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1 | @chapter Output Devices |
2 | @c man begin OUTPUT DEVICES |
3 | |
4 | Output devices are configured elements in FFmpeg that can write |
5 | multimedia data to an output device attached to your system. |
6 | |
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". |
10 | |
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}". |
15 | |
16 | The option "-devices" of the ff* tools will display the list of |
17 | enabled output devices. |
18 | |
19 | A description of the currently available output devices follows. |
20 | |
21 | @section alsa |
22 | |
23 | ALSA (Advanced Linux Sound Architecture) output device. |
24 | |
25 | @subsection Examples |
26 | |
27 | @itemize |
28 | @item |
29 | Play a file on default ALSA device: |
30 | @example |
31 | ffmpeg -i INPUT -f alsa default |
32 | @end example |
33 | |
34 | @item |
35 | Play a file on soundcard 1, audio device 7: |
36 | @example |
37 | ffmpeg -i INPUT -f alsa hw:1,7 |
38 | @end example |
39 | @end itemize |
40 | |
41 | @section caca |
42 | |
43 | CACA output device. |
44 | |
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. |
48 | |
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. |
52 | |
53 | For more information about libcaca, check: |
54 | @url{http://caca.zoy.org/wiki/libcaca} |
55 | |
56 | @subsection Options |
57 | |
58 | @table @option |
59 | |
60 | @item window_title |
61 | Set the CACA window title, if not specified default to the filename |
62 | specified for the output device. |
63 | |
64 | @item window_size |
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. |
68 | |
69 | @item driver |
70 | Set display driver. |
71 | |
72 | @item algorithm |
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}. |
77 | |
78 | @item antialias |
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}. |
82 | |
83 | @item charset |
84 | Set which characters are going to be used when rendering text. |
85 | The accepted values are listed with @code{-list_dither charsets}. |
86 | |
87 | @item color |
88 | Set color to be used when rendering text. |
89 | The accepted values are listed with @code{-list_dither colors}. |
90 | |
91 | @item list_drivers |
92 | If set to @option{true}, print a list of available drivers and exit. |
93 | |
94 | @item list_dither |
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}. |
98 | @end table |
99 | |
100 | @subsection Examples |
101 | |
102 | @itemize |
103 | @item |
104 | The following command shows the @command{ffmpeg} output is an |
105 | CACA window, forcing its size to 80x25: |
106 | @example |
107 | ffmpeg -i INPUT -vcodec rawvideo -pix_fmt rgb24 -window_size 80x25 -f caca - |
108 | @end example |
109 | |
110 | @item |
111 | Show the list of available drivers and exit: |
112 | @example |
113 | ffmpeg -i INPUT -pix_fmt rgb24 -f caca -list_drivers true - |
114 | @end example |
115 | |
116 | @item |
117 | Show the list of available dither colors and exit: |
118 | @example |
119 | ffmpeg -i INPUT -pix_fmt rgb24 -f caca -list_dither colors - |
120 | @end example |
121 | @end itemize |
122 | |
123 | @section decklink |
124 | |
125 | The decklink output device provides playback capabilities for Blackmagic |
126 | DeckLink devices. |
127 | |
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}. |
132 | |
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. |
136 | |
137 | @subsection Options |
138 | |
139 | @table @option |
140 | |
141 | @item list_devices |
142 | If set to @option{true}, print a list of devices and exit. |
143 | Defaults to @option{false}. |
144 | |
145 | @item list_formats |
146 | If set to @option{true}, print a list of supported formats and exit. |
147 | Defaults to @option{false}. |
148 | |
149 | @item preroll |
150 | Amount of time to preroll video in seconds. |
151 | Defaults to @option{0.5}. |
152 | |
153 | @end table |
154 | |
155 | @subsection Examples |
156 | |
157 | @itemize |
158 | |
159 | @item |
160 | List output devices: |
161 | @example |
162 | ffmpeg -i test.avi -f decklink -list_devices 1 dummy |
163 | @end example |
164 | |
165 | @item |
166 | List supported formats: |
167 | @example |
168 | ffmpeg -i test.avi -f decklink -list_formats 1 'DeckLink Mini Monitor' |
169 | @end example |
170 | |
171 | @item |
172 | Play video clip: |
173 | @example |
174 | ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 'DeckLink Mini Monitor' |
175 | @end example |
176 | |
177 | @item |
178 | Play video clip with non-standard framerate or video size: |
179 | @example |
180 | ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 -s 720x486 -r 24000/1001 'DeckLink Mini Monitor' |
181 | @end example |
182 | |
183 | @end itemize |
184 | |
185 | @section fbdev |
186 | |
187 | Linux framebuffer output device. |
188 | |
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 |
192 | @file{/dev/fb0}. |
193 | |
194 | For more detailed information read the file |
