2 @c man begin INPUT DEVICES
4 Input devices are configured elements in FFmpeg which allow to access
5 the data coming from a multimedia device attached to your system.
7 When you configure your FFmpeg build, all the supported input devices
8 are enabled by default. You can list all available ones using the
9 configure option "--list-indevs".
11 You can disable all the input devices using the configure option
12 "--disable-indevs", and selectively enable an input device using the
13 option "--enable-indev=@var{INDEV}", or you can disable a particular
14 input device using the option "--disable-indev=@var{INDEV}".
16 The option "-formats" of the ff* tools will display the list of
17 supported input devices (amongst the demuxers).
19 A description of the currently available input devices follows.
23 ALSA (Advanced Linux Sound Architecture) input device.
25 To enable this input device during configuration you need libasound
26 installed on your system.
28 This device allows capturing from an ALSA device. The name of the
29 device to capture has to be an ALSA card identifier.
31 An ALSA identifier has the syntax:
33 hw:@var{CARD}[,@var{DEV}[,@var{SUBDEV}]]
36 where the @var{DEV} and @var{SUBDEV} components are optional.
38 The three arguments (in order: @var{CARD},@var{DEV},@var{SUBDEV})
39 specify card number or identifier, device number and subdevice number
42 To see the list of cards currently recognized by your system check the
43 files @file{/proc/asound/cards} and @file{/proc/asound/devices}.
45 For example to capture with @file{ffmpeg} from an ALSA device with
46 card id 0, you may run the command:
48 ffmpeg -f alsa -i hw:0 alsaout.wav
51 For more information see:
52 @url{http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html}
56 BSD video input device.
60 Linux DV 1394 input device.
66 To enable this input device during configuration you need libjack
67 installed on your system.
69 A JACK input device creates one or more JACK writable clients, one for
70 each audio channel, with name @var{client_name}:input_@var{N}, where
71 @var{client_name} is the name provided by the application, and @var{N}
72 is a number which identifies the channel.
73 Each writable client will send the acquired data to the FFmpeg input
76 Once you have created one or more JACK readable clients, you need to
77 connect them to one or more JACK writable clients.
79 To connect or disconnect JACK clients you can use the
80 @file{jack_connect} and @file{jack_disconnect} programs, or do it
81 through a graphical interface, for example with @file{qjackctl}.
83 To list the JACK clients and their properties you can invoke the command
86 Follows an example which shows how to capture a JACK readable client
89 # Create a JACK writable client with name "ffmpeg".
90 $ ffmpeg -f jack -i ffmpeg -y out.wav
92 # Start the sample jack_metro readable client.
93 $ jack_metro -b 120 -d 0.2 -f 4000
95 # List the current JACK clients.
104 # Connect metro to the ffmpeg writable client.
105 $ jack_connect metro:120_bpm ffmpeg:input_1
108 For more information read:
109 @url{http://jackaudio.org/}
113 IIDC1394 input device, based on libdc1394 and libraw1394.
117 Open Sound System input device.
119 The filename to provide to the input device is the device node
120 representing the OSS input device, and is usually set to
123 For example to grab from @file{/dev/dsp} using @file{ffmpeg} use the
126 ffmpeg -f oss -i /dev/dsp /tmp/oss.wav
129 For more information about OSS see:
130 @url{http://manuals.opensound.com/usersguide/dsp.html}
132 @section video4linux and video4linux2
134 Video4Linux and Video4Linux2 input video devices.
136 The name of the device to grab is a file device node, usually Linux
137 systems tend to automatically create such nodes when the device
138 (e.g. an USB webcam) is plugged into the system, and has a name of the
139 kind @file{/dev/video@var{N}}, where @var{N} is a number associated to
142 Video4Linux and Video4Linux2 devices only support a limited set of
143 @var{width}x@var{height} sizes and framerates. You can check which are
144 supported for example with the command @file{dov4l} for Video4Linux
145 devices and the command @file{v4l-info} for Video4Linux2 devices.
147 If the size for the device is set to 0x0, the input device will
148 try to autodetect the size to use.
149 Only for the video4linux2 device, if the frame rate is set to 0/0 the
150 input device will use the frame rate value already set in the driver.
152 Video4Linux support is deprecated since Linux 2.6.30, and will be
153 dropped in later versions.
155 Follow some usage examples of the video4linux devices with the ff*
158 # Grab and show the input of a video4linux device, frame rate is set
159 # to the default of 25/1.
160 ffplay -s 320x240 -f video4linux /dev/video0
162 # Grab and show the input of a video4linux2 device, autoadjust size.
163 ffplay -f video4linux2 /dev/video0
165 # Grab and record the input of a video4linux2 device, autoadjust size,
166 # frame rate value defaults to 0/0 so it is read from the video4linux2
168 ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
173 VfW (Video for Windows) capture input device.
175 The filename passed as input is the capture driver number, ranging from
176 0 to 9. You may use "list" as filename to print a list of drivers. Any
177 other filename will be interpreted as device number 0.
181 X11 video input device.
183 This device allows to capture a region of an X11 display.
185 The filename passed as input has the syntax:
187 [@var{hostname}]:@var{display_number}.@var{screen_number}[+@var{x_offset},@var{y_offset}]
190 @var{hostname}:@var{display_number}.@var{screen_number} specifies the
191 X11 display name of the screen to grab from. @var{hostname} can be
192 ommitted, and defaults to "localhost". The environment variable
193 @env{DISPLAY} contains the default display name.
195 @var{x_offset} and @var{y_offset} specify the offsets of the grabbed
196 area with respect to the top-left border of the X11 screen. They
199 Check the X11 documentation (e.g. man X) for more detailed information.
201 Use the @file{dpyinfo} program for getting basic information about the
202 properties of your X11 display (e.g. grep for "name" or "dimensions").
204 For example to grab from @file{:0.0} using @file{ffmpeg}:
206 ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpg
208 # Grab at position 10,20.
209 ffmpeg -f x11grab -25 -s cif -i :0.0+10,20 out.mpg
212 @c man end INPUT DEVICES