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 Windows DirectShow input device.
62 DirectShow support is enabled when FFmpeg is built with mingw-w64.
63 Currently only audio and video devices are supported.
65 Multiple devices may be opened as separate inputs, but they may also be
66 opened on the same input, which should improve synchronism between them.
68 The input name should be in the format:
71 @var{TYPE}=@var{NAME}[:@var{TYPE}=@var{NAME}]
74 where @var{TYPE} can be either @var{audio} or @var{video},
75 and @var{NAME} is the device's name.
79 If no options are specified, the device's defaults are used.
80 If the device does not support the requested options, it will
86 Set the video size in the captured video.
89 Set the framerate in the captured video.
92 Set the sample rate (in Hz) of the captured audio.
95 Set the sample size (in bits) of the captured audio.
98 Set the number of channels in the captured audio.
101 If set to @option{true}, print a list of devices and exit.
104 If set to @option{true}, print a list of selected device's options
114 Print the list of DirectShow supported devices and exit:
116 $ ffmpeg -list_devices true -f dshow -i dummy
120 Open video device @var{Camera}:
122 $ ffmpeg -f dshow -i video="Camera"
126 Open video device @var{Camera} and audio device @var{Microphone}:
128 $ ffmpeg -f dshow -i video="Camera":audio="Microphone"
132 Print the list of supported options in selected device and exit:
134 $ ffmpeg -list_options true -f dshow -i video="Camera"
141 Linux DV 1394 input device.
145 Linux framebuffer input device.
147 The Linux framebuffer is a graphic hardware-independent abstraction
148 layer to show graphics on a computer monitor, typically on the
149 console. It is accessed through a file device node, usually
152 For more detailed information read the file
153 Documentation/fb/framebuffer.txt included in the Linux source tree.
155 To record from the framebuffer device @file{/dev/fb0} with
158 ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi
161 You can take a single screenshot image with the command:
163 ffmpeg -f fbdev -vframes 1 -r 1 -i /dev/fb0 screenshot.jpeg
166 See also @url{http://linux-fbdev.sourceforge.net/}, and fbset(1).
172 To enable this input device during configuration you need libjack
173 installed on your system.
175 A JACK input device creates one or more JACK writable clients, one for
176 each audio channel, with name @var{client_name}:input_@var{N}, where
177 @var{client_name} is the name provided by the application, and @var{N}
178 is a number which identifies the channel.
179 Each writable client will send the acquired data to the FFmpeg input
182 Once you have created one or more JACK readable clients, you need to
183 connect them to one or more JACK writable clients.
185 To connect or disconnect JACK clients you can use the
186 @file{jack_connect} and @file{jack_disconnect} programs, or do it
187 through a graphical interface, for example with @file{qjackctl}.
189 To list the JACK clients and their properties you can invoke the command
192 Follows an example which shows how to capture a JACK readable client
195 # Create a JACK writable client with name "ffmpeg".
196 $ ffmpeg -f jack -i ffmpeg -y out.wav
198 # Start the sample jack_metro readable client.
199 $ jack_metro -b 120 -d 0.2 -f 4000
201 # List the current JACK clients.
210 # Connect metro to the ffmpeg writable client.
211 $ jack_connect metro:120_bpm ffmpeg:input_1
214 For more information read:
215 @url{http://jackaudio.org/}
219 Libavfilter input virtual device.
221 This input device reads data from the open output pads of a libavfilter
224 For each filtergraph open output, the input device will create a
225 corresponding stream which is mapped to the generated output. Currently
226 only video data is supported. The filtergraph is specified through the
227 option @option{graph}.
229 To enable this input device, you need to configure your build with
230 @code{--enable-libavfilter}.
237 Specify the filtergraph to use as input. Each video open output must be
238 labelled by a unique string of the form "out@var{N}", where @var{N} is a
239 number starting from 0 corresponding to the mapped input stream
240 generated by the device.
