ffmpeg-devices - FFmpeg devices
This document describes the input and output devices provided by the libavdevice
library.
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.
Input devices are configured elements in FFmpeg which enable accessing 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.
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>
Options
- sample_rate
- Set the sample rate in Hz. Default is 48000.
- channels
- Set the number of channels. Default is 2.
Android camera input device.
This input devices uses the Android Camera2 NDK API which is available on
devices with API level 24+. The availability of android_camera is autodetected
during configuration.
This device allows capturing from all cameras on an Android device, which are
integrated into the Camera2 NDK API.
The available cameras are enumerated internally and can be selected with the
camera_index parameter. The input file string is discarded.
Generally the back facing camera has index 0 while the front facing camera has
index 1.
Options
- video_size
- Set the video size given as a string such as 640x480 or
hd720. Falls back to the first available configuration reported by Android
if requested video size is not available or by default.
- framerate
- Set the video framerate. Falls back to the first available
configuration reported by Android if requested framerate is not available
or by default (-1).
- camera_index
- Set the index of the camera to use. Default is 0.
- input_queue_size
- Set the maximum number of frames to buffer. Default is
5.
AVFoundation input device.
AVFoundation is the currently recommended framework by Apple for streamgrabbing
on OSX >= 10.7 as well as on iOS.
The input filename has to be given in the following syntax:
-i "[[VIDEO]:[AUDIO]]"
The first entry selects the video input while the latter selects the audio
input. The stream has to be specified by the device name or the device index
as shown by the device list. Alternatively, the video and/or audio input
device can be chosen by index using the
B<-video_device_index E<lt>INDEXE<gt>>
and/or
B<-audio_device_index E<lt>INDEXE<gt>>
, overriding any device name or index given in the input filename.
All available devices can be enumerated by using
-list_devices true,
listing all device names and corresponding indices.
There are two device name aliases:
- "default"
- Select the AVFoundation default device of the corresponding
type.
- "none"
- Do not record the corresponding media type. This is
equivalent to specifying an empty device name or index.
Options
AVFoundation supports the following options:
- -list_devices <TRUE|FALSE>
- If set to true, a list of all available input devices is
given showing all device names and indices.
- -video_device_index <INDEX>
- Specify the video device by its index. Overrides anything
given in the input filename.
- -audio_device_index <INDEX>
- Specify the audio device by its index. Overrides anything
given in the input filename.
- -pixel_format <FORMAT>
- Request the video device to use a specific pixel format. If
the specified format is not supported, a list of available formats is
given and the first one in this list is used instead. Available pixel
formats are: "monob, rgb555be, rgb555le, rgb565be, rgb565le, rgb24,
bgr24, 0rgb, bgr0, 0bgr, rgb0,
bgr48be, uyvy422, yuva444p, yuva444p16le, yuv444p, yuv422p16, yuv422p10,
yuv444p10,
yuv420p, nv12, yuyv422, gray"
- -framerate
- Set the grabbing frame rate. Default is "ntsc",
corresponding to a frame rate of "30000/1001".
- -video_size
- Set the video frame size.
- -capture_cursor
- Capture the mouse pointer. Default is 0.
- -capture_mouse_clicks
- Capture the screen mouse clicks. Default is 0.
- -capture_raw_data
- Capture the raw device data. Default is 0. Using this
option may result in receiving the underlying data delivered to the
AVFoundation framework. E.g. for muxed devices that sends raw DV data to
the framework (like tape-based camcorders), setting this option to false
results in extracted video frames captured in the designated pixel format
only. Setting this option to true results in receiving the raw DV stream
untouched.
Examples
- •
- Print the list of AVFoundation supported devices and exit:
$ ffmpeg -f avfoundation -list_devices true -i ""
- •
- Record video from video device 0 and audio from audio
device 0 into out.avi:
$ ffmpeg -f avfoundation -i "0:0" out.avi
- •
- Record video from video device 2 and audio from audio
device 1 into out.avi:
$ ffmpeg -f avfoundation -video_device_index 2 -i ":1" out.avi
- •
- Record video from the system default video device using the
pixel format bgr0 and do not record any audio into out.avi:
$ ffmpeg -f avfoundation -pixel_format bgr0 -i "default:none" out.avi
- •
- Record raw DV data from a suitable input device and write
the output into out.dv:
$ ffmpeg -f avfoundation -capture_raw_data true -i "zr100:none" out.dv
BSD video input device.
Options
- framerate
- Set the frame rate.
- video_size
- Set the video frame size. Default is "vga".
