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}.
234 Specify the filtergraph to use as input. Each video open output must be
235 labelled by a unique string of the form "out@var{N}", where @var{N} is a
236 number starting from 0 corresponding to the mapped input stream
237 generated by the device.
238 The first unlabelled output is automatically assigned to the "out0"
239 label, but all the others need to be specified explicitely.
241 If not specified defaults to the filename specified for the input
249 Create a color video stream and play it back with @file{ffplay}:
251 ffplay -f lavfi -graph "color=pink [out0]" dummy
255 As the previous example, but use filename for specifying the graph
256 description, and omit the "out0" label:
258 ffplay -f lavfi color=pink
262 Create three different video test filtered sources and play them:
264 ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3
268 Read an audio stream from a file using the amovie source and play it
269 back with @file{ffplay}:
271 ffplay -f lavfi "amovie=test.wav"
275 Read an audio stream and a video stream and play it back with
278 ffplay -f lavfi "movie=test.avi[out0];amovie=test.wav[out1]"
285 IIDC1394 input device, based on libdc1394 and libraw1394.
289 The OpenAL input device provides audio capture on all systems with a
290 working OpenAL 1.1 implementation.
292 To enable this input device during configuration, you need OpenAL
293 headers and libraries installed on your system, and need to configure
294 FFmpeg with @code{--enable-openal}.
296 OpenAL headers and libraries should be provided as part of your OpenAL
297 implementation, or as an additional download (an SDK). Depending on your
298 installation you may need to specify additional flags via the
299 @code{--extra-cflags} and @code{--extra-ldflags} for allowing the build
300 system to locate the OpenAL headers and libraries.
302 An incomplete list of OpenAL implementations follows:
306 The official Windows implementation, providing hardware acceleration
307 with supported devices and software fallback.
308 See @url{http://openal.org/}.
310 Portable, open source (LGPL) software implementation. Includes
311 backends for the most common sound APIs on the Windows, Linux,
312 Solaris, and BSD operating systems.
313 See @url{http://kcat.strangesoft.net/openal.html}.
315 OpenAL is part of Core Audio, the official Mac OS X Audio interface.
316 See @url{http://developer.apple.com/technologies/mac/audio-and-video.html}
319 This device allows to capture from an audio input device handled
322 You need to specify the name of the device to capture in the provided
323 filename. If the empty string is provided, the device will
324 automatically select the default device. You can get the list of the
325 supported devices by using the option @var{list_devices}.
332 Set the number of channels in the captured audio. Only the values
333 @option{1} (monaural) and @option{2} (stereo) are currently supported.
334 Defaults to @option{2}.
337 Set the sample size (in bits) of the captured audio. Only the values
338 @option{8} and @option{16} are currently supported. Defaults to
342 Set the sample rate (in Hz) of the captured audio.
343 Defaults to @option{44.1k}.
346 If set to @option{true}, print a list of devices and exit.
347 Defaults to @option{false}.
353 Print the list of OpenAL supported devices and exit:
355 $ ffmpeg -list_devices true -f openal -i dummy out.ogg
358 Capture from the OpenAL device @file{DR-BT101 via PulseAudio}:
360 $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out.ogg
363 Capture from the default device (note the empty string '' as filename):
365 $ ffmpeg -f openal -i '' out.ogg
368 Capture from two devices simultaneously, writing to two different files,
369 within the same @file{ffmpeg} command:
371 $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out1.ogg -f openal -i 'ALSA Default' out2.ogg
373 Note: not all OpenAL implementations support multiple simultaneous capture -
374 try the latest OpenAL Soft if the above does not work.
378 Open Sound System input device.
380 The filename to provide to the input device is the device node
381 representing the OSS input device, and is usually set to
384 For example to grab from @file{/dev/dsp} using @file{ffmpeg} use the
387 ffmpeg -f oss -i /dev/dsp /tmp/oss.wav
390 For more information about OSS see:
391 @url{http://manuals.opensound.com/usersguide/dsp.html}
397 To enable this input device during configuration you need libsndio
398 installed on your system.