195 | @file{Documentation/fb/framebuffer.txt} included in the Linux source tree. |
196 | |
197 | @subsection Options |
198 | @table @option |
199 | |
200 | @item xoffset |
201 | @item yoffset |
202 | Set x/y coordinate of top left corner. Default is 0. |
203 | @end table |
204 | |
205 | @subsection Examples |
206 | Play a file on framebuffer device @file{/dev/fb0}. |
207 | Required pixel format depends on current framebuffer settings. |
208 | @example |
209 | ffmpeg -re -i INPUT -vcodec rawvideo -pix_fmt bgra -f fbdev /dev/fb0 |
210 | @end example |
211 | |
212 | See also @url{http://linux-fbdev.sourceforge.net/}, and fbset(1). |
213 | |
214 | @section opengl |
215 | OpenGL output device. |
216 | |
217 | To enable this output device you need to configure FFmpeg with @code{--enable-opengl}. |
218 | |
219 | This output device allows one to render to OpenGL context. |
220 | Context may be provided by application or default SDL window is created. |
221 | |
222 | When device renders to external context, application must implement handlers for following messages: |
223 | @code{AV_DEV_TO_APP_CREATE_WINDOW_BUFFER} - create OpenGL context on current thread. |
224 | @code{AV_DEV_TO_APP_PREPARE_WINDOW_BUFFER} - make OpenGL context current. |
225 | @code{AV_DEV_TO_APP_DISPLAY_WINDOW_BUFFER} - swap buffers. |
226 | @code{AV_DEV_TO_APP_DESTROY_WINDOW_BUFFER} - destroy OpenGL context. |
227 | Application is also required to inform a device about current resolution by sending @code{AV_APP_TO_DEV_WINDOW_SIZE} message. |
228 | |
229 | @subsection Options |
230 | @table @option |
231 | |
232 | @item background |
233 | Set background color. Black is a default. |
234 | @item no_window |
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. |
237 | @item window_title |
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. |
240 | @item window_size |
241 | Set preferred window size, can be a string of the form widthxheight or a video size abbreviation. |
242 | If not specified it defaults to the size of the input video, downscaled according to the aspect ratio. |
243 | Mostly usable when @option{no_window} is not set. |
244 | |
245 | @end table |
246 | |
247 | @subsection Examples |
248 | Play a file on SDL window using OpenGL rendering: |
249 | @example |
250 | ffmpeg -i INPUT -f opengl "window title" |
251 | @end example |
252 | |
253 | @section oss |
254 | |
255 | OSS (Open Sound System) output device. |
256 | |
257 | @section pulse |
258 | |
259 | PulseAudio output device. |
260 | |
261 | To enable this output device you need to configure FFmpeg with @code{--enable-libpulse}. |
262 | |
263 | More information about PulseAudio can be found on @url{http://www.pulseaudio.org} |
264 | |
265 | @subsection Options |
266 | @table @option |
267 | |
268 | @item server |
269 | Connect to a specific PulseAudio server, specified by an IP address. |
270 | Default server is used when not provided. |
271 | |
272 | @item name |
273 | Specify the application name PulseAudio will use when showing active clients, |
274 | by default it is the @code{LIBAVFORMAT_IDENT} string. |
275 | |
276 | @item stream_name |
277 | Specify the stream name PulseAudio will use when showing active streams, |
278 | by default it is set to the specified output name. |
279 | |
280 | @item device |
281 | Specify the device to use. Default device is used when not provided. |
282 | List of output devices can be obtained with command @command{pactl list sinks}. |
283 | |
284 | @item buffer_size |
285 | @item buffer_duration |
286 | Control the size and duration of the PulseAudio buffer. A small buffer |
287 | gives more control, but requires more frequent updates. |
288 | |
289 | @option{buffer_size} specifies size in bytes while |
290 | @option{buffer_duration} specifies duration in milliseconds. |
291 | |
292 | When both options are provided then the highest value is used |
293 | (duration is recalculated to bytes using stream parameters). If they |
294 | are set to 0 (which is default), the device will use the default |
295 | PulseAudio duration value. By default PulseAudio set buffer duration |
296 | to around 2 seconds. |
297 | |
298 | @item prebuf |
299 | Specify pre-buffering size in bytes. The server does not start with |
300 | playback before at least @option{prebuf} bytes are available in the |
301 | buffer. By default this option is initialized to the same value as |
302 | @option{buffer_size} or @option{buffer_duration} (whichever is bigger). |
303 | |
304 | @item minreq |
305 | Specify minimum request size in bytes. The server does not request less |
306 | than @option{minreq} bytes from the client, instead waits until the buffer |
307 | is free enough to request more bytes at once. It is recommended to not set |
308 | this option, which will initialize this to a value that is deemed sensible |
309 | by the server. |
310 | |
311 | @end table |
312 | |
