Archive for January 2008

lcms speed

Note for other open source color management system users searching for more transform speed from the LittleCMS library:

Turning off the one-entry cache cuts 40% from runtime – unless you’re transforming large uniform blocks for which a one-entry cache is actually suitable.

Eliminating the general-purpose byte packing and unpacking functions and replacing them with inline encoding-specific equivalents cuts another 15% of runtime.

Compound savings: 49%, or 2x speedup, which is what someone claimed on an lcms mailing list once without providing the code.

Future work: The cached performance could be made better by observing that all the thread-safe memory locking I find in lcms-1.17 is unnecessary if you assume that thread-local caches on the stack are just fine. Forget the locking, and inline the cache comparisons. I had no need to implement it though, so this is only theoretical.

[If you found this by search engine and it helped you out, drop me a note.]

Prediction for 2008: Service providers avoid straightforward DTV answers

Like many others in 2008, I am cheap, don’t buy TVs very often, subscribe only to basic cable, and have questions about the impending February 17 2009 shutdown of analog over-the-air TV channels.

My prediction for 2008 is that confusion will reign because part of the answer is provided by cable, satellite, or telephone service companies, and their incentive is to maintain confusion because that’s an effective “up-sell” technique.

The simple story is that over-the-air (OTA) analog goes away, replaced by OTA digital. For OTA consumers, it’s just a matter of getting an ATSC tuner (built-in to a newer TV, or standalone with a government-subsidizied coupon).

The part that is different for every locality and service provider: what to do with analog TVs on analog cable systems. For every locality there is a simple cable story: the cable company could tell you their plans for analog channels, e.g. “We’ll continue to carry local channels for our analog customers through [let’s say] 2012.” But the cable companies will generally avoid that story. (I tried to extract it from TWC and they failed the first test, answered the wrong question entirely.)

Why would they tell you a simple “analog on cable is OK for N years” story when they would rather upgrade you to a new digital cable set-top box, and while they’re at it, try to replace your phone too?

So, even if it’s true that analog cable customers will live just fine on the analog cable plant for quite some time, you’ll only see it either in extremely fine print, or omitted as a choice at all in most promotional materials.

Now, it is also true that for bandwidth utilization reasons, the cable companies would like to convert their cable plant to all-digital. If they somehow manage to convert all their cheap $8/month basic cable customers to some fatter bundle, all the better for them. The good thing is that digital OTA tuners will provide competition, so the cable company had better have something that competes with free digital for cheap customers, or they’ll just lose the low end altogether. (The only reason I have basic cable is because my analog OTA reception is poor. Once digital OTA becomes cheap (it’s not yet, standalone tuners are too expensive), I’ll be a digital OTA customer unless cable really makes it worthwhile not to switch. It’s a race to the bottom for my dollar.)

Once they start losing a significant number of customers to digital OTA, then they will start publicizing cheap basic analog and constructing cheap basic digital. But they will wait as long as possible.