1 @chapter Output Devices
2 @c man begin OUTPUT DEVICES
4 Output devices are configured elements in FFmpeg that can write
5 multimedia data to an output device attached to your system.
7 When you configure your FFmpeg build, all the supported output devices
8 are enabled by default. You can list all available ones using the
9 configure option "--list-outdevs".
11 You can disable all the output devices using the configure option
12 "--disable-outdevs", and selectively enable an output device using the
13 option "--enable-outdev=@var{OUTDEV}", or you can disable a particular
14 input device using the option "--disable-outdev=@var{OUTDEV}".
16 The option "-devices" of the ff* tools will display the list of
17 enabled output devices.
19 A description of the currently available output devices follows.
23 ALSA (Advanced Linux Sound Architecture) output device.
29 Play a file on default ALSA device:
31 ffmpeg -i INPUT -f alsa default
35 Play a file on soundcard 1, audio device 7:
37 ffmpeg -i INPUT -f alsa hw:1,7
45 This output device allows one to show a video stream in CACA window.
46 Only one CACA window is allowed per application, so you can
47 have only one instance of this output device in an application.
49 To enable this output device you need to configure FFmpeg with
50 @code{--enable-libcaca}.
51 libcaca is a graphics library that outputs text instead of pixels.
53 For more information about libcaca, check:
54 @url{http://caca.zoy.org/wiki/libcaca}
61 Set the CACA window title, if not specified default to the filename
62 specified for the output device.
65 Set the CACA window size, can be a string of the form
66 @var{width}x@var{height} or a video size abbreviation.
67 If not specified it defaults to the size of the input video.
73 Set dithering algorithm. Dithering is necessary
74 because the picture being rendered has usually far more colours than
75 the available palette.
76 The accepted values are listed with @code{-list_dither algorithms}.
79 Set antialias method. Antialiasing smoothens the rendered
80 image and avoids the commonly seen staircase effect.
81 The accepted values are listed with @code{-list_dither antialiases}.
84 Set which characters are going to be used when rendering text.
85 The accepted values are listed with @code{-list_dither charsets}.
88 Set color to be used when rendering text.
89 The accepted values are listed with @code{-list_dither colors}.
92 If set to @option{true}, print a list of available drivers and exit.
95 List available dither options related to the argument.
96 The argument must be one of @code{algorithms}, @code{antialiases},
97 @code{charsets}, @code{colors}.
104 The following command shows the @command{ffmpeg} output is an
105 CACA window, forcing its size to 80x25:
107 ffmpeg -i INPUT -c:v rawvideo -pix_fmt rgb24 -window_size 80x25 -f caca -
111 Show the list of available drivers and exit:
113 ffmpeg -i INPUT -pix_fmt rgb24 -f caca -list_drivers true -
117 Show the list of available dither colors and exit:
119 ffmpeg -i INPUT -pix_fmt rgb24 -f caca -list_dither colors -
125 The decklink output device provides playback capabilities for Blackmagic
128 To enable this output device, you need the Blackmagic DeckLink SDK and you
129 need to configure with the appropriate @code{--extra-cflags}
130 and @code{--extra-ldflags}.
131 On Windows, you need to run the IDL files through @command{widl}.
133 DeckLink is very picky about the formats it supports. Pixel format is always
134 uyvy422, framerate, field order and video size must be determined for your
135 device with @command{-list_formats 1}. Audio sample rate is always 48 kHz.
142 If set to @option{true}, print a list of devices and exit.
143 Defaults to @option{false}.
146 If set to @option{true}, print a list of supported formats and exit.
147 Defaults to @option{false}.
150 Amount of time to preroll video in seconds.
151 Defaults to @option{0.5}.
154 Sets the decklink device duplex mode. Must be @samp{unset}, @samp{half} or @samp{full}.
155 Defaults to @samp{unset}.
166 ffmpeg -i test.avi -f decklink -list_devices 1 dummy
170 List supported formats:
172 ffmpeg -i test.avi -f decklink -list_formats 1 'DeckLink Mini Monitor'
178 ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 'DeckLink Mini Monitor'
182 Play video clip with non-standard framerate or video size:
184 ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 -s 720x486 -r 24000/1001 'DeckLink Mini Monitor'
191 Linux framebuffer output device.
193 The Linux framebuffer is a graphic hardware-independent abstraction
194 layer to show graphics on a computer monitor, typically on the
195 console. It is accessed through a file device node, usually
198 For more detailed information read the file
199 @file{Documentation/fb/framebuffer.txt} included in the Linux source tree.
