Custom Cutoff for OPUS

[rnie sura]

Hey there experts! I've got meself into a little dilemma. I'm encoding an audio from Bluray

Source:

Audio
Format : DTS XLL
Format/Info : Digital Theater Systems
Commercial name : DTS-HD Master Audio
Bit rate mode : Variable
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 48.0 kHz
Frame rate : 93.750 FPS (512 SPF)
Bit depth : 24 bits
Compression mode : Lossless

[Attachment 77860 - Click to enlarge]

I wanna set cutoff 18khz cuz I wanna get rid of that noise so that Opus's VBR doesnt allocate bits to high freq information
How to set a custom cutoff?

[Brazil]

The noise is dither, it helps to avoid quantization errors. At -110 dB and such high frequencies you can't hear it anyway.

[pandy]

The noise is dither, it helps to avoid quantization errors. At -110 dB and such high frequencies you can't hear it anyway.

Technically it is noiseshaped dither and still it is not recommended to keep it in lossy compressed audio.

[pandy]

I wanna set cutoff 18khz cuz I wanna get rid of that noise so that Opus's VBR doesnt allocate bits to high freq information
How to set a custom cutoff?

Depends on tool you are using to encode - seem opus encoder do to allow to specify low pass filter so other tool need to be involved - in ffmpeg this should be possible without problem.
btw - this noiseshaped dither looks strange - seem to be incorrect - it looks like modulated by signal i.e. wrong.

[rnie sura]

I wanna set cutoff 18khz cuz I wanna get rid of that noise so that Opus's VBR doesnt allocate bits to high freq information
How to set a custom cutoff?

Depends on tool you are using to encode - seem opus encoder do to allow to specify low pass filter so other tool need to be involved - in ffmpeg this should be possible without problem.
btw - this noiseshaped dither looks strange - seem to be incorrect - it looks like modulated by signal i.e. wrong.

Noise profile is straight from the source (DTS-MA). Also I found a solution. Instead of using a custom cutoff (which OPUS doesnt allow). I first converted dts into flac with sox using sinc 23.5k-16.5k to remove all the noise. it helped reducing the size of course, then I converted to OPUS 256k for stereo and 448k for 5.1 audio.

[rnie sura]

I wanna set cutoff 18khz cuz I wanna get rid of that noise so that Opus's VBR doesnt allocate bits to high freq information
How to set a custom cutoff?

Depends on tool you are using to encode - seem opus encoder do to allow to specify low pass filter so other tool need to be involved - in ffmpeg this should be possible without problem.
btw - this noiseshaped dither looks strange - seem to be incorrect - it looks like modulated by signal i.e. wrong.

i've tried various lowpasses, it doesnt work. it only reduces the dither by some dB, not completely eliminate it