I have to begin by congratulating the developers who worked on Hydrogen. It's very intuitive and powerful. Excellent work!

When I export a MIDI file, I get a file that is recognized as MIDI by QuickTime Player, Finale, Pro Tools, etc., but the contents of the file aren't anything like I'd expect. Even with a test file of one drum hit several times in a measure, it translates to different notes at a faster tempo, and this behavior is consistent across the above software. I can successfully import MIDI drums from other sources. This behavior is consistent across PPC and Intel Macs using the latest system and QuickTime software. Is it just me?

FWIW, the only audio system that works is CoreAudio. I tried compiling the source from the terminal, but just got a lot of errors.

I think you have the problem which is described in this thread:
http://www.hydrogen-music.org/forum/index.php?action=show_thread&thread=486&fid=6&page=1

Your problem isn't caused by quicktime or by any other player;
the midi export of hydrogen doesn't work properly.

To get a midi file from hydrogen, I wrote a little program called "h2midi". Just look at my post in the other thread to download it.
I think you should be able to compile it under mac os x without any problems, but I didn't test this because I only have win and linux.

Thanks for the reply. I didn't see your thread because I only searched the OS X section of the forum. When I clicked on the link to the page with your program, the entire page quickly turned into an ad, and the only possible way to see that page is to click on something within that ad (the ad was not a popup in a separate window). When an ad is so aggressive it takes over a page this way, I won't take its bait and click anywhere in it, so I closed the window without downloading your program.

I hope the Hydrogen development team takes note of the problem and of your solution and incorporates it into a future build of Hydrogen.

I use Firefox with the Adblock Plus Plugin, which blocks the ad on this site successfully.
I didn't notice that the download page is full of ad, because my ad blocker is always active.

I'd like to know who to buy medical products form online stores.
Is it innocuous ?

Here's the h2midi app compiled for macosx attached as a zipfile.