 |
YARP
Yet Another Robot Platform
|
|
|
YARP
Yet Another Robot Platform
|
|
The command-line utility "yarpdev" can create devices and wrap them for network visibility.
This is useful in cases where you wish to control devices on remote machines.
The devices available to "yarpdev" depend on the options set when compiling YARP. The most important devices are enabled by default. To disable all device plugins, you can set to OFF the YARP_COMPILE_DEVICE_PLUGINS option in CMake. You can select and deselect each device using the relative ENABLE_* options in CMake. Often this will require that you install particular libraries or operating system device drivers.
The utility gives a message if called with no arguments to confirm that it exists, and to give tips on where to get started using it. Our current implementation says:
$ yarpdev Welcome to yarpdev, a program to create YARP devices To see the devices available, try: yarpdev --list To create a device whose name you know, call yarpdev like this: yarpdev --device DEVICENAME --OPTION VALUE ... For example: yarpdev --device fakeFrameGrabber --width 32 --height 16 --name /grabber You can always move options to a configuration file: yarpdev [--device DEVICENAME] --file CONFIG_FILENAME If you have problems, you can add the "verbose" flag to get more information yarpdev --verbose --device ffmpeg_grabber
With the –list option present, the devices available on your system are listed. For example:
$ yarpdev --list Here are devices listed for your system: Device "dragonfly", C++ class DragonflyDeviceDriver, wrapped by "grabber" Device "esd", C++ class EsdMotionControl, wrapped by "controlboard" Device "esd_sniffer", C++ class EsdMessageSniffer, has no network wrapper Device "microphone", C++ class MicrophoneDeviceDriver, wrapped by "grabber" Device "inertiacube2", C++ class InertiaCube2, has no network wrapper Device "jamesarmcalibrator", C++ class JamesArmCalibrator, has no network wrapper Device "jameshead", C++ class JamesHead, has no network wrapper Device "XSensMTx", C++ class XSensMTx, wrapped by "inertial" Device "opencv_grabber", C++ class OpenCVGrabber, wrapped by "grabber" Device "ffmpeg_grabber", C++ class FfmpegGrabber, wrapped by "grabber" Device "fakeFrameGrabber", C++ class FakeFrameGrabber, wrapped by "grabber" Device "remote_grabber", C++ class RemoteFrameGrabber, wrapped by "grabber" Device "grabber", C++ class ServerFrameGrabber, is a network wrapper. Device "inertial", C++ class ServerInertial, is a network wrapper. Device "sound_grabber", C++ class ServerSoundGrabber, is a network wrapper. Device "remote_controlboard", C++ class RemoteControlBoard, wrapped by "controlboard" Device "controlboard", C++ class ServerControlBoard, is a network wrapper. Device "portaudioPlayer", available on request (found in <prefix>/lib/yarp/yarp_portaudioPlayer.so library), wrapped by "AudioPlayerWrapper". Device "portaudioRecorder", available on request (found in <prefix>/lib/yarp/yarp_portaudioRecorder.so library), wrapped by "AudioRecorderWrapper".
where the first keyword like "fakeFrameGrabber" is the device name used to instantiate it, class is the name of the class that implements it and the latter explains if the device is a network wrapper or it has a default network wrapper to be used or it does not have a default wrapper.
This is the normal way to start up a device. For example:
$ yarpdev --device fakeFrameGrabber --period 0.5 --width 640 --height 480 Test grabber period 0.5 / freq 2, mode [line] yarpdev: created device <fakeFrameGrabber>. See C++ class FakeFrameGrabber for documentation. yarp: Port /grabber listening at tcp://130.251.4.155:10032 Grabber for images No framerate specified, polling the device yarpdev: created wrapper <grabber>. See C++ class ServerFrameGrabber for documentation. yarpdev: device active... yarpdev: device active... [...]
Here we've asked to create the "fakeFrameGrabber" device, which acts as a fake image source. We've specified the image size and the rate at which images are created. The yarpdev program eventually said "device active" – this is a good sign.
