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 @file{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 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
	@file{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 -vframes 1 -r 1 -i /dev/fb0 screenshot.jpeg
	@end example

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

	@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
	@file{jack_connect} and @file{jack_disconnect} programs, or do it
	through a graphical interface, for example with @file{qjackctl}.

	To list the JACK clients and their properties you can invoke the command
	@file{jack_lsp}.

	Follows an example which shows how to capture a JACK readable client
	with @file{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 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 @file{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 @file{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 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 @file{ffmpeg} use the
	command:
	@example
	ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav
	@end example

	@section video4linux and video4linux2

	Video4Linux and Video4Linux2 input video devices.

	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.

	Video4Linux and Video4Linux2 devices only support a limited set of
	@var{width}x@var{height} sizes and framerates. You can check which are
	supported for example with the command @file{dov4l} for Video4Linux
	devices and the command @file{v4l-info} for Video4Linux2 devices.

	If the size for the device is set to 0x0, the input device will
	try to autodetect the size to use.
	Only for the video4linux2 device, if the frame rate is set to 0/0 the
	input device will use the frame rate value already set in the driver.

	Video4Linux support is deprecated since Linux 2.6.30, and will be
	dropped in later versions.

	Follow some usage examples of the video4linux devices with the ff*
	tools.
	@example
	# Grab and show the input of a video4linux device, frame rate is set
	# to the default of 25/1.
	ffplay -s 320x240 -f video4linux /dev/video0

	# Grab and show the input of a video4linux2 device, autoadjust size.
	ffplay -f video4linux2 /dev/video0

	# Grab and record the input of a video4linux2 device, autoadjust size,
	# frame rate value defaults to 0/0 so it is read from the video4linux2
	# driver.
	ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
	@end example

	@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
	ommitted, 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 @file{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 @file{ffmpeg}:
	@example
	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
	@end example

	@subsection @var{follow_mouse} AVOption

	The syntax is:
	@example
	-follow_mouse centered\|@var{PIXELS}
	@end example

	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 -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
	@end example

	@subsection @var{show_region} AVOption

	The syntax is:
	@example
	-show_region 1
	@end example

	If @var{show_region} AVOption is specified with @var{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:
	@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
	@end example

	@c man end INPUT DEVICES