Selects the sample rate used for input and output. Normally, in case of trouble this is done automatically, so you should never need this. Trouble (buffer underruns, sound cards that refuse to connect).
Synchronize with Select what to synchronize the display to.See Synchronize to output for a (partial) solution. If you use multiple sound cards which don't share the same clock, the output buffer will at some point get underruns (causing drops in audio) or overruns (causing some pieces of audio to get lost).
If you don't use ASIO, Windows gives you an extra 100-300 ms of latency, which is far too much if you are listening to yourself for example on a headphone. If you want low latency audio, use ASIO for both input and output.
Low-budget non-profit community radio stations here still run analog equipment but the stereo encoder is always included as a plus in low-price low-power transmitters, so there seems to be no need for a software based encoder.Home Download Donate Register Forums HelpĬonfiguration of input and output sound cards, and synchronization.īesides choosing sound cards, this section also lets you configure FM transmitter synchronization, which can be used to synchronize the sound at multiple FM transmitter sites, using a normal Shoutcast or other stream as input. They usually go for 24 ins external sound cards.
PC based recording studios still need them. So audio cards don't seem to be critical in radio work nowadays. Those PCs don't usually rely on audio cards, they stream digital audio straight to the console or routing devices without going analog. Standard PCs still have their place in the typical radio studio audio chain running radio automation software (sophisticated playlist players) although this task is slowly being taken over by the mixing consoles themselves. The only unavoidable analog device in the audio chain seems to be the microphone (and its ADC converter, usually part of the mixing console). Studio-transmitter links are digital, audio consoles are digital, all routing is digital, audio processing is digital. Nowadays state-of-the-art FM TX exciters are digital in-out (direct digital FM synthesis). Finally I dusted out an old Itame encoder which did the work. I ran that test some 10 years ago looking for a temporary solution for one of our unattended repeater stations until proper equipment was bought. Ken, thanks for your interest but I didn't mean I was interested in making this work. The s19 and s38 samples could be obtained by reading preloaded arrays (for efficiency). The L and R streams must be 15 kHz lowpass filtered previously to avoid aliasing. Let's assume you have L and R samples named L and R, a sinusoidal 19 kHz stream of samples named s19 and a 38 kHz stream of samples named s38. The "Balanced Modulator" block that seemed elusive to ken is just a multiply operation.
There are 2 optional SCA and one RDS feeds missing from the scheme, though. If you're still interested in coding your own version just refer to the diagram posted by ken. I tested one of them in our radio station a few years ago with deceiving results. Search for "software fm stereo encoder" in the net. There are a few programs / plugins already available that do this.