FFmpeg Devices Documentation

Table of Contents

1 Description

This document describes the input and output devices provided by the libavdevice library.

2 Device Options

The libavdevice library provides the same interface as libavformat. Namely, an input device is considered like a demuxer, and an output device like a muxer, and the interface and generic device options are the same provided by libavformat (see the ffmpeg-formats manual).

In addition each input or output device may support so-called private options, which are specific for that component.

Options may be set by specifying -option value in the FFmpeg tools, or by setting the value explicitly in the device AVFormatContext options or using the libavutil/opt.h API for programmatic use.

3 Input Devices

Input devices are configured elements in FFmpeg which allow to access the data coming from a multimedia device attached to your system.

When you configure your FFmpeg build, all the supported input devices are enabled by default. You can list all available ones using the configure option "–list-indevs".

You can disable all the input devices using the configure option "–disable-indevs", and selectively enable an input device using the option "–enable-indev=INDEV", or you can disable a particular input device using the option "–disable-indev=INDEV".

The option "-devices" of the ff* tools will display the list of supported input devices.

A description of the currently available input devices follows.

3.1 alsa

ALSA (Advanced Linux Sound Architecture) input device.

To enable this input device during configuration you need libasound installed on your system.

This device allows capturing from an ALSA device. The name of the device to capture has to be an ALSA card identifier.

An ALSA identifier has the syntax:

hw:CARD[,DEV[,SUBDEV]]

where the DEV and SUBDEV components are optional.

The three arguments (in order: CARD,DEV,SUBDEV) specify card number or identifier, device number and subdevice number (-1 means any).

To see the list of cards currently recognized by your system check the files /proc/asound/cards and /proc/asound/devices.

For example to capture with ffmpeg from an ALSA device with card id 0, you may run the command:

ffmpeg -f alsa -i hw:0 alsaout.wav

For more information see: http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html

3.2 avfoundation

AVFoundation input device.

AVFoundation is the currently recommended framework by Apple for streamgrabbing on OSX >= 10.7 as well as on iOS. The older QTKit framework has been marked deprecated since OSX version 10.7.

The filename passed as input is parsed to contain either a device name or index. The device index can also be given by using -video_device_index. A given device index will override any given device name. If the desired device consists of numbers only, use -video_device_index to identify it. The default device will be chosen if an empty string or the device name "default" is given. The available devices can be enumerated by using -list_devices. The pixel format can be set using -pixel_format. Available formats: monob, rgb555be, rgb555le, rgb565be, rgb565le, rgb24, bgr24, 0rgb, bgr0, 0bgr, rgb0, bgr48be, uyvy422, yuva444p, yuva444p16le, yuv444p, yuv422p16, yuv422p10, yuv444p10, yuv420p, nv12, yuyv422, gray

ffmpeg -f avfoundation -i "0" out.mpg
ffmpeg -f avfoundation -video_device_index 0 -i "" out.mpg
ffmpeg -f avfoundation -pixel_format bgr0 -i "default" out.mpg
ffmpeg -f avfoundation -list_devices true -i ""

3.3 bktr

BSD video input device.

3.4 dshow

Windows DirectShow input device.

DirectShow support is enabled when FFmpeg is built with the mingw-w64 project. Currently only audio and video devices are supported.

Multiple devices may be opened as separate inputs, but they may also be opened on the same input, which should improve synchronism between them.

The input name should be in the format:

TYPE=NAME[:TYPE=NAME]

where TYPE can be either audio or video, and NAME is the device’s name.

3.4.1 Options

If no options are specified, the device’s defaults are used. If the device does not support the requested options, it will fail to open.

video_size

Set the video size in the captured video.

framerate

Set the frame rate in the captured video.

sample_rate

Set the sample rate (in Hz) of the captured audio.

sample_size

Set the sample size (in bits) of the captured audio.

channels

Set the number of channels in the captured audio.

list_devices

If set to true, print a list of devices and exit.

list_options

If set to true, print a list of selected device’s options and exit.

video_device_number

Set video device number for devices with same name (starts at 0, defaults to 0).

audio_device_number

Set audio device number for devices with same name (starts at 0, defaults to 0).

pixel_format

Select pixel format to be used by DirectShow. This may only be set when the video codec is not set or set to rawvideo.

