First, I wasn't sure if this should be in Logging, IIS, or Database. Please move if inappropriate.
We host .mp3 and .wmv files. I'm tasked with getting monthly download statistics (which would be very simple), except they want to know how many files are being downloaded, at least, 30% or more of the file. The percentage is supposed to remove those people that left-click on the link and it starts playing, only to then close the player. They want to see legitimate downloads.
We have IIS (Windows Server 2008 R2) logging with the W3c format. I see no file size or amount downloaded statistics. The closest thing that I see is the transfer time (time-taken) field, but that can be radically different from file to file.
Are there any simple ways of doing this? I was thinking that, if a filesize and size downloaded was included, I could do a calculation to base the report on that, but they aren't included.