mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-11-21 10:55:51 +02:00
af49e1766b
Update the examples and remove stale information. Video4linux support had been already removed.
363 lines
9.8 KiB
Plaintext
363 lines
9.8 KiB
Plaintext
@chapter Input Devices
|
|
@c man begin INPUT DEVICES
|
|
|
|
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 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
|
|
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{avconv} from an ALSA device with
|
|
card id 0, you may run the command:
|
|
@example
|
|
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 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
|
|
@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.
|
|
|
|
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 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.
|
|
|
|
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 @command{avconv}.
|
|
@example
|
|
# Create a JACK writable client with name "libav".
|
|
$ avconv -f jack -i libav -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
|
|
libav:input_1
|
|
metro:120_bpm
|
|
|
|
# Connect metro to the avconv writable client.
|
|
$ jack_connect metro:120_bpm libav:input_1
|
|
@end example
|
|
|
|
For more information read:
|
|
@url{http://jackaudio.org/}
|
|
|
|
@section libdc1394
|
|
|
|
IIDC1394 input device, based on libdc1394 and libraw1394.
|
|
|
|
@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{avconv} use the
|
|
command:
|
|
@example
|
|
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 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
|
|
|
|
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 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 framerates. You can check which are
|
|
supported using @command{-list_formats all} for Video4Linux2 devices.
|
|
|
|
Some usage examples of the video4linux2 devices with avconv and avplay:
|
|
|
|
@example
|
|
# 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, 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 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 @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:
|
|
@example
|
|
avconv -f x11grab -show_region 1 -r 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
|