400 The filename to provide to the input device is the device node
401 representing the sndio input device, and is usually set to
404 For example to grab from @file{/dev/audio0} using @file{ffmpeg} use the
407 ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav
410 @section video4linux and video4linux2
412 Video4Linux and Video4Linux2 input video devices.
414 The name of the device to grab is a file device node, usually Linux
415 systems tend to automatically create such nodes when the device
416 (e.g. an USB webcam) is plugged into the system, and has a name of the
417 kind @file{/dev/video@var{N}}, where @var{N} is a number associated to
420 Video4Linux and Video4Linux2 devices only support a limited set of
421 @var{width}x@var{height} sizes and framerates. You can check which are
422 supported for example with the command @file{dov4l} for Video4Linux
423 devices and the command @file{v4l-info} for Video4Linux2 devices.
425 If the size for the device is set to 0x0, the input device will
426 try to autodetect the size to use.
427 Only for the video4linux2 device, if the frame rate is set to 0/0 the
428 input device will use the frame rate value already set in the driver.
430 Video4Linux support is deprecated since Linux 2.6.30, and will be
431 dropped in later versions.
433 Follow some usage examples of the video4linux devices with the ff*
436 # Grab and show the input of a video4linux device, frame rate is set
437 # to the default of 25/1.
438 ffplay -s 320x240 -f video4linux /dev/video0
440 # Grab and show the input of a video4linux2 device, autoadjust size.
441 ffplay -f video4linux2 /dev/video0
443 # Grab and record the input of a video4linux2 device, autoadjust size,
444 # frame rate value defaults to 0/0 so it is read from the video4linux2
446 ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
451 VfW (Video for Windows) capture input device.
453 The filename passed as input is the capture driver number, ranging from
454 0 to 9. You may use "list" as filename to print a list of drivers. Any
455 other filename will be interpreted as device number 0.
459 X11 video input device.
461 This device allows to capture a region of an X11 display.
463 The filename passed as input has the syntax:
465 [@var{hostname}]:@var{display_number}.@var{screen_number}[+@var{x_offset},@var{y_offset}]
468 @var{hostname}:@var{display_number}.@var{screen_number} specifies the
469 X11 display name of the screen to grab from. @var{hostname} can be
470 ommitted, and defaults to "localhost". The environment variable
471 @env{DISPLAY} contains the default display name.
473 @var{x_offset} and @var{y_offset} specify the offsets of the grabbed
474 area with respect to the top-left border of the X11 screen. They
477 Check the X11 documentation (e.g. man X) for more detailed information.
479 Use the @file{dpyinfo} program for getting basic information about the
480 properties of your X11 display (e.g. grep for "name" or "dimensions").
482 For example to grab from @file{:0.0} using @file{ffmpeg}:
484 ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpg
486 # Grab at position 10,20.
487 ffmpeg -f x11grab -r 25 -s cif -i :0.0+10,20 out.mpg
490 @subsection @var{follow_mouse} AVOption
494 -follow_mouse centered|@var{PIXELS}
497 When it is specified with "centered", the grabbing region follows the mouse
498 pointer and keeps the pointer at the center of region; otherwise, the region
499 follows only when the mouse pointer reaches within @var{PIXELS} (greater than
500 zero) to the edge of region.
504 ffmpeg -f x11grab -follow_mouse centered -r 25 -s cif -i :0.0 out.mpg
506 # Follows only when the mouse pointer reaches within 100 pixels to edge
507 ffmpeg -f x11grab -follow_mouse 100 -r 25 -s cif -i :0.0 out.mpg
510 @subsection @var{show_region} AVOption
517 If @var{show_region} AVOption is specified with @var{1}, then the grabbing
518 region will be indicated on screen. With this option, it's easy to know what is
519 being grabbed if only a portion of the screen is grabbed.
523 ffmpeg -f x11grab -show_region 1 -r 25 -s cif -i :0.0+10,20 out.mpg
526 ffmpeg -f x11grab -follow_mouse centered -show_region 1 -r 25 -s cif -i :0.0 out.mpg
529 @c man end INPUT DEVICES