Advogato blog for mbrubeck

2 Apr 2008

Wed, 2 Apr 2008 18:11:55 GMT

Flip Video Ultra on Linux

My Flip video camera arrived yesterday, and I'm quite happy with it. It does everything it's supposed to: starts up fast, records and plays back through an astoundingly simple interface, and mounts as a USB mass storage device. The videos play back perfectly on my Ubuntu 7.10 system, and Kino can import and edit them if ffmpeg is installed.

I did have some problems using the camera with a Windows XP laptop. The Windows program stored on the camera failed to start up, saying that "E:\SYSTEM\VIEWER\PD\settings\pathsInfo.txt does not contain a valid list." The firmware updater from the Flip web site failed with a similar error. Finally I found the Flip Video Program installer, which fixed both of those problems. (It took me a while to figure this out, so I'm documenting it here in case other Flip owners have the same problem.)

26 Nov 2007

Mon, 26 Nov 2007 04:11:09 GMT

PDF on Kindle

I've seen plenty of good commentary on the Amazon Kindle. Robert Love's hands-on review and follow-up cover both Linux-hacker and regular customer views. But there's one question that I haven't seen answered elsewhere: Why doesn't the Kindle support PDF natively?

I think the answer is simple: The Kindle's 800×600 e-ink screen has too few pixels to render a typical PDF file readably, and its refresh rate is too slow for comfortable scrolling. The only practical solution for most PDFs is to extract the text and convert it to a reflowable format like HTML (which Kindle users can do with Amazon's $0.10 wireless service or free PC-based service). The US$700 iLiad (with 64% more pixels) is much better for PDF reading, but will still run into trouble with some files. It seems that the current generation of ebook readers comes with a decision—cheap, e-ink, or PDF: choose any two.

The refresh problem is one reason I'm not sold on e-ink. I'm curious to compare the Kindle screen to my XO laptop, which seems like an interesting compromise between normal LCD and e-ink displays.

Disclaimer: I work for Amazon, but I don't know anything about the Kindle except what I learned from the user's guide and from playing with one at the office.

27 Aug 2007

Mon, 27 Aug 2007 22:59:53 GMT

vim-addons

Joey wonders why vim addons are not enabled by default using the new Debian infrastructure.

For single-user systems, Joey is right: enabling addons by default would be best. But for multi-user systems, I think disabled-by-default is better. Otherwise, installing an add-on would change vim's behavior unexpectedly for all users. (Unlike a daemon, which runs once per system; a vim addon is run by each user, every time they start vim.) This is especially bad because vim users tend to have carefully personalized configurations.

Should the defaults cater to multi-user systems at the expense of single-user ones? Probably not, since admins of large multi-user systems are generally willing and able to figure out how to change their configurations, while many single-user machine owners need something that "just works". Perhaps the default configuration should load all installed addons, but local admins should be able to easily change this to load only addons enabled by the current user.

21 Aug 2007

Tue, 21 Aug 2007 05:57:59 GMT

Problems for shared desktop computers.

I share a home desktop computer with my wife. Our computer use is probably pretty typical of a home computer shared between a small number of users, where only one user is logged in at a time, and users have some shared files and some private files.

I've found many things that don't work as well as they could in this situation. We use Gnome on Debian GNU/Linux, but most other desktops have similar problems. I know fixes or workarounds for most of the problems below, but novice users would probably have a hard time finding them.

Some of the problems below are relatively easy to fix. Most already have bugs filed in the appropriate places, and some already have patches available. A few problems may require hard work or fundamental design changes to solve. Here is the complete list of problems:

User Switching:

If I select my name from FUSA while I'm not already logged in, GDM appears and I have to type my username. (The username should be filled in automatically.)
When GDM is started by FUSA, the X server has slightly settings, causing the fonts on the login screen to be a different size than my normal settings.
When I log out, I am taken either to a login screen or to another user's session, depending on the order in which users originally logged in. This is arbitrary and unpredictable.
If I switch to another user, my screen is locked. Later, if the computer is displaying a login screen and I type my username and password, I need to type my password a second time to unlock the screen.
When I shut down the computer, it does not warn me if other users are still logged in.

Filesystem:

By default, users can read all of each other's files, and write to none of each other's files (umask 0002). This is a reasonably sensible default, but most users on shared systems will want to change this to some degree.
It's very difficult for a user to change which other users can read which of her files. (Some strategies include making some or all files world writeable; adding the other users to her primary group; creating a new shared group and a share setgid directory owned by that group; changing her umask; and/or manually changing permissions of individual files.)
There is no good location by default for shared files. Various programs complain (correctly) about insecurity if my home directory is group-writeable, so I must create a world- or group-writeable (and setgid) directory elsewhere.
Copying from other locations, or using programs that do not respect umask, can cause users to inadvertently put non-group-writeable files in shared setgid directories. Other users of the shared directory have no easy way to fix this.
Some programs modify permissions or groups of files when overwriting them. (Usually this happens if the program moves the original file to a backup location, then writes a new version using the default settings instead of the original file's settings.)

