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 @command{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 the mingw-w64 project.
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
107 @item video_device_number
108 Set video device number for devices with same name (starts at 0,
111 @item audio_device_number
112 Set audio device number for devices with same name (starts at 0,
122 Print the list of DirectShow supported devices and exit:
124 $ ffmpeg -list_devices true -f dshow -i dummy
128 Open video device @var{Camera}:
130 $ ffmpeg -f dshow -i video="Camera"
134 Open second video device with name @var{Camera}:
136 $ ffmpeg -f dshow -video_device_number 1 -i video="Camera"
140 Open video device @var{Camera} and audio device @var{Microphone}:
142 $ ffmpeg -f dshow -i video="Camera":audio="Microphone"
146 Print the list of supported options in selected device and exit:
148 $ ffmpeg -list_options true -f dshow -i video="Camera"
155 Linux DV 1394 input device.
159 Linux framebuffer input device.
161 The Linux framebuffer is a graphic hardware-independent abstraction
162 layer to show graphics on a computer monitor, typically on the
163 console. It is accessed through a file device node, usually
166 For more detailed information read the file
167 Documentation/fb/framebuffer.txt included in the Linux source tree.
169 To record from the framebuffer device @file{/dev/fb0} with
172 ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi
175 You can take a single screenshot image with the command:
177 ffmpeg -f fbdev -frames:v 1 -r 1 -i /dev/fb0 screenshot.jpeg
180 See also @url{http://linux-fbdev.sourceforge.net/}, and fbset(1).
186 To enable this input device during configuration you need libjack
187 installed on your system.
189 A JACK input device creates one or more JACK writable clients, one for
190 each audio channel, with name @var{client_name}:input_@var{N}, where
191 @var{client_name} is the name provided by the application, and @var{N}
192 is a number which identifies the channel.
193 Each writable client will send the acquired data to the FFmpeg input
196 Once you have created one or more JACK readable clients, you need to
197 connect them to one or more JACK writable clients.
199 To connect or disconnect JACK clients you can use the @command{jack_connect}
200 and @command{jack_disconnect} programs, or do it through a graphical interface,
201 for example with @command{qjackctl}.
203 To list the JACK clients and their properties you can invoke the command
206 Follows an example which shows how to capture a JACK readable client
207 with @command{ffmpeg}.
209 # Create a JACK writable client with name "ffmpeg".
210 $ ffmpeg -f jack -i ffmpeg -y out.wav
212 # Start the sample jack_metro readable client.
213 $ jack_metro -b 120 -d 0.2 -f 4000
215 # List the current JACK clients.
224 # Connect metro to the ffmpeg writable client.
225 $ jack_connect metro:120_bpm ffmpeg:input_1
228 For more information read:
229 @url{http://jackaudio.org/}
233 Libavfilter input virtual device.
235 This input device reads data from the open output pads of a libavfilter
238 For each filtergraph open output, the input device will create a
239 corresponding stream which is mapped to the generated output. Currently
240 only video data is supported. The filtergraph is specified through the
241 option @option{graph}.
248 Specify the filtergraph to use as input. Each video open output must be
249 labelled by a unique string of the form "out@var{N}", where @var{N} is a
250 number starting from 0 corresponding to the mapped input stream
251 generated by the device.
252 The first unlabelled output is automatically assigned to the "out0"
253 label, but all the others need to be specified explicitly.
255 If not specified defaults to the filename specified for the input
263 Create a color video stream and play it back with @command{ffplay}:
265 ffplay -f lavfi -graph "color=pink [out0]" dummy
269 As the previous example, but use filename for specifying the graph
270 description, and omit the "out0" label:
272 ffplay -f lavfi color=pink
276 Create three different video test filtered sources and play them:
278 ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3
282 Read an audio stream from a file using the amovie source and play it
283 back with @command{ffplay}:
285 ffplay -f lavfi "amovie=test.wav"
289 Read an audio stream and a video stream and play it back with
292 ffplay -f lavfi "movie=test.avi[out0];amovie=test.wav[out1]"
299 IIDC1394 input device, based on libdc1394 and libraw1394.
303 The OpenAL input device provides audio capture on all systems with a
304 working OpenAL 1.1 implementation.
