Why are 128kbit/s MP3s usually 44,100 Hz? |
Why are 128kbit/s MP3s usually 44,100 Hz? |
 Oct 14 2012, 01:44
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#1
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Group: Members Posts: 30 Joined: 14-October 12 Member No.: 103838  |
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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Oct 14 2012, 04:03
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#2
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 Group: Members Posts: 4131 Joined: 2-September 02 Member No.: 3264 |
QUOTE (eamon123 @ Oct 13 2012, 20:44)  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? Since encoding happens in the frequency domain anyway, there isn't much savings. It'll just not encode those frequencies, which is pretty close to downsampling, but much easier to implement. That said, at very low bitrates LAME does downsample. |
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Oct 15 2012, 05:02
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#3
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Group: Members Posts: 30 Joined: 14-October 12 Member No.: 103838 |
QUOTE (saratoga @ Oct 14 2012, 04:03) Since encoding happens in the frequency domain anyway, there isn't much savings. Listen to these test files and tell me what you think (24 vs 48 kHz, both with 11.5 kHz lpf): https://rapidshare.com/files/666351554/Baba...y24.11.5lpf.mp3 https://rapidshare.com/files/2623776446/Bab...y48.11.5lpf.mp3 QUOTE (halb27) pre-echo issues get worse If you ask me the attack sounds as good in the 24 kHz file as the 48 kHz, and everything else sounds better. What do you make of it? |
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eamon123 Why are 128kbit/s MP3s usually 44,100 Hz? Oct 14 2012, 01:44
splice QUOTE (eamon123 @ Oct 13 2012, 16:44) ...... Oct 14 2012, 01:53
saratoga QUOTE (eamon123 @ Oct 15 2012, 00:02) If ... Oct 15 2012, 05:38
Dynamic QUOTE (eamon123 @ Oct 15 2012, 05:02) Lis... Oct 16 2012, 18:07 eamon123 QUOTE (Dynamic @ Oct 16 2012, 18:07) tona... Oct 17 2012, 19:31 Dynamic QUOTE (eamon123 @ Oct 17 2012, 19:31) QUO... Oct 17 2012, 21:48 halb27 QUOTE (eamon123 @ Oct 17 2012, 20:31) I... Oct 17 2012, 22:19 halb27 Compreession is more effective when using 32 kHz. ... Oct 14 2012, 08:12 slks Indeed, many encoders *do* resample for low bit ra... Oct 14 2012, 21:10 pdq A 128 kbps encoding is the same size regardless of... Oct 15 2012, 03:02 halb27 If you listen to tonal problems at 128 kbps, you... Oct 15 2012, 05:43 robert MPEG-1 Layer 3 frames consist of 2 granules a 576 ... Oct 16 2012, 18:46 Dynamic Oops, thanks Robert. If I could edit my post now, ... Oct 16 2012, 19:39 Martel The problem is - how exactly do you resample a 44.... Oct 18 2012, 15:24 halb27 Sure you can't get 16 kHz bandwidth, but somet... Oct 18 2012, 16:55 |
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Lo-Fi Version | Time is now: 20th May 2013 - 06:34 |
