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}.
162 ffmpeg -i test.avi -f decklink -list_devices 1 dummy
166 List supported formats:
168 ffmpeg -i test.avi -f decklink -list_formats 1 'DeckLink Mini Monitor'
174 ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 'DeckLink Mini Monitor'
178 Play video clip with non-standard framerate or video size:
180 ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 -s 720x486 -r 24000/1001 'DeckLink Mini Monitor'
185 @section libndi_newtek
187 The libndi_newtek output device provides playback capabilities for using NDI (Network
188 Device Interface, standard created by NewTek).
190 Output filename is a NDI name.
192 To enable this output device, you need the NDI SDK and you
193 need to configure with the appropriate @code{--extra-cflags}
194 and @code{--extra-ldflags}.
196 NDI uses uyvy422 pixel format natively, but also supports bgra, bgr0, rgba and
203 @item reference_level
204 The audio reference level in dB. This specifies how many dB above the
205 reference level (+4dBU) is the full range of 16 bit audio.
206 Defaults to @option{0}.
209 These specify whether video "clock" themselves.
210 Defaults to @option{false}.
213 These specify whether audio "clock" themselves.
214 Defaults to @option{false}.
225 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
232 Linux framebuffer output device.
234 The Linux framebuffer is a graphic hardware-independent abstraction
235 layer to show graphics on a computer monitor, typically on the
236 console. It is accessed through a file device node, usually
239 For more detailed information read the file
240 @file{Documentation/fb/framebuffer.txt} included in the Linux source tree.
247 Set x/y coordinate of top left corner. Default is 0.
251 Play a file on framebuffer device @file{/dev/fb0}.
252 Required pixel format depends on current framebuffer settings.
254 ffmpeg -re -i INPUT -c:v rawvideo -pix_fmt bgra -f fbdev /dev/fb0
257 See also @url{http://linux-fbdev.sourceforge.net/}, and fbset(1).
260 OpenGL output device.
262 To enable this output device you need to configure FFmpeg with @code{--enable-opengl}.
264 This output device allows one to render to OpenGL context.
265 Context may be provided by application or default SDL window is created.
267 When device renders to external context, application must implement handlers for following messages:
268 @code{AV_DEV_TO_APP_CREATE_WINDOW_BUFFER} - create OpenGL context on current thread.
269 @code{AV_DEV_TO_APP_PREPARE_WINDOW_BUFFER} - make OpenGL context current.
270 @code{AV_DEV_TO_APP_DISPLAY_WINDOW_BUFFER} - swap buffers.
271 @code{AV_DEV_TO_APP_DESTROY_WINDOW_BUFFER} - destroy OpenGL context.
272 Application is also required to inform a device about current resolution by sending @code{AV_APP_TO_DEV_WINDOW_SIZE} message.
278 Set background color. Black is a default.
280 Disables default SDL window when set to non-zero value.
281 Application must provide OpenGL context and both @code{window_size_cb} and @code{window_swap_buffers_cb} callbacks when set.
283 Set the SDL window title, if not specified default to the filename specified for the output device.
284 Ignored when @option{no_window} is set.
286 Set preferred window size, can be a string of the form widthxheight or a video size abbreviation.
287 If not specified it defaults to the size of the input video, downscaled according to the aspect ratio.
288 Mostly usable when @option{no_window} is not set.
293 Play a file on SDL window using OpenGL rendering:
295 ffmpeg -i INPUT -f opengl "window title"
300 OSS (Open Sound System) output device.
304 PulseAudio output device.
306 To enable this output device you need to configure FFmpeg with @code{--enable-libpulse}.
308 More information about PulseAudio can be found on @url{http://www.pulseaudio.org}
314 Connect to a specific PulseAudio server, specified by an IP address.
315 Default server is used when not provided.
318 Specify the application name PulseAudio will use when showing active clients,
319 by default it is the @code{LIBAVFORMAT_IDENT} string.
322 Specify the stream name PulseAudio will use when showing active streams,
323 by default it is set to the specified output name.
