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Topic: Weird Vorbis stream from aoTuV (Read 1421 times) previous topic - next topic
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Weird Vorbis stream from aoTuV

Hello. Wanting to get a bit higher cutoff than what --managed -m 48 -M 48 --resample 44100 gives (aoTuV, this is to trick the encoder into encoding in CBR and it also results in higher cutoff but still lower than what I want), I added --bitrate 128 to the command planning to increase or decrase this value until I hit the cutoff I want, but this confused aoTuV so bad (examples attached, originals are from Kamedo2).

Why did this happen? And how can I encode good Vorbis streams with cutoff being about 15.5kHz with as low as 48kbps or even lower bitrates? (I accept suggestions for encoders other than aoTuV too - The first command has cutoff at 14kHz.)

Re: Weird Vorbis stream from aoTuV

Reply #1 –
This appears to be a serious problem, why nobody answered?

Re: Weird Vorbis stream from aoTuV

Reply #2 –
It's not a serious problem, there is no provision for the user to define the 'cutoff'. You've told the encoder you want a min. bitrate of 48k, a max. bitrate of 48k, and then told it to average at 128k! No wonder it's confused. The level of control you are trying to exercise doesn't exist in oggvorbis.

Re: Weird Vorbis stream from aoTuV

Reply #3 –
Isn't there an easy way to get Vorbis streams with higher than default cutoffs? Is it so hard to tweak aoTuV to simply have a switch for cutoff/lowpass frequency?

Re: Weird Vorbis stream from aoTuV

Reply #4 –
It's not a user definable option, so no. The whole tuning of the encoder is based upon the limits set within the code. Any changes will almost certainly lead to lower quality unless the the encoder is 're-tuned'. You're trying to operate outside the parameters available.

Re: Weird Vorbis stream from aoTuV

Reply #5 –
I really want to do that, can you tell me how can I compile aoTuV? (I'm planning to try assigning 15.5 to some variables in some places but if you know the exact change to be done, I'll be happy to know that too.)

Re: Weird Vorbis stream from aoTuV

Reply #6 –
I'm sorry, I seem to be having a 'senior moment'! If you download oggdropXPd, aoTuV' variant from rarewares, you will find an option to set a lowpass value on the 'encoding' tab. No idea how titghtly it's applied, but give it a go. Compiling is easiest done with MSVS Community edition, freely downloadable. The aoTuV modified vorbis code is here: https://github.com/AO-Yumi/vorbis_aotuv/releases/tag/beta6.03-2020. You will also need the ogg and vorbis-tools code. It's not too difficult, but non-trivial if you're not familiar with the tools.

Re: Weird Vorbis stream from aoTuV

Reply #7 –
oggdropXPd worked for me with this case (down to 48kbps fullband/superwideband, I didn't try all until nyquist yet) - thank you very much, but with clicks above the cutoff (spectrogram image attached). I expect them to be inaudible but I still don't want them, do you know how can I not have them?

Re: Weird Vorbis stream from aoTuV

Reply #8 –
Quote from: Klymins on
oggdropXPd worked for me with this case (down to 48kbps fullband/superwideband, I didn't try all until nyquist yet) - thank you very much, but with clicks above the cutoff (spectrogram image attached). I expect them to be inaudible but I still don't want them, do you know how can I not have them?
Sorry, I have no idea. The inner workings of these things are way above my pay grade! ;)

Re: Weird Vorbis stream from aoTuV

Reply #9 –
Quote from: Klymins on
clicks above the cutoff (spectrogram image attached). I expect them to be inaudible but I still don't want them, do you know how can I not have them?
Try to do  "pre-cutoff" with some separate lowpass filter.
 

Re: Weird Vorbis stream from aoTuV

Reply #10 –
Quote from: Bogozo on
Quote from: Klymins on
clicks above the cutoff (spectrogram image attached). I expect them to be inaudible but I still don't want them, do you know how can I not have them?
Try to do  "pre-cutoff" with some separate lowpass filter.

For reference, this destroys the audible quality when the codec uses SBR (or that's what I saw so far). Vorbis doesn't of course but I'm still not really comfortable with this. Thanks.