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PO
 

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    <p>We solved a similar problem in the following way. We weren't interested in how fast the download was over the <em>entire</em> time, just roughly how long it was expected to take based on recent activity but, as you say, not so recent that the figures would be jumping all over the place.</p> <p>The reason we weren't interested in the entire time frame was that a download could so 1M/s for half an hour then switch up to 10M/s for the next ten minutes. That first half hour will drag down the average speed quite severely, despite the fact that you're now honkin' along at quite a pace.</p> <p>We created a circular buffer with each cell holding the amount downloaded in a 1-second period. The circular buffer size was 300, allowing for 5 minutes of historical data, and every cell was initialized to zero.</p> <p>We also maintained a total (the sum of all entries in the buffer, so also initially zero) and the count (zero, obviously).</p> <p>Every second, we would figure out how much data had been downloaded since the last second and then:</p> <ul> <li>subtract the current cell from the total.</li> <li>put the current figure into that cell and advance the cell pointer.</li> <li>add that current figure to the total.</li> <li>increase the count if it wasn't already 300.</li> <li>update the figure displayed to the user, based on total / count.</li> </ul> <p>Basically, in pseudo-code:</p> <pre><code>def init (sz): buffer = new int[sz] for i = 0 to sz - 1: buffer[i] = 0 total = 0 count = 0 index = 0 maxsz = sz def update (kbps): total = total - buffer[index] + kbps buffer[index] = kbps index = (index + 1) % maxsz if count &lt; maxsz: count = count + 1 return total / count </code></pre> <p>You can change your resolution (1 second) and history (300) to suit your situation but we found 5 minutes was more than long enough that it smoothed out the irregularities but still gradually adjusted to more permanent changes in a timely fashion.</p>
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    1. POAlgo for a stable 'download-time-remaining' in a download window
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    1. COshouldn't it be: _count = **min** (maxsz, count + 1)_ ?
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    2. CO@phix23: good catch. I can't believe nobody's noticed that for over a _year._ Annhoo, I've modified it to make it work correctly and removed dependency on a function altogether.
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    3. COi can't believe it either, maybe i'm the first who really used this code
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