The possibilities of use of IHU are
endless, for example you can use it like a phone to talk with your
friends all around the world, or at home/work to talk between
computers in the LAN (talkback), etc.
First of all make sure you have the
latest version of IHU (
http://ihu.sourceforge.net).
Follow the instructions contained in README and INSTALL files
to compile the sources (you'll need the
QT
libraries, the
ALSA
sound driver, the
Speex codec,
the
Soundtouch library,
and the
Ogg library).
Anyway the automatic configure script will tell you what is missing.
If you want to transmit your voice/audio, then you need a
microphone linked to your computer (but it's not necessary to use IHU)
and, finally, you need a person to talk with, who has a computer linked to you (through
the Internet or LAN) and IHU installed as well (unfortunately IHU it's
not so useful alone on your
computer, even if I spent hours talking to myself for tests ;-).
Finally, I suggest to use headphones, to prevent
feedback.
IHU's way to work is similar to a telephone: there is somebody who is
waiting for phone calls, and somebody who wants to call this person.
In the next paragraphs, the computer that will make the call
will be named
Caller and the computer
that will receive the call will be named
Receiver.
Now the next two steps are external
to IHU and are necessary before continuing: setting up the network and
the audio system.
1.1.1 Network settings
You need to know how your network is organized, and if firewalls are present between you and your
IHU partner. The most important thing is:
If you
want to receive
calls, then your computer must
be able to receive incoming connections.
Those situations are possible:
- If your computer is connected directly to Internet (or LAN)
and Callers can access it
directly with an IP or DNS address, then
you should be ready to make calls without
problems.
- If your computer is connected through a gateway with
NAT and/or a firewall, then: in order to receive calls, you have set
up the firewall/gateway rules to forward incoming connections to 1793
TCP/UDP port (default, but you can change it from IHU settings).
Instead, in order to make
calls, you have to make sure that the firewall (usually possible) is allowing
outgoing connections on port 1793 (TCP and/or UDP).
If you can't change the rules and you have a very strict
firewall that allows only outgoing connections to important ports like 80, 25, etc.,
you could change the port of IHU to those allowed
ones, but then you have to ask the Receiver
to change his port, and for those port he needs root privileges.
Briefly,
- If both computers are accessible from each other's IP address, no
problem, both can receive and make calls.
- If one computer (or both) computers are behind firewall but you
could change the rules as described abow, still no problem.
- If one computer is behind firewall and you can't change rules,
then on this computer you can't receive calls, but you can still make
calls.
- If both computers are behind firewalls and it is not possible to
change any rules (it seems that you are very unlucky!), then you have
no chances to talk to your friend :-(
Tip: You can easily test if
everything is fine using
the
netcat program:
Receiver
runs "nc -l -p 1793" (or for UDP "nc -u -l -p 1793"), and and
Caller
runs "nc RECEIVER_IP_ADDRESS 1793" (or for UDP "nc -u
RECEIVER_IP_ADDRESS 1793"). If you can see what your
partner is typing (and viceversa), then IHU won't have any kind of
problems.
1.1.2 Audio Settings
Then you need to set up the audio mixer, selecting the audio
source and the optimal volumes. To do this you can open any mixer
program (like "kmix" for KDE), paying attention to the recording
source, that usually should be set to Microphone if you want to send your
voice, and to the recording level (that for ALSA is usually named
"Capture"). Also, take note of the playback volume (usually named
"PCM", the one that you control also with XMMS, for example), because
if it's too low, it will be hard to hear your partner.
Tip: You can easily test the
audio settings directly with IHU. You run
two instances of IHU and,
in the first IHU window you become a silent
Receiver clicking on
Wait for calls and on
Disable audio input,
instead in the second window you become a self-
Caller typing
"localhost" as receiver address (You may need to Disable the audio
output on this one). You will now hear yourself and you can
check settings. But read the quick start to know how to do this if you
have problems calling.
