Reply To: My JoCo Music
Picture a sine wave (because it is actually a tone, a pure tone) analogue is the wave, smooth and unaltered (like what you would get from a record). Converting to digital requires taking samples of the wave at single instances of time and then connecting those samples, leading to a stair step shape following the original curvature of the wave (that’s where the loss of information starts). Things get more complicated when you get more range of sound frequencies (when the sound is not a pure tone, which is not very musical… it can get extremely grating).
There are two things that can alter the quality of digital audio at this point. Bit depth and sampling frequency, the sampling rate is how often (per second) the analogue wave (or original digital wave) is measured for the subsequent stair-step “wave” On CDs this is 44,100 and on DVD it’s 48,000– these numbers are standard to the formats and don’t change. Bit depth is how much memory the sampled information will need to be stored, the standards are 8, 16, 20, and 24. The bit rate is the sampling rate times the bit depth. Many audio file formats add headers and footers on to this numerical data to aid in decoding and transmitting, and that will add to the overall file size.
***Common losses from reducing sampling rate are losing the high frequencies and the need to convert when you want to burn to a CD or DVD… and the data stays lost (garbage in, garbage out). Reducing the bit depth will result in a lot of noise and static (not even AM radio will reduce the bit depth past 16 bit).***
But I would like to add, that while the difference between analogue and digital is not easy to hear, analogue is a more complete representation of any sound we hear in nature, it also tends to be a much more robust signal (**which is why records can last through decades or play in spite of pops and hisses, and CDs can stop functioning completely after scratches get to a certain point**).
***If you are interested in retrieving audio off of your boxes and boxes of vinyl, you can purchase audio cables to plug your record player into your computer (depending on your record player a male to male audio cable (with ends like headphones have) will work) plug it into your microphone jack (if you have a PC, it’s red/pink) and if you have a mac, there’s a picture). Get a free program like audacity, and set it up to record MIC/line input and you can export it as a wav or MP3.***
***And for copyright junkies, all owners of copyrighted material are allowed to make one back up copy for safety purposes, so what you do when you put your played-twice-mint-condition of the Beatles White album on CD so you don’t need to buy it on CD, is legal!***