title: Estimating/forecasting download completion time
body: <p>We've all poked fun at the 'X minutes remaining' dialog which seems to be too simplistic, but how can we improve it? </p>
  
  <p>Effectively, the input is the set of download speeds up to the current time, and we need to use this to estimate the completion time, perhaps with an indication of certainty, like '20-25 mins remaining' using some Y% confidence interval.</p>
  
  <p>Code that did this could be put in a little library and used in projects all over, so is it really that difficult? How would you do it? What weighting would you give to previous download speeds?</p>
  
  <p>Or is there some open source code already out there?</p>
  
  <p><b>Edit: Summarising:</b></p>
  
  <ol><li>Improve estimated completion time via better algo/filter etc.</li>
  <li>Provide interval instead of single time ('1h45-2h30 mins'), or just limit the precision ('about 2 hours').</li>
  <li>Indicate when progress has stalled - although if progress consistently stalls and then continues, we should be able to deal with that. Perhaps 'about 2 hours, currently stalled'</li>
  </ol>