241 The first unlabelled output is automatically assigned to the "out0"
242 label, but all the others need to be specified explicitely.
244 If not specified defaults to the filename specified for the input
252 Create a color video stream and play it back with @file{ffplay}:
254 ffplay -f lavfi -graph "color=pink [out0]" dummy
258 As the previous example, but use filename for specifying the graph
259 description, and omit the "out0" label:
261 ffplay -f lavfi color=pink
265 Create three different video test filtered sources and play them:
267 ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3
271 Read an audio stream from a file using the amovie source and play it
272 back with @file{ffplay}:
274 ffplay -f lavfi "amovie=test.wav"
278 Read an audio stream and a video stream and play it back with
281 ffplay -f lavfi "movie=test.avi[out0];amovie=test.wav[out1]"
288 IIDC1394 input device, based on libdc1394 and libraw1394.
292 The OpenAL input device provides audio capture on all systems with a
293 working OpenAL 1.1 implementation.
295 To enable this input device during configuration, you need OpenAL
296 headers and libraries installed on your system, and need to configure
297 FFmpeg with @code{--enable-openal}.
299 OpenAL headers and libraries should be provided as part of your OpenAL
300 implementation, or as an additional download (an SDK). Depending on your
301 installation you may need to specify additional flags via the
302 @code{--extra-cflags} and @code{--extra-ldflags} for allowing the build
303 system to locate the OpenAL headers and libraries.
305 An incomplete list of OpenAL implementations follows:
309 The official Windows implementation, providing hardware acceleration
310 with supported devices and software fallback.
311 See @url{http://openal.org/}.
313 Portable, open source (LGPL) software implementation. Includes
314 backends for the most common sound APIs on the Windows, Linux,
315 Solaris, and BSD operating systems.
316 See @url{http://kcat.strangesoft.net/openal.html}.
318 OpenAL is part of Core Audio, the official Mac OS X Audio interface.
319 See @url{http://developer.apple.com/technologies/mac/audio-and-video.html}
322 This device allows to capture from an audio input device handled
325 You need to specify the name of the device to capture in the provided
326 filename. If the empty string is provided, the device will
327 automatically select the default device. You can get the list of the
328 supported devices by using the option @var{list_devices}.
335 Set the number of channels in the captured audio. Only the values
336 @option{1} (monaural) and @option{2} (stereo) are currently supported.
337 Defaults to @option{2}.
340 Set the sample size (in bits) of the captured audio. Only the values
341 @option{8} and @option{16} are currently supported. Defaults to
345 Set the sample rate (in Hz) of the captured audio.
346 Defaults to @option{44.1k}.
349 If set to @option{true}, print a list of devices and exit.
350 Defaults to @option{false}.
356 Print the list of OpenAL supported devices and exit:
358 $ ffmpeg -list_devices true -f openal -i dummy out.ogg
361 Capture from the OpenAL device @file{DR-BT101 via PulseAudio}:
363 $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out.ogg
366 Capture from the default device (note the empty string '' as filename):
368 $ ffmpeg -f openal -i '' out.ogg
371 Capture from two devices simultaneously, writing to two different files,
372 within the same @file{ffmpeg} command:
374 $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out1.ogg -f openal -i 'ALSA Default' out2.ogg
376 Note: not all OpenAL implementations support multiple simultaneous capture -
377 try the latest OpenAL Soft if the above does not work.
381 Open Sound System input device.
383 The filename to provide to the input device is the device node
384 representing the OSS input device, and is usually set to
387 For example to grab from @file{/dev/dsp} using @file{ffmpeg} use the
390 ffmpeg -f oss -i /dev/dsp /tmp/oss.wav
393 For more information about OSS see:
394 @url{http://manuals.opensound.com/usersguide/dsp.html}
400 To enable this input device during configuration you need libsndio
401 installed on your system.
