Sunday, March 23, 2008

Geotag photography with n810

In preparation to my trip to Nepal, I'd like to share with you experiments I've conducted in the previous weeks regarding GPS in n810 (thanks Nokia for selecting me in Maemo developer program, BTW) and geotagging photos.

First, some comments about GPS in n810 :

  • it is a good way to learn some things about GPS technology (thanks to Wikipedia) when you want to understand why it is taking so long to get a position fix. And then, you start to speak about sky search (take about 12 minutes to download satellites constellation rough positions for your position, called almanac, valid for several weeks), cold fix (take about 6 minutes to download satellite precise position, called ephemeris, only valid 4 hours) and warm fix (take about 30s, when ephemeris is still valid in the device).
  • Of course, there is no way to easy way to guess what kind of search n810 is doing when starting GPS. For the first time you use it in a geographical area, you can expect to wait for about 20 minutes. If you didn't get a GPS fix in the last 4 hours, you can expect a fix between 5 to 10 minutes. If you got a fix in the last 4 hours, you can get a fix in 30s to 1 minute (it is not impossible, I've been able to get such fast hotfix in a moving bus in Paris ;)
  • You should really install Maemo-Mapper. Preinstalled software (called Maps) is a stripped version of Navicore. Unfortunately, it is barely usable, since its main goal is to see license for full version. Its main feature is using vectoral maps (so you get France maps for about 300MB) and being able to do address search offline. It is quite funny to discover it uses ogg vorbis audio files, despite no "official" support for Ogg Vorbis in IT2008 from Nokia. OTOH, Maemo Mapper, after preloading maps from either OpenStreetmap, Google, Yahoo or Virtual Earth, is way more powerful : you can easily record tracks, way points, import POI (with help of gpsbabel, you get virtually import any GPS data into Maemo Mapper).
My first experiment was done in Brussels during FOSDEM in February. I spent an entire day walking and photographing in Brussels, with GPS tracking enabled (with Maemo-Mapper) on my n810. It worked fine with a full charge (about 7h of tracking) but the initial fix was quite slow to get (it was my first real experience with GPS, I learned a lot about it after FOSDEM). You take a photo of n810 displaying GPS time (to record time offset between camera and GPS) and then, you can start shooting and keep Maemo-Mapper in tracking mode. A nice addition to Maemo-Mapper would add a "low consumption" mode (ie no maps nor tracks drawing) but if you disable "auto-center","display track" and "show GPS details", you can get something decent.

Then, back at home, after developing Raw photos (using Ufraw), I geotagged them, using gpscorrelate and gpx track from Maemo-Mapper and pushed photos to Flickr. Et voilà : they are available on Flickr, with geo data. I've noticed a Geotag extension for F-Spot is being developed so I hope to be able to use it for my next batch of photos.

Crazy April

I'm feeling a crazy month of April coming :

  • we are in the final rush for Mandriva Linux 2008 Spring (RC2 was released some days ago) and it should be out in the first days of April.
  • I've accepted new responsabilities at Mandriva : in addition of being GNOME / HAL / guy, I'm now Manager of France Engineering team (located in Paris), whose main task is to work on Mandriva Linux distribution (as well with our Brazilian colleagues).
  • As part of those new responsibilities, I'll be flying to Linux Foundation Collaboration Submit to attend Desktop Architect Meeting (I'll be part of the Distributions panel) in Austin, TX from April 8 to April 10 (but I'll be in Austin from April 5).
  • just one week after this meeting, I'll be flying to Nepal for two weeks holidays (part visit, part trekking). I'll share my photo setup soon.
A side note for French readers : I've started back to blog in french on subjects only relevant to French people (or French speakers). Those posts won't be visible in Planet GNOME and Planet Mandriva.

Un accès à Internet mobile à un tarif raisonnable ?

(Ouvrez le ban) J'ai décidé de blogger aussi en français, mais uniquement pour des sujets qui intéressent les lecteurs français (ou francophones), pour éviter de polluer les quelques planètes où mes posts en anglais avec des infos à caractère "local" ;) (Fermez le ban)

Depuis des années, j'ai un dilemne avec mon téléphone portable : je l'utilise extrêmement peu (je ne suis pas très téléphone et pour la plupart de mes appels, ma Freebox fait parfaitement son office), donc les forfaits 72h par mois, très peu pour moi. Pendant plusieurs années, mon mobile restait dans mon sac à dos, éteint, en mobicarte et sans crédit activé.. Maintenant, j'ai évolué (en cas de coup dur, c'est quand même bien pratique) et je fais en sorte d'avoir du crédit actif, ce qui revient à un coût d'environ 12€ par mois (pour environ 0 minutes de comm passées par mois). Donc, au final, je me retrouve avec un crédit qui augmente chaque mois, sans réelle utilisation.

D'un autre côté, avec mon n810, c'est parfois ralant de ne pas pouvoir accéder à Internet lorsqu'il n'y a pas de wifi à proximité. Pendant un bon moment, Orange se fichait royalement de ses clients Mobicarte avec un forfait royal de 5Mo par mois pour 3€ et une tarification hors forfait de 0.15€ pour 10Ko consommé. Et malheureusement, chez la concurrence, c'est pas mieux (il y a eu un faible espoir quand Ten a été créé, espoir décu, vu qu'ils se fait racheter par Orange). Hors, il semblerait qu'il y ait enfin un effet iPhone / EEE, avec, enfin des formules "data". Bon, de fausses formules "illimitées data" (avec de jolis quotas à la clé, plus interdiction de VoIP et autres), mais c'est un début (on verra bien ce que Leclerc proposera au 2eme semestre, et Free si jamais ils obtiennent la license 3G).