- standard
- Available values are:
- pal
- ntsc
- secam
- paln
- palm
- ntscj
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 of the input
can be set with
raw_format. 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 can be 2, 8 or 16. Note that all audio channels
are bundled in one single audio track.
Options
- list_devices
- If set to true, print a list of devices and exit.
Defaults to false. This option is deprecated, please use the
"-sources" option of ffmpeg to list the available input
devices.
- list_formats
- If set to true, print a list of supported formats
and exit. Defaults to false.
- format_code <FourCC>
- This sets the input video format to the format given by the
FourCC. To see the supported values of your device(s) use
list_formats. Note that there is a FourCC 'pal ' that can
also be used as pal (3 letters). Default behavior is autodetection
of the input video format, if the hardware supports it.
- raw_format
- Set the pixel format of the captured video. Available
values are:
- auto
- This is the default which means 8-bit YUV 422 or 8-bit ARGB
if format autodetection is used, 8-bit YUV 422 otherwise.
- uyvy422
- 8-bit YUV 422.
- yuv422p10
- 10-bit YUV 422.
- argb
- 8-bit RGB.
- bgra
- 8-bit RGB.
- rgb10
- 10-bit RGB.
- teletext_lines
- If set to nonzero, an additional teletext stream will be
captured from the vertical ancillary data. Both SD PAL (576i) and HD
(1080i or 1080p) sources are supported. In case of HD sources, OP47
packets are decoded.
This option is a bitmask of the SD PAL VBI lines captured, specifically
lines 6 to 22, and lines 318 to 335. Line 6 is the LSB in the mask.
Selected lines which do not contain teletext information will be ignored.
You can use the special all constant to select all possible lines,
or standard to skip lines 6, 318 and 319, which are not compatible
with all receivers.
For SD sources, ffmpeg needs to be compiled with
"--enable-libzvbi". For HD sources, on older (pre-4K) DeckLink
card models you have to capture in 10 bit mode.
- channels
- Defines number of audio channels to capture. Must be
2, 8 or 16. Defaults to 2.
- duplex_mode
- Sets the decklink device duplex/profile mode. Must be
unset, half, full, one_sub_device_full,
one_sub_device_half, two_sub_device_full,
four_sub_device_half Defaults to unset.
Note: DeckLink SDK 11.0 have replaced the duplex property by a profile
property. For the DeckLink Duo 2 and DeckLink Quad 2, a profile is shared
between any 2 sub-devices that utilize the same connectors. For the
DeckLink 8K Pro, a profile is shared between all 4 sub-devices. So
DeckLink 8K Pro support four profiles.
Valid profile modes for DeckLink 8K Pro(with DeckLink SDK >= 11.0):
one_sub_device_full, one_sub_device_half,
two_sub_device_full, four_sub_device_half
Valid profile modes for DeckLink Quad 2 and DeckLink Duo 2: half,
full
- timecode_format
- Timecode type to include in the frame and video stream
metadata. Must be none, rp188vitc, rp188vitc2,
rp188ltc, rp188hfr, rp188any, vitc,
vitc2, or serial. Defaults to none (not included).
In order to properly support 50/60 fps timecodes, the ordering of the
queried timecode types for rp188any is HFR, VITC1, VITC2 and LTC
for >30 fps content. Note that this is slightly different to the
ordering used by the DeckLink API, which is HFR, VITC1, LTC, VITC2.
- video_input
- Sets the video input source. Must be unset,
sdi, hdmi, optical_sdi, component,
composite or s_video. Defaults to unset.
- audio_input
- Sets the audio input source. Must be unset,
embedded, aes_ebu, analog, analog_xlr,
analog_rca or microphone. Defaults to unset.
- video_pts
- Sets the video packet timestamp source. Must be
video, audio, reference, wallclock or
abs_wallclock. Defaults to video.
- audio_pts
- Sets the audio packet timestamp source. Must be
video, audio, reference, wallclock or
abs_wallclock. Defaults to audio.
- draw_bars
- If set to true, color bars are drawn in the event of
a signal loss. Defaults to true.
- queue_size
- Sets maximum input buffer size in bytes. If the buffering
reaches this value, incoming frames will be dropped. Defaults to
1073741824.
- audio_depth
- Sets the audio sample bit depth. Must be 16 or
32. Defaults to 16.
- decklink_copyts
- If set to true, timestamps are forwarded as they are
without removing the initial offset. Defaults to false.
