MP3 with frequency response to 21kHz - how?!

[Xoanon]

Ive got a lot of 320kbps CBR MP3s that I have either downloaded or being sent on disc that have a frequency response all the way to 21kHz! How is this possible?! I thought MP3s rolled off material at around 16Khz.

The best high end I can get using LAME at 320kbps is around 16-17kHz maximum, with LAME's Alt Preset Extreme being the best quality I can get. With this setting, a high end of 18-19kHz is achieveable.

So how is it possible for an MP3 to contain so much information? It looks like an uncompressed CD track would, so whats the secret here?

Thank you to anyone in advance.

[vitualis]

Ive got a lot of 320kbps CBR MP3s that I have either downloaded or being sent on disc that have a frequency response all the way to 21kHz! How is this possible?! I thought MP3s rolled off material at around 16Khz.

No, that is not true.

The best high end I can get using LAME at 320kbps is around 16-17kHz maximum, with LAME's Alt Preset Extreme being the best quality I can get. With this setting, a high end of 18-19kHz is achieveable.

The issue is that you are using presets.

So how is it possible for an MP3 to contain so much information? It looks like an uncompressed CD track would, so whats the secret here?

Thank you to anyone in advance.

The reason why LAME uses a low-pass filter for many of its presets is that contrary to popular opinion, for the vast majority of audio, those high end frequencies don't add anything to the quality. LAME chooses to sacrifice the (for the large part inaudible) very upper frequency range so that bitrate is distributed to the more significant audible parts of the audio. Certainly at low bitrates, MP3s sound worse if you don't do this.

If you are a purist, then don't use the presets and encode your MP3 as plain CBR at 320 kbit/s. Look at the command line settings with LAME. You may actually have to set something to prevent the filter (I'm guessing because I haven't looked into it, but just navigate the LAME website).

Regards.

[Xoanon]

OK, so 320kb will yeild a full frequency range, but I need to change the command line options?

And how do these MP3s sound compared to the CD masters?

[Xoanon]

The best high end I can get using LAME at 320kbps is around 16-17kHz maximum, with LAME's Alt Preset Extreme being the best quality I can get. With this setting, a high end of 18-19kHz is achieveable.

The issue is that you are using presets.

No, as I said I can only get 16-17khz maximum using 320kbps. That is not a preset, thats just me setting 320k CBR in dBpoweramp.

[aedipuss]

it's not dbpoweramp or lame. using them to convert wavs i get 0-22khz checking with soundforge. i use vbr extreme settings. 192-320 kbps.

[Xoanon]

I use Alt Preset Extreme too, but only get 19kHz or so. How are you achieving your results?

[Cornucopia]

Don't have a direct answer to your question, but as an aside, make sure you have a program that goes beyond 21kHz to begin with, so you'll be able to tell the difference.

Scott

[Xoanon]

What do you mean by program?