@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
+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".
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.
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
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.
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.
-ffplay -s 320x240 -f video4linux /dev/video0
+# Grab and show the input of a video4linux device, frame rate is set
+# to the default of 25/1.
+avplay -s 320x240 -f video4linux /dev/video0
# Grab and show the input of a video4linux2 device, autoadjust size.
-ffplay -f video4linux2 /dev/video0
+avplay -f video4linux2 /dev/video0
-# Grab and record the input of a video4linux2 device, autoadjust size.
+# 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
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.
ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpg
# Grab at position 10,20.
-ffmpeg -f x11grab -25 -s cif -i :0.0+10,20 out.mpg
+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
projects / ffmpeg / blobdiff