View Single Post
Old 02 September 2016, 19:57   #8
Registered User
Join Date: Sep 2011
Location: Cardiff, UK
Posts: 1,121
I think I need further clarification on how Amiga PCM actually works, Meynaf.

I know that it's 8-bit, so I assume that means a range of 0 to 255 with 128 being the centre line, or something like -128 to 127 with 0 being the centre line if it's signed, right?

It's one channel playing at volume 64 (doing the top 8 bits) mixed with another playing at volume 1 (doing the bottom 6 bits). Weird mixture, but total is really 14-bit (actually slightly more due to calibration).
I suppose that's only active with a memory location set to 1 or something? (I'm thinking of POKEs) Also, would the 14 bits be represented by the range 0 to 16383 or something similar? It's just that as far as I can see, your description above would favour the top 8 bits over the bottom 6 bits, and so it would be rather skewed. What I mean is, if the memory for the audio was POKEd from 0 to 16383 across 16384 memory registers, would it be a straight line from minimum to maximum?

Also, I know that there are volume settings for each channel, and I think a master for all of them, but I figured that they controlled the volume independently of whatever the waveform data was, down to the circuitry of Paula. Are you saying that the volume settings are 100% digital rather than analogue?
Foebane is online now  
Page generated in 0.03938 seconds with 10 queries