Trouble looping samples...

[(>o_o)>]

Hi, I'm new(Don't kill me.)

I've just started to get into composing/tracking. I recently purchased a midi keyboard and so far I've basically just been messing around with it a little, as well as reading alot of tutorials on music theory and stuff. So far I have a VERY basic understanding of the concept of tracking, as well as samples, melodies, chords, etc, though I still have trouble with alot of musical terminology and things like that so bare with me.

Anyway, I've been having trouble looping samples...for example, I record a synthetic string instrument and I want the sample to loop. I load it into modplug tracker, and I set the loop start and end point as best as I can, only I keep getting these annoying clicks and pops every time. Is there an easy way to make a string instrument loop without the clicks and pops?

[Squirrel Havoc]

I am pretty good at looping, but I couldnt tell you how. It does take practice to learn where on a waveform to put the loop points (I go for peaks of 0 crosses), but Im sure someone here will have a nice trick that will work.

[Squirrel Havoc]

I realized you might not know what I am talking about, so I took some screen grabs of what I am talking about

This is a loop point set at a peak: http://www.rodent-revenge.com/blog/peak.jpg

Those are good for BiDi loops

This is a loop point set at a 0 crossing: http://www.rodent-revenge.com/blog/cross.jpg

Good for forward looping


Forward looping has some advantages im sure, but its much harder (for me atleast) to pull off, so i go for BiDi almost all the time. Just practice and when it really works or really doesn't look at where the loop point is on the waveform at different zoom levels, that will show you what to do and what not to do.

[(>o_o)>]

Ah, thanks a million for that. I'm starting to understand this stuff alot better. So, would you say that bidirectional looping is common practice, at least for string instruments? When does forward looping a sample have an advantage? And what is the difference between a loop and a sustain loop? I know, it sounds like I have a million questions, heh...

[Squirrel Havoc]

I'm not really a loop expert (no one taught me, I just learned), but I can try to help.

Ah, thanks a million for that. I'm starting to understand this stuff alot better. So, would you say that bidirectional looping is common practice, at least for string instruments?

Yeah, I really can't see any advantage of forward looping for strings, but a good loop will sound the same no matter what kind it is.

When does forward looping a sample have an advantage?

I really dont know, the only time I use it is when I am working in a format (like XM) that doesnt support bidi.

And what is the difference between a loop and a sustain loop?

I'm sure I'm wrong about this, but I think a sustain loop is similar, except when there is a note-off command in the pattern then the sample playback position continues past the loop points until it gets to the end of the sample.

I know, it sounds like I have a million questions, heh...

Well thats what we are here for, this place has been a little quiet lately, we need to spice things up. And besides, no one ever has questions, just general chit-chat on these boards, it's a nice change of pace  

[LPChip]

I'm not really a loop expert (no one taught me, I just learned), but I can try to help.

Ah, thanks a million for that. I'm starting to understand this stuff alot better. So, would you say that bidirectional looping is common practice, at least for string instruments?

Yeah, I really can't see any advantage of forward looping for strings, but a good loop will sound the same no matter what kind it is.

I can You can't pingpong loop a saw wave because it goes like: /|/|/|, which will produce a noticable effect when pingponglooping it.

When does forward looping a sample have an advantage?

I really dont know, the only time I use it is when I am working in a format (like XM) that doesnt support bidi.

Eh, I'm pretty sure FastTracker introduced pingpong loops, and thereby should be possible to use.

Forward looping has much meaning with drumloop samples etc, text samples, and basically anything that shouldn't be played backwards at all.

And what is the difference between a loop and a sustain loop?

I'm sure I'm wrong about this, but I think a sustain loop is similar, except when there is a note-off command in the pattern then the sample playback position continues past the loop points until it gets to the end of the sample.

Not that much... A sustain loop will go on for as long as there is no note-off command (not either from the instrument NNA settings). It can be combined with a normal loop to have your sample be looped with 2 loop points that can be controlled by a note-off command. For instance: of you have a speech sample with someone shouting: Yeehaa, you can loop the "ee" part with a sustain loop, and the "aa" part with a normal loop.

You play the sound and it goes: Yeee... untill you have a note off (==) and it goes haaa (untill the note is being cut (^^).

I know, it sounds like I have a million questions, heh...

Well thats what we are here for, this place has been a little quiet lately, we need to spice things up. And besides, no one ever has questions, just general chit-chat on these boards, it's a nice change of pace  

Yeah, I'd say, join in make yourself at home, just don't steal my beer ok?

[Harbinger]

First of all, if you want an acoustic sound, Bidi looping is very unnatural sounding, except in a few circumstances. If you want to keep an acoustic sound natural, forget bidi, it alters the waveform, the pitch (even if it changes micro-audially), and therefore, the timbre. The exceptions are strings (not solo, an orchestra's worth) and non-vibrato wind instruments that rely on square/rectangle waveforms (solo or ensemble). Even then, you have to carefully find the loop points that, when reversed, do not alter the tones or subtones.

However, this info is for those scant few who are using sample manipulation for acoustic projects. Most of us are either not trying to do a perfect representation of an acoustic work, or we're into synthetic sounds anyway. Bidi looping can make a 'normal' sample sound beautifully synthetic.

Secondly, bidi looping can make sound sustaining a lot easier. You can waste alot of time trying to find the perfect looping points for a sound you want to sustain by forward-looping. I just find a section of the sample that doesn't change in pitch or volume and set the bidi between there for the sustain part of the "envelope".

Thirdly, bidi looping can be used as an effect unto itself. Take a BD/snare beat in 2/4 and apply bidi to the whole sample. You can prob'ly use that somewhere in that Trance track you were working on. :wink:

[Sam_Zen]

I've made a page about the aspects of looping samples
In fact the work must be done before, to create the ideal, maybe multiplied, sample to use for the loop.

[(>o_o)>]

Thank you very much for that. You inadvertantly gave me a very good idea...take screenshots of the start and end point and paste them next to each other to make sure they line up...brilliant! Why didn't I think of that before.

[Sam_Zen]

You're welcome. Sound is a process in time, so one has to be aware of the natural consequenses of the transitions between the stop of something, and the start of a repeat of it, or the start of something else.

You talked about annoying clicks and pops at the start of this topic. If you'd considered your recording as "raw material", so still in need to clean up things and making a smooth sample to be used as an instrument, then this would have been solved for the most. Basic thing at least :
You can never be sure that a recording begins and end with a zero-value. Non-zero is source nr 1 for getting clicks.
A tiny edit on a few bytes with the functions fade in and out with a wav-editor is sufficient.