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Topic: LAME 3.98b3 and 16KHz filter CBR and Stereo (Read 6009 times) previous topic - next topic
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LAME 3.98b3 and 16KHz filter CBR and Stereo

Hello. I'm new to these forums. I'm going to dive right in because I have a question about LAME CBR and stereo and lowpass filter of 16 KHz.

Over the last week, in my spare time, I have been ripping (re ripping) my large CD collection to MP3 using EAC, LAME 3.98b3, and AccurateRip, as usual. Due to having some hardware that prefers CBR over VBR, I've ripped to CBR 256 instead of VBR, and... I've also used the -m s switch so that I have stereo MP3s instead of JS ones (that was just my choice and I don't really want to get into a which is better thing).

Anyhow, after album 40ish I thought I'd better start listening to a few albums via my headphones before I actually got into doing any more (a couple of thousand) and although I was happy with the rips, there was something about the sound that I couldn't put my finger on. Don't get me wrong, I'm generally happy with the sound, given it is MP3 format, and being able to plug a flash drive or SD card into my car stereo and play my MP3s where ever I go is excellent. But there was something still not there that I couldn't put my finger on.

Anyhow, I whacked a few Mp3s into Adobe Audition and checked them using the frequency analysis, and I immediately noticed that the sound dropped off at 16 KHz. Now after poncing about for a while using different LAME parameters (like -V0 --vbr-new) I discover that this 16 KHz filtering occurs using CBR with the stereo switch -m s. The VBR rips all drop off at 19 KHz. So I thought I'd try changing the lowpass manually using the --lowpass switch but that had no effect at all.

Does anyone know:

1) why all my CBR 256 rips in stereo mode drop off at 16 KHz instead of 19, like with VBR rips?

2) how to change the lowpass filter, to increase it 19 KHz?

I realise that a lot of people won't see any point in doing this, due to ATH, and age considerations, etc., and from what I've read here already there are some that would *passionately* discourage fiddling, but I'd still appreciate some help.


Thankyou.

Simon

LAME 3.98b3 and 16KHz filter CBR and Stereo

Reply #1 –
Either your LAME compile is broken, or your parameters are wrong.
My LAME 3.98b3 from rarewares does fine with -b 256 -m s. Lowpass @19.7kHz; checked with EncSpot pro and Voxengo SPAN.

LAME 3.98b3 and 16KHz filter CBR and Stereo

Reply #2 –
Quote from: Polouess on
Either your LAME compile is broken, or your parameters are wrong.
My LAME 3.98b3 from rarewares does fine with -b 256 -m s. Lowpass @19.7kHz; checked with EncSpot pro and Voxengo SPAN.


My LAME parameters aren't wrong, my compile is also from rarewares, and EncSpot pro also *reports* the correct lowpass filter. However, check those same Mp3s using frequency analysis and you will see the 16 KHz drop off as clear as day. Check a VBR rip and the drop off is clearly 19KHz.

LAME 3.98b3 and 16KHz filter CBR and Stereo

Reply #4 –
I just ran a test using the latest beta3 with cbr 256 and --lowpass 19700, then looked at the spectral view in Audition and got exactly what was expected.

LAME 3.98b3 and 16KHz filter CBR and Stereo

Reply #5 –
Without a sample, and without knowing which genre the music is, the only thing that I can add to what has been said already is that the encoder doesn't have enough bits to encode more than that. Of course, if this is the case, the frequency cutoff should not be a flat line.

If it really is a flat line, check your CD. The cutoff almost 100% sure is there.

LAME 3.98b3 and 16KHz filter CBR and Stereo

Reply #6 –
Quote from: john33 on
I just ran a test using the latest beta3 with cbr 256 and --lowpass 19700, then looked at the spectral view in Audition and got exactly what was expected.



Hmm, okay then. I'll re download the b3 version from your site.

But I suspect I'm being directed to the obvious? ;-) That maybe the differences I'm seeing (in the spectral analysis) and hearing (via my headphones)  between VBR and CBR are simply an indication of the quality difference between VBR and CBR. Always used VBR before now. If it wasn't  for the hardware probs with VBR I'd stick with it.

Well it's not exactly critical anyway. I'm over forty and although I'd like to think that I can still hear a pin drop a hundred yards away, realistically my ears aren't anywhere near as good as they used to be so what the heck. I can always listen to the original CD if I want the best sound quality :-)

--edit and no, it isn't a flat line on any of the mp3s (mixed genre)

LAME 3.98b3 and 16KHz filter CBR and Stereo

Reply #7 –
Quote
Over the last week, in my spare time, I have been ripping (re ripping) my large CD collection to MP3 using EAC, LAME 3.98b3, and AccurateRip, as usual. Due to having some hardware that prefers CBR over VBR, I've ripped to CBR 256 instead of VBR, and... I've also used the -m s switch so that I have stereo MP3s instead of JS ones (that was just my choice and I don't really want to get into a which is better thing).


Just thought using a new compile for your whole collection was kind of risky. As far as i know, LAME 3.97 is the stable release. Might want to rethink this. 

cheers,
herefornow
cast out...

LAME 3.98b3 and 16KHz filter CBR and Stereo

Reply #8 –
It's not a simple lowpass, but CBR always behave this way. As it doesn't consider sfb21 to compute bits needed, you will only have content in the sfb21 if it's cheap enough.

LAME 3.98b3 and 16KHz filter CBR and Stereo

Reply #9 –
Haha ! That will shatter countless cbr 192 .. 256 'stereo' freaks out there. They have been Ultra-HF deprived.. well unless they used -k.
 

LAME 3.98b3 and 16KHz filter CBR and Stereo

Reply #10 –
Quote from: Gabriel on
It's not a simple lowpass, but CBR always behave this way. As it doesn't consider sfb21 to compute bits needed, you will only have content in the sfb21 if it's cheap enough.



Okay, thanks for the reply. I'll just forge ahead regardless in that case... or buy some better hardware and go back to VBR.