306 To enable this input device during configuration, you need OpenAL
307 headers and libraries installed on your system, and need to configure
308 FFmpeg with @code{--enable-openal}.
310 OpenAL headers and libraries should be provided as part of your OpenAL
311 implementation, or as an additional download (an SDK). Depending on your
312 installation you may need to specify additional flags via the
313 @code{--extra-cflags} and @code{--extra-ldflags} for allowing the build
314 system to locate the OpenAL headers and libraries.
316 An incomplete list of OpenAL implementations follows:
320 The official Windows implementation, providing hardware acceleration
321 with supported devices and software fallback.
322 See @url{http://openal.org/}.
324 Portable, open source (LGPL) software implementation. Includes
325 backends for the most common sound APIs on the Windows, Linux,
326 Solaris, and BSD operating systems.
327 See @url{http://kcat.strangesoft.net/openal.html}.
329 OpenAL is part of Core Audio, the official Mac OS X Audio interface.
330 See @url{http://developer.apple.com/technologies/mac/audio-and-video.html}
333 This device allows to capture from an audio input device handled
336 You need to specify the name of the device to capture in the provided
337 filename. If the empty string is provided, the device will
338 automatically select the default device. You can get the list of the
339 supported devices by using the option @var{list_devices}.
346 Set the number of channels in the captured audio. Only the values
347 @option{1} (monaural) and @option{2} (stereo) are currently supported.
348 Defaults to @option{2}.
351 Set the sample size (in bits) of the captured audio. Only the values
352 @option{8} and @option{16} are currently supported. Defaults to
356 Set the sample rate (in Hz) of the captured audio.
357 Defaults to @option{44.1k}.
360 If set to @option{true}, print a list of devices and exit.
361 Defaults to @option{false}.
367 Print the list of OpenAL supported devices and exit:
369 $ ffmpeg -list_devices true -f openal -i dummy out.ogg
372 Capture from the OpenAL device @file{DR-BT101 via PulseAudio}:
374 $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out.ogg
377 Capture from the default device (note the empty string '' as filename):
379 $ ffmpeg -f openal -i '' out.ogg
382 Capture from two devices simultaneously, writing to two different files,
383 within the same @command{ffmpeg} command:
385 $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out1.ogg -f openal -i 'ALSA Default' out2.ogg
387 Note: not all OpenAL implementations support multiple simultaneous capture -
388 try the latest OpenAL Soft if the above does not work.
392 Open Sound System input device.
394 The filename to provide to the input device is the device node
395 representing the OSS input device, and is usually set to
398 For example to grab from @file{/dev/dsp} using @command{ffmpeg} use the
401 ffmpeg -f oss -i /dev/dsp /tmp/oss.wav
404 For more information about OSS see:
405 @url{http://manuals.opensound.com/usersguide/dsp.html}
409 pulseaudio input device.
411 To enable this input device during configuration you need libpulse-simple
412 installed in your system.
414 The filename to provide to the input device is a source device or the
417 To list the pulse source devices and their properties you can invoke
418 the command @command{pactl list sources}.
421 ffmpeg -f pulse -i default /tmp/pulse.wav
424 @subsection @var{server} AVOption
428 -server @var{server name}
431 Connects to a specific server.
433 @subsection @var{name} AVOption
437 -name @var{application name}
440 Specify the application name pulse will use when showing active clients,
441 by default it is the LIBAVFORMAT_IDENT string
443 @subsection @var{stream_name} AVOption
447 -stream_name @var{stream name}
450 Specify the stream name pulse will use when showing active streams,
451 by default it is "record"
453 @subsection @var{sample_rate} AVOption
457 -sample_rate @var{samplerate}
460 Specify the samplerate in Hz, by default 48kHz is used.
462 @subsection @var{channels} AVOption
469 Specify the channels in use, by default 2 (stereo) is set.
471 @subsection @var{frame_size} AVOption
475 -frame_size @var{bytes}
478 Specify the number of byte per frame, by default it is set to 1024.
480 @subsection @var{fragment_size} AVOption
484 -fragment_size @var{bytes}
487 Specify the minimal buffering fragment in pulseaudio, it will affect the
488 audio latency. By default it is unset.
