@chapter Input Devices
@c man begin INPUT DEVICES
-Input devices are configured elements in FFmpeg which allow to access
+Input devices are configured elements in Libav 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 them using the configure option
-"--list-indevs".
+When you configure your Libav 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
To enable this input device during configuration you need libasound
installed on your system.
-This device allows to capture from an ALSA device. The name of the
+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:
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
+For example to capture with @command{avconv} from an ALSA device with
card id 0, you may run the command:
@example
-ffmpeg -f alsa -i hw:0 alsaout.wav
+avconv -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 audio_beos
-
-BeOS audio input device.
-
@section bktr
BSD video input device.
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{avconv}:
+@example
+avconv -f fbdev -r 10 -i /dev/fb0 out.avi
+@end example
+
+You can take a single screenshot image with the command:
+@example
+avconv -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 jack
-Jack input device.
+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
+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
+Each writable client will send the acquired data to the Libav input
device.
-Once you have created one or more jack readable clients, you need to
-connect them to one or more jack writable clients.
+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
+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
+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}.
+Follows an example which shows how to capture a JACK readable client
+with @command{avconv}.
@example
-# create a jack writable client with name "ffmpeg"
-$ ffmpeg -f jack -i ffmpeg -y out.wav
+# Create a JACK writable client with name "libav".
+$ avconv -f jack -i libav -y out.wav
-# start the sample jack_metro readable client
+# Start the sample jack_metro readable client.
$ jack_metro -b 120 -d 0.2 -f 4000
-# list the current jack clients
+# List the current JACK clients.
$ jack_lsp -c
system:capture_1
system:capture_2
system:playback_1
system:playback_2
-ffmpeg:input_1
+libav:input_1
metro:120_bpm
-# connect metro to the ffmpeg writable client
-$ jack_connect metro:120_bpm ffmpeg:input_1
+# Connect metro to the avconv writable client.
+$ jack_connect metro:120_bpm libav:input_1
@end example
For more information read:
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/}.
+@file{/dev/dsp}.
-For example to grab from @file{/dev/dsp/} using @file{ffmpeg} use the
+For example to grab from @file{/dev/dsp} using @command{avconv} use the
command:
@example
-ffmpeg -f oss -i /dev/dsp /tmp/oss.wav
+avconv -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 video4linux and video4linux2
+@section 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 @file{pactl list sources}.
+
+@example
+avconv -f pulse -i default /tmp/pulse.wav
+@end example
+
+@subsection @var{server} AVOption
+
+The syntax is:
+@example
+-server @var{server name}
+@end example
+
+Connects to a specific server.
+
+@subsection @var{name} AVOption
+
+The syntax is:
+@example
+-name @var{application name}
+@end example
+
+Specify the application name pulse will use when showing active clients,
+by default it is "libav"
+
+@subsection @var{stream_name} AVOption
+
+The syntax is:
+@example
+-stream_name @var{stream name}
+@end example
+
+Specify the stream name pulse will use when showing active streams,
+by default it is "record"
+
+@subsection @var{sample_rate} AVOption
+
+The syntax is:
+@example
+-sample_rate @var{samplerate}
+@end example
+
+Specify the samplerate in Hz, by default 48kHz is used.
+
+@subsection @var{channels} AVOption
+
+The syntax is:
+@example
+-channels @var{N}
+@end example
-Video4Linux and Video4Linux2 input video devices.
+Specify the channels in use, by default 2 (stereo) is set.
+
+@subsection @var{frame_size} AVOption
+
+The syntax is:
+@example
+-frame_size @var{bytes}
+@end example
+
+Specify the number of byte per frame, by default it is set to 1024.
+
+@subsection @var{fragment_size} AVOption
+
+The syntax is:
+@example
+-fragment_size @var{bytes}
+@end example
+
+Specify the minimal buffering fragment in pulseaudio, it will affect the
+audio latency. By default it is unset.
+
+@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{avconv} use the
+command:
+@example
+avconv -f sndio -i /dev/audio0 /tmp/oss.wav
+@end example
+
+@section 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 to the system, and has a name of the
+(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
+Video4Linux2 devices usually support a limited set of
@var{width}x@var{height} sizes and framerates. You can check which are
-supported for example using the command @file{dov4l} for Video4Linux
-devices, and the command @file{v4l-info} for Video4Linux2 devices.
+supported using @command{-list_formats all} for Video4Linux2 devices.
-If the size for the device is set to 0x0, the input device will
-try to autodetect the size to use.
+Some usage examples of the video4linux2 devices with avconv and avplay:
-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
-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 show the input of a video4linux2 device.
+avplay -f video4linux2 -framerate 30 -video_size hd720 /dev/video0
-# grab and record the input of a video4linux2 device, autoadjust size
-ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
+# Grab and record the input of a video4linux2 device, leave the
+framerate and size as previously set.
+avconv -f video4linux2 -input_format mjpeg -i /dev/video0 out.mpeg
@end example
@section vfwcap
-VFW (Video For Window) catpure input device.
+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
This device allows to capture a region of an X11 display.
-The filename passed in input has the syntax:
+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 not
-specified, and defaults to "localhost". The environment variable
+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 image. They
+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 screen (e.g. grep for "name" or
-"dimensions").
+properties of your X11 display (e.g. grep for "name" or "dimensions").
+
+For example to grab from @file{:0.0} using @command{avconv}:
+@example
+avconv -f x11grab -r 25 -s cif -i :0.0 out.mpg
+
+# Grab at position 10,20.
+avconv -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
+avconv -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
+avconv -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 to grab from @file{:0.0} using @file{ffmpeg}:
+For example:
@example
-ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpg
+avconv -f x11grab -show_region 1 -r 25 -s cif -i :0.0+10,20 out.mpg
-# grab at position 10,20
-ffmpeg -f x11grab -25 -s cif -i :0.0+10,20 out.mpg
+# With follow_mouse
+avconv -f x11grab -follow_mouse centered -show_region 1 -r 25 -s cif -i :0.0 out.mpg
@end example
@c man end INPUT DEVICES
projects / ffmpeg / blobdiff