forked from KolibriOS/kolibrios
451 lines
13 KiB
Plaintext
451 lines
13 KiB
Plaintext
@chapter Output Devices
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@c man begin OUTPUT DEVICES
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Output devices are configured elements in FFmpeg that can write
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multimedia data to an output device attached to your system.
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When you configure your FFmpeg build, all the supported output devices
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are enabled by default. You can list all available ones using the
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configure option "--list-outdevs".
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You can disable all the output devices using the configure option
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"--disable-outdevs", and selectively enable an output device using the
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option "--enable-outdev=@var{OUTDEV}", or you can disable a particular
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input device using the option "--disable-outdev=@var{OUTDEV}".
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The option "-devices" of the ff* tools will display the list of
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enabled output devices.
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A description of the currently available output devices follows.
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@section alsa
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ALSA (Advanced Linux Sound Architecture) output device.
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@subsection Examples
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@itemize
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@item
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Play a file on default ALSA device:
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@example
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ffmpeg -i INPUT -f alsa default
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@end example
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@item
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Play a file on soundcard 1, audio device 7:
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@example
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ffmpeg -i INPUT -f alsa hw:1,7
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@end example
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@end itemize
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@section caca
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CACA output device.
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This output device allows one to show a video stream in CACA window.
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Only one CACA window is allowed per application, so you can
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have only one instance of this output device in an application.
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To enable this output device you need to configure FFmpeg with
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@code{--enable-libcaca}.
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libcaca is a graphics library that outputs text instead of pixels.
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For more information about libcaca, check:
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@url{http://caca.zoy.org/wiki/libcaca}
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@subsection Options
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@table @option
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@item window_title
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Set the CACA window title, if not specified default to the filename
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specified for the output device.
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@item window_size
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Set the CACA window size, can be a string of the form
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@var{width}x@var{height} or a video size abbreviation.
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If not specified it defaults to the size of the input video.
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@item driver
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Set display driver.
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@item algorithm
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Set dithering algorithm. Dithering is necessary
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because the picture being rendered has usually far more colours than
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the available palette.
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The accepted values are listed with @code{-list_dither algorithms}.
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@item antialias
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Set antialias method. Antialiasing smoothens the rendered
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image and avoids the commonly seen staircase effect.
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The accepted values are listed with @code{-list_dither antialiases}.
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@item charset
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Set which characters are going to be used when rendering text.
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The accepted values are listed with @code{-list_dither charsets}.
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@item color
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Set color to be used when rendering text.
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The accepted values are listed with @code{-list_dither colors}.
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@item list_drivers
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If set to @option{true}, print a list of available drivers and exit.
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@item list_dither
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List available dither options related to the argument.
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The argument must be one of @code{algorithms}, @code{antialiases},
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@code{charsets}, @code{colors}.
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@end table
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@subsection Examples
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@itemize
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@item
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The following command shows the @command{ffmpeg} output is an
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CACA window, forcing its size to 80x25:
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@example
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ffmpeg -i INPUT -vcodec rawvideo -pix_fmt rgb24 -window_size 80x25 -f caca -
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@end example
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@item
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Show the list of available drivers and exit:
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@example
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ffmpeg -i INPUT -pix_fmt rgb24 -f caca -list_drivers true -
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@end example
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@item
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Show the list of available dither colors and exit:
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@example
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ffmpeg -i INPUT -pix_fmt rgb24 -f caca -list_dither colors -
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@end example
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@end itemize
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@section decklink
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The decklink output device provides playback capabilities for Blackmagic
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DeckLink devices.
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To enable this output device, you need the Blackmagic DeckLink SDK and you
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need to configure with the appropriate @code{--extra-cflags}
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and @code{--extra-ldflags}.
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On Windows, you need to run the IDL files through @command{widl}.
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DeckLink is very picky about the formats it supports. Pixel format is always
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uyvy422, framerate and video size must be determined for your device with
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@command{-list_formats 1}. Audio sample rate is always 48 kHz.
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@subsection Options
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@table @option
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@item list_devices
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If set to @option{true}, print a list of devices and exit.
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Defaults to @option{false}.
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@item list_formats
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If set to @option{true}, print a list of supported formats and exit.
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Defaults to @option{false}.
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@item preroll
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Amount of time to preroll video in seconds.
