why does bitrate reduction lead to loss of highs?
Posted on May 23, 2007 06:20 am
Member Since: Jan 18, 2003
when you upload to myspace, i think it re-encodes your song and brings the bitrate down. you can always hear a reduction in the highs. why does this reduction to the highs happen, and why to 'real bands' seem to get around this?
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May 23, 2007 07:33 am Most any form of compression seems remove the extreme highs and lows first and move more toward center the more the compression is applied. MySpace likely does this to shrink file size in order to save bandwidth and disk space and increase performance, since many users have music start playing on page load (which makes me leave, personally). Why compression works like that I can't tell you...what I CAN tell you is that HRC does NOT recompress or reprocess uploads in any way, shape or form. :-)
May 23, 2007 07:47 am Common sense tells me:
Highs = smaller wavelength + more detailed = needs more samples to reproduce 1 second timeframe
Lows = Longer wavelength + less detailed = needs less samples to reproduce 1 second timeframe
Therefore the easiest way to cut file size is to use less samples (accuracy) in HF's.
'Real bands' have mixes focussed around mid frequencies. Also the louder it is, the more bits your using.
TadpuiI am not a crook's headMember
May 23, 2007 11:11 am I agree dB, HRC has the highest fidelity user music around. I usually use either 160 kbps or 192 kbps for my music, and I've always appreciated the fact that our player here does not "dumb down" the bitrate like the other music sites do.
Since: Mar 14, 2003
As a point of interest, when I signed up for MySpace, one of the calling points was "no compression on your music!". Pfffft. Total Bullshit.
May 24, 2007 08:32 pm Thanks there CS.. that explains a lot! No wonder same thing happens when encoding to a lower bit rate mp3 format. Thought it was all from low quality dithering.
Since: May 15, 2004
WaltChief Cook and Bottle WasherMember
May 25, 2007 09:34 am Gotta ditto CS,
Since: May 10, 2002
Rule of thumb per sample rate has always been publisized as 2X highest frequency to be reproduced. That is where 44.1 came from, roughly 2X 20Khz top of hearing range avg. That holds a thread of truth. Most folks can hear the difference between 44.1 and 48. 96, I don't know, haven't done any yet.
Per comment on 'real' bands or If I may be so bold 'well funded bands', I'm sure they take the time and effort to create a mix and master for each media they will be using e.g. radio, myspace, etc. CS is right. Most radio play stuff has a big frown eq on it to better match the bandwidth of the media. And then theres wav vs mp3. Infered sound. Yikes!
RunicenDuke of Stewed PrunesMember
Jun 01, 2007 08:16 pm One thing that may have something to do with what you're hearing with compression (and I'd be surprised if anybody would argue that high frequency information was preserved at lower encoding rates...) is that high frequency information - pitch in particular - is something our ears are, by default, a lot more sensitive and perceptive towards than low frequency information.
Since: Jun 01, 2007
While I have no interest in lab trials to test out this theory, it would probably stand to reason that low freq sounds are altered to a similar (if not the same) degree, but we simply can't hear the difference as readily.
Jun 03, 2007 02:46 pm Walt hit the Nyquist theorum right on! Good response. Bit rate deals with dynamic range and sample rate deals with frequency response. When recording at 44.1khz the highest frequency you can record accurately is 20,050hz. Anything above this may produce aliases or false frequencies that are above the Nyquist frequency and got converted.
Jun 03, 2007 03:56 pm Recording at 44.1KHz, a 20KHz sine wave looks like a triangle wave. A triangle wave and a sine wave do not sound the same. The A/D can only collect 2 samples (if that, errors happen all the time), and 2 samples is hardly enough to approximate a sine wave. I call the sound "brittle". You can really hear the difference when you record at 88.2KHz or higher. Much smoother, cleaner highs...
Jun 28, 2007 02:21 am how did i get the above post ^^^ in my e-mail?
said it was from email@example.com
Noize2uCzar of MidiAdministrator
Jul 01, 2007 12:13 am did you click the subscribe to thread button?
Since: Apr 04, 2002
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