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u-law
Neuron
post Dec 16 2012, 01:50
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How come u-law was not used with high sample rates in the old days of computing? A quick search here says u-law is not good for sampling above 16 khz because of high frequency distortion, but when I encoded a 320 kbps mp3 44.1 khz into an 8-bit u-law 44.1 khz format it actually sounded quite ok especially compared to 8-bit linear PCM and even 4-bit ADPCM. So how come it was not used in games and multimedia at good sample rates before mp3 came? I understand that it distorts the sound slightly however this distortion is much less hearable on my samples created with audacity than in the same sample encoded to either linear 8-bit PCM or 4-bit ADPCM. And that encoded music was a 1980s OMD track with high dynamic range, not a modern day overcopressed/clipped sample. I am kind of interested in old formats and computing, so that's why I'm asking. I would insert short sound samples, but I don't know how to add them on this forum.

EDIT - I uploaded some sample files here http://www.hydrogenaudio.org/forums/index....showtopic=98358 .

This post has been edited by Neuron: Dec 16 2012, 02:09
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psycho
post Dec 18 2012, 19:47
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A little something more to read regarding CPU usage (namely cache). I'm not saying this means that μ-law was too much for CPUs from back in the day, I'm just linking to something I found and might be interesting for this discussion.


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Neuron
post Dec 29 2012, 02:22
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QUOTE (psycho @ Dec 18 2012, 19:47) *
A little something more to read regarding CPU usage (namely cache). I'm not saying this means that μ-law was too much for CPUs from back in the day, I'm just linking to something I found and might be interesting for this discussion.


Thanks but I think the CPU usage would be high only on primitive microcontrollers, considering televisions since early 1990s were able to decode NICAM http://en.wikipedia.org/wiki/NICAM easily, and NICAM is basically a much better form of what u-law is (10 to 14 bit companding instead of 8 to 12, adaptively increasing or decreasing bit rate etc.). Most 8-bit samplers of the 1980s also used conpanding. In PC situations, it would really help sample storage in the Sound Blaster 16 era as many games back then used raw 8-bit samples that could have sounded a lot better with u-law/other companding algorithms.
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