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Defaults to @option{0.5}.
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@end table
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@subsection Examples
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@itemize
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@item
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List output devices:
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@example
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ffmpeg -i test.avi -f decklink -list_devices 1 dummy
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@end example
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@item
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List supported formats:
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@example
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ffmpeg -i test.avi -f decklink -list_formats 1 'DeckLink Mini Monitor'
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@end example
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@item
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Play video clip:
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@example
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ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 'DeckLink Mini Monitor'
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@end example
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@item
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Play video clip with non-standard framerate or video size:
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@example
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ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 -s 720x486 -r 24000/1001 'DeckLink Mini Monitor'
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@end example
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@end itemize
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@section fbdev
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Linux framebuffer output device.
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The Linux framebuffer is a graphic hardware-independent abstraction
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layer to show graphics on a computer monitor, typically on the
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console. It is accessed through a file device node, usually
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@file{/dev/fb0}.
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For more detailed information read the file
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@file{Documentation/fb/framebuffer.txt} included in the Linux source tree.
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@subsection Options
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@table @option
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@item xoffset
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@item yoffset
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Set x/y coordinate of top left corner. Default is 0.
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@end table
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@subsection Examples
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Play a file on framebuffer device @file{/dev/fb0}.
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Required pixel format depends on current framebuffer settings.
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@example
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ffmpeg -re -i INPUT -vcodec rawvideo -pix_fmt bgra -f fbdev /dev/fb0
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@end example
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See also @url{http://linux-fbdev.sourceforge.net/}, and fbset(1).
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@section opengl
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OpenGL output device.
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To enable this output device you need to configure FFmpeg with @code{--enable-opengl}.
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This output device allows one to render to OpenGL context.
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Context may be provided by application or default SDL window is created.
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When device renders to external context, application must implement handlers for following messages:
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@code{AV_DEV_TO_APP_CREATE_WINDOW_BUFFER} - create OpenGL context on current thread.
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@code{AV_DEV_TO_APP_PREPARE_WINDOW_BUFFER} - make OpenGL context current.
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@code{AV_DEV_TO_APP_DISPLAY_WINDOW_BUFFER} - swap buffers.
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@code{AV_DEV_TO_APP_DESTROY_WINDOW_BUFFER} - destroy OpenGL context.
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Application is also required to inform a device about current resolution by sending @code{AV_APP_TO_DEV_WINDOW_SIZE} message.
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@subsection Options
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@table @option
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@item background
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Set background color. Black is a default.
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@item no_window
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Disables default SDL window when set to non-zero value.
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Application must provide OpenGL context and both @code{window_size_cb} and @code{window_swap_buffers_cb} callbacks when set.
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@item window_title
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Set the SDL window title, if not specified default to the filename specified for the output device.
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Ignored when @option{no_window} is set.
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@item window_size
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Set preferred window size, can be a string of the form widthxheight or a video size abbreviation.
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If not specified it defaults to the size of the input video, downscaled according to the aspect ratio.
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Mostly usable when @option{no_window} is not set.
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@end table
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@subsection Examples
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Play a file on SDL window using OpenGL rendering:
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@example
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ffmpeg -i INPUT -f opengl "window title"
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@end example
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@section oss
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OSS (Open Sound System) output device.
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@section pulse
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PulseAudio output device.
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To enable this output device you need to configure FFmpeg with @code{--enable-libpulse}.
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More information about PulseAudio can be found on @url{http://www.pulseaudio.org}
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@subsection Options
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@table @option
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@item server
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Connect to a specific PulseAudio server, specified by an IP address.
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Default server is used when not provided.
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@item name
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Specify the application name PulseAudio will use when showing active clients,
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by default it is the @code{LIBAVFORMAT_IDENT} string.
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@item stream_name
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Specify the stream name PulseAudio will use when showing active streams,
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by default it is set to the specified output name.
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@item device
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Specify the device to use. Default device is used when not provided.
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List of output devices can be obtained with command @command{pactl list sinks}.
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@item buffer_size
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@item buffer_duration
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Control the size and duration of the PulseAudio buffer. A small buffer
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gives more control, but requires more frequent updates.
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@option{buffer_size} specifies size in bytes while
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@option{buffer_duration} specifies duration in milliseconds.
