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 frame rate 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,
116 Select pixel format to be used by DirectShow. This may only be set when
117 the video codec is not set or set to rawvideo.
119 @item audio_buffer_size
120 Set audio device buffer size in milliseconds (which can directly
121 impact latency, depending on the device).
122 Defaults to using the audio device's
123 default buffer size (typically some multiple of 500ms).
124 Setting this value too low can degrade performance.
126 @url{http://msdn.microsoft.com/en-us/library/windows/desktop/dd377582(v=vs.85).aspx}
135 Print the list of DirectShow supported devices and exit:
137 $ ffmpeg -list_devices true -f dshow -i dummy
141 Open video device @var{Camera}:
143 $ ffmpeg -f dshow -i video="Camera"
147 Open second video device with name @var{Camera}:
149 $ ffmpeg -f dshow -video_device_number 1 -i video="Camera"
153 Open video device @var{Camera} and audio device @var{Microphone}:
155 $ ffmpeg -f dshow -i video="Camera":audio="Microphone"
159 Print the list of supported options in selected device and exit:
161 $ ffmpeg -list_options true -f dshow -i video="Camera"
168 Linux DV 1394 input device.
172 Linux framebuffer input device.
174 The Linux framebuffer is a graphic hardware-independent abstraction
175 layer to show graphics on a computer monitor, typically on the
176 console. It is accessed through a file device node, usually
179 For more detailed information read the file
180 Documentation/fb/framebuffer.txt included in the Linux source tree.
182 To record from the framebuffer device @file{/dev/fb0} with
185 ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi
188 You can take a single screenshot image with the command:
190 ffmpeg -f fbdev -frames:v 1 -r 1 -i /dev/fb0 screenshot.jpeg
193 See also @url{http://linux-fbdev.sourceforge.net/}, and fbset(1).
197 FireWire DV/HDV input device using libiec61883.
199 To enable this input device, you need libiec61883, libraw1394 and
200 libavc1394 installed on your system. Use the configure option
201 @code{--enable-libiec61883} to compile with the device enabled.
203 The iec61883 capture device supports capturing from a video device
204 connected via IEEE1394 (FireWire), using libiec61883 and the new Linux
205 FireWire stack (juju). This is the default DV/HDV input method in Linux
206 Kernel 2.6.37 and later, since the old FireWire stack was removed.
208 Specify the FireWire port to be used as input file, or "auto"
209 to choose the first port connected.
216 Override autodetection of DV/HDV. This should only be used if auto
217 detection does not work, or if usage of a different device type
218 should be prohibited. Treating a DV device as HDV (or vice versa) will
219 not work and result in undefined behavior.
220 The values @option{auto}, @option{dv} and @option{hdv} are supported.
223 Set maxiumum size of buffer for incoming data, in frames. For DV, this
224 is an exact value. For HDV, it is not frame exact, since HDV does
225 not have a fixed frame size.
228 Select the capture device by specifying it's GUID. Capturing will only
229 be performed from the specified device and fails if no device with the
230 given GUID is found. This is useful to select the input if multiple
231 devices are connected at the same time.
232 Look at /sys/bus/firewire/devices to find out the GUIDs.
241 Grab and show the input of a FireWire DV/HDV device.
243 ffplay -f iec61883 -i auto
247 Grab and record the input of a FireWire DV/HDV device,
248 using a packet buffer of 100000 packets if the source is HDV.
250 ffmpeg -f iec61883 -i auto -hdvbuffer 100000 out.mpg
259 To enable this input device during configuration you need libjack
260 installed on your system.
262 A JACK input device creates one or more JACK writable clients, one for
263 each audio channel, with name @var{client_name}:input_@var{N}, where
264 @var{client_name} is the name provided by the application, and @var{N}
265 is a number which identifies the channel.
266 Each writable client will send the acquired data to the FFmpeg input
269 Once you have created one or more JACK readable clients, you need to
270 connect them to one or more JACK writable clients.
