Wednesday, November 17, 2021

TECHNIQUE: The Art of Sampling. Part Two. Basic Sampling Mechanics and Editing.


So I guess, like anything else, before we can begin to 'have fun' with, and start looking at some more creative aspects of sampling, we need some basics. We need to understand the principles and basic mechanics of sampling. 

For the purposes of this piece we're really dealing with 'musical instrument' type sampling. Whilst 'sampling' and 'digital recording' are essentially the same process, 'sampling', for our purposes, means the recording of short sections of audio to be mapped across a keyboard and played at different pitches, usually +/- a semitone. 

'Musical Instrument' type sampling has it's own set of concepts, ideas, and processes which we will take a look at here. 

A dedicated hardware sampler would record samples from an external source, whilst a computer based sampler with an audio interface can record samples from external sources, or other sound generating devices within the computer. 

For the purposes of this piece, and the accompanying video, I'll use the sampling facilities from Reason, but the editing processes are the same for all sampling systems. 

Here's a quick video that also goes through some of the following concepts and procedures.


So first we have to capture our section of audio, or 'sample'. This usually involves 'hitting' a record or 'arm' button. We then play our note from the sample source. It doesn't really matter if we are not recording sound the moment hit 'record' as we can trim our sample later. So we hit the record button and record our sample, then hit stop. Most modern computer or hardware samplers give us  visual representation of our sample. 

'Musical Instrument' type sampling usually involves taking multiple samples and 'mapping' them across different sections of the keyboard (this is called multi-sampling, and we'll take a closer look at this in Part 3) but here we'll just deal with a single sample. 

So now we have our basic sample there are a number of sampling editing functions we can carry out. We'll use some images from Reason's sample editing window, but you'll find the processes very similar for other progarms/platforms. 

So I've played a C3 using a choir sample and recorded it into Reason's sampling 'engine'. 

When I open the editing window, I can see this. 

So there are a number of editing facilities that we can use to make this choir sample more usable. 

First of all, we can normalise the level. The sample isn't quite at optimum level, so we can run the normalising routine which will maximise the audio level of the sound without it distorting. 

Normalising: (sometimes referred to as 'normalling'). This is a powerful computer routine that maximises the audio content of a sample whilst minimising noise or 'hiss' If your sample isn't initially recorded at the optimum level (and it can be quite difficult to achieve this) the normalising routine will maximise the audio level without distortion. 

So we get a 'healthier' looking waveform. 

There's a gap at the beginning of the sample and some silence at the end, so we can 'trim' the front of the sample so it starts at the right time and remove the silence at the end so we're not wasting memory. 

Trimming: (sometime referred to as 'truncating', or 'cropping'). Allows us to 'trim' a sample between two points so that the sample starts and ends at the desired points.  

So we get this:

Reversing: We can instantly reverse a sample and play it backwards if we like. 

Finally we'll take a look at looping which is a very important part of 'musical instrument' type sampling. 

Looping: Some instruments have a natural decay. If you play a note on a piano, the strings will gradually vibrate more quietly and the sound will fade away. Other instruments, such as an organ, can sound as long as they are played. A violinist can draw his or her bow across the strings backward and forwards to create constant sound. So some sampled instruments will require looping so they can sound indefinitely. In sampling's earlier days most instruments needed to be looped due to memory limitations. Even if an instrument had a natural decay, there often wasn't enough memory to allow such a long decay, so some form of looping had to be employed. 

Speaking of the 'earlier days' of sampling, anyone who remembers using more basic sampling hardware will remember how notoriously difficult it was to find suitable loops points. There was nearly always a 'click' as the sample looped around. These days, we have a number of things that can help us such as 'crossfade' looping and forward/backwards looping which can help remove the dreaded 'click', and some instruments have routines to find suitable looping points.
So here you can see the two green 'loop' markers that the sample cycles around. In this mode the sample plays to the 'R' marker and then starts again at the 'L' marker. The 'loop mode' selection at the top also offers a forwards/backwards loop mode where the sample plays to the 'R' marker then reverses back to the 'L' marker. 

So there are some basic recording and essential sample editing functions for a single sample. 

In the next part, we'll take a look at mapping several samples across the keyboard (multi-sampling) and why, and in what circumstances we may need to do that. 

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