- timestamp_align
- Capture start time alignment in seconds. If set to nonzero,
input frames are dropped till the system timestamp aligns with configured
value. Alignment difference of up to one frame duration is tolerated. This
is useful for maintaining input synchronization across N different
hardware devices deployed for 'N-way' redundancy. The system time of
different hardware devices should be synchronized with protocols such as
NTP or PTP, before using this option. Note that this method is not
foolproof. In some border cases input synchronization may not happen due
to thread scheduling jitters in the OS. Either sync could go wrong by 1
frame or in a rarer case timestamp_align seconds. Defaults to
0.
-
wait_for_tc (bool)
- Drop frames till a frame with timecode is received.
Sometimes serial timecode isn't received with the first input frame. If
that happens, the stored stream timecode will be inaccurate. If this
option is set to true, input frames are dropped till a frame with
timecode is received. Option timecode_format must be specified.
Defaults to false.
-
enable_klv(bool)
- If set to true, extracts KLV data from VANC and
outputs KLV packets. KLV VANC packets are joined based on MID and PSC
fields and aggregated into one KLV packet. Defaults to false.
Examples
- •
- List input devices:
ffmpeg -sources decklink
- •
- List supported formats:
ffmpeg -f decklink -list_formats 1 -i 'Intensity Pro'
- •
- Capture video clip at 1080i50:
ffmpeg -format_code Hi50 -f decklink -i 'Intensity Pro' -c:a copy -c:v copy output.avi
- •
- Capture video clip at 1080i50 10 bit:
ffmpeg -raw_format yuv422p10 -format_code Hi50 -f decklink -i 'UltraStudio Mini Recorder' -c:a copy -c:v copy output.avi
- •
- Capture video clip at 1080i50 with 16 audio channels:
ffmpeg -channels 16 -format_code Hi50 -f decklink -i 'UltraStudio Mini Recorder' -c:a copy -c:v copy output.avi
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 or alternative name..
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 the same name
(starts at 0, defaults to 0).
- audio_device_number
- Set audio device number for devices with the 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>
- video_pin_name
- Select video capture pin to use by name or alternative
name.
- audio_pin_name
- Select audio capture pin to use by name or alternative
name.
- crossbar_video_input_pin_number
- Select video input pin number for crossbar device. This
will be routed to the crossbar device's Video Decoder output pin. Note
that changing this value can affect future invocations (sets a new
default) until system reboot occurs.
- crossbar_audio_input_pin_number
- Select audio input pin number for crossbar device. This
will be routed to the crossbar device's Audio Decoder output pin. Note
that changing this value can affect future invocations (sets a new
default) until system reboot occurs.
- show_video_device_dialog
- If set to true, before capture starts, popup a
display dialog to the end user, allowing them to change video filter
properties and configurations manually. Note that for crossbar devices,
adjusting values in this dialog may be needed at times to toggle between
PAL (25 fps) and NTSC (29.97) input frame rates, sizes, interlacing, etc.
Changing these values can enable different scan rates/frame rates and
avoiding green bars at the bottom, flickering scan lines, etc. Note that
with some devices, changing these properties can also affect future
invocations (sets new defaults) until system reboot occurs.
- show_audio_device_dialog
- If set to true, before capture starts, popup a
display dialog to the end user, allowing them to change audio filter
properties and configurations manually.
- show_video_crossbar_connection_dialog
- If set to true, before capture starts, popup a
display dialog to the end user, allowing them to manually modify crossbar
pin routings, when it opens a video device.
- show_audio_crossbar_connection_dialog
- If set to true, before capture starts, popup a
display dialog to the end user, allowing them to manually modify crossbar
pin routings, when it opens an audio device.
- show_analog_tv_tuner_dialog
- If set to true, before capture starts, popup a
display dialog to the end user, allowing them to manually modify TV
channels and frequencies.
- show_analog_tv_tuner_audio_dialog
- If set to true, before capture starts, popup a
display dialog to the end user, allowing them to manually modify TV audio
(like mono vs. stereo, Language A,B or C).
- audio_device_load
- Load an audio capture filter device from file instead of
searching it by name. It may load additional parameters too, if the filter
supports the serialization of its properties to. To use this an audio
capture source has to be specified, but it can be anything even fake
one.
- audio_device_save
- Save the currently used audio capture filter device and its
parameters (if the filter supports it) to a file. If a file with the same
name exists it will be overwritten.
- video_device_load
- Load a video capture filter device from file instead of
searching it by name. It may load additional parameters too, if the filter
supports the serialization of its properties to. To use this a video
capture source has to be specified, but it can be anything even fake
one.