audio_buffer_size

Set audio device buffer size in milliseconds (which can directly impact latency, depending on the device). Defaults to using the audio device’s default buffer size (typically some multiple of 500ms). Setting this value too low can degrade performance. See also http://msdn.microsoft.com/en-us/library/windows/desktop/dd377582(v=vs.85).aspx

3.4.2 Examples

  • Print the list of DirectShow supported devices and exit:
    $ ffmpeg -list_devices true -f dshow -i dummy
    
  • Open video device Camera:
    $ ffmpeg -f dshow -i video="Camera"
    
  • Open second video device with name Camera:
    $ ffmpeg -f dshow -video_device_number 1 -i video="Camera"
    
  • Open video device Camera and audio device Microphone:
    $ ffmpeg -f dshow -i video="Camera":audio="Microphone"
    
  • Print the list of supported options in selected device and exit:
    $ ffmpeg -list_options true -f dshow -i video="Camera"
    

3.5 dv1394

Linux DV 1394 input device.

3.6 fbdev

Linux framebuffer input device.

The Linux framebuffer is a graphic hardware-independent abstraction layer to show graphics on a computer monitor, typically on the console. It is accessed through a file device node, usually /dev/fb0.

For more detailed information read the file Documentation/fb/framebuffer.txt included in the Linux source tree.

To record from the framebuffer device /dev/fb0 with ffmpeg:

ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi

You can take a single screenshot image with the command:

ffmpeg -f fbdev -frames:v 1 -r 1 -i /dev/fb0 screenshot.jpeg

See also http://linux-fbdev.sourceforge.net/, and fbset(1).

3.7 gdigrab

Win32 GDI-based screen capture device.

This device allows you to capture a region of the display on Windows.

There are two options for the input filename:

desktop

or

title=window_title

The first option will capture the entire desktop, or a fixed region of the desktop. The second option will instead capture the contents of a single window, regardless of its position on the screen.

For example, to grab the entire desktop using ffmpeg:

ffmpeg -f gdigrab -framerate 6 -i desktop out.mpg

Grab a 640x480 region at position 10,20:

ffmpeg -f gdigrab -framerate 6 -offset_x 10 -offset_y 20 -video_size vga -i desktop out.mpg

Grab the contents of the window named "Calculator"

ffmpeg -f gdigrab -framerate 6 -i title=Calculator out.mpg

3.7.1 Options

draw_mouse

Specify whether to draw the mouse pointer. Use the value 0 to not draw the pointer. Default value is 1.

framerate

Set the grabbing frame rate. Default value is ntsc, corresponding to a frame rate of 30000/1001.

show_region

Show grabbed region on screen.

If show_region is specified with 1, then the grabbing region will be indicated on screen. With this option, it is easy to know what is being grabbed if only a portion of the screen is grabbed.

Note that show_region is incompatible with grabbing the contents of a single window.

For example:

ffmpeg -f gdigrab -show_region 1 -framerate 6 -video_size cif -offset_x 10 -offset_y 20 -i desktop out.mpg
video_size

Set the video frame size. The default is to capture the full screen if desktop is selected, or the full window size if title=window_title is selected.

offset_x

When capturing a region with video_size, set the distance from the left edge of the screen or desktop.

Note that the offset calculation is from the top left corner of the primary monitor on Windows. If you have a monitor positioned to the left of your primary monitor, you will need to use a negative offset_x value to move the region to that monitor.

offset_y

When capturing a region with video_size, set the distance from the top edge of the screen or desktop.

Note that the offset calculation is from the top left corner of the primary monitor on Windows. If you have a monitor positioned above your primary monitor, you will need to use a negative offset_y value to move the region to that monitor.

3.8 iec61883

FireWire DV/HDV input device using libiec61883.

To enable this input device, you need libiec61883, libraw1394 and libavc1394 installed on your system. Use the configure option --enable-libiec61883 to compile with the device enabled.

The iec61883 capture device supports capturing from a video device connected via IEEE1394 (FireWire), using libiec61883 and the new Linux FireWire stack (juju). This is the default DV/HDV input method in Linux Kernel 2.6.37 and later, since the old FireWire stack was removed.

Specify the FireWire port to be used as input file, or "auto" to choose the first port connected.

