Pro Plus 2

[Dirk Hohndel]

On Jan 15, 2012, at 11:39 AM, Jef Driesen wrote:
>> Here's the moment where libDC gets to define the semantics and make them reasonable, and the software that uses libDC (MacDive, DivingLog, Subsurface) can then rely on that semantic. So once you release version 1.0, you should simply define that there is NO SUCH THING as a guarantee that the samples are evenly spaced and that instead the user of libDC has to take the time information in every sample into account.
>> 
>> In that case you can simply distribute the samples within that minute range (what a weird thing to do on Oceanic's part…). And if there are more than 60 of them, go to half second sampling rate (and simply announce that somewhere in the data structure).
>> 
>> This way whatever junk the dive computer throws at us, libDC converts it into something reasonable and consistent that the software can then rely on and use.
>> 
>> Bingo, everyone wins.
> 
> Don't worry, libdc has never guaranteed evenly spaced samples, and never will. Providing the time info is just more general and more future proof.

Awesome, so you can just fix Philip's problem in libDC by spreading out the samples :-)

> I doubt we'll ever see more than 60 samples a minute. If you manage to change depth at a speed of at least 5ft every second, I'm very impressed! But you never know of course. Sometimes the amount of junk can get frustrating :-)

Never say never. Several computers offer a 1 sec sample rate (Suunto D4, Aeris T3, Aeris Manta, Oceanic Datamask, etc) and if they sneak in an additional sample for some weird reason… :-)

Oh, and the crazy free diving people do indeed do more than 5ft a second… look at Herbert Nitsch:

http://dsc.discovery.com/adventure/5-longest-free-dives-of-all-time.html
"In no limit free diving, the diver uses a weight sled to descend to a predetermined depth, at which point he or she activates an inflatable balloon to return to the surface. If this seems like cheating, think about the fact that to descend to the current deepest mark of 214 meters, Herbert Nitsch went 4 minutes, 24 seconds without taking a breath."

So 214m = 702ft - down and up that's 1404ft. In 4:24 or 264 sec. So his AVERAGE was 5.3ft/sec

Yeah, not your average diver, not your average dive. Just never say never :-)

/D