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When both options are provided then the highest value is used
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(duration is recalculated to bytes using stream parameters). If they
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are set to 0 (which is default), the device will use the default
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PulseAudio duration value. By default PulseAudio set buffer duration
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to around 2 seconds.
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@item prebuf
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Specify pre-buffering size in bytes. The server does not start with
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playback before at least @option{prebuf} bytes are available in the
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buffer. By default this option is initialized to the same value as
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@option{buffer_size} or @option{buffer_duration} (whichever is bigger).
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@item minreq
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Specify minimum request size in bytes. The server does not request less
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than @option{minreq} bytes from the client, instead waits until the buffer
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is free enough to request more bytes at once. It is recommended to not set
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this option, which will initialize this to a value that is deemed sensible
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by the server.
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@end table
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@subsection Examples
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Play a file on default device on default server:
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@example
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ffmpeg -i INPUT -f pulse "stream name"
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@end example
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@section sdl
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SDL (Simple DirectMedia Layer) output device.
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This output device allows one to show a video stream in an SDL
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window. Only one SDL window is allowed per application, so you can
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have only one instance of this output device in an application.
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To enable this output device you need libsdl installed on your system
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when configuring your build.
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For more information about SDL, check:
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@url{http://www.libsdl.org/}
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@subsection Options
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@table @option
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@item window_title
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Set the SDL window title, if not specified default to the filename
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specified for the output device.
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@item icon_title
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Set the name of the iconified SDL window, if not specified it is set
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to the same value of @var{window_title}.
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@item window_size
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Set the SDL window size, can be a string of the form
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@var{width}x@var{height} or a video size abbreviation.
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If not specified it defaults to the size of the input video,
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downscaled according to the aspect ratio.
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@item window_fullscreen
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Set fullscreen mode when non-zero value is provided.
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Default value is zero.
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@end table
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@subsection Interactive commands
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The window created by the device can be controlled through the
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following interactive commands.
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@table @key
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@item q, ESC
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Quit the device immediately.
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@end table
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@subsection Examples
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The following command shows the @command{ffmpeg} output is an
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SDL window, forcing its size to the qcif format:
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@example
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ffmpeg -i INPUT -vcodec rawvideo -pix_fmt yuv420p -window_size qcif -f sdl "SDL output"
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@end example
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@section sndio
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sndio audio output device.
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@section xv
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XV (XVideo) output device.
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This output device allows one to show a video stream in a X Window System
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window.
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@subsection Options
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@table @option
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@item display_name
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Specify the hardware display name, which determines the display and
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communications domain to be used.
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The display name or DISPLAY environment variable can be a string in
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the format @var{hostname}[:@var{number}[.@var{screen_number}]].
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@var{hostname} specifies the name of the host machine on which the
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display is physically attached. @var{number} specifies the number of
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the display server on that host machine. @var{screen_number} specifies
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the screen to be used on that server.
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If unspecified, it defaults to the value of the DISPLAY environment
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variable.
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For example, @code{dual-headed:0.1} would specify screen 1 of display
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0 on the machine named ``dual-headed''.
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Check the X11 specification for more detailed information about the
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display name format.
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@item window_id
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When set to non-zero value then device doesn't create new window,
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but uses existing one with provided @var{window_id}. By default
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this options is set to zero and device creates its own window.
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@item window_size
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Set the created window size, can be a string of the form
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@var{width}x@var{height} or a video size abbreviation. If not
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specified it defaults to the size of the input video.
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Ignored when @var{window_id} is set.
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@item window_x
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@item window_y
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Set the X and Y window offsets for the created window. They are both
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set to 0 by default. The values may be ignored by the window manager.
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Ignored when @var{window_id} is set.
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@item window_title
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Set the window title, if not specified default to the filename
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specified for the output device. Ignored when @var{window_id} is set.
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@end table
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For more information about XVideo see @url{http://www.x.org/}.
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@subsection Examples
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@itemize
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@item
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Decode, display and encode video input with @command{ffmpeg} at the
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same time:
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@example
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ffmpeg -i INPUT OUTPUT -f xv display
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@end example
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@item
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Decode and display the input video to multiple X11 windows:
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@example
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ffmpeg -i INPUT -f xv normal -vf negate -f xv negated
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@end example
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@end itemize
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@c man end OUTPUT DEVICES
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