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Old 04 September 2003, 22:45   #1
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Cybiko 8SVX player in C

This is driving me insane. I'm trying to write an IFF-8SVX sample player for the Cybiko (budget PDA) in C, but cannot get the samples to play back properly.

So far, the Cybiko loads the file, but it plays back noise. The problem is (I think) that I don't actually know what the data in the sample represents.

I've found descriptions of the IFF file format, and the body of the file (the sample data itself) apparently consists of signed bytes - values between -128 and 127.

What do these signed bytes represent? At the moment, I'm treating each byte as a frequency, and playing a sound at that frequency (the actual playback frequency is arbitrary, but relative to all other sounds played back, so in theory I should get something that sounds at least vaguely like the original sample). This appears to be completely wrong.

I've looked around on Google, the Aminet, and everywhere else I can think of looking, but have come up with very little. Does this have anything to do with PCM? Do I need to decode the PCM stream, or something? Or is it something to do with cycles? I remember from my OctaMED and Blitz Basic days that the Amiga tends to use "cycles", such as "428" for middle-C, instead of Hz. Is the same true of IFF samples?

The samples I'm working with aren't compressed, so I don't think that's an issue.
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Old 05 September 2003, 03:36   #2
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Each byte represents a sample of the waveform in time. This should be played out as a stream of data in the Cybiko's output format.

I'd strongly suggest that you read up on digital samples before proceeding any further as you've completely got the wrong end of the stick about how it works.

Don't search for IFF or anything like, just serach for digital audio.
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Old 05 September 2003, 10:30   #3
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Digital audio, eh? I'll have a look around for that. Thanks for the info!
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