Author Topic: highest possible quality resample filter (plugin)  (Read 1991 times)

hiccup

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Be that as it may, your response has the potential to leave us in the dark when it comes to the question of upsampling…
…when iFriend has already confirmed that he hears sound degradation…

I have been trying to shed some light on things by explaining that MusicBee uses Bass as the audio engine, and that Bass will also take care of the upsampling part.
I am not saying input from MusicBee's developer couldn't shed extra light on the matter, but for as far as I read this thread there are two things going on here:

1. What the technical details of the upsampling algorithm that MusicBee uses are.

2. A user stating that he heard a clear difference using 'another' upsampler.

The first item should be asked to the Bass developer, using the Bass forum. (I gave a link to that before)
And if anyone is convinced that Bass is using an inferior method of upsampling, it would be good if he would then present any assumed flaws, and suggest possible improvements to the Bass developer (un4seen).

The second item should be substantiated a bit better to have any chance of being a benefit to other MusicBee users.
What upsampler? How was testing done exactly? Is it available in any way or form so that it has a reasonable chance to be used by MusicBee as e.g. a plugin?
 (and to be factually correct; he did not say that there was a 'sound degradation', he said that he could hear a 'clear difference')

About the technicalities of upsampling and discussing them here, I agree with what Sveakul just said:
Discussions on the technical details, usefulness, purposes or differences between upsampling methods are best to be had on fora that pertain to the technicalities of audio.
There are many fora that are frequented by, and contributed to by audio professionals that have experience and expertise on such matters.
The quality of both the discussions and the answers about something like resampling will likely be higher there.
Last Edit: May 27, 2022, 07:29:50 PM by hiccup

ikonomov

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I have been trying to shed some light on things by explaining that MusicBee uses Bass as the audio engine, and that Bass will also take care of the upsampling part.
Perhaps I should have been more concise and clear about exactly what I'm asking.  Most sound libraries allow parameters to be set when implementing them into a program.  I know for a fact that some resampler libraries do not and only have a default setting.  I tried to look this up in the BASS documentation and I could not find it, yet according to this post that I've linked already (http://www.un4seen.com/forum/?topic=17860.msg125464#msg125464) it leads me to believe that 1. the ASIO output can be configured with two different resamplers and 2. the resampler that BASSmix uses can likely be further configured via BASS_ATTRIB_SRC attribute.  Those 2 things must be configured in MB as the library was implemented.  This is specifically what I'm asking and hopefully somebody knows and can answer before we can try to find more information about the resampler in the un4seen forum.

Steven

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i havent read through all of this thread but just to confirm MB configures bass to use the highest quality setting available and secondly, some time ago the bass developer upgraded the re-sampling algorithm so any comparison tests done a long time ago are no longer applicable

ikonomov

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i havent read through all of this thread but just to confirm MB configures bass to use the highest quality setting available and secondly, some time ago the bass developer upgraded the re-sampling algorithm so any comparison tests done a long time ago are no longer applicable
Thank you Steven!

ikonomov

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According to the documentation http://www.un4seen.com/doc/#bass/BASS_ATTRIB_SRC.html the highest resampling quality setting is 4 which uses 64 point sinc interpolation.  The documentation is quite limited and there is no mention about the type of filter used.  I've posted my question here https://www.un4seen.com/forum/?topic=19778.0 so hopefully we get a bit more information.

ikonomov

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Thanks to information provided by Ian Luck, the developer of BASS, the resampler's quality with BASS_CONFIG_SRC=4 (maybe Steven can confirm) should be pretty close to the results from "iZotope RX 8.1 (Default)" that has been tested at http://src.infinitewave.ca/.  Here it is compared to SOX with VHQ Linear Phase setting that can be considered a reference.





Unless somebody specifically tests BASS with the setting that MB uses we can't be 100% sure, but if those results give some sort of approximation, it looks practically flawless.

hiccup

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Unless somebody specifically tests BASS with the setting that MB uses we can't be 100% sure, but if those results give some sort of approximation, it looks practically flawless.
I was curious how you meant 'flawless'.

Do you mean both resemble a lot?
(passband and transition are a bit different though)

I am assuming you don't mean 'technically' perfect?
There is no such thing as 'perfect' where it concerns re-sampling.
It will always involve choices of methods of filtering, that each have their own strengths and weaknesses.

In Izotope you can adjust a lot of the filtering aspects yourself to match any personal preference:



Another important filtering choice is to use linear vs. minimum phase filtering.
One is technically more correct, the other may 'sound better' sometimes.

While there may exist mediocre resamplers, most these days are pretty good.
But as soon as you decide to use one you will have to accept that you are altering the original signal, and it will be subjective for every person and situation if it makes any sense to do so.

PS
I am guessing I am not telling you anything you didn't already know.
But other—less technically savvy—users may be following this topic, and they might get the impression that upsampling can be 'perfect', or that it will undisputably improve things.

ikonomov

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Indeed.  This is why I said "practically flawless".  I inserted the "practically" in there in an attempt not to rattle the cage of the kind of audiophiles that must find this discussion suffocating.  As for the technicality of being flawless, such a concept cannot exist for audio in general and also specifically when it comes to DA converters that oversample because we want them to.  I personally started to use upsampling recently (for lower than 96kHz sources) simply for convenience because of my setup and that is it.  When upsampling an easy way to ruin the quality of audio is to use bad resamplers, since they do exist, and the reason why I've taken an interest in the resampler used by MusicBee.

hiccup

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Indeed.  This is why I said "practically flawless".
I apologise. I should have included 'practically' when I made a reference to what you wrote.

hiccup

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…in an attempt not to rattle the cage of the kind of audiophiles that must find this discussion suffocating.
Feel free to rattle all the cages that you want.
I'm not sure what 'audiophiles' you think that would find this discussion 'suffocating'.
If suffocated audiophiles exist (and are reading this topic), they would be welcome to join the discussion and speak for themselves.

Facts should be leading in all this.
And where facts can't be provided, let's just call everything else personal and subjective opinions.