What is the sinc resampling/interpolation?

jmkz · September 27, 2009, 17:13:43

Hello, i've found in many trackers the feature of sinc interpolation (such XMPlay) and some people says the sinc resampling is "perfect". :?: Can someone tell me how it works and (if possible) why OpenMPT don not has this funcion? Thanks.

psishock · September 27, 2009, 18:46:31

QuoteBeware when using organic or bad shaped samples. They may have a perfect effect during play in the editor, when you use Arguru's sinc interpolation, the sample may sound very different from the generated wave-file. Listen to the two examples:

Cubic rendered
vs.
Arguru rendered

QuoteNotice the different sounds between the two mp3-files. Though they use the exact same sample and the exact same bitrate and frequency, the interpolation changes the sample-structure drasticly enough to create these differences. So try cubic interpolation first as well as the current frequency rate your sound-card is currently set to, to play your samples....

so basically "perfect" is yet again a huge overstatement, it clearly depends on the situation. Chiptunes example or lot of "interesting" samples needs those noise and high frequencies to sound nice and bright (without them, they sound muddy). I cant really agree with the "bad shaped samples" statement in the quote, let the composer decide what feels natural for his ears, there are no general ways to determine what is good or bad in this case. You simply cant do "perfect" interpolation. Personally i wouldn't use any interpolation at all, but only on those samples individually, that feels bad as they are (or use different ones), and avoid any algorithms on full songs, if possible.

g · September 27, 2009, 19:36:46

Quote from: "psishock"it clearly depends on the situation.

Well yes, if you *want* distortion coming from bad interpolation it would be stupid to then render the track with good interpolation. The problem with sinc as I see it is that you can't really use it in real-time.

psishock · September 27, 2009, 20:05:20

Quote from: "g"Well yes, if you *want* distortion coming from bad interpolation it would be stupid to then render the track with good interpolation.

I would put it in different way, basically it's the interpolation that distort the sample (applies mathematical algorithms), so i don't want any of that, but play the sample as it is.

g · September 28, 2009, 05:42:21

Quote from: "psishock"I would put it in different way, basically it's the interpolation that distort the sample (applies mathematical algorithms), so i don't want any of that, but play the sample as it is.

Actually sinc is closer to playing back the sample "as it is", but you want to keep the distortion added by the resampling technique you use at playback. And there's nothing wrong with that.

psishock · September 28, 2009, 12:16:44

I admit, that your knowledge of the interpolation must be a lot greater than mine. I'm aware that renoise applies cubic interpolation on the editor level no matter what, but i thought that ompt does not applies any, if you switch it off. Further more, we have the fact that sinc cannot be applied efficiently in real time.
Sometimes i want distortions yes, sometimes im aiming for the clear sounds, both can be archived if wanted, however i know one thing for sure with my redneck composer brain, that i want the final render to be exactly the same as i hear it in the composing phase, i'm applying a lot of effects, distortions, lo-fi stuff, etc, and setting up the sounding carefully on the wanted exact levels. If a render would give me a (totally) different sounding that i've spent so much time to archive, i would most likely be unsatisfied with it.

Saga Musix · September 28, 2009, 12:27:55

Quote from: "djmakas"Hello, i've found in many trackers the feature of sinc interpolation (such XMPlay) and some people says the sinc resampling is "perfect". :?: Can someone tell me how it works and (if possible) why OpenMPT don not has this funcion? Thanks.

You must be God if you can spot a substantial difference between Polyphase or XMMS resampling and Sinc interpolation...

g · September 28, 2009, 16:35:39

Quote from: "psishock"but i thought that ompt does not applies any, if you switch it off.

Well, it doesn't, which is the worst kind!

The interpolation tries to fix what the resampling fucks up so to speak.

Anyway, I think it's worth noting that the MPT interpolation only affects native samples, not plugins (they use their own resampling if needed). (Just a general FYI, I know no one has stated otherwise)

jmkz · September 29, 2009, 18:47:47

Thanks. I heard some chiptunes, and I like much more whitout an interpolation. It sounds more rich, so the interpolation was better if you use high quality samples (maybe) or when the noise is bad in the song.

Saga Musix · September 29, 2009, 19:58:58

That's exactly it, most people prefer listening to chiptunes or tunes with LQ samples in general without interpolation, but there are also some weirdos who leave it on all the time.

LPChip · September 29, 2009, 21:25:47

So you're calling me a weirdo now huh?

Saga Musix · September 29, 2009, 22:36:09

I thought I always did?

LPChip · September 30, 2009, 08:40:08

Quote from: "Jojo"I thought I always did?

Good point...

g · September 30, 2009, 16:24:39

Quote from: "Jojo"That's exactly it, most people prefer listening to chiptunes or tunes with LQ samples in general without interpolation, but there are also some weirdos who leave it on all the time.

Some weirdos like to always have "surround" on

psishock · September 30, 2009, 19:32:05

That's nuttin, i've seen some of the weirdest sht: interpolation AND surround, both turned on! :shock: