mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-02 03:06:28 +02:00
204 lines
6.1 KiB
Plaintext
204 lines
6.1 KiB
Plaintext
@chapter Input Devices
|
|
@c man begin 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=@var{INDEV}", or you can disable a particular
|
|
input device using the option "--disable-indev=@var{INDEV}".
|
|
|
|
The option "-formats" of the ff* tools will display the list of
|
|
supported input devices (amongst the demuxers).
|
|
|
|
A description of the currently available input devices follows.
|
|
|
|
@section 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:
|
|
@example
|
|
hw:@var{CARD}[,@var{DEV}[,@var{SUBDEV}]]
|
|
@end example
|
|
|
|
where the @var{DEV} and @var{SUBDEV} components are optional.
|
|
|
|
The three arguments (in order: @var{CARD},@var{DEV},@var{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 @file{/proc/asound/cards} and @file{/proc/asound/devices}.
|
|
|
|
For example to capture with @file{ffmpeg} from an ALSA device with
|
|
card id 0, you may run the command:
|
|
@example
|
|
ffmpeg -f alsa -i hw:0 alsaout.wav
|
|
@end example
|
|
|
|
For more information see:
|
|
@url{http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html}
|
|
|
|
@section bktr
|
|
|
|
BSD video input device.
|
|
|
|
@section dv1394
|
|
|
|
Linux DV 1394 input device.
|
|
|
|
@section 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 @var{client_name}:input_@var{N}, where
|
|
@var{client_name} is the name provided by the application, and @var{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
|
|
@file{jack_connect} and @file{jack_disconnect} programs, or do it
|
|
through a graphical interface, for example with @file{qjackctl}.
|
|
|
|
To list the JACK clients and their properties you can invoke the command
|
|
@file{jack_lsp}.
|
|
|
|
Follows an example which shows how to capture a JACK readable client
|
|
with @file{ffmpeg}.
|
|
@example
|
|
# 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
|
|
@end example
|
|
|
|
For more information read:
|
|
@url{http://jackaudio.org/}
|
|
|
|
@section libdc1394
|
|
|
|
IIDC1394 input device, based on libdc1394 and libraw1394.
|
|
|
|
@section 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
|
|
@file{/dev/dsp}.
|
|
|
|
For example to grab from @file{/dev/dsp} using @file{ffmpeg} use the
|
|
command:
|
|
@example
|
|
ffmpeg -f oss -i /dev/dsp /tmp/oss.wav
|
|
@end example
|
|
|
|
For more information about OSS see:
|
|
@url{http://manuals.opensound.com/usersguide/dsp.html}
|
|
|
|
@section video4linux and video4linux2
|
|
|
|
Video4Linux and Video4Linux2 input video devices.
|
|
|
|
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 @file{/dev/video@var{N}}, where @var{N} is a number associated to
|
|
the device.
|
|
|
|
Video4Linux and Video4Linux2 devices only support a limited set of
|
|
@var{width}x@var{height} sizes and framerates. You can check which are
|
|
supported for example with the command @file{dov4l} for Video4Linux
|
|
devices and the command @file{v4l-info} for Video4Linux2 devices.
|
|
|
|
If the size for the device is set to 0x0, the input device will
|
|
try to autodetect the size to use.
|
|
|
|
Video4Linux support is deprecated since Linux 2.6.30, and will be
|
|
dropped in later versions.
|
|
|
|
Follow some usage examples of the video4linux devices with the ff*
|
|
tools.
|
|
@example
|
|
# Grab and show the input of a video4linux device.
|
|
ffplay -s 320x240 -f video4linux /dev/video0
|
|
|
|
# Grab and show the input of a video4linux2 device, autoadjust size.
|
|
ffplay -f video4linux2 /dev/video0
|
|
|
|
# Grab and record the input of a video4linux2 device, autoadjust size.
|
|
ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
|
|
@end example
|
|
|
|
@section vfwcap
|
|
|
|
VfW (Video for Windows) capture input device.
|
|
|
|
@section x11grab
|
|
|
|
X11 video input device.
|
|
|
|
This device allows to capture a region of an X11 display.
|
|
|
|
The filename passed as input has the syntax:
|
|
@example
|
|
[@var{hostname}]:@var{display_number}.@var{screen_number}[+@var{x_offset},@var{y_offset}]
|
|
@end example
|
|
|
|
@var{hostname}:@var{display_number}.@var{screen_number} specifies the
|
|
X11 display name of the screen to grab from. @var{hostname} can be
|
|
ommitted, and defaults to "localhost". The environment variable
|
|
@env{DISPLAY} contains the default display name.
|
|
|
|
@var{x_offset} and @var{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 @file{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 @file{:0.0} using @file{ffmpeg}:
|
|
@example
|
|
ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpg
|
|
|
|
# Grab at position 10,20.
|
|
ffmpeg -f x11grab -25 -s cif -i :0.0+10,20 out.mpg
|
|
@end example
|
|
|
|
@c man end INPUT DEVICES
|