272 To connect or disconnect JACK clients you can use the @command{jack_connect}
273 and @command{jack_disconnect} programs, or do it through a graphical interface,
274 for example with @command{qjackctl}.
276 To list the JACK clients and their properties you can invoke the command
279 Follows an example which shows how to capture a JACK readable client
280 with @command{ffmpeg}.
282 # Create a JACK writable client with name "ffmpeg".
283 $ ffmpeg -f jack -i ffmpeg -y out.wav
285 # Start the sample jack_metro readable client.
286 $ jack_metro -b 120 -d 0.2 -f 4000
288 # List the current JACK clients.
297 # Connect metro to the ffmpeg writable client.
298 $ jack_connect metro:120_bpm ffmpeg:input_1
301 For more information read:
302 @url{http://jackaudio.org/}
306 Libavfilter input virtual device.
308 This input device reads data from the open output pads of a libavfilter
311 For each filtergraph open output, the input device will create a
312 corresponding stream which is mapped to the generated output. Currently
313 only video data is supported. The filtergraph is specified through the
314 option @option{graph}.
321 Specify the filtergraph to use as input. Each video open output must be
322 labelled by a unique string of the form "out@var{N}", where @var{N} is a
323 number starting from 0 corresponding to the mapped input stream
324 generated by the device.
325 The first unlabelled output is automatically assigned to the "out0"
326 label, but all the others need to be specified explicitly.
328 If not specified defaults to the filename specified for the input
332 Set the filename of the filtergraph to be read and sent to the other
333 filters. Syntax of the filtergraph is the same as the one specified by
334 the option @var{graph}.
342 Create a color video stream and play it back with @command{ffplay}:
344 ffplay -f lavfi -graph "color=c=pink [out0]" dummy
348 As the previous example, but use filename for specifying the graph
349 description, and omit the "out0" label:
351 ffplay -f lavfi color=c=pink
355 Create three different video test filtered sources and play them:
357 ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3
361 Read an audio stream from a file using the amovie source and play it
362 back with @command{ffplay}:
364 ffplay -f lavfi "amovie=test.wav"
368 Read an audio stream and a video stream and play it back with
371 ffplay -f lavfi "movie=test.avi[out0];amovie=test.wav[out1]"
378 IIDC1394 input device, based on libdc1394 and libraw1394.
382 The OpenAL input device provides audio capture on all systems with a
383 working OpenAL 1.1 implementation.
385 To enable this input device during configuration, you need OpenAL
386 headers and libraries installed on your system, and need to configure
387 FFmpeg with @code{--enable-openal}.
389 OpenAL headers and libraries should be provided as part of your OpenAL
390 implementation, or as an additional download (an SDK). Depending on your
391 installation you may need to specify additional flags via the
392 @code{--extra-cflags} and @code{--extra-ldflags} for allowing the build
393 system to locate the OpenAL headers and libraries.
395 An incomplete list of OpenAL implementations follows:
399 The official Windows implementation, providing hardware acceleration
400 with supported devices and software fallback.
401 See @url{http://openal.org/}.
403 Portable, open source (LGPL) software implementation. Includes
404 backends for the most common sound APIs on the Windows, Linux,
405 Solaris, and BSD operating systems.
406 See @url{http://kcat.strangesoft.net/openal.html}.
408 OpenAL is part of Core Audio, the official Mac OS X Audio interface.
409 See @url{http://developer.apple.com/technologies/mac/audio-and-video.html}
412 This device allows to capture from an audio input device handled
415 You need to specify the name of the device to capture in the provided
416 filename. If the empty string is provided, the device will
417 automatically select the default device. You can get the list of the
418 supported devices by using the option @var{list_devices}.
425 Set the number of channels in the captured audio. Only the values
426 @option{1} (monaural) and @option{2} (stereo) are currently supported.
