02-06-2016, 10:53 PM
(02-06-2016, 03:18 PM)admin Wrote: Everything is deliberately index referenced as that is the only way to align tracks correctly. I don't mind that there is more than 1 rev per track in an image. This actually helps in determining the write splice location, weak bits, strong bits, etc.
I don't use "filler", I use the actual track data. So, rev 1 is written followed by however much of rev 2 is required.
When only a single rev is needed (Atari ST, PC, etc.) then it is easy enough to calculate the destination drive speed and compress/expand the track data so that the write splice is dead on.
Ok. At the moment I only generate images with a single revolution, for both emulation and for write-to-disk. Tracks which have data straddling the index I simply rotate so that the splice is at the index, with the splice usually at the midpoint of the track gap. I get worried about theoretical issues with this simple approach, but in practice I haven't yet found any formats that both straddle the index and care about their offset relative to the index.
For weak regions in a single-revolution image, I inject randomness during 'replay' (emulated read) by jittering samples a little and also randomly ignoring short (<1us) pulses. I only do this in my disk-analyser right now, though it's also a candidate for porting across to the SCP parser in UAE. That said I'm not sure many people use SCP as an image format for generated/analysed images, so UAE is probably mostly seeing multi-revolution raw dumps.