313 | @subsection Examples |
314 | Play a file on default device on default server: |
315 | @example |
316 | ffmpeg -i INPUT -f pulse "stream name" |
317 | @end example |
318 | |
319 | @section sdl |
320 | |
321 | SDL (Simple DirectMedia Layer) output device. |
322 | |
323 | This output device allows one to show a video stream in an SDL |
324 | window. Only one SDL window is allowed per application, so you can |
325 | have only one instance of this output device in an application. |
326 | |
327 | To enable this output device you need libsdl installed on your system |
328 | when configuring your build. |
329 | |
330 | For more information about SDL, check: |
331 | @url{http://www.libsdl.org/} |
332 | |
333 | @subsection Options |
334 | |
335 | @table @option |
336 | |
337 | @item window_title |
338 | Set the SDL window title, if not specified default to the filename |
339 | specified for the output device. |
340 | |
341 | @item icon_title |
342 | Set the name of the iconified SDL window, if not specified it is set |
343 | to the same value of @var{window_title}. |
344 | |
345 | @item window_size |
346 | Set the SDL window size, can be a string of the form |
347 | @var{width}x@var{height} or a video size abbreviation. |
348 | If not specified it defaults to the size of the input video, |
349 | downscaled according to the aspect ratio. |
350 | |
351 | @item window_fullscreen |
352 | Set fullscreen mode when non-zero value is provided. |
353 | Default value is zero. |
354 | @end table |
355 | |
356 | @subsection Interactive commands |
357 | |
358 | The window created by the device can be controlled through the |
359 | following interactive commands. |
360 | |
361 | @table @key |
362 | @item q, ESC |
363 | Quit the device immediately. |
364 | @end table |
365 | |
366 | @subsection Examples |
367 | |
368 | The following command shows the @command{ffmpeg} output is an |
369 | SDL window, forcing its size to the qcif format: |
370 | @example |
371 | ffmpeg -i INPUT -vcodec rawvideo -pix_fmt yuv420p -window_size qcif -f sdl "SDL output" |
372 | @end example |
373 | |
374 | @section sndio |
375 | |
376 | sndio audio output device. |
377 | |
378 | @section xv |
379 | |
380 | XV (XVideo) output device. |
381 | |
382 | This output device allows one to show a video stream in a X Window System |
383 | window. |
384 | |
385 | @subsection Options |
386 | |
387 | @table @option |
388 | @item display_name |
389 | Specify the hardware display name, which determines the display and |
390 | communications domain to be used. |
391 | |
392 | The display name or DISPLAY environment variable can be a string in |
393 | the format @var{hostname}[:@var{number}[.@var{screen_number}]]. |
394 | |
395 | @var{hostname} specifies the name of the host machine on which the |
396 | display is physically attached. @var{number} specifies the number of |
397 | the display server on that host machine. @var{screen_number} specifies |
398 | the screen to be used on that server. |
399 | |
400 | If unspecified, it defaults to the value of the DISPLAY environment |
401 | variable. |
402 | |
403 | For example, @code{dual-headed:0.1} would specify screen 1 of display |
404 | 0 on the machine named ``dual-headed''. |
405 | |
406 | Check the X11 specification for more detailed information about the |
407 | display name format. |
408 | |
409 | @item window_id |
410 | When set to non-zero value then device doesn't create new window, |
411 | but uses existing one with provided @var{window_id}. By default |
412 | this options is set to zero and device creates its own window. |
413 | |
414 | @item window_size |
415 | Set the created window size, can be a string of the form |
416 | @var{width}x@var{height} or a video size abbreviation. If not |
417 | specified it defaults to the size of the input video. |
418 | Ignored when @var{window_id} is set. |
419 | |
420 | @item window_x |
421 | @item window_y |
422 | Set the X and Y window offsets for the created window. They are both |
423 | set to 0 by default. The values may be ignored by the window manager. |
424 | Ignored when @var{window_id} is set. |
425 | |
426 | @item window_title |
427 | Set the window title, if not specified default to the filename |
428 | specified for the output device. Ignored when @var{window_id} is set. |
429 | @end table |
430 | |
431 | For more information about XVideo see @url{http://www.x.org/}. |
432 | |
433 | @subsection Examples |
434 | |
435 | @itemize |
436 | @item |
437 | Decode, display and encode video input with @command{ffmpeg} at the |
438 | same time: |
439 | @example |
440 | ffmpeg -i INPUT OUTPUT -f xv display |
441 | @end example |
442 | |
443 | @item |
444 | Decode and display the input video to multiple X11 windows: |
445 | @example |
446 | ffmpeg -i INPUT -f xv normal -vf negate -f xv negated |
447 | @end example |
448 | @end itemize |
449 | |
450 | @c man end OUTPUT DEVICES |
451 |