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Topic: mp3 with 20~22.1 kHz ? (Read 7345 times) previous topic - next topic
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mp3 with 20~22.1 kHz ?

I found a mp3 file which has perfect spectral frequency even in 20~22.1 kHz.
However, when I tried to encode with lame -b 320, I loss almost over 20kHz.
How can I get encode to mp3 with 20~22.1 kHz?
Is there a special option for Lame? or other encoder?

Don't say you don't need so high frequency part.
When I checked my ear, I could hear 21.4 kHz. (Yes I'm young lol)

mp3 with 20~22.1 kHz ?

Reply #1 –
Quote from: dltbxkf on
When I checked my ear, I could hear 21.4 kHz. (Yes I'm young lol)



Lucky you.  The problem for an encoder is that as bits are scarce they are nearly always best spent encoding lower frequencies where there is more signal.  Try upping the bit rate until the very high frequencies reappear.

mp3 with 20~22.1 kHz ?

Reply #2 –
Quote from: dltbxkf on
When I checked my ear, I could hear 21.4 kHz. (Yes I'm young lol)
As a single tone, maybe. In a complex music signal? Extremely unlikely!

Carry out an ABX test to find out what you actually need before jumping to conclusions.

Cheers, Slipstreem. 

mp3 with 20~22.1 kHz ?

Reply #3 –
We hear with our ears, not our eyes.

Pick some tracks out of your collection and see if you can distinguish a lossy encoding from the original lossless source with a blind test.  Increase the bitrate until you can longer tell the difference between the two.  I recommend starting with Lame 3.98 -V5.

There is far more involved in lossy compression than frequency response.

mp3 with 20~22.1 kHz ?

Reply #4 –
Quote from: dltbxkf on
Don't say you don't need so high frequency part.


Why would we say something like that which is the truth?  Don't agree with us?  Provide your blind ABX test results that say otherwise.  Also conduct listening tests to determine if you can actually hear frequencies of music (not just single notes/sounds) up that high.  There is a world of difference trying to hear single tones/notes/sounds that high and actual music (a song with multiple parts) at frequencies those high.

Also, as greynol pointed out, lossy encoding involves much more than just looking at the frequencies.

mp3 with 20~22.1 kHz ?

Reply #5 –
Ok, guys. Let's suppose that I cannot find any diffrence the musics.
I just want to know, since I found the mp3 file with 20~22.1 kHz frequencies.
Just curious.

How can I get encode to mp3 with 20~22.1 kHz?
Is there a special option for Lame? or other encoder?

mp3 with 20~22.1 kHz ?

Reply #6 –
Yes.

Cheers, Slipstreem. 

mp3 with 20~22.1 kHz ?

Reply #7 –
the --lowpass option. check lame.exe --longhelp in your CMD.
try --lowpass 22 (=22kHz)

You could also try the -k option. This one sets lame to do no lowpass filtering at all.

BTW which mp3 analyzer brought you the information about lowpass frequencies?
FB2K,APE&LAME

mp3 with 20~22.1 kHz ?

Reply #9 –
Correct me if I'm wrong, greynol. I used the lowpass switch in the 3.90.3 times. Worked well.
FB2K,APE&LAME

mp3 with 20~22.1 kHz ?

Reply #10 –
It's not going to do what you want with 3.98.  I just tried it with -k and am happy to see the switch didn't do anything but prompt for a much deserved chastisement.

...but since we're going backwards in time, I say we point the OP to Blade.

In all seriousness though, if it's frequency response you're after mp3 is not where you want to go.

mp3 with 20~22.1 kHz ?

Reply #11 –
But bearing in mind that the OP says...
Quote from: dltbxkf on
Ok, guys. Let's suppose that I cannot find any diffrence the musics.
...followed by...
Quote
How can I get encode to mp3 with 20~22.1 kHz?
...it seems to me that he has absolutely no interest whatsoever in finding out whether it's actually necessary for his needs and wishes to abuse the MP3 format out of wilful ignorance, and if he has no interest in learning anything then I have no interest in teaching him anything.

On the basis that we've been here a hundred times before on HA and it nearly always leads to at least some of us ranting at the OP, this is the point where I step down before I ruin someone's day.

Cheers, Slipstreem. 

mp3 with 20~22.1 kHz ?

Reply #12 –
@dltbxkf
As far as i know the actual lame encoder cannot achieve full frequency range.
If you think you need it you may change to another mp3 encoder on high bitrates (fraunhofer mp3 should give what you want) just to alloy your conscience .
But you will probably have other more annoying effects than a loss of an in most cases inaudible frequency range...

If you want to achieve best quality at all - without frequency cut or artifacts - you should think about changing to lossless encoding (FLAC, WavPack, Monkey Audio etc.).

mp3 with 20~22.1 kHz ?

Reply #13 –
I don't ignore you.
If you feel like that I apologize to that.
I understand that it's not a good idea to encode high frequency.

My problem is...
I thought mp3 with 20~22.1 kHz cannot exist.
But I found it.
It stimulate my curiosity. Since it beyonds my knowledge.
How could it happen?

mp3 with 20~22.1 kHz ?

Reply #14 –
lame 3.97 will happily encode a tone sweep all the way up to 22.05kHz, simply with

lame -b320 -k tone_seep.wav

It will probably choose to dump higher frequencies with real music though. You can make this less likely by disabling the ath, and even less likely by disabling the psy model altogether. You might need an alpha build to get access to these switches, if they're still in there at all.

This will completely wreck the quality - yes, you'll be able to see the high frequency content on the graph, but the resulting file will have lots of extra noise within the audible range, and it'll sound terrible.

Since a "good" mp3 file only has about 25dB SNR within the most audible range, it's very silly to force the encoder to reduce quality even further in that most audible range by using precious bits preserving frequencies that are inaudible in real music. The best approach is to let the encoder use the lowpass filter that it thinks best. If you don't even trust the encoder to do that properly, you should be using lossless, not mp3.


btw, most sound cards, speakers and headphones mess up higher frequencies anyway - it's not necessarily 21kHz you're hearing when you play a 21kHz tone through your system, though it could be if you have an excellent system, excellent hearing, and play it very loud. Such listening levels, especially with high frequency content, can destroy the tweeters in your speakers almost instantly.

Cheers,
David.

mp3 with 20~22.1 kHz ?

Reply #15 –
AFAIK the Lame psymodel is limited to 20kHz, there is none or very little energy encoded above that frequency. It might be able to encode a sweep (but I doubt it) but there won't be anything with real music.

If you really want to fill the spectrum, try Helix mp3 encoder from rarewares.

Edit: Woops it does not work. Lame 3.93.1 with "alt-preset insane -k" does work.

mp3 with 20~22.1 kHz ?

Reply #16 –
try fhg if you want to see fuller graphs across the spectrum up to 22khz, even if you cannot distinguish a -V0 lame encode from a VBR 100 fhg.
"Listen to me...
Never take unsolicited advice..."
 

mp3 with 20~22.1 kHz ?

Reply #17 –
Quote from: jmartis on
AFAIK the Lame psymodel is limited to 20kHz


Yes, even when I set --lowpass 21, 22, etc, the encoder limits it to 20.5 khz. This only happen in Lame with nspsytune psymodel (3.94a to 3.98). If you use an older version of lame (say 3.93) it will enocde up 22 khz.