1.2 Quick start
Ok, you are ready to use IHU! Now you just need to know the
address (IP or DNS) of the friends to call.
Each IHU user who wants to receive calls should give his address to his
IHU friends. Personally, I strongly suggest to register to a dynamic
DNS service (such as
dyndns), where
you can register your computer with a fancy DNS address easy to
remember (such as
myhostname.homelinux.org);
then each time you go online, your IP should update and your
friends can always call you with that address.
Lets suppose now that your internet address is
hostname.org
and that you want the receive calls from your friends. Then, first of
all, you have to run IHU and press the
Wait for calls button. Your friend
now will type your address (
hostname.org)
in the
Receiver address field
and will press the
Call button.
Hopefully you will see an inbound call notification and sound and if
you want, you can answer by clicking on the
Answer
button. At this point you should see the TX and RX leds flashing, and you
should hear something, now you can finally cry out: "I Hear U!!!" ;-)
2. Detailed description
2.1 The main window
The main window (see
screenshot)
is composed by :
- Receiver address: here
you write the address (IP or DNS hostname) of the computer that you
want to call, then press Enter or click the Call button to start the
communication. As port, IHU is using the default port in the Settings
(usually 1793), but if you want to temporarily use another port for a specific host
(without changing the default port in the settings), you can quickly specify the
port just after the IP address in the form ADDRESS:PORT
(for example to use the port number 1790 "host.homelinux.org:1790").
- Call
(ALT+C):
after you type the Receiver address,
click this button to start the communication. IHU will first ring the Receiver and then, if he
answers, it will capture and send your voice to your partner and you
will receive your partner's voice. If your are Waiting
for calls and you received a new call, than this button will
become Answer (ALT+A),
and will allow you to answer the call.
- Ring
(ALT+B) (the button in the center with a
little bell): this is a special button. When you click this button,
your partner, instead of listening to your voice, will hear a nice
ringing sound, similar to the phone (it is usually so loud that could
eventually damage his
ears ;-). To stop ringing just click the button again. The button is
available also during conversation, useful for
example when you want to notify you're back after a pause, or for other
many reasons you can think of. To disable the ringing tone when
receiving new calls, just disable the audio output (see below).
N.B. IHU will automatically
activate this button when you make
a call, and will stop ringing either if your partner answers or
refuses. But you can
also stop ringing before, without waiting for the answer clicking the
button manually. This is useful, for example, to:
- Let your partner recognize your voice, or call him by voice
(funny, isn't it? ;-).
- Leave a message (like an answering machine) if your partner is
recording calls (see below for details).
- Hang up
(ALT+H): when you click this button, IHU
will close the current communication. If you are waiting for calls and you just
received a new call, this button will become Refuse (ALT+R) and you can refuse the call.
- Wait for
calls (ALT+W): when you click this button IHU
will wait for incoming calls (remember that it isn't toggled by
default when you run IHU, unless you enable the proper option in the
settings, see below).
When you receive an incoming call, IHU will NOT send your voice to
the caller until you press Answer.
If you don't want to receive calls or you can't answer calls at the
particular moment, then just deactivate this button.
- TX led: this red led is
on when IHU is transmitting data.
- RX led: this green led
is on when IHU is receiving data, or, when waiting for calls, if
you missed some calls.
- TX threshold: the
volume
level (0-100%) to be considered silence. When threshold is greater than
zero, IHU won't send any data that is considered silence. This allows
you to save network bandwith when you are not speaking. You should change
this value to a suitable
value so that TX led is off when you are not speaking. Of course this
does not affect the data that you are receiving.
N.B. When you are playing pre-recorded files, this slidebar
becomes File progress, and
you can change the current file position.
- AGC volume the
volume
level (0-100%) used as reference for the Automatic Gain Control (that
controls the playback volume), but it is available only if you
activate the AGC option (see options below).
- Disable audio input
(ALT+I) (button with microphone): click
this button to disable audio capture or to mute your microphone (for
private moments ;-)
- Disable audio output (ALT+O) (button
with speaker): click this button to disable playback or to mute the speakers (but incoming data
will be received anyway, and eventually recorded).