206 Set x/y coordinate of top left corner. Default is 0.
210 Play a file on framebuffer device @file{/dev/fb0}.
211 Required pixel format depends on current framebuffer settings.
213 ffmpeg -re -i INPUT -c:v rawvideo -pix_fmt bgra -f fbdev /dev/fb0
216 See also @url{http://linux-fbdev.sourceforge.net/}, and fbset(1).
218 @section libndi_newtek
220 The libndi_newtek output device provides playback capabilities for using NDI (Network
221 Device Interface, standard created by NewTek).
223 Output filename is a NDI name.
225 To enable this output device, you need the NDI SDK and you
226 need to configure with the appropriate @code{--extra-cflags}
227 and @code{--extra-ldflags}.
229 NDI uses uyvy422 pixel format natively, but also supports bgra, bgr0, rgba and
236 @item reference_level
237 The audio reference level in dB. This specifies how many dB above the
238 reference level (+4dBU) is the full range of 16 bit audio.
239 Defaults to @option{0}.
242 These specify whether video "clock" themselves.
243 Defaults to @option{false}.
246 These specify whether audio "clock" themselves.
247 Defaults to @option{false}.
258 ffmpeg -i "udp://@@239.1.1.1:10480?fifo_size=1000000&overrun_nonfatal=1" -vf "scale=720:576,fps=fps=25,setdar=dar=16/9,format=pix_fmts=uyvy422" -f libndi_newtek NEW_NDI1
264 OpenGL output device.
266 To enable this output device you need to configure FFmpeg with @code{--enable-opengl}.
268 This output device allows one to render to OpenGL context.
269 Context may be provided by application or default SDL window is created.
271 When device renders to external context, application must implement handlers for following messages:
272 @code{AV_DEV_TO_APP_CREATE_WINDOW_BUFFER} - create OpenGL context on current thread.
273 @code{AV_DEV_TO_APP_PREPARE_WINDOW_BUFFER} - make OpenGL context current.
274 @code{AV_DEV_TO_APP_DISPLAY_WINDOW_BUFFER} - swap buffers.
275 @code{AV_DEV_TO_APP_DESTROY_WINDOW_BUFFER} - destroy OpenGL context.
276 Application is also required to inform a device about current resolution by sending @code{AV_APP_TO_DEV_WINDOW_SIZE} message.
282 Set background color. Black is a default.
284 Disables default SDL window when set to non-zero value.
285 Application must provide OpenGL context and both @code{window_size_cb} and @code{window_swap_buffers_cb} callbacks when set.
287 Set the SDL window title, if not specified default to the filename specified for the output device.
288 Ignored when @option{no_window} is set.
290 Set preferred window size, can be a string of the form widthxheight or a video size abbreviation.
291 If not specified it defaults to the size of the input video, downscaled according to the aspect ratio.
292 Mostly usable when @option{no_window} is not set.
297 Play a file on SDL window using OpenGL rendering:
299 ffmpeg -i INPUT -f opengl "window title"
304 OSS (Open Sound System) output device.
308 PulseAudio output device.
310 To enable this output device you need to configure FFmpeg with @code{--enable-libpulse}.
312 More information about PulseAudio can be found on @url{http://www.pulseaudio.org}
318 Connect to a specific PulseAudio server, specified by an IP address.
319 Default server is used when not provided.
322 Specify the application name PulseAudio will use when showing active clients,
323 by default it is the @code{LIBAVFORMAT_IDENT} string.
326 Specify the stream name PulseAudio will use when showing active streams,
327 by default it is set to the specified output name.
330 Specify the device to use. Default device is used when not provided.
331 List of output devices can be obtained with command @command{pactl list sinks}.
334 @item buffer_duration
335 Control the size and duration of the PulseAudio buffer. A small buffer
336 gives more control, but requires more frequent updates.
