Introduction to digital audio - Gary explains

no loss of any of that data that was used to record the sound originally and the other is lossy which means that there has been some quality lost during the production of the sound file now the wave. wav files that you might find on PCS is really a raw PCM format and that is lossless there's nothing loss in that there's also this very popular codec called flak and that also is lossless now flak has the advantage that while it doesn't lose any of the data in the file it does use compression which means it can shrink down the file size to to roughly a half however that's still pretty big so then we move on to the lossy formats now the way these work for example MP3 is a classic example of a lossy format is there are algorithms that are used trying to understand how the brain works trying to understand how the ear interprets these sounds and chops out bits that they reckon can't be heard now of course those that are very sensitive about music will say but you can hear it there is a big difference and I'm not going to get into that argument but the idea of a loss lossy compression algorithm is it doesn't just strip away randomly things it tries to strip away things that are not needed and then it also uses compression on top of that to reduce the file size so for example 4 minutes of might be 40 megabytes but 4 minutes of an MP3 at 320 kilobit per second might only be 9 mgab 10 megabytes so that's really like a quarter of the size and that's why MP3 is so popular today because we can have relatively high quality music near CD quality music that is actually a lot smaller which is great for streaming and great for storing on our devices now there are other loss lossy formats other than just MP3 three there's also OG vorbis which is an open source codec and there's also the advanced audio codec AAC and AAC plus which is used more predominantly by Apple and within iTunes and so on however Android can play AAC files that don't have any DRM now the advantage of AAC is that at lower bit rates it certainly has a greater audio quality than MP3 files at higher bit rates there are arguments between people about which one's actually best probably AAC comes out on top however at higher bit rates they certainly are comparable with each other so let's just sum up audio is recorded by measuring the amplitude of a wave at a certain time interval and we measure that roughly nowadays at 44,000 times a second or 48,000 times a second the measure the gradient that's used to measure that is 16 bit is 65,000 different levels 24 bit is 16 million different levels and that produces the accuracy of which we're registering something that come from from the analog world into a digital representation now when that gets into your phone and you want to turn it back into analog again it goes through a Dack and the Dack converts that data back into a soundwave and it's got lots of clever technology inside of it that does things like smoothing and shaping that actually makes the sound that comes out as close as possible to the original and there are different quality dacks and different quality phones have different dacks in them and they are able to produce different qualities of sound and that's basically based on the cost of the Dack inside of that phone