- Settings (ALT+S): to
open the settings dialog and configure IHU (see below).
- View Log (ALT+L): this
button opens the Log window. In this window IHU keeps the most
important messages that appear in the status bar when IHU is working,
showing the timestamp of the message.
This log window is important to see if you received some
calls, the address/name of the person who called you, the encryption
key used, and much more informations on calls. The log is cleared each
time you close IHU, but you can also save it to file
(see security settings below).
2.1.1 The
FILE menu (ALT+F)
The FILE menu offers these simple functions:
- Play IHU file (CTRL+F): to play a previously
recorded IHU file (please read the settings section to know
how to record a stream to file). If the stream was encrypted than it is
not possible to play the fileat this time, unless you know its passphrase (IHU
will automatically ask you the passphrase when encountering encrypted streams).
- Convert .ihu file to .spx (CTRL+T): this function is useful to convert
the files recorded with IHU (.ihu extension) to standard speex files
(.spx extension). The .spx files are standard Ogg files and are readable
also by other applications, such as speexdec. Note that for each speex mode
encountered in the .ihu file (i.e. with different sampling rates, 8000, 16000 or
32000), IHU will create a new logical stream inside the Ogg file; you can
use other external applications to demultiplex the stream.
- Quit (CTRL+Q): to quit ;-)
2.1.2 The
OPTIONS menu (ALT+P)
The OPTIONS menu offers some interesting functions:
- Encrypt outgoing stream (CTRL+E):
if you check this option, IHU will encrypt the outgoing stream. Your
partner will be able to decrypt thanks to an
automatic (and secure) key exchange. You can check/uncheck
this option also during the communication.
N.B. This option will only
affect your outgoing
traffic. The
incoming traffic is independent and can be encrypted or not, it doesn't
matter. However, when one peer is encrypting the stream, then his
partner will be "invited" to do the same, automatically enabling
encryption too but the user is always able to decide whether to crypt
or not so you can disable this option at any time during conversation.
- Change encryption key (CTRL+K):
to change your encryption
key with a new key. You can change the key also during communication,
whenever you want (so IHU is compatible with paranoid individuals
;-)
- Set/reset decryption key
(CTRL+D): this is useful to reset the decryption
key or to change it, but, at the moment, it is only possible to set a
text passphrase.
So if you need, for any reason, to set a different passphrase,
or you want to reset your
decryption key in order to receive a fresh decryption key, then this
function is for you.
- Audio Delay Reduction (ADR)
(CTRL+R): since there might be a delay between the time you
receive the data and the time you listen through your speakers,
you may want to reduce this delay. Check this option to let IHU keep
the audio delay as minimum as possible (you can set up your delay value
in the settings window).
- Automatic Gain Control (AGC)
(CTRL+G): check this option to activate an automatic system that
keeps the playback volume always at
the same level. If the voice of your partner is too soft, AGC will
amplify it, instead if too loud AGC will soften it. You can adjust the
volume thanks to the AGC
volume level slidebar.
Please
note: this option works well only when your partner who is
speaking is properly using sound
threshold (greater than zero), otherwise when your partner
doesn't speak, the silence will get amplified so much that when he
starts to speak again, the sound will become distorted. If there is no
way to convince your partner to properly use TX threshold level, than adjust
gain
settings manually (see below).
- Settings (CTRL+S): to
open the settings dialog and adjust IHU parameters (see below).
2.1.3 The
HELP menu (ALT+E)
There are not so many things to say here, the only help available is
what you are reading now! ;-)
2.2 The settings
dialog
You can access the
setting dialog from the
Settings
button in the main window or
from the option menu (ALT+S or CTRL+S).
The settings dialog allows you to change all the parameters and
options of IHU. It is organized in several tabs (please note that
the default button will set the default parameters only for the
current tab):
2.2.1 General settings
- My name: here you can
write your name, nickname, address, or whatever you want that your
partner will see in order to recognize you. In my opinion it's
important to write something here, but feel free to leave it
empty.