The program reported that the "fakeFrameGrabber" device was created. It also mentions a "grabber" device that is also created. Why is this? It is because most devices themselves know nothing about the network; instead they need to be "wrapped" in a special "network wrapper device" that knows how to put them on the network. For fakeFrameGrabber and other camera-like devices, this wrapper is called "grabber". In fact, our original request of:
$ yarpdev --device fakeFrameGrabber --period 0.5 --width 640 --height 480
was automatically expanded to:
$ yarpdev --device grabberDual --subdevice fakeFrameGrabber --period 0.5 --width 640 --height 480
If we add the "--verbose" flag, yarpdev will report information about device configuration. This can help a lot to work out what properties a device takes. For example, suppose we notice in the documentation that there is an "ffmpeg_grabber" which can read images from an avi file. But what options should we supply it? To find out, just add the "--verbose" flag and try to create the device without any options:
$ yarpdev --verbose --device ffmpeg_grabber
Could not open avi file default.avi
yarpdev: ***ERROR*** driver <ffmpeg_grabber> was found but could not open
yarpdev: ***ERROR*** driver <grabber> was found but could not open
===============================================================
== Options checked by device:
==
device=ffmpeg_grabber
grabber.subdevice=ffmpeg_grabber
name (or nested configuration) of device to wrap
ffmpeg_grabber.device=ffmpeg_grabber
ffmpeg_grabber.source [default.avi]
movie file to read from
ffmpeg_grabber.v4l
if present, read from video4linux
ffmpeg_grabber.ieee1394
if present, read from firewire
grabber.device=grabber
==
===============================================================
yarpdev: ***ERROR*** device not available.
Suggestions:
+ Do "yarpdev --list" to see list of supported devices.
+ Or append "--verbose" option to get more information.
The "--verbose" option adds the "options checked by device" information. We see that for the ffmpeg_grabber, there is an option called "source" which defaults to "default.avi" and is the "movie file to read from". Now if we do:
$ yarpdev --device ffmpeg_grabber --source your_movie.avi
The device starts correctly.
The "--verbose" information also mentioned an option called "v4l" with the comment "if present, read from video4linux". If we try adding this option, yarpdev may or may not succeed (depending on whether video4linux is present and how it is configured on your machine). A typical failed output is:
$ yarpdev --verbose --device ffmpeg_grabber --v4l
/dev/video0: No such file or directory
Could not open Video4Linux input
yarpdev: ***ERROR*** driver <ffmpeg_grabber> was found but could not open
yarpdev: ***ERROR*** driver <grabber> was found but could not open
===============================================================
== Options checked by device:
==
device=ffmpeg_grabber
grabber.subdevice=ffmpeg_grabber
name (or nested configuration) of device to wrap
ffmpeg_grabber.device=ffmpeg_grabber
ffmpeg_grabber.source [default.avi]
movie file to read from
ffmpeg_grabber.v4l
if present, read from video4linux
ffmpeg_grabber.v4ldevice [/dev/video0]
device name
ffmpeg_grabber.channel [0]
channel identifier
ffmpeg_grabber.standard [ntsc]
pal versus ntsc
ffmpeg_grabber.width [640]
width of image
ffmpeg_grabber.height [480]
height of image
ffmpeg_grabber.time_base_den [29]
denominator of basic time unit
ffmpeg_grabber.time_base_num [1]
numerator of basic time unit
grabber.device=grabber
==
===============================================================
yarpdev: ***ERROR*** device not available.
Suggestions:
+ Do "yarpdev --list" to see list of supported devices.
+ Or append "--verbose" option to get more information.
So now we see another level of configuration which we can do to make the device match our system.
Each device class has a description page where input parameters are described in more detail. You can find a list of devices in Device implementation page subdivided by type.
For example the description for the
controlboardwrapper2 device is in the Device implementation -> Network Wrapper -> controlboardwrapper2 device page
analogServer device is in the Device implementation -> Network Wrapper -> analogServer device page
inertial device is in the Device implementation -> Network Wrapper -> inertial device page
batteryWrapper device is in the Device implementation -> Network Wrapper -> batteryWrapper device page
RGBDSensorWrapper device is in the Device implementation -> Network Wrapper -> RGBDSensorWrapper device page
grabberDual device is in the Device implementation -> Network Wrapper -> grabberDual device page
1.8.20