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Why are 128kbit/s MP3s usually 44,100 Hz?
eamon123
post Oct 14 2012, 01:44
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Since 128kbit/s MP3s usually has a low-pass filter at 16,000 Hz, and the Nyquist-Shannon theorem states that all frequencies under f/2 Hz can be totally described at an f Hz sampling rate, why not encode at 32,000 Hz? Wouldn't it save more space?
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slks
post Oct 14 2012, 21:10
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Indeed, many encoders *do* resample for low bit rates. I've never seen any that do it at 128 kb/s, but once you drop below 100 kb/s it's more common. I forgot exactly where it kicks in with LAME, but LAME does this if you set the quality low enough (V6 maybe? V7?)


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