3.8.1 Options

dvtype

Override autodetection of DV/HDV. This should only be used if auto detection does not work, or if usage of a different device type should be prohibited. Treating a DV device as HDV (or vice versa) will not work and result in undefined behavior. The values auto, dv and hdv are supported.

dvbuffer

Set maxiumum size of buffer for incoming data, in frames. For DV, this is an exact value. For HDV, it is not frame exact, since HDV does not have a fixed frame size.

dvguid

Select the capture device by specifying it’s GUID. Capturing will only be performed from the specified device and fails if no device with the given GUID is found. This is useful to select the input if multiple devices are connected at the same time. Look at /sys/bus/firewire/devices to find out the GUIDs.

3.8.2 Examples

  • Grab and show the input of a FireWire DV/HDV device.
    ffplay -f iec61883 -i auto
    
  • Grab and record the input of a FireWire DV/HDV device, using a packet buffer of 100000 packets if the source is HDV.
    ffmpeg -f iec61883 -i auto -hdvbuffer 100000 out.mpg
    

3.9 jack

JACK input device.

To enable this input device during configuration you need libjack installed on your system.

A JACK input device creates one or more JACK writable clients, one for each audio channel, with name client_name:input_N, where client_name is the name provided by the application, and N is a number which identifies the channel. Each writable client will send the acquired data to the FFmpeg input device.

Once you have created one or more JACK readable clients, you need to connect them to one or more JACK writable clients.

To connect or disconnect JACK clients you can use the jack_connect and jack_disconnect programs, or do it through a graphical interface, for example with qjackctl.

To list the JACK clients and their properties you can invoke the command jack_lsp.

Follows an example which shows how to capture a JACK readable client with ffmpeg.

# Create a JACK writable client with name "ffmpeg".
$ ffmpeg -f jack -i ffmpeg -y out.wav

# Start the sample jack_metro readable client.
$ jack_metro -b 120 -d 0.2 -f 4000

# List the current JACK clients.
$ jack_lsp -c
system:capture_1
system:capture_2
system:playback_1
system:playback_2
ffmpeg:input_1
metro:120_bpm

# Connect metro to the ffmpeg writable client.
$ jack_connect metro:120_bpm ffmpeg:input_1

For more information read: http://jackaudio.org/

3.10 lavfi

Libavfilter input virtual device.

This input device reads data from the open output pads of a libavfilter filtergraph.

For each filtergraph open output, the input device will create a corresponding stream which is mapped to the generated output. Currently only video data is supported. The filtergraph is specified through the option graph.

3.10.1 Options

graph

Specify the filtergraph to use as input. Each video open output must be labelled by a unique string of the form "outN", where N is a number starting from 0 corresponding to the mapped input stream generated by the device. The first unlabelled output is automatically assigned to the "out0" label, but all the others need to be specified explicitly.

If not specified defaults to the filename specified for the input device.

graph_file

Set the filename of the filtergraph to be read and sent to the other filters. Syntax of the filtergraph is the same as the one specified by the option graph.

3.10.2 Examples

  • Create a color video stream and play it back with ffplay:
    ffplay -f lavfi -graph "color=c=pink [out0]" dummy
    
  • As the previous example, but use filename for specifying the graph description, and omit the "out0" label:
    ffplay -f lavfi color=c=pink
    
  • Create three different video test filtered sources and play them:
    ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3
    
  • Read an audio stream from a file using the amovie source and play it back with ffplay:
    ffplay -f lavfi "amovie=test.wav"
    
  • Read an audio stream and a video stream and play it back with ffplay:
    ffplay -f lavfi "movie=test.avi[out0];amovie=test.wav[out1]"
    

3.11 libcdio

Audio-CD input device based on cdio.

To enable this input device during configuration you need libcdio installed on your system. Requires the configure option --enable-libcdio.

This device allows playing and grabbing from an Audio-CD.

For example to copy with ffmpeg the entire Audio-CD in /dev/sr0, you may run the command:

ffmpeg -f libcdio -i /dev/sr0 cd.wav

3.12 libdc1394

IIDC1394 input device, based on libdc1394 and libraw1394.

Requires the configure option --enable-libdc1394.

3.13 openal

The OpenAL input device provides audio capture on all systems with a working OpenAL 1.1 implementation.

To enable this input device during configuration, you need OpenAL headers and libraries installed on your system, and need to configure FFmpeg with --enable-openal.

