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Question about changing Vorbis psychoacoustic curves

I am currently using Vorbis on my studies to reduce the required amount of data for a specific acoustic signal.

This signal does not require to work within audible range, where the frequency range of interest lies below 8 kHz.

My first attempt was to remove the signals that belong to over 8 kHz by setting the frequency values for the tone masks in the masking.h file to the extreme value of -999. 

From this test, I was expecting to remove all the frequency content above 8kHz from my data, but unfortunately, that did not work as intended since my recovery data present components in the entire audible range.

I am using the encoder_example to encoded the Vorbis file, and the vorbisfile_example to decode.

Does anyone has any ideas or thoughts on how to tweak the masking tone curves from Vorbis?

Thanks in advance for your time.

Re: Question about changing Vorbis psychoacoustic curves

Reply #1
This signal does not require to work within audible range, where the frequency range of interest lies below 8 kHz.

Assuming you that you have an audible signal with no information above 8 KHz, just low pass filter the signal at 8 kHz and/or resample to 16 kHz. 

 

Re: Question about changing Vorbis psychoacoustic curves

Reply #2
Thanks for the help.

By filtering the input data I was able to reduce by 17% for lower bitrate and 28% for higher bitrate the amount of data to store the signal.

 ;D


 
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