- Wait for incoming calls at
startup: if you prefer to immediately be able to receive calls
when you launch IHU, without need to click on Wait for calls button, you can
enable this option.
- Answer automatically the calls:
with this option you have the ability to automatically answer a new
incoming call, without need to click
the Answer button. This is
useful for example if you want to receive calls but you're too busy to
use the mouse or keyboard to click the button.
N.B. When IHU automatically
answers, it will start to send to your partner audio captured by the
microphone (unless you disable the audio input), so be careful to not
use this option when you actually can't answer the call!
- Show tray icon: to
enable/disable the IHU system tray icon. The tray icon is useful if you
need to have a quick access to IHU buttons without need of keeping the
window visible.
- Start minimized: when you
enable the system tray icon, you have the possibility to launch IHU
without opening the main window. This is useful, for example, when you
enable IHU
to auto-run at system startup.
- Record stream to file: to
record the audio stream to a ".ihu" file. At the
moment IHU just dumps all the data packets to file. You can only play
this file using the Play
file
function from the File
menu. Remember that if you record an encrypted stream, then you won't be able
to play it, unless you know the encryption passphrase.
Unfortunately, at the moment, it is possible only to record the incoming stream seperately
from the outoing stream. This means that your voice will be recorded to one
file, while your partner's voice will be recorded to another file. But
this is already useful for example to:
- Record messages when you can't answer calls (see the Ring button above)
- Save important converstations, so that you can listen them
again in the future whenever you want.
2.2.2 Network settings
This tab is divided into two parts. The first is about your
IHU as
Receiver (when you
receive calls), the second is about your IHU as
Caller (when you make calls):
- Receiver allowed protocols:
here you can choose which protocol you want to enable on your Receiver. IHU can accept both UDP
and TCP by default (recommended), so that callers can
choose their preferred protocol, but you have the possibility to
disable the protocols that you don't want to use. Of course you have to
enable at least one protocol to receive calls.
- Receiver port: this is
the UDP/TCP port number on which your IHU is receiving calls (default
is 1793). Please note: this port is
very important and usually you shouldn't change it. If you really need
to change this port, please make sure that your
callers know your new port number, otherwise nobody can call you. In
order to use ports lower than 1024 you must have root privileges.
- Caller preferred protocol:
this is the protocol used for outgoing calls (only one protocol is
possible for each call). If the Receiver
you want to call has both TCP and UDP enabled, then you can choose your
preferred protocol, otherwise you have to use the protocol chosen by
the Receiver. If you receive
errors like "Connection refused" or "Connection rejected" when making a
call, try to change the
protocol.
- Caller default port: this is the
default port number for outgoing calls. If you don't specify any port after
the address in the main window, then IHU is using this default port.
2.2.3 Sound settings
- Sound driver: here you
can choose the sound driver for input (capture) and for output
(playback). By default IHU is using ALSA for both input/output, but if
you have JACK sound driver installed on your computer, then IHU should
have compiled with JACK driver support. This means that you can also
choose to use JACK as input and ALSA as output, or JACK for input/output (note
that you can't use ALSA for input and JACK for output).
A little note for JACK
sound
driver:
Jack can give better sound performance (against audio
latency), but requires a little more attention: please make
sure that your Jack server is properly configured for IHU (i.e. the same
sample rate, sample width, etc..) and that when
you start playback or recording, IHU Jack ports are properly connected
to capture and playback devices. Note also that when using Jack
as output driver, the ADR option is not available (there is no need!
;-).
- Sound interface: here you
can choose the input and output interfaces for ALSA. For each sound
card ALSA offers two interfaces, hw
and plughw. If you have more
than one
sound card, you can change the sound card, giving the right card
number (for example plughw:1,
please read the /proc/asound/card
file to know the card numbers). And, for each soundcard you can change
the device, giving the right device number (for example plughw:1,3, please read the /proc/asound/devices file to know
the device numbers). By default IHU is using the "default" interface,
which will automatically choose the best
interface and device for you.