427 Defaults to @option{2}.
430 Set the sample size (in bits) of the captured audio. Only the values
431 @option{8} and @option{16} are currently supported. Defaults to
435 Set the sample rate (in Hz) of the captured audio.
436 Defaults to @option{44.1k}.
439 If set to @option{true}, print a list of devices and exit.
440 Defaults to @option{false}.
446 Print the list of OpenAL supported devices and exit:
448 $ ffmpeg -list_devices true -f openal -i dummy out.ogg
451 Capture from the OpenAL device @file{DR-BT101 via PulseAudio}:
453 $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out.ogg
456 Capture from the default device (note the empty string '' as filename):
458 $ ffmpeg -f openal -i '' out.ogg
461 Capture from two devices simultaneously, writing to two different files,
462 within the same @command{ffmpeg} command:
464 $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out1.ogg -f openal -i 'ALSA Default' out2.ogg
466 Note: not all OpenAL implementations support multiple simultaneous capture -
467 try the latest OpenAL Soft if the above does not work.
471 Open Sound System input device.
473 The filename to provide to the input device is the device node
474 representing the OSS input device, and is usually set to
477 For example to grab from @file{/dev/dsp} using @command{ffmpeg} use the
480 ffmpeg -f oss -i /dev/dsp /tmp/oss.wav
483 For more information about OSS see:
484 @url{http://manuals.opensound.com/usersguide/dsp.html}
488 PulseAudio input device.
490 To enable this output device you need to configure FFmpeg with @code{--enable-libpulse}.
492 The filename to provide to the input device is a source device or the
495 To list the PulseAudio source devices and their properties you can invoke
496 the command @command{pactl list sources}.
498 More information about PulseAudio can be found on @url{http://www.pulseaudio.org}.
503 Connect to a specific PulseAudio server, specified by an IP address.
504 Default server is used when not provided.
507 Specify the application name PulseAudio will use when showing active clients,
508 by default it is the @code{LIBAVFORMAT_IDENT} string.
511 Specify the stream name PulseAudio will use when showing active streams,
512 by default it is "record".
515 Specify the samplerate in Hz, by default 48kHz is used.
518 Specify the channels in use, by default 2 (stereo) is set.
521 Specify the number of bytes per frame, by default it is set to 1024.
524 Specify the minimal buffering fragment in PulseAudio, it will affect the
525 audio latency. By default it is unset.
529 Record a stream from default device:
531 ffmpeg -f pulse -i default /tmp/pulse.wav
538 To enable this input device during configuration you need libsndio
539 installed on your system.
541 The filename to provide to the input device is the device node
542 representing the sndio input device, and is usually set to
545 For example to grab from @file{/dev/audio0} using @command{ffmpeg} use the
548 ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav
551 @section video4linux2, v4l2
553 Video4Linux2 input video device.
555 "v4l2" can be used as alias for "video4linux2".
557 If FFmpeg is built with v4l-utils support (by using the
558 @code{--enable-libv4l2} configure option), it is possible to use it with the
559 @code{-use_libv4l2} input device option.
561 The name of the device to grab is a file device node, usually Linux
562 systems tend to automatically create such nodes when the device
563 (e.g. an USB webcam) is plugged into the system, and has a name of the
564 kind @file{/dev/video@var{N}}, where @var{N} is a number associated to
567 Video4Linux2 devices usually support a limited set of
568 @var{width}x@var{height} sizes and frame rates. You can check which are
569 supported using @command{-list_formats all} for Video4Linux2 devices.
570 Some devices, like TV cards, support one or more standards. It is possible
571 to list all the supported standards using @command{-list_standards all}.
573 The time base for the timestamps is 1 microsecond. Depending on the kernel
574 version and configuration, the timestamps may be derived from the real time
575 clock (origin at the Unix Epoch) or the monotonic clock (origin usually at
576 boot time, unaffected by NTP or manual changes to the clock). The
577 @option{-timestamps abs} or @option{-ts abs} option can be used to force
578 conversion into the real time clock.