- video_device_save
- Save the currently used video capture filter device and its
parameters (if the filter supports it) to a file. If a file with the same
name exists it will be overwritten.
- use_video_device_timestamps
- If set to false, the timestamp for video frames will
be derived from the wallclock instead of the timestamp provided by the
capture device. This allows working around devices that provide unreliable
timestamps.
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"
- •
- Specify pin names to capture by name or alternative name,
specify alternative device name:
$ ffmpeg -f dshow -audio_pin_name "Audio Out" -video_pin_name 2 -i video=video="@device_pnp_\\?\pci#ven_1a0a&dev_6200&subsys_62021461&rev_01#4&e2c7dd6&0&00e1#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\{ca465100-deb0-4d59-818f-8c477184adf6}":audio="Microphone"
- •
- Configure a crossbar device, specifying crossbar pins,
allow user to adjust video capture properties at startup:
$ ffmpeg -f dshow -show_video_device_dialog true -crossbar_video_input_pin_number 0
-crossbar_audio_input_pin_number 3 -i video="AVerMedia BDA Analog Capture":audio="AVerMedia BDA Analog Capture"
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.
See also <
http://linux-fbdev.sourceforge.net/>, and
fbset(1).
To record from the framebuffer device
/dev/fb0 with
ffmpeg:
ffmpeg -f fbdev -framerate 10 -i /dev/fb0 out.avi
You can take a single screenshot image with the command:
ffmpeg -f fbdev -framerate 1 -i /dev/fb0 -frames:v 1 screenshot.jpeg
Options
- framerate
- Set the frame rate. Default is 25.
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
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.
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.
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 maximum 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 its 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.
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 -dvbuffer 100000 out.mpg
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/>
Options
- channels
- Set the number of channels. Default is 2.
KMS video input device.
Captures the KMS scanout framebuffer associated with a specified CRTC or plane
as a DRM object that can be passed to other hardware functions.
Requires either DRM master or CAP_SYS_ADMIN to run.
If you don't understand what all of that means, you probably don't want this.
Look at
x11grab instead.
Options
- device
- DRM device to capture on. Defaults to
/dev/dri/card0.
- format
- Pixel format of the framebuffer. This can be autodetected
if you are running Linux 5.7 or later, but needs to be provided for
earlier versions. Defaults to bgr0, which is the most common format
used by the Linux console and Xorg X server.
- format_modifier
- Format modifier to signal on output frames. This is
necessary to import correctly into some APIs. It can be autodetected if
you are running Linux 5.7 or later, but will need to be provided
explicitly when needed in earlier versions. See the libdrm documentation
for possible values.
- crtc_id
- KMS CRTC ID to define the capture source. The first active
plane on the given CRTC will be used.
- plane_id
- KMS plane ID to define the capture source. Defaults to the
first active plane found if neither crtc_id nor plane_id are
specified.
- framerate
- Framerate to capture at. This is not synchronised to any
page flipping or framebuffer changes - it just defines the interval at
which the framebuffer is sampled. Sampling faster than the framebuffer
update rate will generate independent frames with the same content.
Defaults to 30.
Examples
- •
- Capture from the first active plane, download the result to
normal frames and encode. This will only work if the framebuffer is both
linear and mappable - if not, the result may be scrambled or fail to
download.
ffmpeg -f kmsgrab -i - -vf 'hwdownload,format=bgr0' output.mp4
- •
- Capture from CRTC ID 42 at 60fps, map the result to VAAPI,
convert to NV12 and encode as H.264.
ffmpeg -crtc_id 42 -framerate 60 -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,scale_vaapi=w=1920:h=1080:format=nv12' -c:v h264_vaapi output.mp4
- •
- To capture only part of a plane the output can be cropped -
this can be used to capture a single window, as long as it has a known
absolute position and size. For example, to capture and encode the middle
quarter of a 1920x1080 plane:
ffmpeg -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,crop=960:540:480:270,scale_vaapi=960:540:nv12' -c:v h264_vaapi output.mp4
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.
Options
- graph
- Specify the filtergraph to use as input. Each video open
output must be labelled by a unique string of the form "out
N", 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.
The suffix "+subcc" can be appended to the output label to create
an extra stream with the closed captions packets attached to that output
(experimental; only for EIA-608 / CEA-708 for now). The subcc streams are
created after all the normal streams, in the order of the corresponding
stream. For example, if there is "out19+subcc",
"out7+subcc" and up to "out42", the stream #43 is
subcc for stream #7 and stream #44 is subcc for stream #19.
