DL4YHF's Amateur Radio Software:
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What are the Audio-I/O-Libraries ?
The Audio-I/O-Libraries are a simple way to send uncompressed audio streams
from one application to another. At the moment, both applications must run
on the same PC. The Audio-I/O bundle (consisting of the compiled binaries, the C sourcecodes, and the manual) can be downloaded from this site. But first, read the next chapter...
Disclaimer(Ok, I hate this paranoid stuff, but someone told me it's wise to have it here..) Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1.Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2.Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3.Neither the name of the author nor the name of other contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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Downloading and InstallationThe Audio-I/O-Libraries, including the manual, the compiled binaries and the C sourcecode, can be downloaded from here: http://www.qsl.net/dl4yhf/AudioIO/AudioIO.zip (if the page has moved, ask your friendly search engine) The "installation" is straightforward: Just unpack the compressed archive into a directory of your choice. In it, you will find (at least) the following files:
How to get started with the Audio-I/O-DLLs is described in the manual (PDF document). If you want to take a quick look without downloading and unpacking it, look here: AudioIO_Manual.pdf (beware, the manual in the archive will almost certainly be more update than the document on this website).
Sending an audio stream to an Icecast server with Spectrum Lab, Audio-I/O, Winamp, and Oddcast This chapter is, at the moment, not much more than a hasty wish-wash of Spectrum Lab's author to send an audio stream to an Icecast server (thanks Paul for setting it up !). You'll need a couple of programs to send your own stream...
In the configuration described below, Spectrum Lab receives the stream from a soundcard (or a software-defined radio), removes unwanted signals, and sends the output to Winamp. Let's start with this part: Select the Audio-I/O-DLL as input source: In SL's main menu, select "Options".."Audio Settings and I/O device selection". Under "Audio Output Device", select "Audio-I/O DLL". Also set the output sampling rate to 22050, 32000, or 44100 samples per second (depending on the bandwidth. For a VLF "Natural Radio" stream, 32000 samples/sec is sufficient. For an SSB radio receiver, 11025 samples/sec is ok). To start with (on VLF), select "Quick Settings"..."Natural Radio"..."Sferics, Tweeks, Whistlers with filtered audio output" in Spectrum Lab's main menu. In this configuration, both the hum filter and the FFT-based audio filter are enabled. More details are in the SL help system (file "natradio.htm", last chapter). It's advisable to find the optimum configuration for your VLF receiver while sending the audio to the line-out signal of your soundcard, before trying to send the audio to Winamp, as described in the next step.
Make sure the file in_AudioIO.dll is in Winamp's plugin directory (details
in the Audio-I/O manual). Start Spectrum Lab's processing (Start...Sound Thread), so it begins to fill the buffer in Winamp's input plugin. Shortly after that, Winamp should start playing the audio (which it receives from SL) to the speakers. If it doesn't, click the "play"-button. If that doesn't help, click the "stop" button, and again the "play" button. After this, Winamp should show the sampling rate and the number of channels (mono/stereo) which it receives from the Audio I/O library . If you try to start Winamp's playback without SpecLab running, Winamp track timer gets stuck at zero, until it receives the first audio samples from Audio-I/O. You will also notice, that when you stop the audio-processing in SpecLab, Winamp keeps playing for a few seconds more (this is caused by various buffer stages in SpecLab, in the Audio-I/O interface, and in Winamp itself). If this works, proceed... Installation and operation of Oddcast Download the Oddcast plugin for Winamp from www.oddsock.org . Install it as described (there are dozens of sites on this.. search for "internet radio station winamp oddcast icecast Lame" or similar..). BTW the Lame MP3 encoder library ( lame_enc.dll ) is sometimes in Winamp's plugin directory, but Oddcast expected it in Winamp's main directory (where winamp.exe is, too). After installation of Oddcast, restart Winamp, and select "Options"..."Preferences"..."Plug-ins"..."DSP/Effect". In the list of DSP/Effect plug-ins, select "oddcast DSP vX", and click "Configure.." (but usually the Oddcast control panel opens automatically). Add a new encoder, then select that encoder, and click on it with the right mouse button. In the context menu, select "Configure". There are three tabs, most important are the "Basic Settings". These must be carefully filled out.. for example: Bitrate: 64 (which means 64 kBit per second compressed audio). Only if your DSL *uplink* speed is too slow, try 32 kBit/second - the quality will be much poorer then, especially with MP3 encoding. Samplerate: 44100 or 32000 (the latter preferred for VLF) Channels: 1 (unless you send a quadrature stream from an SDR...) Encoder Type: MP3 Lame (or OggVorbis, if supported by the receiving server) Server IP, Server Port: Cannot tell you that... ask your friendly Icecast service provider ;-) Encoder Password : Won't tell you that... same as above. Mount Point: See Oddcast (or Icecast) reference. If it doesn't work, try a forward slash before the stream name. For example, the VLF radio streams used mountpoints like /vlf3, /vlf6, etc . Reconnect Seconds: 10 ( = default value ) On Oddcast's "YP Settings", give the stream a name and description (these will be displayed in the listener's audio player). Since many DSL providers kick you out deliberately once every day (to prevent people doing things like these), don't forget to set the checkmark "AutoConnect" on the Oddcast main configuration panel. Whenever the audio connection between your PC and the Icecast server breaks down, the program will automatically try to set it up again after the ten "Reconnect Seconds". Then close Oddcast's configuration panel ("OK"), and click "Connect" to try if Oddcast can connect the remote (or local, see below) Icecast server. If it doesn't work, get in touch with someone who knows a bit more about internet radio streaming than the author of these lines.
Installation and operation of Icecast
Icecast is, in analogy to the old AM/FM steam radio, the "radio transmitter".
In contrast to your local ISDN- or ADSL uplink, a dedicated Icecast server
can broadcast to dozen or hundreds of receivers simultaneously (btw, most
if not all such providers charge a moderate fee for their service, so consider
making a small donation to the one who offered you to share "his" server...)
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Finding an Icecast server, or setting up your own As already mentioned, an Icecast server typically runs on a machine with a real broadband access (not an home ADSL connection) to serve dozens or even hundreds of listeners simultaneously. ADSL, the most popular access by the time of this writing (2008) has a large downstream bandwidth (once 768 kBit/second, nowadays 2000 to 6000 kBit/seconds under ideal conditions), but the upstream bandwidth is too limited to serve more than a few listeners. This is the reason why Icecast is typically *not* installed on your home PC, but on a machine dedicated to audio streaming.
There seemed to be a few free Icecast providers out there in 2006,
but all of them seem to have disappeared. Today (2008), you will find questions
asked in forums like "Hello ! I want a free icecast server." (what a joker).
To find companies hosting Icecast servers, ask your friendly search engine for terms like
For a start, or if your audience will always be limited to a few listeners, you can try to set up your own server (on your 'local PC') if you can convince your DSL router / firewall / etc to accept incoming calls. Furthermore, check (with your DSL provider) if you have a permanent IP address which makes things a lot easier. I never succeeded in setting up my own Icecast server (last not least because there was no need to try), so you're own your own at this point. Just a few hints... search the net for subjects like
< To Be Continued >
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