Please
note: this
setting is VERY important for IHU, so I strongly
suggest to select the interfaces which work better for your computer.
The plughw and hw should give
better performance and low latency, but they have one disadvantage: they don't
allow more than one capture stream per time on the interface (and
eventually also playback, depends on your soundcard). So if
you need to use other capture programs, then you have to choose another
interface which use the dsnoop
plugin. Or if you have other kind of problems then try to change
the interface (try first the plughw
interface, then the hw
interface, or other custom interfaces). Anyway, if you decide
to change the interface, than you're responsible to check the ALSA settings
(read ALSA documentation
for more informations on how to configure ALSA), and keep in mind that
the performance of IHU can be greatly affected (long delay and bad
sound quality) if you choose the wrong interface. I recommend
the use of the Jack sound driver, where
possible, because doens't have the disadvantages described above.
- Input format: to
change
the audio quality (adjusting input sample rate and format). At the
moment only three rates are possible (according to Speex rates): 8000
Hz (low quality), 16000 Hz (medium quality) and 32000 Hz (high
quality). The higher the quality, the higher the use of network.
- Stop TX after (silence secs):
when you are using a threshold
greater than zero, it's useful to continue the transmission for some
seconds, to preserve the stream against small speech pauses.
- Packets prebuffer:
number of packets to prebuffer before starting to play. A high number
of packets ensure audio continuity, but it could increase the audio
delay.
- Ring Volume: here you can
adjust the volume of ring tone for incoming calls.
2.2.4 Encoder settings
Here you can change the settings of your
Speex encoder (so only for your
outgoing
stream). Those settings are very important to determine the
sound quality of your
voice and the use of
network,
so adjust them very carefully (please refer to the
Speex website for more details).
- Bitrate mode: you can choose a Constant Bitrate (CBR), where
bitrate stays constant during the
communication, using always the same amount of outgoing traffic (adjust
bitrate with CBR Quality, see
below). Or you can choose a Variable
Bitrate (VBR), where the encoder
decides automatically which bitrate to use for each frame, according
to the complexity of data (adjust bitrate with VBR
Quality, see below). Or you can finally choose an Average bitrate (ABR), that is a
kind
of variable bitrate, but the average bitrate is constant (adjust
bitrate directly with ABR kbps
parameter, see below).
- CBR Quality: to select the bitrate for
CBR (1: lowest quality, 10: highest quality).
- VBR Quality: to
select bitrate for VBR (1: lowest quality, 10: highest quality). Higher
quality means higher bitrate, but due to
variable bitrate, it can be lower or higher than what you chose,
depending on the complexity of audio signal to be encoded.
- ABR kbps: to
select an average bitrate for ABR (Kbit/second). Bitrate is variable
but the average should be around the value you specified.
- Complexity: it is a
parameter to select the algorithmic quality. (1: lowest, 10: highest).
Higher complexity means
also higher CPU use.
- Voice Activity Detection (VAD):
when enabled, it detects whether the audio being
encoded is speech or silence/background noise. VAD is implicitly
activated when encoding is VBR.
- Discontinuous TX (DTX): it's
an addition to VAD/VBR operation, that allows to stop transmitting
completely when background noise is stationary.
2.2.5 Options settings
Here you find some settings about the
Audio
Delay Reduction (ADR) option:
- Time change percentage:
this is
the time percentage (0-50%) that determines the speed of delay
adjustment. With a high time change, the delay will be adapted faster,
instead with a small time change, the delay will be adjusted more gradually
(suggested, because a time change too high might affect the sound
quality or might render the speech incomprehensible, or just too fast
;-).
- Minimum delay: this is
the minimum delay (milliseconds). When ADR is activated, if the delay
on the playback sound interface is smaller than this value, IHU will try
to increase the delay to this reference value, in order to avoid sound
crackle.
