Musepack Forums  

Go Back   Musepack Forums > Main > General

Thread Tools Search this Thread Display Modes
Old 05 October 2005, 10:58 am   #1
Join Date: Oct 2005
Posts: 2
Default mpc cuts off high frequencies?!

I've done spectral analyse of source FLAC file and decoded mpc - when using --insane profile, there is cut at 19kHz ..
Q-W-Y is offline   Reply With Quote
Old 05 October 2005, 11:20 am   #2
Join Date: Aug 2004
Posts: 10

Well, if the psy-model decides that it can't "hear" frequencies above 19khz in certain passages, to me it seems perfectly normal for it to cut off those frequencies.

As you can see from the 'Insane' profile definition, the maximum encodable bandwidth is set to 22khz.

 SV 7.0 + XLevel coding, Profile 'Insane'

 PCM fader                : fade-in: 0.00 s, fade-out: 0.00 s, shape: 1
 Scaling input by         : left 1.00000, right: 1.00000
 Maximum encoded bandwidth: 22.0 kHz
 Adaptive Noise Shaping   : max. 6th order
 Clear Voice Detection    : Dual
 Mid/Side Stereo          : Mid/Side Stereo when superior + enhanced (3/12 dB)
 Threshold of Hearing     : Model 570: min(Klemm,Busch), Max ATH: 64 dB, Offset:
 -12 dB, +Offset@20 kHz:-12 dB
 Noise masks Tone Ratio   :  9.5 dB
 Tone masks Noise Ratio   : 24.0 dB
 Exploitation of temporal post masking
 Minimum Signal-to-Mask   :  3.0 dB
 No deleting of input file after encoding
cane is offline   Reply With Quote
Old 05 October 2005, 02:22 pm   #3
Join Date: Sep 2005
Location: Bulgaria
Posts: 19

Most people are unable to hear these frequencies and the psychoacoustic model of MPC is designed after this. Cutting off and masking is something normal which our ears do and of course it can be seen with a FFT analysis, for example. Musepack just emulates our psychoacoustics. All these things are a part of the psychoacoustic model, which is perfectly adjusted, so the ear cannot notice differences in quality. The bandwidth switch sets the maximum frequency which can be encoded, but doesn't "enforce" the encoder to always encode up to that frequency. This switch is just a lowpass filter. The ATH determines the real bandwidth. To increase the bandwidth, if you are so pedant and want to keep these high frequencies, then you can change some settings manually. Increase the negative value of the HF offset. Changing other options like --ltq_gain (overall ATH offset) and the masking thresholds is not needed.
Generally, using values around the BrainDead profile and above will give you the same spectral picture as FLAC, but it isn't needed and in most cases even a sensitive ear won't notice anything.
So I can say, though MPC is a lossy format, you lose nothing.

Last edited by Kamen; 13 July 2009 at 10:15 am. Reason: corrected spelling mistakes and outdated information
Kamen is offline   Reply With Quote
Old 05 October 2005, 03:28 pm   #4
Join Date: Oct 2005
Posts: 2

oki, thank you ppl :P
Q-W-Y is offline   Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
My return to using MPC... Gow General 11 01 July 2006 01:02 am
tag mpc winamp5 carnut MPC for Windows 3 08 January 2006 07:50 pm
All MPC files broken after file restore deus62 MPC for Windows 3 19 August 2005 05:55 pm
low level clicks and noise davidm General 20 29 June 2005 09:05 am
WAV > MPC > WAV -- Same length? wickedwild General 1 24 January 2005 04:48 am

All times are GMT. The time now is 02:04 am.

Powered by vBulletin® Version 3.8.11 Beta 2
Copyright ©2000 - 2021, vBulletin Solutions Inc.