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 "-formats" of the ff* tools will display the list of
17 enabled output devices (amongst the muxers).
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 -vcodec 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 and video size must be determined for your device with
135 @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'
187 Linux framebuffer output device.
189 The Linux framebuffer is a graphic hardware-independent abstraction
190 layer to show graphics on a computer monitor, typically on the
191 console. It is accessed through a file device node, usually
194 For more detailed information read the file
195 @file{Documentation/fb/framebuffer.txt} included in the Linux source tree.
202 Set x/y coordinate of top left corner. Default is 0.
206 Play a file on framebuffer device @file{/dev/fb0}.
207 Required pixel format depends on current framebuffer settings.
209 ffmpeg -re -i INPUT -vcodec rawvideo -pix_fmt bgra -f fbdev /dev/fb0
212 See also @url{http://linux-fbdev.sourceforge.net/}, and fbset(1).
215 OpenGL output device.
217 To enable this output device you need to configure FFmpeg with @code{--enable-opengl}.
219 This output device allows one to render to OpenGL context.
220 Context may be provided by application or default SDL window is created.
222 When device renders to external context, application must implement handlers for following messages:
223 @code{AV_CTL_MESSAGE_CREATE_WINDOW_BUFFER} - create OpenGL context on current thread.
224 @code{AV_CTL_MESSAGE_PREPARE_WINDOW_BUFFER} - make OpenGL context current.
225 @code{AV_CTL_MESSAGE_DISPLAY_WINDOW_BUFFER} - swap buffers.
226 @code{AV_CTL_MESSAGE_DESTROY_WINDOW_BUFFER} - destroy OpenGL context.
227 Application is also required to inform a device about current resolution by sending @code{AV_DEVICE_WINDOW_RESIZED} message.
233 Set background color. Black is a default.
235 Disables default SDL window when set to non-zero value.
236 Application must provide OpenGL context and both @code{window_size_cb} and @code{window_swap_buffers_cb} callbacks when set.
238 Set the SDL window title, if not specified default to the filename specified for the output device.
239 Ignored when @option{no_window} is set.
244 Play a file on SDL window using OpenGL rendering:
246 ffmpeg -i INPUT -f opengl "window title"
251 OSS (Open Sound System) output device.
255 PulseAudio output device.
257 To enable this output device you need to configure FFmpeg with @code{--enable-libpulse}.
259 More information about PulseAudio can be found on @url{http://www.pulseaudio.org}
265 Connect to a specific PulseAudio server, specified by an IP address.
266 Default server is used when not provided.
269 Specify the application name PulseAudio will use when showing active clients,
270 by default it is the @code{LIBAVFORMAT_IDENT} string.
273 Specify the stream name PulseAudio will use when showing active streams,
274 by default it is set to the specified output name.
277 Specify the device to use. Default device is used when not provided.
278 List of output devices can be obtained with command @command{pactl list sinks}.
281 @item buffer_duration
282 Control the size and duration of the PulseAudio buffer. A small buffer
283 gives more control, but requires more frequent updates.
285 @option{buffer_size} specifies size in bytes while
286 @option{buffer_duration} specifies duration in milliseconds.
288 When both options are provided then the highest value is used
289 (duration is recalculated to bytes using stream parameters). If they
290 are set to 0 (which is default), the device will use the default
291 PulseAudio duration value. By default PulseAudio set buffer duration
295 Specify pre-buffering size in bytes. The server does not start with
296 playback before at least @option{prebuf} bytes are available in the
297 buffer. By default this option is initialized to the same value as
298 @option{buffer_size} or @option{buffer_duration} (whichever is bigger).
301 Specify minimum request size in bytes. The server does not request less
302 than @option{minreq} bytes from the client, instead waits until the buffer
303 is free enough to request more bytes at once. It is recommended to not set
304 this option, which will initialize this to a value that is deemed sensible
310 Play a file on default device on default server:
312 ffmpeg -i INPUT -f pulse "stream name"
317 SDL (Simple DirectMedia Layer) output device.
319 This output device allows one to show a video stream in an SDL
320 window. Only one SDL window is allowed per application, so you can
321 have only one instance of this output device in an application.
323 To enable this output device you need libsdl installed on your system
324 when configuring your build.
326 For more information about SDL, check:
327 @url{http://www.libsdl.org/}
334 Set the SDL window title, if not specified default to the filename
335 specified for the output device.
338 Set the name of the iconified SDL window, if not specified it is set
339 to the same value of @var{window_title}.
342 Set the SDL window size, can be a string of the form
343 @var{width}x@var{height} or a video size abbreviation.
344 If not specified it defaults to the size of the input video,
345 downscaled according to the aspect ratio.
347 @item window_fullscreen
348 Set fullscreen mode when non-zero value is provided.
349 Default value is zero.
352 @subsection Interactive commands
354 The window created by the device can be controlled through the
355 following interactive commands.
359 Quit the device immediately.
364 The following command shows the @command{ffmpeg} output is an
365 SDL window, forcing its size to the qcif format:
367 ffmpeg -i INPUT -vcodec rawvideo -pix_fmt yuv420p -window_size qcif -f sdl "SDL output"
372 sndio audio output device.
376 XV (XVideo) output device.
378 This output device allows one to show a video stream in a X Window System
385 Specify the hardware display name, which determines the display and
386 communications domain to be used.
388 The display name or DISPLAY environment variable can be a string in
389 the format @var{hostname}[:@var{number}[.@var{screen_number}]].
391 @var{hostname} specifies the name of the host machine on which the
392 display is physically attached. @var{number} specifies the number of
393 the display server on that host machine. @var{screen_number} specifies
394 the screen to be used on that server.
396 If unspecified, it defaults to the value of the DISPLAY environment
399 For example, @code{dual-headed:0.1} would specify screen 1 of display
400 0 on the machine named ``dual-headed''.
402 Check the X11 specification for more detailed information about the
406 When set to non-zero value then device doesn't create new window,
407 but uses existing one with provided @var{window_id}. By default
408 this options is set to zero and device creates its own window.
411 Set the created window size, can be a string of the form
412 @var{width}x@var{height} or a video size abbreviation. If not
413 specified it defaults to the size of the input video.
414 Ignored when @var{window_id} is set.
418 Set the X and Y window offsets for the created window. They are both
419 set to 0 by default. The values may be ignored by the window manager.
420 Ignored when @var{window_id} is set.
423 Set the window title, if not specified default to the filename
424 specified for the output device. Ignored when @var{window_id} is set.
427 For more information about XVideo see @url{http://www.x.org/}.
433 Decode, display and encode video input with @command{ffmpeg} at the
436 ffmpeg -i INPUT OUTPUT -f xv display
440 Decode and display the input video to multiple X11 windows:
442 ffmpeg -i INPUT -f xv normal -vf negate -f xv negated
446 @c man end OUTPUT DEVICES