338 @option{buffer_size} specifies size in bytes while
339 @option{buffer_duration} specifies duration in milliseconds.
341 When both options are provided then the highest value is used
342 (duration is recalculated to bytes using stream parameters). If they
343 are set to 0 (which is default), the device will use the default
344 PulseAudio duration value. By default PulseAudio set buffer duration
348 Specify pre-buffering size in bytes. The server does not start with
349 playback before at least @option{prebuf} bytes are available in the
350 buffer. By default this option is initialized to the same value as
351 @option{buffer_size} or @option{buffer_duration} (whichever is bigger).
354 Specify minimum request size in bytes. The server does not request less
355 than @option{minreq} bytes from the client, instead waits until the buffer
356 is free enough to request more bytes at once. It is recommended to not set
357 this option, which will initialize this to a value that is deemed sensible
363 Play a file on default device on default server:
365 ffmpeg -i INPUT -f pulse "stream name"
370 SDL (Simple DirectMedia Layer) output device.
372 This output device allows one to show a video stream in an SDL
373 window. Only one SDL window is allowed per application, so you can
374 have only one instance of this output device in an application.
376 To enable this output device you need libsdl installed on your system
377 when configuring your build.
379 For more information about SDL, check:
380 @url{http://www.libsdl.org/}
387 Set the SDL window title, if not specified default to the filename
388 specified for the output device.
391 Set the name of the iconified SDL window, if not specified it is set
392 to the same value of @var{window_title}.
395 Set the SDL window size, can be a string of the form
396 @var{width}x@var{height} or a video size abbreviation.
397 If not specified it defaults to the size of the input video,
398 downscaled according to the aspect ratio.
400 @item window_fullscreen
401 Set fullscreen mode when non-zero value is provided.
402 Default value is zero.
404 @item window_enable_quit
405 Enable quit action (using window button or keyboard key)
406 when non-zero value is provided.
407 Default value is 1 (enable quit action)
410 @subsection Interactive commands
412 The window created by the device can be controlled through the
413 following interactive commands.
417 Quit the device immediately.
422 The following command shows the @command{ffmpeg} output is an
423 SDL window, forcing its size to the qcif format:
425 ffmpeg -i INPUT -c:v rawvideo -pix_fmt yuv420p -window_size qcif -f sdl "SDL output"
430 sndio audio output device.
434 Video4Linux2 output device.
438 XV (XVideo) output device.
440 This output device allows one to show a video stream in a X Window System
447 Specify the hardware display name, which determines the display and
448 communications domain to be used.
450 The display name or DISPLAY environment variable can be a string in
451 the format @var{hostname}[:@var{number}[.@var{screen_number}]].
453 @var{hostname} specifies the name of the host machine on which the
454 display is physically attached. @var{number} specifies the number of
455 the display server on that host machine. @var{screen_number} specifies
456 the screen to be used on that server.
458 If unspecified, it defaults to the value of the DISPLAY environment
461 For example, @code{dual-headed:0.1} would specify screen 1 of display
462 0 on the machine named ``dual-headed''.
464 Check the X11 specification for more detailed information about the
468 When set to non-zero value then device doesn't create new window,
469 but uses existing one with provided @var{window_id}. By default
470 this options is set to zero and device creates its own window.
473 Set the created window size, can be a string of the form
474 @var{width}x@var{height} or a video size abbreviation. If not
475 specified it defaults to the size of the input video.
476 Ignored when @var{window_id} is set.
480 Set the X and Y window offsets for the created window. They are both
481 set to 0 by default. The values may be ignored by the window manager.
482 Ignored when @var{window_id} is set.
485 Set the window title, if not specified default to the filename
486 specified for the output device. Ignored when @var{window_id} is set.
489 For more information about XVideo see @url{http://www.x.org/}.
495 Decode, display and encode video input with @command{ffmpeg} at the
498 ffmpeg -i INPUT OUTPUT -f xv display
502 Decode and display the input video to multiple X11 windows:
504 ffmpeg -i INPUT -f xv normal -vf negate -f xv negated
508 @c man end OUTPUT DEVICES