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Junior Varsity
How audio is transferred through wiring.
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<blockquote data-quote="Paul Johnson" data-source="post: 217586" data-attributes="member: 2643"><p>What are you going to achieve with filtering the analogue output - that's not what digital filters do? You seem to have a basic grasp, but your analogies are a bit odd. Sound pressure is an analogue function between a source and a transducer. If a sample goes out of the range you do NOT hear a nasty distortion, it will depend on how long that distortion is maintained. You can have many thousand errors every second corrected - basically looking at the waveform and using an algorithm to put back in a sample value that is best guess. You can record an audio stream that sounds great and then when you look in an editor see huge spikes up to maximum that are very short, and totally missed. You can see errors in the data stream so that the point where the negative waveform crosses the line and goes positive gets shifted and again, these errors are often invisible to then ear. This idea of -1 and 1 sample polarities is also a red herring. Your input voltage could be .775V or 1.4V - measured as an AC waveform, peak to peak. At some point, the device has to decide what voltage = digital maximum, and of course this is usually made variable - so it's possible to record too low and too high. Full scale levels are always described as bad, because all we really want is the range between 0 and full. what constitutes full we fiddle with between brands and device types. We even get it more confused when we talk about balanced inputs because these swing either side of the 0V crosspoint, but an unbalanced signal also exhibits this swing, but gets measured differently. I've read so many articles on the A-D-A process at GCSE to PhD level that's easy to spot how difficult the entire concept is, because the basic function of chopping up, recording the level and reconstituting is quite simple - the problems come from the noise created by the stepped waveform that creates harmonics that need removing with usually filters. That's when it gets tricky!</p></blockquote><p></p>
[QUOTE="Paul Johnson, post: 217586, member: 2643"] What are you going to achieve with filtering the analogue output - that's not what digital filters do? You seem to have a basic grasp, but your analogies are a bit odd. Sound pressure is an analogue function between a source and a transducer. If a sample goes out of the range you do NOT hear a nasty distortion, it will depend on how long that distortion is maintained. You can have many thousand errors every second corrected - basically looking at the waveform and using an algorithm to put back in a sample value that is best guess. You can record an audio stream that sounds great and then when you look in an editor see huge spikes up to maximum that are very short, and totally missed. You can see errors in the data stream so that the point where the negative waveform crosses the line and goes positive gets shifted and again, these errors are often invisible to then ear. This idea of -1 and 1 sample polarities is also a red herring. Your input voltage could be .775V or 1.4V - measured as an AC waveform, peak to peak. At some point, the device has to decide what voltage = digital maximum, and of course this is usually made variable - so it's possible to record too low and too high. Full scale levels are always described as bad, because all we really want is the range between 0 and full. what constitutes full we fiddle with between brands and device types. We even get it more confused when we talk about balanced inputs because these swing either side of the 0V crosspoint, but an unbalanced signal also exhibits this swing, but gets measured differently. I've read so many articles on the A-D-A process at GCSE to PhD level that's easy to spot how difficult the entire concept is, because the basic function of chopping up, recording the level and reconstituting is quite simple - the problems come from the noise created by the stepped waveform that creates harmonics that need removing with usually filters. That's when it gets tricky! [/QUOTE]
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How audio is transferred through wiring.
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