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.
- dumpgraph
- Dump graph to stderr.
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]"
- •
- Dump decoded frames to images and closed captions to a file
(experimental):
ffmpeg -f lavfi -i "movie=test.ts[out0+subcc]" -map v frame%08d.png -map s -c copy -f rawvideo subcc.bin
Audio-CD input device based on libcdio.
To enable this input device during configuration you need libcdio installed on
your system. It 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
Options
- speed
- Set drive reading speed. Default value is 0.
The speed is specified CD-ROM speed units. The speed is set through the
libcdio "cdio_cddap_speed_set" function. On many CD-ROM drives,
specifying a value too large will result in using the fastest speed.
- paranoia_mode
- Set paranoia recovery mode flags. It accepts one of the
following values:
- disable
- verify
- overlap
- neverskip
- full
Default value is
disable.
For more information about the available recovery modes, consult the paranoia
project documentation.
IIDC1394 input device, based on libdc1394 and libraw1394.
Requires the configure option "--enable-libdc1394".
Options
- framerate
- Set the frame rate. Default is "ntsc",
corresponding to a frame rate of "30000/1001".
- pixel_format
- Select the pixel format. Default is
"uyvy422".
- video_size
- Set the video size given as a string such as
"640x480" or "hd720". Default is
"qvga".
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.
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.
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.
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>
Options
- sample_rate
- Set the sample rate in Hz. Default is 48000.
- channels
- Set the number of channels. Default is 2.
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>.
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
- This option does nothing and is deprecated.
- fragment_size
- Specify the size in bytes of the minimal buffering fragment
in PulseAudio, it will affect the audio latency. By default it is set to
50 ms amount of data.
- wallclock
- Set the initial PTS using the current time. Default is
1.
Examples
Record a stream from default device:
ffmpeg -f pulse -i default /tmp/pulse.wav
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
Options
- sample_rate
- Set the sample rate in Hz. Default is 48000.
- channels
- Set the number of channels. Default is 2.
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
widthx
height
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:
- •
- List supported formats for a video4linux2 device:
ffplay -f video4linux2 -list_formats all /dev/video0
- •
- 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/>.
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".
- use_libv4l2
- Use libv4l2 (v4l-utils) conversion functions. Default is
0.
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.
Options
- video_size
- Set the video frame size.
- framerate
- Set the grabbing frame rate. Default value is
"ntsc", corresponding to a frame rate of
"30000/1001".
X11 video input device.
To enable this input device during configuration you need libxcb installed on
your system. It will be automatically detected during configuration.
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
xdpyinfo 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
Options
- select_region
- Specify whether to select the grabbing area graphically
using the pointer. A value of 1 prompts the user to select the grabbing
area graphically by clicking and dragging. A single click with no dragging
will select the whole screen. A region with zero width or height will also
select the whole screen. This option overwrites the video_size,
grab_x, and grab_y options. Default value is 0.
- draw_mouse
- Specify whether to draw the mouse pointer. A value of 0
specifies 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.
- region_border
- Set the region border thickness if -show_region 1 is
used. Range is 1 to 128 and default is 3 (XCB-based x11grab only).
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
- window_id
- Grab this window, instead of the whole screen. Default
value is 0, which maps to the whole screen (root window).
The id of a window can be found using the xwininfo program, possibly
with options -tree and -root.
If the window is later enlarged, the new area is not recorded. Video ends
when the window is closed, unmapped (i.e., iconified) or shrunk beyond the
video size (which defaults to the initial window size).
This option disables options follow_mouse and
select_region.
- video_size
- Set the video frame size. Default is the full desktop or
window.
- grab_x
- grab_y
- Set the grabbing region coordinates. They are expressed as
offset from the top left corner of the X11 window and correspond to the
x_offset and y_offset parameters in the device name. The
default value for both options is 0.
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.
ALSA (Advanced Linux Sound Architecture) output device.
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
AudioToolbox output device.
Allows native output to CoreAudio devices on OSX.
The output filename can be empty (or "-") to refer to the default
system output device or a number that refers to the device index as shown
using: "-list_devices true".
Alternatively, the audio input device can be chosen by index using the
B<-audio_device_index E<lt>INDEXE<gt>>
, overriding any device name or index given in the input filename.
All available devices can be enumerated by using
-list_devices true,
listing all device names, UIDs and corresponding indices.