OpenAL headers and libraries should be provided as part of your OpenAL implementation, or as an additional download (an SDK). Depending on your installation you may need to specify additional flags via the --extra-cflags and --extra-ldflags for allowing the build system to locate the OpenAL headers and libraries.

An incomplete list of OpenAL implementations follows:

Creative

The official Windows implementation, providing hardware acceleration with supported devices and software fallback. See http://openal.org/.

OpenAL Soft

Portable, open source (LGPL) software implementation. Includes backends for the most common sound APIs on the Windows, Linux, Solaris, and BSD operating systems. See http://kcat.strangesoft.net/openal.html.

Apple

OpenAL is part of Core Audio, the official Mac OS X Audio interface. See http://developer.apple.com/technologies/mac/audio-and-video.html

This device allows one to capture from an audio input device handled through OpenAL.

You need to specify the name of the device to capture in the provided filename. If the empty string is provided, the device will automatically select the default device. You can get the list of the supported devices by using the option list_devices.

3.13.1 Options

channels

Set the number of channels in the captured audio. Only the values 1 (monaural) and 2 (stereo) are currently supported. Defaults to 2.

sample_size

Set the sample size (in bits) of the captured audio. Only the values 8 and 16 are currently supported. Defaults to 16.

sample_rate

Set the sample rate (in Hz) of the captured audio. Defaults to 44.1k.

list_devices

If set to true, print a list of devices and exit. Defaults to false.

3.13.2 Examples

Print the list of OpenAL supported devices and exit:

$ ffmpeg -list_devices true -f openal -i dummy out.ogg

Capture from the OpenAL device DR-BT101 via PulseAudio:

$ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out.ogg

Capture from the default device (note the empty string ” as filename):

$ ffmpeg -f openal -i '' out.ogg

Capture from two devices simultaneously, writing to two different files, within the same ffmpeg command:

$ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out1.ogg -f openal -i 'ALSA Default' out2.ogg

Note: not all OpenAL implementations support multiple simultaneous capture - try the latest OpenAL Soft if the above does not work.

3.14 oss

Open Sound System input device.

The filename to provide to the input device is the device node representing the OSS input device, and is usually set to /dev/dsp.

For example to grab from /dev/dsp using ffmpeg use the command:

ffmpeg -f oss -i /dev/dsp /tmp/oss.wav

For more information about OSS see: http://manuals.opensound.com/usersguide/dsp.html

3.15 pulse

PulseAudio input device.

To enable this output device you need to configure FFmpeg with --enable-libpulse.

The filename to provide to the input device is a source device or the string "default"

To list the PulseAudio source devices and their properties you can invoke the command pactl list sources.

More information about PulseAudio can be found on http://www.pulseaudio.org.

3.15.1 Options

server

Connect to a specific PulseAudio server, specified by an IP address. Default server is used when not provided.

name

Specify the application name PulseAudio will use when showing active clients, by default it is the LIBAVFORMAT_IDENT string.

stream_name

Specify the stream name PulseAudio will use when showing active streams, by default it is "record".

sample_rate

Specify the samplerate in Hz, by default 48kHz is used.

channels

Specify the channels in use, by default 2 (stereo) is set.

frame_size

Specify the number of bytes per frame, by default it is set to 1024.

fragment_size

Specify the minimal buffering fragment in PulseAudio, it will affect the audio latency. By default it is unset.

3.15.2 Examples

Record a stream from default device:

ffmpeg -f pulse -i default /tmp/pulse.wav

3.16 qtkit

QTKit input device.

The filename passed as input is parsed to contain either a device name or index. The device index can also be given by using -video_device_index. A given device index will override any given device name. If the desired device consists of numbers only, use -video_device_index to identify it. The default device will be chosen if an empty string or the device name "default" is given. The available devices can be enumerated by using -list_devices.

ffmpeg -f qtkit -i "0" out.mpg
ffmpeg -f qtkit -video_device_index 0 -i "" out.mpg
ffmpeg -f qtkit -i "default" out.mpg
ffmpeg -f qtkit -list_devices true -i ""

3.17 sndio

sndio input device.

To enable this input device during configuration you need libsndio installed on your system.

The filename to provide to the input device is the device node representing the sndio input device, and is usually set to /dev/audio0.

For example to grab from /dev/audio0 using ffmpeg use the command:

ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav

3.18 video4linux2, v4l2

Video4Linux2 input video device.