- Maximum delay: this is
the maximum delay (milliseconds). If you activated ADR, IHU will try to minimize the
audio delay to this value. Be careful with too little values of max
delay, which could deteriorate the sound quality, or with values of Maximum delay too near
to Minimum Delay, give at least
40/50 ms of tolerance.
You find also some settings about the
Automatic
Gain Control (ADR) option:
- Volume change speed: this is the
speed factor of playback volume adapting, in order to reach
the reference volume value (the one you control in the main window, see
above). Increase if you want the volume to adapt faster, reduce to make
the volume change more gradual.
- Minimum gain factor:
this
is the minimum amplification factor, to soften the sound.
A value of zero means that sound can be reduced to total silence.
Instead, if you don't want to reach silence, than increase this
value.
- Maximum gain factor: this
is the maximum amplification factor, to amplify the sound.
You should decrease this value if silence is amplified too much and the
sound gets too loud and distorted when user is speaking, instead
increase if the volume is not well amplified enough.
2.2.6 Security settings
Here you can find some settings about security and cryptography:
- Encryption key type:
you can choose the type of key used for the symmetric encryption
(Blowfish) of your data. You have two possibilities:
- Random with constant
length: if you choose a random key, than IHU will automatically
choose a new random key each time you enable Encrypt outgoing stream, or each
time you Change the encryption key.
You can choose the length of the key (in bits); bigger keys should be
more difficult to crack. Please remember also that with a random key it
will be impossible to play recorded streams.
- Text passphrase
(please use phrases of at least 30 chars, max 56 chars): each time
you enable Encrypt outgoing
stream, or you Change the
encryption key, IHU will ask you to enter a new passphrase, that
will be used for encryption. This is useful, for example, if you want
to record the crypted stream to file and you want to have the
possibilty to play this file later with IHU (instead with a random key
it's not possible).
- Show decryption key of
incoming stream in
the Log: this option will show the decryption key type, and
eventually the passphrase, of the incoming stream in the
Log.
When the incoming stream is using a new encyrption key, then a
new message will appear in the Log,
and if the key is a text passphrase, then it will be showed, otherwise
IHU will just write "random key". This is useful if you are recording
the stream and you want to be able to play the
stream with Play File
option. Since the passphrase is a confidential information, if you don't
need to know the passphrase, then please do not use this option.
- Write a copy of the Log also to
file: if you want to save the Log
(the one you open with View Log
button) to file. This is useful if you want to save call informations
for the future, or if you want to carefully log all incoming
connections and calls (for security reasons).
N.B Please take care of this file
because it could contain confidential informations!
3. Quick launch
If you are a command-line lover, you have the possibility to launch IHU
with some quick launch options. Here
is the list of available options (which you can get by starting with
"--help"):
USAGE
ihu [OPTIONS]
OPTIONS
--wait Wait for incoming calls
--call HOST Call HOST (DNS or IP address)
--file FILE Play a IHU FILE
--encrypt Encrypt the outgoing stream
--noinput Disable audio INPUT
--nooutput Disable audio OUTPUT
--nogui Start without GUI (no interaction)
As you can see there is one option (--nogui), which allows you to run
IHU without GUI. This is
useful when you don't have the possibility to use a X server or when
you want to launch
IHU on remote computers, but then you don't have any possibility to
interact
with the
program. I strongly suggest to use this option
only for special cases, please use the GUI instead, which offers a
better interface (please note that when using --nogui you have to
change settings directly from qt config file, usually
"$HOME/.qt/ihurc").
4. Final notes
Please use the
Tracker at
IHU sourceforge page
to report bugs, patch, support requests. For any other kind of
informations, suggestions, flames (ouch!), just mail the author.
Now enjoy IHU!!
Copyright (C) 2003-2006
Matteo Trotta <mtrotta@users.sourceforge.net>
Permission is granted to copy, distribute and/or modify this document
under the terms of the
GNU
General Public License.
IHU Manual Page