Options
AudioToolbox supports the following options:
- -audio_device_index <INDEX>
- Specify the audio device by its index. Overrides anything
given in the output filename.
Examples
- •
- Print the list of supported devices and output a sine wave
to the default device:
$ ffmpeg -f lavfi -i sine=r=44100 -f audiotoolbox -list_devices true -
- •
- Output a sine wave to the device with the index 2,
overriding any output filename:
$ ffmpeg -f lavfi -i sine=r=44100 -f audiotoolbox -audio_device_index 2 -
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>
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
widthx height 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".
Examples
- •
- The following command shows the ffmpeg output is an
CACA window, forcing its size to 80x25:
ffmpeg -i INPUT -c:v 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 -
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, field order and video size must be determined for your
device with
-list_formats 1. Audio sample rate is always 48 kHz.
Options
- list_devices
- If set to true, print a list of devices and exit.
Defaults to false. This option is deprecated, please use the
"-sinks" option of ffmpeg to list the available output
devices.
- 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.
- duplex_mode
- Sets the decklink device duplex/profile mode. Must be
unset, half, full, one_sub_device_full,
one_sub_device_half, two_sub_device_full,
four_sub_device_half Defaults to unset.
Note: DeckLink SDK 11.0 have replaced the duplex property by a profile
property. For the DeckLink Duo 2 and DeckLink Quad 2, a profile is shared
between any 2 sub-devices that utilize the same connectors. For the
DeckLink 8K Pro, a profile is shared between all 4 sub-devices. So
DeckLink 8K Pro support four profiles.
Valid profile modes for DeckLink 8K Pro(with DeckLink SDK >= 11.0):
one_sub_device_full, one_sub_device_half,
two_sub_device_full, four_sub_device_half
Valid profile modes for DeckLink Quad 2 and DeckLink Duo 2: half,
full
- timing_offset
- Sets the genlock timing pixel offset on the used output.
Defaults to unset.
- link
- Sets the SDI video link configuration on the used output.
Must be unset, single link SDI, dual link SDI or
quad link SDI. Defaults to unset.
- sqd
- Enable Square Division Quad Split mode for Quad-link SDI
output. Must be unset, true or false. Defaults to
unset.
- level_a
- Enable SMPTE Level A mode on the used output. Must be
unset, true or false. Defaults to unset.
Examples
- •
- List output devices:
ffmpeg -sinks decklink
- •
- 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'
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.
Options
- xoffset
- yoffset
- Set x/y coordinate of top left corner. Default is 0.
Examples
Play a file on framebuffer device
/dev/fb0. Required pixel format depends
on current framebuffer settings.
ffmpeg -re -i INPUT -c:v rawvideo -pix_fmt bgra -f fbdev /dev/fb0
See also <
http://linux-fbdev.sourceforge.net/>, and
fbset(1).
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.
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.
Examples
Play a file on SDL window using OpenGL rendering:
ffmpeg -i INPUT -f opengl "window title"
OSS (Open Sound System) output device.
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>
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.
Examples
Play a file on default device on default server:
ffmpeg -i INPUT -f pulse "stream name"
SDL (Simple DirectMedia Layer) output device.
"sdl2" can be used as alias for "sdl".
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/>
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
widthx height or a video size abbreviation. If not specified
it defaults to the size of the input video, downscaled according to the
aspect ratio.
- window_x
- window_y
- Set the position of the window on the screen.
- window_fullscreen
- Set fullscreen mode when non-zero value is provided.
Default value is zero.
- window_enable_quit
- Enable quit action (using window button or keyboard key)
when non-zero value is provided. Default value is 1 (enable quit
action)
Interactive commands
The window created by the device can be controlled through the following
interactive commands.
- q, ESC
- Quit the device immediately.
Examples
The following command shows the
ffmpeg output is an SDL window, forcing
its size to the qcif format:
ffmpeg -i INPUT -c:v rawvideo -pix_fmt yuv420p -window_size qcif -f sdl "SDL output"
sndio audio output device.
Video4Linux2 output device.
XV (XVideo) output device.
This output device allows one to show a video stream in a X Window System
window.
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/>.
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
ffmpeg(1),
ffplay(1),
ffprobe(1),
libavdevice(3)
The FFmpeg developers.
For details about the authorship, see the Git history of the project
(
https://git.ffmpeg.org/ffmpeg), e.g. by typing the command
git log in
the FFmpeg source directory, or browsing the online repository at <
https://git.ffmpeg.org/ffmpeg>.
Maintainers for the specific components are listed in the file
MAINTAINERS in the source code tree.