"v4l2" can be used as alias for "video4linux2".

If FFmpeg is built with v4l-utils support (by using the --enable-libv4l2 configure option), it is possible to use it with the -use_libv4l2 input device option.

The name of the device to grab is a file device node, usually Linux systems tend to automatically create such nodes when the device (e.g. an USB webcam) is plugged into the system, and has a name of the kind /dev/videoN, where N is a number associated to the device.

Video4Linux2 devices usually support a limited set of widthxheight sizes and frame rates. You can check which are supported using -list_formats all for Video4Linux2 devices. Some devices, like TV cards, support one or more standards. It is possible to list all the supported standards using -list_standards all.

The time base for the timestamps is 1 microsecond. Depending on the kernel version and configuration, the timestamps may be derived from the real time clock (origin at the Unix Epoch) or the monotonic clock (origin usually at boot time, unaffected by NTP or manual changes to the clock). The -timestamps abs or -ts abs option can be used to force conversion into the real time clock.

Some usage examples of the video4linux2 device with ffmpeg and ffplay:

  • Grab and show the input of a video4linux2 device:
    ffplay -f video4linux2 -framerate 30 -video_size hd720 /dev/video0
    
  • Grab and record the input of a video4linux2 device, leave the frame rate and size as previously set:
    ffmpeg -f video4linux2 -input_format mjpeg -i /dev/video0 out.mpeg
    

For more information about Video4Linux, check http://linuxtv.org/.

3.18.1 Options

standard

Set the standard. Must be the name of a supported standard. To get a list of the supported standards, use the list_standards option.

channel

Set the input channel number. Default to -1, which means using the previously selected channel.

video_size

Set the video frame size. The argument must be a string in the form WIDTHxHEIGHT or a valid size abbreviation.

pixel_format

Select the pixel format (only valid for raw video input).

input_format

Set the preferred pixel format (for raw video) or a codec name. This option allows one to select the input format, when several are available.

framerate

Set the preferred video frame rate.

list_formats

List available formats (supported pixel formats, codecs, and frame sizes) and exit.

Available values are:

all

Show all available (compressed and non-compressed) formats.

raw

Show only raw video (non-compressed) formats.

compressed

Show only compressed formats.

list_standards

List supported standards and exit.

Available values are:

all

Show all supported standards.

timestamps, ts

Set type of timestamps for grabbed frames.

Available values are:

default

Use timestamps from the kernel.

abs

Use absolute timestamps (wall clock).

mono2abs

Force conversion from monotonic to absolute timestamps.

Default value is default.

3.19 vfwcap

VfW (Video for Windows) capture input device.

The filename passed as input is the capture driver number, ranging from 0 to 9. You may use "list" as filename to print a list of drivers. Any other filename will be interpreted as device number 0.

3.20 x11grab

X11 video input device.

Depends on X11, Xext, and Xfixes. Requires the configure option --enable-x11grab.

This device allows one to capture a region of an X11 display.

The filename passed as input has the syntax:

[hostname]:display_number.screen_number[+x_offset,y_offset]

hostname:display_number.screen_number specifies the X11 display name of the screen to grab from. hostname can be omitted, and defaults to "localhost". The environment variable DISPLAY contains the default display name.

x_offset and y_offset specify the offsets of the grabbed area with respect to the top-left border of the X11 screen. They default to 0.

Check the X11 documentation (e.g. man X) for more detailed information.

Use the dpyinfo program for getting basic information about the properties of your X11 display (e.g. grep for "name" or "dimensions").

For example to grab from :0.0 using ffmpeg:

ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0 out.mpg

Grab at position 10,20:

ffmpeg -f x11grab -framerate 25 -video_size cif -i :0.0+10,20 out.mpg

3.20.1 Options

draw_mouse

Specify whether to draw the mouse pointer. A value of 0 specify not to draw the pointer. Default value is 1.

follow_mouse

Make the grabbed area follow the mouse. The argument can be centered or a number of pixels PIXELS.

When it is specified with "centered", the grabbing region follows the mouse pointer and keeps the pointer at the center of region; otherwise, the region follows only when the mouse pointer reaches within PIXELS (greater than zero) to the edge of region.

