dfu's ramblings

linux-uvc_flip updates

2008-11-06T07:04:00.004-06:00

I've updated several times, and at the moment it works with SVN-261 of linux-uvc. If anyone has any problems with certain kernel versions, or with certain parameters compiled in, let me know. It seems to work with 2.6.27.4, but I will need to look into some delay issues I'm experiencing at 640x480.

http://github.com/dfu/linux-uvc_flip

linux-uvc_flip update

2008-07-05T11:09:00.003-05:00

Updated linux-uvc_flip to svn-223 of linux-uvc. Grab it from the git repository:
git://github.com/dfu/linux-uvc_flip.git

Git Repository for linux-uvc hack

2008-06-21T07:58:00.003-05:00

Since there is an issue with downloading my patch, I've started a git repository for my linux-uvc_flip hack. It's still the same as before, but I'll update it eventually to use the current svn version of the linux-uvc driver (217 currently).

git://github.com/dfu/linux-uvc_flip.git

UVC Webcam Flip Patch v03

2008-05-24T01:10:00.004-05:00

I updated the patch slightly to copy whole lines of data, instead of 4 byte chunks.

http://www.uhacc.org/~dfu/uvc-hack-v03.tar.gz
http://www.uhacc.org/~dfu/uvc-hack-v03.patch

Updated UVC Flip Hack

2008-05-15T05:19:00.003-05:00

I've created an updated patch to fix a couple issues of the original patch. In the original the image was not only flipped vertically, but horizontally too. However, since my understanding of the video format was not the greatest, the luminance bits were not flipped. Every four bytes corresponds to two pixels, with each pixel having its own luminance, but the chrominance is shared between the two. Well, since I didn't switch the luminance bits, it looked blocky at low resolutions.

This new patch is somewhat more complex, but, is also more accurate. It creates a vertical flip by understanding the height and width of the image, and not just dealing with the length of the array.

Again, this is for Asus Laptops using the Chicony based webcam:
http://www.uhacc.org/~dfu/uvc-hack-v02.tar.gz
http://www.uhacc.org/~dfu/uvc-hack-v02.patch

Chicony 04f2:b012 Webcam UVC Hack

2008-05-06T01:48:00.005-05:00

Since on the Asus W7S, the cam is installed upside down, I did a small hack for the Linux UVC driver to flip the Chicony webcam's image vertically. At the moment it is very hacky, but works fine. This really shouldn't be in the kernel, but I would rather have the cam work than not.

Based on SVN Rev 207 of the UVC driver: http://www.uhacc.org/~dfu/uvc-hack.tar.gz
If you want to see what I did: http://www.uhacc.org/~dfu/uvc-hack.patch

I will post more findings later.

Gentoo Linux on the Asus W7S-A1B

2007-08-20T17:09:00.000-05:00

I've been using my Asus W7S-A1B for awhile now, and it's a cool little notebook. I, as usual, put Linux on it when I first received it with little headache. Just make sure to use a 2.6.22+ kernel so that you have the mac80211 stack for the Intel 4965 wireless controller. The SDHCI drivers work flawless too, and it's nice to actually be able to use the integrated SD card reader. The only caveat is that the webcam has no driver. Maybe I found a new little side project. :)

However, lately I've been looking into bandwidth while transferring files and noticed it is extremely slow with not only wireless, but wired too. Needless to say I will have to look into it. Maybe it's something I compiled in the kernel (or lack of something).

New workings

2007-03-01T14:57:00.000-06:00

My personal projects now encompass way too many things:

I was hacking on a small threaded client/server to further my unix programming skills (sockets + pthreads), and now it's turning into a small game server. Threaded programming with sockets is giving me somewhat of a hard time. There seems to be papers saying that event driven programming is better, especially since you have the context switching going on with threads. However, others say that it really doesn't matter, and if you do it right, threads will be just as fast (if not faster). At the moment, I'm doing one thread per connection, which in some cases is bad, since it's pretty much limited by our maximum thread count. Each thread takes up space on the stack (which you can *try* to limit as best as possible) and then you multiply that by the number of threads, trying to keep it in bounds of memory. Maybe I'll just have to try different methods after I actually get this working correctly.

I suppose I've been reading more about electronics too, as I have some ideas for embedded systems projects. Atmel AVRs are pretty damn cheap and can do some cool things. I have two projects in mind, and I'm just reading through a basic electronics book making sure I'm going to create my circuits correctly.

All of my Linux kernel projects seem to keep being put on hold. I try and read all the new patches, but seem to fall behind. I suppose I'll just continue to read, and work on things when I can. If nothing pans out, maybe I'll create some patches for Kernel Janitors.

Well, there is obviously more than that, which includes small things I need to spend more time on.

DS Development

2006-12-18T21:13:00.000-06:00

So, I've been doing some Nintendo DS development as of late. Using devkitPro and ndslib I decided to try and port my snowglobe I made for my graphics class. There is an image of it on the right. It has snow particles that bounce around the globe. Yay!