ANALOG TO DIGITAL CONVERSION PROCESS INTRODUCTION Hi there, my name is Cristina Guadalupe Juárez Chablé, and I'm from México. This is the lesson analog to digital conversion process, taught by the professor Loundon Stearns, of Week 2 for the Introduction to Music Production on Coursera.org. LESSON Analog to digital conversion is a process to go from the continually variable sound into the stream of ones and zeros. Binary information is based primarily on the bit, and a bit is a single, kind of, memory location. A bit = “0” or “1” Every number is collection of those ones and zeros. So the number of bits, determines the maximum number of states, or the biggest number that you can represent. Then if we have a single bit, we can represent two things, on or off. If we want to represent large numbers, we have to start collecting bits into words. And word is a collection of bits. In the MIDI data is used commonly seven bit words. Or if we’re dealing with digital audio, we use 16 bit words. 2 wordlength
1 Bit word
2 Bit word
3 Bit word
If I have a two bit word, we have values of zerozero, zeroone, onezero, oneone, so we can represent four things, like the seasons of the year for example. Now, it’s good to know what’s the largest number you can represent. And it’s always two to the power of the wordlength is going to give you the number of numbers, the value that you can represent. 21 =2 22 =4 23 =8 24 =16 25 =32 Note: the exponential number is the bit word.
You are going to find that there’s a couple standard. CD standard is a 16 bit word. It’s done in that quality but in the studio we tend to use a higher wordlength, and maybe 24 would be a great setting for when you’re recording. What that gives you is a wider dynamic range. What we’re talking about right now is wordlength is related to amplitude and the sampling rate is related to frequency. So, if I have a 24 bit wordlength I have a wider dynamic range (the longer wordlength). But what it does allow you to do is not record at such a high value. And when we’re recording we want to get as loud as possible without clipping or distorting. So is better you set the interface with the DAW to work in 24 bit mode. So like we said before, when we’re converting from analog to digital, we’re making many measurements per second. And each one of those measurements has a specific wordlength. But how often we do the measurements is known as the sampling rate. The fact is, the higher the sampling rate the higher frequency that can be represented accurately in the digital domain. So the CD standard sampling rate of 44,100 herts (it is 22,050 hertz in digital domain) can accurately represent everything we can hear as human beings. So it’s better to use the higher settings we can have in a CD. REFLECTION It’s elementary to know the analog to digital conversion process for understand how work the two main parameters of digital audio (wordlength and sampling rate), and what is the function of each of them. In this way, we can improve the quality of our record.