For example:

ffmpeg -f x11grab -follow_mouse centered -framerate 25 -video_size cif -i :0.0 out.mpg

To follow only when the mouse pointer reaches within 100 pixels to edge:

ffmpeg -f x11grab -follow_mouse 100 -framerate 25 -video_size cif -i :0.0 out.mpg
framerate

Set the grabbing frame rate. Default value is ntsc, corresponding to a frame rate of 30000/1001.

show_region

Show grabbed region on screen.

If show_region is specified with 1, then the grabbing region will be indicated on screen. With this option, it is easy to know what is being grabbed if only a portion of the screen is grabbed.

For example:

ffmpeg -f x11grab -show_region 1 -framerate 25 -video_size cif -i :0.0+10,20 out.mpg

With follow_mouse:

ffmpeg -f x11grab -follow_mouse centered -show_region 1 -framerate 25 -video_size cif -i :0.0 out.mpg
video_size

Set the video frame size. Default value is vga.

use_shm

Use the MIT-SHM extension for shared memory. Default value is 1. It may be necessary to disable it for remote displays.

3.21 decklink

The decklink input device provides capture capabilities for Blackmagic DeckLink devices.

To enable this input device, you need the Blackmagic DeckLink SDK and you need to configure with the appropriate --extra-cflags and --extra-ldflags. On Windows, you need to run the IDL files through widl.

DeckLink is very picky about the formats it supports. Pixel format is always uyvy422, framerate and video size must be determined for your device with -list_formats 1. Audio sample rate is always 48 kHz and the number of channels currently is limited to 2 (stereo).

3.21.1 Options

list_devices

If set to true, print a list of devices and exit. Defaults to false.

list_formats

If set to true, print a list of supported formats and exit. Defaults to false.

3.21.2 Examples

  • List input devices:
    ffmpeg -f decklink -list_devices 1 -i dummy
    
  • List supported formats:
    ffmpeg -f decklink -list_formats 1 -i 'Intensity Pro'
    
  • Capture video clip at 1080i50 (format 11):
    ffmpeg -f decklink -i 'Intensity Pro@11' -acodec copy -vcodec copy output.avi
    

4 Output Devices

Output devices are configured elements in FFmpeg that can write multimedia data to an output device attached to your system.

When you configure your FFmpeg build, all the supported output devices are enabled by default. You can list all available ones using the configure option "–list-outdevs".

You can disable all the output devices using the configure option "–disable-outdevs", and selectively enable an output device using the option "–enable-outdev=OUTDEV", or you can disable a particular input device using the option "–disable-outdev=OUTDEV".

The option "-devices" of the ff* tools will display the list of enabled output devices.

A description of the currently available output devices follows.

4.1 alsa

ALSA (Advanced Linux Sound Architecture) output device.

4.1.1 Examples

  • Play a file on default ALSA device:
    ffmpeg -i INPUT -f alsa default
    
  • Play a file on soundcard 1, audio device 7:
    ffmpeg -i INPUT -f alsa hw:1,7
    

4.2 caca

CACA output device.

This output device allows one to show a video stream in CACA window. Only one CACA window is allowed per application, so you can have only one instance of this output device in an application.

To enable this output device you need to configure FFmpeg with --enable-libcaca. libcaca is a graphics library that outputs text instead of pixels.

For more information about libcaca, check: http://caca.zoy.org/wiki/libcaca

4.2.1 Options

window_title

Set the CACA window title, if not specified default to the filename specified for the output device.

window_size

Set the CACA window size, can be a string of the form widthxheight or a video size abbreviation. If not specified it defaults to the size of the input video.

driver

Set display driver.

algorithm

Set dithering algorithm. Dithering is necessary because the picture being rendered has usually far more colours than the available palette. The accepted values are listed with -list_dither algorithms.

antialias

Set antialias method. Antialiasing smoothens the rendered image and avoids the commonly seen staircase effect. The accepted values are listed with -list_dither antialiases.

charset

Set which characters are going to be used when rendering text. The accepted values are listed with -list_dither charsets.

color

Set color to be used when rendering text. The accepted values are listed with -list_dither colors.

list_drivers

If set to true, print a list of available drivers and exit.

list_dither

List available dither options related to the argument. The argument must be one of algorithms, antialiases, charsets, colors.