494 To enable this input device during configuration you need libsndio
495 installed on your system.
497 The filename to provide to the input device is the device node
498 representing the sndio input device, and is usually set to
501 For example to grab from @file{/dev/audio0} using @command{ffmpeg} use the
504 ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav
507 @section video4linux2
509 Video4Linux2 input video device.
511 The name of the device to grab is a file device node, usually Linux
512 systems tend to automatically create such nodes when the device
513 (e.g. an USB webcam) is plugged into the system, and has a name of the
514 kind @file{/dev/video@var{N}}, where @var{N} is a number associated to
517 Video4Linux2 devices usually support a limited set of
518 @var{width}x@var{height} sizes and framerates. You can check which are
519 supported using @command{-list_formats all} for Video4Linux2 devices.
521 Some usage examples of the video4linux2 devices with ffmpeg and ffplay:
523 The time base for the timestamps is 1 microsecond. Depending on the kernel
524 version and configuration, the timestamps may be derived from the real time
525 clock (origin at the Unix Epoch) or the monotonic clock (origin usually at
526 boot time, unaffected by NTP or manual changes to the clock). The
527 @option{-timestamps abs} or @option{-ts abs} option can be used to force
528 conversion into the real time clock.
530 Note that if FFmpeg is build with v4l-utils support ("--enable-libv4l2"
531 option), it will always be used.
533 # Grab and show the input of a video4linux2 device.
534 ffplay -f video4linux2 -framerate 30 -video_size hd720 /dev/video0
536 # Grab and record the input of a video4linux2 device, leave the
537 framerate and size as previously set.
538 ffmpeg -f video4linux2 -input_format mjpeg -i /dev/video0 out.mpeg
541 "v4l" and "v4l2" can be used as aliases for the respective "video4linux" and
546 VfW (Video for Windows) capture input device.
548 The filename passed as input is the capture driver number, ranging from
549 0 to 9. You may use "list" as filename to print a list of drivers. Any
550 other filename will be interpreted as device number 0.
554 X11 video input device.
556 This device allows to capture a region of an X11 display.
558 The filename passed as input has the syntax:
560 [@var{hostname}]:@var{display_number}.@var{screen_number}[+@var{x_offset},@var{y_offset}]
563 @var{hostname}:@var{display_number}.@var{screen_number} specifies the
564 X11 display name of the screen to grab from. @var{hostname} can be
565 omitted, and defaults to "localhost". The environment variable
566 @env{DISPLAY} contains the default display name.
568 @var{x_offset} and @var{y_offset} specify the offsets of the grabbed
569 area with respect to the top-left border of the X11 screen. They
572 Check the X11 documentation (e.g. man X) for more detailed information.
574 Use the @command{dpyinfo} program for getting basic information about the
575 properties of your X11 display (e.g. grep for "name" or "dimensions").
577 For example to grab from @file{:0.0} using @command{ffmpeg}:
579 ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpg
581 # Grab at position 10,20.
582 ffmpeg -f x11grab -r 25 -s cif -i :0.0+10,20 out.mpg
585 @subsection @var{follow_mouse} AVOption
589 -follow_mouse centered|@var{PIXELS}
592 When it is specified with "centered", the grabbing region follows the mouse
593 pointer and keeps the pointer at the center of region; otherwise, the region
594 follows only when the mouse pointer reaches within @var{PIXELS} (greater than
595 zero) to the edge of region.
599 ffmpeg -f x11grab -follow_mouse centered -r 25 -s cif -i :0.0 out.mpg
601 # Follows only when the mouse pointer reaches within 100 pixels to edge
602 ffmpeg -f x11grab -follow_mouse 100 -r 25 -s cif -i :0.0 out.mpg
605 @subsection @var{show_region} AVOption
612 If @var{show_region} AVOption is specified with @var{1}, then the grabbing
613 region will be indicated on screen. With this option, it's easy to know what is
614 being grabbed if only a portion of the screen is grabbed.
618 ffmpeg -f x11grab -show_region 1 -r 25 -s cif -i :0.0+10,20 out.mpg
621 ffmpeg -f x11grab -follow_mouse centered -show_region 1 -r 25 -s cif -i :0.0 out.mpg
624 @c man end INPUT DEVICES