580 Some usage examples of the video4linux2 device with @command{ffmpeg}
581 and @command{ffplay}:
584 Grab and show the input of a video4linux2 device:
586 ffplay -f video4linux2 -framerate 30 -video_size hd720 /dev/video0
590 Grab and record the input of a video4linux2 device, leave the
591 frame rate and size as previously set:
593 ffmpeg -f video4linux2 -input_format mjpeg -i /dev/video0 out.mpeg
597 For more information about Video4Linux, check @url{http://linuxtv.org/}.
603 Set the standard. Must be the name of a supported standard. To get a
604 list of the supported standards, use the @option{list_standards}
608 Set the input channel number. Default to -1, which means using the
609 previously selected channel.
612 Set the video frame size. The argument must be a string in the form
613 @var{WIDTH}x@var{HEIGHT} or a valid size abbreviation.
616 Select the pixel format (only valid for raw video input).
619 Set the preferred pixel format (for raw video) or a codec name.
620 This option allows to select the input format, when several are
624 Set the preferred video frame rate.
627 List available formats (supported pixel formats, codecs, and frame
630 Available values are:
633 Show all available (compressed and non-compressed) formats.
636 Show only raw video (non-compressed) formats.
639 Show only compressed formats.
643 List supported standards and exit.
645 Available values are:
648 Show all supported standards.
652 Set type of timestamps for grabbed frames.
654 Available values are:
657 Use timestamps from the kernel.
660 Use absolute timestamps (wall clock).
663 Force conversion from monotonic to absolute timestamps.
666 Default value is @code{default}.
671 VfW (Video for Windows) capture input device.
673 The filename passed as input is the capture driver number, ranging from
674 0 to 9. You may use "list" as filename to print a list of drivers. Any
675 other filename will be interpreted as device number 0.
679 X11 video input device.
681 This device allows to capture a region of an X11 display.
683 The filename passed as input has the syntax:
685 [@var{hostname}]:@var{display_number}.@var{screen_number}[+@var{x_offset},@var{y_offset}]
688 @var{hostname}:@var{display_number}.@var{screen_number} specifies the
689 X11 display name of the screen to grab from. @var{hostname} can be
690 omitted, and defaults to "localhost". The environment variable
691 @env{DISPLAY} contains the default display name.
693 @var{x_offset} and @var{y_offset} specify the offsets of the grabbed
694 area with respect to the top-left border of the X11 screen. They
697 Check the X11 documentation (e.g. man X) for more detailed information.
699 Use the @command{dpyinfo} program for getting basic information about the
700 properties of your X11 display (e.g. grep for "name" or "dimensions").
702 For example to grab from @file{:0.0} using @command{ffmpeg}:
704 ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0 out.mpg
707 Grab at position @code{10,20}:
709 ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0+10,20 out.mpg
716 Specify whether to draw the mouse pointer. A value of @code{0} specify
717 not to draw the pointer. Default value is @code{1}.
720 Make the grabbed area follow the mouse. The argument can be
721 @code{centered} or a number of pixels @var{PIXELS}.
723 When it is specified with "centered", the grabbing region follows the mouse
724 pointer and keeps the pointer at the center of region; otherwise, the region
725 follows only when the mouse pointer reaches within @var{PIXELS} (greater than
726 zero) to the edge of region.
730 ffmpeg -f x11grab -follow_mouse centered -framerate 25 -video_size cif -i :0.0 out.mpg
733 To follow only when the mouse pointer reaches within 100 pixels to edge:
735 ffmpeg -f x11grab -follow_mouse 100 -framerate 25 -video_size cif -i :0.0 out.mpg
739 Set the grabbing frame rate. Default value is @code{ntsc},
740 corresponding to a frame rate of @code{30000/1001}.
743 Show grabbed region on screen.
745 If @var{show_region} is specified with @code{1}, then the grabbing
746 region will be indicated on screen. With this option, it is easy to
747 know what is being grabbed if only a portion of the screen is grabbed.
751 ffmpeg -f x11grab -show_region 1 -framerate 25 -video_size cif -i :0.0+10,20 out.mpg
754 With @var{follow_mouse}:
756 ffmpeg -f x11grab -follow_mouse centered -show_region 1 -framerate 25 -video_size cif -i :0.0 out.mpg
760 Set the video frame size. Default value is @code{vga}.
763 @c man end INPUT DEVICES