This will be much better than posting in the comment section.

Funny you tried the 5% as well - I did the same thing yesterday (testing my new app) and found it to work much better as well. Once I have compiled the app for Windows, Linux and MacOS X, I'll give lower % a try as well.

Black seems to be sensitive indeed. I'm guessing it has to be pure black for everything to switch off, which does happen occasionally (see my test video), but it also seems that other very very dark colors are too often seen as a too bright version of that color. I guess that's where setting the gamma per color comes in - but I haven't tried that yet.

Interesting you have not experienced lag, I guess your computer must be more powerful than the tiny AMD box that I use .

The test video: I'll email it to you after I finished this post. Let me know what you think. (I made it, believe it or not, with Photoshop)

Wow you're fast  ...

I just emailed you the video ...

That test video is great. I guess I do have a little bit of lag when watching that video. It's hard to notice when I'm just watching a movie or a tv show. I spent some time testing the black level setting in the colors, but that seems to just make the colors more washed out. I'll have to play with the gamma settings and see if that helps.

Thansk!
I'm glad to hear that you like the test video ... I guess I'll make it available for others, either today or tomorrow.

I'm in the middle of writing an article for the app I created, almost takes more work to write how it works, than to actually build it haha ... and for my website I actually write it in 2 languages (Dutch and English), so I hope to complete that one tomorrow.

You can already take a look at the Downloads page, look for "Boblight Config Maker" (under the Arduino section) if you'd like to give it a try - all feedback is welcome.

For detecting the lag, I kinda make my hand into a spy glass and focus on a small piece of the screen, specially with the color changes for full screen or the larger blocks. But you're right: in movies it's much less obvious.

I'm curious about your findings when tampering with the gamma settings.
If I understand the Boblight config info correctly, you can define all kinds of colors, not just red, green an blue. But I'd hate to define 16.8 million colors like that .
Changing the values for red, green or blue: does that impact all "reds"?

OK, published the application with manual today ... you can find it here: link to Boblight Config Maker

If I remember correctly, you're using XBMC on a Windows PC right?
Is the device under Windows a COM-port or also a /dev/ttyACM0?

That is a very thorough right up. I'll take a look through that tonight. That app looks really nice. Yes, I am on windows and I'm using a com port.

Thanks for the compliment Dave  ...

No hurry, take your time ... working on my write up for doing Boblight with OpenElec and the WS2811/WS2812 LEDs. 
Hope to finish it tomorrow, but I'd still have to translate it after that ...

I just saw your config app over at the XBMC forums. I'm sure that will help a lot of people over there.

I hope so ... I did see that somebody also wrote a nice comment (link).
Always good to see that people like what you do, right?

Just noticed how badly other plugins can influence boblight.
When I use a service called "watchdog", every boblight color delays by almost 2 seconds ... 

Another observation is that increasing the value for "interval" seems to have a positive effect (up to a point) on the lag we've seen.
Still trying to find a balance between delay and smooth moving color changes. 

That's interesting.  I'll have to check out what add-ons that I have running.  I have played around with the interval setting a bit, but I was only ever trying with a movie where the lag is much less noticeable. 

I tried your config app today and while it is excellent and easy to use, I'm not sure I can use it without some manual modification because my LEDs start at the bottom right corner of my TV and not in the middle. So I guess I'm stuck with the other program that I've been using.

I still have to play around with the gamma settings to see if I can get the blacks working a little better.

One more thing. What baud rate are you using and have you tested other baud rates? I'm still using 9600, but I've been wondering if there is any benefit to using a higher baud.

I'm still playing with "Interval". My current config works really well with movies - change in interval actually seemed to have a positive effect on the colors as well (black actually occurs betters than before, but fast effects like the ending of my video seem to flicker a little with the white beam).
Oh and I use 5% LED depth but I'm planning to experiment with even lower values ... 

[device]
name            Ambilight
type            momo
output          /dev/ttyACM0
channels        867
prefix          41 64 61 00 18 4D
interval        40000
rate            460800
debug           off
delayafteropen  1000000
threadpriority  99

As you can see, speed is pretty high, but it works well ... I guess the amount of LEDs matters in this case as well.
I've got quite a bunch of LEDs (my TV is 80"), so the amount of data is pretty big ... I see a lot of folks use 38400 and 115200 ... you could give 115200 a try and see if it even matters for your setup.

Boblight Config Maker:
Can you describe (TV rear view) how your config looks like? As far as I can see, you should be able to do just that, but maybe I'm not understanding your setup.
Otherwise I'd like to look into adding the option if it isn't possible ... 
Right now you can start: Left, middle, right. (mind the proper orientation of course, but bow orientations will work for all 3).
Did you experiment with letting the bottom left and bottom center set to zero? (dito for bottom right and bottom center)

Plugins:
My XBMC runs on a tiny AMD Fusion computer, so I'm sure apps like watchdog combined with boblight is pushing the [timing] limits.
I'm considering looking at something more potent, like the new intel NUC, but I'd prefer it to be potent enough for experimenting with SteamOS in the future as well.

I have seen others work with the Raspberry Pi, but I was thinking of using it independently. Meaning: "digitize" the video signal, have Raspberry Pi analyze it and control the LEDs so the Ambilight would also work with other devices ... problem so far is finding a HDMI pass-through device that allows digitizing (which comes with issues when the HDMI signal is encrypted) ...