Larry’s Personal & Tech ramblings

I’ve been thinking more about JPEG decode optimization and have come up with some new ideas.  My latest goal is a fast image preview which works with EXIF thumbnail images.  I’ve been targeting Desktop Windows and so far, all of the code is written in C.  The latest experiment was on a Core 2 Duo T7250 (2.0Ghz) laptop.  The results of decompressing 500 EXIF (160×120) thumbnail images into 16bpp flat bitmaps resulted in an average decode time of 0.7 milliseconds per thumbnail image.  That works out to about 35 nanoseconds per pixel.  I used my same optimized C code from before, but this time I made better use of memory.  Maybe some good x86 asm can get it to go even faster…

On a whim, I stopped at a local T-Mobile kiosk the other day and wanted to see what I could get for a 2-year contract extension. I’ve been happy with T-Mobile for a long time, so another 2-year commitment is no issue. The new device they had to offer is the Shadow. It cost $159, but has a $50 mail-in-rebate, so $109 is not bad for the latest Windows Mobile standard device. My overall impression of the device is positive. It’s the thinest, lightest QVGA Windows Mobile phone I’ve seen. It’s got a slide up keyboard. The keyboard is both good and bad at the same time. I really like having a slide open/close device for answering/hanging up calls. The phone feels a bit fragile, but the slider mechanism feels like it will work for a while. The keyboard is sort of between a numeric and full querty keyboard. Each key has 2 letters on it and it uses a strange variation of T9 input for guessing what word you want to type. For typing normal English text, the word prediction works quite well, but if you need to type in unique words such as email addresses or web URLs, the keyboard can be slow and painful.

The device is completely T-Mobile branded, but HTC has started to exert more effort to make their branding known; there’s a small HTC symbol on the back of the phone.

I’ve read other reviewers criticize the new GUI, but I find it to be quite useful and a real time saver. The “today” screen is a rotating icon list which allows quick access to functions such as messaging, web, calendar, alerts, and settings. What’s missing from this interface is access to the last used programs, but a hardware button can be assigned to bring up that list. I find the GUI to be quick to do the things that I want to do (email, web, calendar). This device is the first I’ve seen to include a small rotating wheel on the d-pad. I don’t particularly like the wheel because it seems to be inconsistent at times. It takes a 1/4 rotation to register a change.

For now, this is the phone I carry in my pocket (temporarily retiring the HTC Vox), but it will take a few weeks to determine if it’s really my favorite phone.

For gaming, the phone has a nice 2.6″ LCD, but the buttons are not ideal. The off-hook and on-hook buttons don’t do anything on a press, only a release. This makes them useful as Start/Select, but not much more.

3/22/08 Update: After using it for a week,  I really like it.  The size and feel of it is quite good.  I like the slider for answering calls and locking the device.  There have only been two negatives so far: 1) The battery life.  I highly doubt that it could get 5 hours of continuous talk time.  On a day of heavy usage (maybe 1 hour of talking, and 30 minutes of PDA usage), the battery was down to 1 bar.  I usually don’t talk much and use the PDA functions for about 1/2 hour a day, so it’s acceptable, but someone using their phone for long periods will need to find another device.  2) The cell reception is a little bit worse than my HTC S710.  In a weak signal area where my S710 works fine, the Shadow drops calls.

I’ve decided to release the source code to my SN76496 sound chip emulator. It’s not the most accurate, but it sounds good to my ears. Perhaps someone in the programming community will make improvements to it. This is really an experiment to see how well it’s received and see if it’s worth releasing other source code. The sound code rarely takes much of the CPU time in most games, but I wanted to have some fun optimizing this code. The zip file includes the C code as well as the hand-written ARM assembly language.

Enjoy,

L.B.

sn76496.zip