Quote:Originally posted by Camacho
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Quote:Sounds Types and Sampling Rates

Analog
(Analogue): Continuously variable signal. A sound wave is analog and it varies continuously in amplitude. Recorded analog sound results when a pressure wave hits a microphone. The microphone is made from a vibrating membrane. The vibrating membrane pushes a wire through a magnetic field, which produces an electrical current. This current will vary in amplitude depending on the strength of the original sound wave

Digital
Digital sound is represented in numbers. All information is stored as 0 and 1 and the more 0 and 1's that are used to represent a part of a sound then the better the sound quality. This is covered in the Sampling Rates and Bits

Conversion Between Analogue and Digital
An analogue electrical signal can be converted to digital by sampling the sound; i.e., determining the voltage (amplitude) at regular time intervals. This converts a gradually changing wave into numbers that then can be stored and manipulated by a computer. When the sound is played back through a speaker it is reproduced as an analogue wave.

Sampling Rates and Bits
Sampling is not just a case of plug-in and record, well not if you want a good quality sample. Some have said that sampling is an art form in itself and should be treated so. Many make the mistake of just recording a sound source and then save it to disk and that is the end of the process, this is not the case for a serious use of samples in any program.

Many considerations have to be taken into place when recording a sound for a sample. What is the sample rate, how many bits used will affect the final sound, tidying up the sample, pop and clicks, loops, compression and normalisation are to name a few. Then there is the possibility to add effects like reverb (which I feel is necessary, reason later), delay, chorus and filters that will give the sample dynamics.

Every time a sound is sampled its amplitude is recorded. The actual amplitude is rounded off to the nearest available amplitude. The greater the bit depth, the more amplitude levels available. For example, when digitizing an analogue wave, the amplitude may actually be 1.1 units of sound intensity at a time of 1.234 s. But the amplitude may have to be rounded off to 1 because only certain discrete amplitudes are allowed. The more amplitude levels available, the higher quality the sound recording.

Why at a sample rate of 44,100 Hz?
Put quite simply, the human ear can only hear sounds up to 22,000 Hz and nothing after that. But with a digital recording, all the frequencies that a human can hear requires sampling at twice the rate. So this means recording a sample of 44,100Hz

Bit Depth
Use 8, 16, 24 or 32 bits? Simply put, to record a sample, the computer must convert the analogue sound and convert it into a digital sound. This means that the computer stores the sample as numerical data, it stores the sample as numbers in the computers memory or on a disk.

An 8bit number can have one of 256 values (28); a 16bit number one of 65,536 values (216). The more bits available to the sampler then the more accurate the description of the sound will be in the final sample.

The dynamic range of a sound represents the difference between the softest sound present in a recording and the loudest sound. An 8bit digitizer has a dynamic range of 48 decibels and a 16bit digitizer has a dynamic range of 96 dB. By comparison, the dynamic range of the human ear is approximately from silence to 120 db.

The best way to understand the difference between 8 bits & 16 bits is to record a sample at both resolutions and listen to the each, you will notice the difference in sound quality and also the size of the sample.

The 8bit sample is slowly being used less, as the 16bit sample is now the standard for everything to do with music.
Many newer software samplers can use and edit in 24 or 32-bit, but there are still many programs that cannot playback these types of rates, I suggest that you record and edit your sample in 24 or 32 and then convert the sample back to 16 bits. This will give a good quality sample in the end result. Remember to keep the 24 or 32 bit sample as a backup.

Technical tip: If you want to convert a 16bit to 8bit sample, change the frequency first and then change the resolution afterwards. This should make for just a good quality sample.

Frequencies
There are two types of frequency waves;


Shrill, this is a high frequency wave.
Bass tone is a low frequency wave.

In theory, bass tones are not required to be sampled at 44,100 Hz. These types of instruments can be recorded at 44.100 and then drop it to 22.050hz. This should be without any loss of quality to the sample. Sampling any instrument under 22.050hz is not recommended for any serious sample and the advice is, always sample at a higher Hz and then down-sample afterwards if needed.

Quote:Carlos, can I help with those tutorials? You sent me one a month or two ago, but I couldn't open it (it was empty in textedit, and double-clicking it just opened Danlab's crazy golf game...) and never heard anything more...