Application data:

Applications that maintain a database of files (e.g. photo managers, music players) must be updated for each user when one user adds new files to a shared directory. For example, when I rip a CD to our shared music directory, my wife can't see the songs in her music player until she adds the new files to her database.
Applications that store their data in hard-coded locations in user home directories (e.g. Tomboy, Miro) can't share files between users. There is no setting or permission that will let my wife open Tomboy and view my Tomboy notes, for example.

Installing software:

When I install software using the system admin tools, it changes the application menu for all other users too.

25 Jul 2007

Wed, 25 Jul 2007 17:25:53 GMT

Retiring from Debian

In response to the inactive developer ping, I have decided to retire from the Debian project. Between my job and the new baby, my time for hacking on other projects is nonexistent, or possibly negative. I have already passed Audacity maintainership to the debian-multimedia team.

I still use and like Debian, and I hope someday I'll return from "emeritus" status to become an active developer again.

Cyclone

While browsing through some very old backup files, I rediscovered one of my first real software projects, an IRC client for BeOS. This was a neat collaborative effort, but we weren't really on the ball with project hosting or version control. This is from a file I wrote documenting what was left of the project after it stopped:

Cyclone was started in spring 1998 by a group of developers who hung out in the #bedev channel on EFNet. The original Cyclone team included Jason Gosnell (Avatar), Jeff Hamilton (Pyrus), Matt Lewinski (mattl), John Wiggins (prok), and Matt Brubeck (mgb), with contributions from several other #bedev regulars.

The Cyclone project produced a small, elegant IRC client. Unfortunately, the team dissolved as several members moved around the country to go to new schools or jobs at the end of summer 1998. Along with the loss of some important pieces of source code, this prevented Cyclone from ever seeing a public release.

I also found some poetry I wrote in middle school, but it's compressed using a version of StuffIt that does not seem to be compatible with any open source tools. This is probably a good thing.

14 Jul 2007

Sat, 14 Jul 2007 02:59:32 GMT

Check out this black and white digital back for medium-format cameras. Why aren't there any dedicated black-and-white sensors available in compact digicams or DSLRs? The sensor would have much more light to work with than a color sensor with a Bayer filter. It would also be able to use colored filters without throwing away so much information.

It would be a niche product for sure, but it would be perfect in something like the Ricoh GR-D or the Sigma DP1. The people buying those cameras are already sacrificing flexibility (both have fixed prime lenses), and many of them are street photographers and shoot primarily black and white already. Wouldn't a dedicated black and white sensor improve dynamic range and sensitivity for available-light shooting?

Add this to my DMD wishlist. Not that I could actually afford it if it existed.

5 Jun 2007

Tue, 5 Jun 2007 19:01:12 GMT

My toy is cheaper than yours.

My recent purchases:

$20 digital camera and $5 memory card.
Free + $6 shipping USB dance pad (to hack for StepMania).

15 Apr 2007

Sun, 15 Apr 2007 23:24:47 GMT

A hacker remembers

This story by David Humphrey from last week really hit home:

She told about how my grandfather made his living repairing radios, toasters, fans–anything and everything electrical. He’d only received a 4th grade education in Scotland, before he had to start earning a living to support the family. She described how their entire house, with its mechanical and other systems, was kept working through his creativity and persistence. When the well pump went, he made a new one out of parts from three others…

David could have been describing my own grandfather, who died last month. I knew him as Ojiichan ("Grandpa"). A child of immigrant farmers, his formal education stopped after the sixth grade. As a young man during the internment, he took a correspondence course in radio repair, and after the war started a life-long career in electronics. He worked on electronics at home too, building projects like a cruise control for his own car. Almost up until his death at 93, he lived alone, still drove, and still flew every year to keep his pilot's license up to date. At his memorial service, his family remembered his love of tricky, hard-to-solve problems.

Many of Ojiichan's children and grandchildren have grown up to be engineers, but few of us could do some the things he did. He was a lively embodiment of the hacker spirit.

9 Apr 2007

Mon, 9 Apr 2007 06:14:26 GMT

lkcl: Ratings and reports are explained in the Advogato FAQ, by the way. One thing I can't tell whether you realized or not: The report at /rating/report/lkcl does not show what other people think of your diary. It shows what you (and the people you certified) think of other users' diaries.

The lumpiness of the histogram is because most users don't use the full range of ratings. And since confidence scores fall off exponentially by network distance, your confidence-weighted histogram will be skewed toward ratings given out by yourself and people you directly certified. For example, I tend to rate most diaries between 4 and 9, so I expect my report to be skewed toward those values.

8 Apr 2007

Sun, 8 Apr 2007 23:09:08 GMT

Planet Venus as a personal home page

Planet Matt is my shiny new home page, based on the Planet Venus feed aggregator. It displays my recent updates from Advogato, LiveJournal, Flickr, and elsewhere. It also provides a single feed for friends who want to subscribe to all of my updates without tracking down a username and feed for each new service.

This gives some of the same benefits as ClaimID or Red Hat's MugShot, but it runs at a domain I control, and doesn't depend on any one third-party service. As a bonus, the home page is also my new OpenID URL (using delegation).

Right now I'm using a slightly modified version of the "classic_fancy" theme that comes with Planet, plus some simple custom filters. I'm developing a new theme that will be more suited for use as a personal home page, which I plan to contribute back to Planet Venus for others to use. Let me know if you're interested.