MP3 Compression or Bad Mastering?

When I heard Jay-Z and Kanye’s “Murder to Excellence” on the radio and internet, the song sounded muffled.  The cymbals aren’t crisp.  The entire song, including the vocals, sounds like it’s coming out of bad speakers.  I figured maybe the spectral range of the song was too broad for mp3 compression and it was losing the high frequency detail.  I wanted to hear the real thing, so I bought the CD to get a good copy of the song.  Here’s what I got.  It’s the WAV file of Murder to Excellence from the Watch the Throne CD.

poorly mastered song

Murder to Excellence WAV file

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Avoiding Computer Viruses

The first thing to note when discussing computer viruses is that viruses are just programs, sort of like how spam is just email.  Computer users demand the ability to run any program they want, without restrictions, not have any viruses, and also not be asked any questions before running a program.  That is impossible.  I’m going to discuss four common approaches to dealing with the problem of protecting computers from unwanted programs. Continue reading

HTTPS and Web Certificates

When you go to a website and the address says https instead of http or you see a little lock button in the address bar, it means the data being transmitted back and forth is encrypted.  Any other computer along the way on the internet cannot read the contents of the transmissions.  However, sometimes you get a warning about visiting an encrypted site that says your identity is being phished or that you cannot trust the connection.  I’m going to explain what that means and when you should bypass the warning anyway and when you should not. Continue reading

Dropbox Hashing

If you add a file to your Dropbox folder that already exists on Dropbox’s servers, you don’t have to send the file.  They just mark the existing file as also being owned by you.  In fact, Dropbox works on files in 4 MB chunks, so if you modify a large file and most of it remains unchanged, they only need you to upload any 4 MB chunks that changed and don’t already exist somewhere else on Dropbox.  A lot of people are amazed or confused by this technology.  How can Dropbox’s server and your computer know that two 4 MB chunks are the same without comparing them side-by-side? Continue reading

Dropbox International Performance

I recently attended this:

Dropbox: International Performance

Come hear about several recent and future improvements to Dropbox’s international performance. Dropbox Engineer, Nipunn Koorapati, will talk about the Dropbox server architecture as well as recent optimizations to the client-server protocol for small and large files focused on our high latency international users.

We face international performance challenges at Offroad too, with systems in Switzerland and the US.  We have fairly high bandwidth between the sites, but the high round-trip times (latency) leads to problems. Continue reading

Optimal Fuel Hedging for Airlines

Some airlines are currently losing money because their fuel hedges have locked in higher prices as ticket prices fall.  I’m not sure they understand the difference between hedging and speculation.

Does anyone know how much the fuel hedging teams at airlines talk to the pricing teams?

The problem is that airlines seem to think only about hedging expenses, not revenues.  They know they have all these future scheduled flights that will consume a certain amount of fuel.  So airlines talk about pre-purchasing all that fuel.  Or they buy a particular percentage of it and call it partial hedging.  Then when fuel prices fall, new carriers can enter the market at lower prices, reducing the revenue of airlines who have already locked in their expenses. Continue reading