4.2.2 Examples

  • The following command shows the ffmpeg output is an CACA window, forcing its size to 80x25:
    ffmpeg -i INPUT -vcodec rawvideo -pix_fmt rgb24 -window_size 80x25 -f caca -
    
  • Show the list of available drivers and exit:
    ffmpeg -i INPUT -pix_fmt rgb24 -f caca -list_drivers true -
    
  • Show the list of available dither colors and exit:
    ffmpeg -i INPUT -pix_fmt rgb24 -f caca -list_dither colors -
    

4.3 decklink

The decklink output device provides playback capabilities for Blackmagic DeckLink devices.

To enable this output device, you need the Blackmagic DeckLink SDK and you need to configure with the appropriate --extra-cflags and --extra-ldflags. On Windows, you need to run the IDL files through widl.

DeckLink is very picky about the formats it supports. Pixel format is always uyvy422, framerate and video size must be determined for your device with -list_formats 1. Audio sample rate is always 48 kHz.

4.3.1 Options

list_devices

If set to true, print a list of devices and exit. Defaults to false.

list_formats

If set to true, print a list of supported formats and exit. Defaults to false.

preroll

Amount of time to preroll video in seconds. Defaults to 0.5.

4.3.2 Examples

  • List output devices:
    ffmpeg -i test.avi -f decklink -list_devices 1 dummy
    
  • List supported formats:
    ffmpeg -i test.avi -f decklink -list_formats 1 'DeckLink Mini Monitor'
    
  • Play video clip:
    ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 'DeckLink Mini Monitor'
    
  • Play video clip with non-standard framerate or video size:
    ffmpeg -i test.avi -f decklink -pix_fmt uyvy422 -s 720x486 -r 24000/1001 'DeckLink Mini Monitor'
    

4.4 fbdev

Linux framebuffer output device.

The Linux framebuffer is a graphic hardware-independent abstraction layer to show graphics on a computer monitor, typically on the console. It is accessed through a file device node, usually /dev/fb0.

For more detailed information read the file Documentation/fb/framebuffer.txt included in the Linux source tree.

4.4.1 Options

xoffset
yoffset

Set x/y coordinate of top left corner. Default is 0.

4.4.2 Examples

Play a file on framebuffer device /dev/fb0. Required pixel format depends on current framebuffer settings.

ffmpeg -re -i INPUT -vcodec rawvideo -pix_fmt bgra -f fbdev /dev/fb0

See also http://linux-fbdev.sourceforge.net/, and fbset(1).

4.5 opengl

OpenGL output device.

To enable this output device you need to configure FFmpeg with --enable-opengl.

This output device allows one to render to OpenGL context. Context may be provided by application or default SDL window is created.

When device renders to external context, application must implement handlers for following messages: AV_DEV_TO_APP_CREATE_WINDOW_BUFFER - create OpenGL context on current thread. AV_DEV_TO_APP_PREPARE_WINDOW_BUFFER - make OpenGL context current. AV_DEV_TO_APP_DISPLAY_WINDOW_BUFFER - swap buffers. AV_DEV_TO_APP_DESTROY_WINDOW_BUFFER - destroy OpenGL context. Application is also required to inform a device about current resolution by sending AV_APP_TO_DEV_WINDOW_SIZE message.

4.5.1 Options

background

Set background color. Black is a default.

no_window

Disables default SDL window when set to non-zero value. Application must provide OpenGL context and both window_size_cb and window_swap_buffers_cb callbacks when set.

window_title

Set the SDL window title, if not specified default to the filename specified for the output device. Ignored when no_window is set.

window_size

Set preferred window size, can be a string of the form widthxheight or a video size abbreviation. If not specified it defaults to the size of the input video, downscaled according to the aspect ratio. Mostly usable when no_window is not set.

4.5.2 Examples

Play a file on SDL window using OpenGL rendering:

ffmpeg  -i INPUT -f opengl "window title"

4.6 oss

OSS (Open Sound System) output device.

4.7 pulse

PulseAudio output device.

To enable this output device you need to configure FFmpeg with --enable-libpulse.