Et il semblerait que les nouvelles options "illimités data" d'Orange soient accessibles aux clients Mobicarte (bon, forcement, les clients de second classe que sont les Mobicartes ont droit à moins de chose pour le même prix avec la même option..).

Donc hier, je me suis lancé et j'ai pris l'option "Internet Max" (9€ par mois, pour un quota de 200Mo, utilisable 24h/24) hier, histoire de tester :

  • accès web en GPRS via mon mobile : ça marche et c'est bien dans le "forfait"
  • accès web en GPRS sur le n810 en bluetooth via le mobile : ça marche (ouf) et c'est aussi dans la forfait (youpi)
  • accès à un shell SSH sur le n810 (en bluetooth via le mobile en GPRS) : ça marche aussi (j'en connais qui vont être content) et c'est aussi dans le forfait !!
Au final, sur les 12€ de rechargement mensuel, avec une option de 9€, il reste 3€ de consommation (largement suffisant en ce qui me concerne), sans compter le crédit des mois précédents.

Donc, je vais voir ce que ça donne sur le long terme, en espérant que ces infos puissent servir à d'autres personnes qui ont des besoins similaires..

Sunday, March 9, 2008

Recovering photos from a damaged card

4 years ago, I visited Vietnam but I had a big problem with my digicam at that time. Just before the trip, I bought a microdrive 2GB (second hand) and changed my camera from an old Powershot A20 to Powershot S50 (only Canon compact camera to handle microdrives at that time). And I did a newbie mistake :"ok, with one 2GB card, I'll have plenty of space for the entire trip". And of course, the card died on the 4th day of my 2-week trip (and I was fortunate to travel with other people who lend me additional cards I unload quite often to CD-R in various Internet shops across Vietnam).

When I came back, I tried to access the card with my card reader but kernel was not seeing anything. But I never dumped the card, thinking "one day, I'll send it to a recovery company if it doesn't cost too much".

And today, I thought : why not try again, since I heard good opinions about PhotoRec (I quickly met its author at Solutions Linux last month). And guess what : it worked !!

I started PhotoRec in "scan the entire drive" mode and it found 159 files. Then I tried to mount the drive as a FAT partition and it also worked (maybe kernel code for vfat or for usb retry became more robust since last time I checked) and recovered 155 files.

For now, I've been able to confirm 139 files as valid (retrieved by both PhotoRec and direct mount access, with identical md5sum). I have 16 files from "mount method" which have different md5sum as their PhotoRec counterparts. According to file naming, I'm still missing 54 files but I think I have removed them during my trip.

So, I had to dig a little into Photorec recoved files ; some files contains additional padding or even start of next file on disk, after last JPEG end mark (FFD9), which is changing file md5sum. I confirmed 15 files from "mount method" had similar md5sum than PhotoRec files, truncated with help of Hexedit. The last one has only a partial recovery version from counterpart from PhotoRec recovery

Fortunately, I found interesting informations on PhotoRec website, such as file numbering being included in Canon EXIF JPEG file (Canon maker tag 0008, see here or use exiv2 and check image number field), which helped me to fill gaps in the PhotoRec recovered files.

According to file naming/numbering, 54 files are missing but I think I have removed them during my trip, when I discovered photos were bad.

In short, I've been able to recover all files from my damaged microdrive (I don't know yet if I'll dump it in the trash or keep it as a souvenir), thanks to PhotoRec. For people interested, I've uploaded those pictures to my Flickr account (I haven't sorted them, despite my recent decision to try to only upload selected photos Flickr, but I want to be sure those specific pictures are hosted in several physical locations ;), and I've tagged them with photorec tag.

Saturday, March 8, 2008

Mandriva Linux is NOT a purely "KDE distribution"

No, Michael, Mandriva Linux is NOT a purely "KDE distribution" and it hasn't been for the last 7 years !

  • All our tools, including our installer, are developed using GTK2 (mostly using Perl bindings for Gtk)
  • our theme (Ia Ora) is available in both GNOME (ie Gtk2) and KDE (Qt) flavor, to make sure applications have a similar look, even if they are not run under their "native" environment
  • we favor default applications to "native" ones for each desktop (ie using KDE applications under KDE and GNOME apps under GNOME)
  • we try to develop features and graphics design in both environments at the same time
  • we ship our live CDs (called Mandriva One) in two flavors (KDE and GNOME)
  • people using our classic installer products (either Powerpack or Free) are asked if they want to install GNOME or KDE (or any other environments we ship, like XFCE)
  • we even offered a GNOME based Mandriva Flash to all attendee to GUADEC last year in Birmingham.
  • for Firefox, we even split the gnome specific modules in a separate package which is installed by defaut only for GNOME install
  • we developped a XSettings server for KDE which tries to ensure GTK2 applications looks decent under KDE, following KDE settings (unfortunately, it is not possible to do the same for Qt/KDE apps under GNOME)
So, I repeat, Mandriva Linux is NOT a purely KDE distribution. It might have been 8 or 9 years ago, when it was originally created, but it is no longer the case for more than half a decade now.