Does anyone here have a decent working knowledge of quantisation in it's application as the basis of lossy codecs? As I understand it, the fundamental tool of data compression (in the context of audio files) is the quantisation of numbers and the degree to which the codec can get away with doing this. Again, as I understand it, if I have a list of numbers that I want to store and they are too big, I can divide them by another number - which makes them smaller. When I want my data back I multiply by the original number and there's my data all back again. So for example, if I have a list of numbers between 100 and 199 (sticking to base 10 for now as that's all I understand) but only have two columns to write them in, I could divide them all by 2 and I now have a list of numbers between 50 and 98 which will fit my columns. When I multiply them by 2 though, it becomes apparent that the even numbers have done alright but the odd numbers have now become even as well. There is therefore an error - the quantisation error. It is this quantisation error that the codec tries to hide by making use of 'audio masking'* I suspect that quantisation is vastly more complicated than this but would like to know whether my basic understanding is at least on the right track. [SIZE="1"] *Audio masking generally becomes the focus of discussions I have seen on lossy compression; it also appears to be widely misunderstood so if possible I'd like to leave it to one side for now.[/SIZE]