326 Specify the device to use. Default device is used when not provided.
327 List of output devices can be obtained with command @command{pactl list sinks}.
330 @item buffer_duration
331 Control the size and duration of the PulseAudio buffer. A small buffer
332 gives more control, but requires more frequent updates.
334 @option{buffer_size} specifies size in bytes while
335 @option{buffer_duration} specifies duration in milliseconds.
337 When both options are provided then the highest value is used
338 (duration is recalculated to bytes using stream parameters). If they
339 are set to 0 (which is default), the device will use the default
340 PulseAudio duration value. By default PulseAudio set buffer duration
344 Specify pre-buffering size in bytes. The server does not start with
345 playback before at least @option{prebuf} bytes are available in the
346 buffer. By default this option is initialized to the same value as
347 @option{buffer_size} or @option{buffer_duration} (whichever is bigger).
350 Specify minimum request size in bytes. The server does not request less
351 than @option{minreq} bytes from the client, instead waits until the buffer
352 is free enough to request more bytes at once. It is recommended to not set
353 this option, which will initialize this to a value that is deemed sensible
359 Play a file on default device on default server:
361 ffmpeg -i INPUT -f pulse "stream name"
366 SDL (Simple DirectMedia Layer) output device.
368 This output device allows one to show a video stream in an SDL
369 window. Only one SDL window is allowed per application, so you can
370 have only one instance of this output device in an application.
372 To enable this output device you need libsdl installed on your system
373 when configuring your build.
375 For more information about SDL, check:
376 @url{http://www.libsdl.org/}
383 Set the SDL window title, if not specified default to the filename
384 specified for the output device.
387 Set the name of the iconified SDL window, if not specified it is set
388 to the same value of @var{window_title}.
391 Set the SDL window size, can be a string of the form
392 @var{width}x@var{height} or a video size abbreviation.
393 If not specified it defaults to the size of the input video,
394 downscaled according to the aspect ratio.
396 @item window_fullscreen
397 Set fullscreen mode when non-zero value is provided.
398 Default value is zero.
401 @subsection Interactive commands
403 The window created by the device can be controlled through the
404 following interactive commands.
408 Quit the device immediately.
413 The following command shows the @command{ffmpeg} output is an
414 SDL window, forcing its size to the qcif format:
416 ffmpeg -i INPUT -c:v rawvideo -pix_fmt yuv420p -window_size qcif -f sdl "SDL output"
421 sndio audio output device.
425 XV (XVideo) output device.
427 This output device allows one to show a video stream in a X Window System
434 Specify the hardware display name, which determines the display and
435 communications domain to be used.
437 The display name or DISPLAY environment variable can be a string in
438 the format @var{hostname}[:@var{number}[.@var{screen_number}]].
440 @var{hostname} specifies the name of the host machine on which the
441 display is physically attached. @var{number} specifies the number of
442 the display server on that host machine. @var{screen_number} specifies
443 the screen to be used on that server.
445 If unspecified, it defaults to the value of the DISPLAY environment
448 For example, @code{dual-headed:0.1} would specify screen 1 of display
449 0 on the machine named ``dual-headed''.
451 Check the X11 specification for more detailed information about the
455 When set to non-zero value then device doesn't create new window,
456 but uses existing one with provided @var{window_id}. By default
457 this options is set to zero and device creates its own window.
460 Set the created window size, can be a string of the form
461 @var{width}x@var{height} or a video size abbreviation. If not
462 specified it defaults to the size of the input video.
463 Ignored when @var{window_id} is set.
467 Set the X and Y window offsets for the created window. They are both
468 set to 0 by default. The values may be ignored by the window manager.
469 Ignored when @var{window_id} is set.
472 Set the window title, if not specified default to the filename
473 specified for the output device. Ignored when @var{window_id} is set.
476 For more information about XVideo see @url{http://www.x.org/}.
482 Decode, display and encode video input with @command{ffmpeg} at the
485 ffmpeg -i INPUT OUTPUT -f xv display
489 Decode and display the input video to multiple X11 windows:
491 ffmpeg -i INPUT -f xv normal -vf negate -f xv negated
495 @c man end OUTPUT DEVICES