More information about PulseAudio can be found on http://www.pulseaudio.org

4.7.1 Options

server

Connect to a specific PulseAudio server, specified by an IP address. Default server is used when not provided.

name

Specify the application name PulseAudio will use when showing active clients, by default it is the LIBAVFORMAT_IDENT string.

stream_name

Specify the stream name PulseAudio will use when showing active streams, by default it is set to the specified output name.

device

Specify the device to use. Default device is used when not provided. List of output devices can be obtained with command pactl list sinks.

buffer_size
buffer_duration

Control the size and duration of the PulseAudio buffer. A small buffer gives more control, but requires more frequent updates.

buffer_size specifies size in bytes while buffer_duration specifies duration in milliseconds.

When both options are provided then the highest value is used (duration is recalculated to bytes using stream parameters). If they are set to 0 (which is default), the device will use the default PulseAudio duration value. By default PulseAudio set buffer duration to around 2 seconds.

prebuf

Specify pre-buffering size in bytes. The server does not start with playback before at least prebuf bytes are available in the buffer. By default this option is initialized to the same value as buffer_size or buffer_duration (whichever is bigger).

minreq

Specify minimum request size in bytes. The server does not request less than minreq bytes from the client, instead waits until the buffer is free enough to request more bytes at once. It is recommended to not set this option, which will initialize this to a value that is deemed sensible by the server.

4.7.2 Examples

Play a file on default device on default server:

ffmpeg  -i INPUT -f pulse "stream name"

4.8 sdl

SDL (Simple DirectMedia Layer) output device.

This output device allows one to show a video stream in an SDL window. Only one SDL window is allowed per application, so you can have only one instance of this output device in an application.

To enable this output device you need libsdl installed on your system when configuring your build.

For more information about SDL, check: http://www.libsdl.org/

4.8.1 Options

window_title

Set the SDL window title, if not specified default to the filename specified for the output device.

icon_title

Set the name of the iconified SDL window, if not specified it is set to the same value of window_title.

window_size

Set the SDL window size, can be a string of the form widthxheight or a video size abbreviation. If not specified it defaults to the size of the input video, downscaled according to the aspect ratio.

window_fullscreen

Set fullscreen mode when non-zero value is provided. Default value is zero.

4.8.2 Interactive commands

The window created by the device can be controlled through the following interactive commands.

q, ESC

Quit the device immediately.

4.8.3 Examples

The following command shows the ffmpeg output is an SDL window, forcing its size to the qcif format:

ffmpeg -i INPUT -vcodec rawvideo -pix_fmt yuv420p -window_size qcif -f sdl "SDL output"

4.9 sndio

sndio audio output device.

4.10 xv

XV (XVideo) output device.

This output device allows one to show a video stream in a X Window System window.

4.10.1 Options

display_name

Specify the hardware display name, which determines the display and communications domain to be used.

The display name or DISPLAY environment variable can be a string in the format hostname[:number[.screen_number]].

hostname specifies the name of the host machine on which the display is physically attached. number specifies the number of the display server on that host machine. screen_number specifies the screen to be used on that server.

If unspecified, it defaults to the value of the DISPLAY environment variable.

For example, dual-headed:0.1 would specify screen 1 of display 0 on the machine named “dual-headed”.

Check the X11 specification for more detailed information about the display name format.

window_id

When set to non-zero value then device doesn’t create new window, but uses existing one with provided window_id. By default this options is set to zero and device creates its own window.

window_size

Set the created window size, can be a string of the form widthxheight or a video size abbreviation. If not specified it defaults to the size of the input video. Ignored when window_id is set.

window_x
window_y

Set the X and Y window offsets for the created window. They are both set to 0 by default. The values may be ignored by the window manager. Ignored when window_id is set.

window_title

Set the window title, if not specified default to the filename specified for the output device. Ignored when window_id is set.

For more information about XVideo see http://www.x.org/.

4.10.2 Examples

  • Decode, display and encode video input with ffmpeg at the same time:
    ffmpeg -i INPUT OUTPUT -f xv display
    
  • Decode and display the input video to multiple X11 windows:
    ffmpeg -i INPUT -f xv normal -vf negate -f xv negated
    

5 See Also

ffmpeg, ffplay, ffprobe, ffserver, libavdevice

6 Authors

The FFmpeg developers.

For details about the authorship, see the Git history of the project (git://source.ffmpeg.org/ffmpeg), e.g. by typing the command git log in the FFmpeg source directory, or browsing the online repository at http://source.ffmpeg.org.

Maintainers for the specific components are listed in the file MAINTAINERS in the source code tree.

This document was generated on October 31, 2014 using makeinfo.