403 The filename to provide to the input device is the device node
404 representing the sndio input device, and is usually set to
407 For example to grab from @file{/dev/audio0} using @file{ffmpeg} use the
410 ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav
413 @section video4linux and video4linux2
415 Video4Linux and Video4Linux2 input video devices.
417 The name of the device to grab is a file device node, usually Linux
418 systems tend to automatically create such nodes when the device
419 (e.g. an USB webcam) is plugged into the system, and has a name of the
420 kind @file{/dev/video@var{N}}, where @var{N} is a number associated to
423 Video4Linux and Video4Linux2 devices only support a limited set of
424 @var{width}x@var{height} sizes and framerates. You can check which are
425 supported for example with the command @file{dov4l} for Video4Linux
426 devices and the command @file{v4l-info} for Video4Linux2 devices.
428 If the size for the device is set to 0x0, the input device will
429 try to autodetect the size to use.
430 Only for the video4linux2 device, if the frame rate is set to 0/0 the
431 input device will use the frame rate value already set in the driver.
433 Video4Linux support is deprecated since Linux 2.6.30, and will be
434 dropped in later versions.
436 Follow some usage examples of the video4linux devices with the ff*
439 # Grab and show the input of a video4linux device, frame rate is set
440 # to the default of 25/1.
441 ffplay -s 320x240 -f video4linux /dev/video0
443 # Grab and show the input of a video4linux2 device, autoadjust size.
444 ffplay -f video4linux2 /dev/video0
446 # Grab and record the input of a video4linux2 device, autoadjust size,
447 # frame rate value defaults to 0/0 so it is read from the video4linux2
449 ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
454 VfW (Video for Windows) capture input device.
456 The filename passed as input is the capture driver number, ranging from
457 0 to 9. You may use "list" as filename to print a list of drivers. Any
458 other filename will be interpreted as device number 0.
462 X11 video input device.
464 This device allows to capture a region of an X11 display.
466 The filename passed as input has the syntax:
468 [@var{hostname}]:@var{display_number}.@var{screen_number}[+@var{x_offset},@var{y_offset}]
471 @var{hostname}:@var{display_number}.@var{screen_number} specifies the
472 X11 display name of the screen to grab from. @var{hostname} can be
473 ommitted, and defaults to "localhost". The environment variable
474 @env{DISPLAY} contains the default display name.
476 @var{x_offset} and @var{y_offset} specify the offsets of the grabbed
477 area with respect to the top-left border of the X11 screen. They
480 Check the X11 documentation (e.g. man X) for more detailed information.
482 Use the @file{dpyinfo} program for getting basic information about the
483 properties of your X11 display (e.g. grep for "name" or "dimensions").
485 For example to grab from @file{:0.0} using @file{ffmpeg}:
487 ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpg
489 # Grab at position 10,20.
490 ffmpeg -f x11grab -r 25 -s cif -i :0.0+10,20 out.mpg
493 @subsection @var{follow_mouse} AVOption
497 -follow_mouse centered|@var{PIXELS}
500 When it is specified with "centered", the grabbing region follows the mouse
501 pointer and keeps the pointer at the center of region; otherwise, the region
502 follows only when the mouse pointer reaches within @var{PIXELS} (greater than
503 zero) to the edge of region.
507 ffmpeg -f x11grab -follow_mouse centered -r 25 -s cif -i :0.0 out.mpg
509 # Follows only when the mouse pointer reaches within 100 pixels to edge
510 ffmpeg -f x11grab -follow_mouse 100 -r 25 -s cif -i :0.0 out.mpg
513 @subsection @var{show_region} AVOption
520 If @var{show_region} AVOption is specified with @var{1}, then the grabbing
521 region will be indicated on screen. With this option, it's easy to know what is
522 being grabbed if only a portion of the screen is grabbed.
526 ffmpeg -f x11grab -show_region 1 -r 25 -s cif -i :0.0+10,20 out.mpg
529 ffmpeg -f x11grab -follow_mouse centered -show_region 1 -r 25 -s cif -i :0.0 out.mpg
532 @c man end INPUT DEVICES