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Topic: Question - What compression to use for an FM Radio station (Read 3058 times) previous topic - next topic
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Question - What compression to use for an FM Radio station

WMTH is a student run high school radio station. Audio quality isn't a huge concern, as we currently run through a single, direct telephone line, giving us only mono and less than stellar audio quality. However, i'd like to encode our music so it's as close as possible to the original. Are there any special treatments anyone would recommend? I'm currently planning on using a plextor drive with EAC and mpc encoding at quality 7. Also if anyone has any ideas for a cheap way to transfer our audio to the transmitter (i.e. how to build a hardware codec),  i'd like to hear it. From what i've heard, our schools (3 campuses sharing time) have either a fiber or just plain network link, so that could probably work too.

edit: I suppose I should also mention that all our audio is sourced from kids bringing in their own CDs... yep, totally freeform, so the goal is to have a usable library, all we have now are about a hundred minidiscs (yuck!) and a crapload of LPs that we don't want barely-trained DJs to mess with, so we'd be transferring LP tracks, cleaning them up with goldwave, and encoding those too

Question - What compression to use for an FM Radio station

Reply #1 –
I like to use oggvorbis at quality 1, which uses a lowpass of 15,8 Khz; seems appropiate for an fm broadcast... In that application, musepack seems a bit overkill for me  I suppose the radio profile could be useful... Hmm cheap hardware decoder? How about running an old machine with soundcard using a free open source OS (say, Linux, Openbsd or something like it)? You could stream your broadcast using icecast to that machine which could endlessly play the stream to the transmitter.
She is waiting in the air

Question - What compression to use for an FM Radio station

Reply #2 –
I would suggest Ogg Vorbis for this purpose, as since your high school based radio station (good work to you guys for running the station ). Vorbis for a two reasons, first its FREE and second its tuned for low bitrate applications such as the one you are using it for.

Hope it all works out for you and the radio station!

Cheers
AgentMil
-=MusePack... Living Audio Compression=-

Honda - The Power of Dreams

Question - What compression to use for an FM Radio station

Reply #3 –
mppenc --standard --lowpass 15000

Should be very transparent and the files won't be very large (150-160kbps average).

Question - What compression to use for an FM Radio station

Reply #4 –
Quote
Originally posted by mithrandir
mppenc --standard --lowpass 15000

Should be very transparent and the files won't be very large (150-160kbps average).
Or, like Artemis3 said, you could use mppenc --radio (hence the preset name... ). Quality 7 shouldn't be necessary unless you want the option of one day running a downloadable, high-quality transcoded audio stream, and even then Quality 5 (equivalent to mithrandir's commandline, without the lowpass for FM transmission) will in most cases sound flawless. Although if you do think you might someday soon host audio streams, Ogg is once again the winner, since bitrate peeling will eventually make streaming simple.

To be honest, though, if you're running the music through a telephone, you could get away with CD-Quality WMA @ 64kbps.

Unless you anticipate using a higher-fidelity distribution medium in the near future (one can always hope for his or her own high-powered radio tower), Ogg -q1 or -q2 will probably sound more than good enough.
 

Question - What compression to use for an FM Radio station

Reply #5 –
Yeah, my main concern is just storing these for archival and broadcast purposes. I don't want to have to have anyone mess around with ripping, encoding, and the whole process again, so I was thinking i'd use mpc. It sounds like my best bet would be Quality 4.5, using K-12? And were we to begin streaming, we would use... a second computer solely for this with ogg q1? (We've supposedly had talks with a server, i'm not sure) What would the switches be for mpc? Also, i'm under the assumption that --radio just means it's FM-quality, not intended for FM-use... you always want a higher quality source than your equipment, right?