Rockbox and the 240Gbyte iPod

 Computing  No Responses »
Dec 222009
 

So in the interests of science (ok, I wanted a new toy with a large amount of storage for music), I bought a pre-upgraded iPod 5.5 with a 240Gbyte hard disk in it. Loaded up Rockbox as soon as it arrived with the special version for upgraded iPods and everything was working …

Well … sort of. I could copy most of my music onto it, but nothing with a filename that broke the rules of pure FAT … no long extensions (so no FLAC files!!), no UTF-8 filenames (and “f#a#oo” isn’t quite a catchy a name as “f♯a♯∞”). So I rebuild the filesystem with the standard Linux tool mkfs.vfat

Bad move! Whilst all the files now copied onto the iPod, the Rockbox bootloader was now unable to load the main rockbox binary (“rockbox.ipod”). Seems that Rockbox’s idea of FAT32 on large disks isn’t quite the same as Linux’s version (or to be fair OSX either). So I spend ages hunting around to see how to create an appropriate filesystem on the iPod to allow things to work, without success.

Thus this page.

First of all, connect up the iPod and determine what device it is (mine showed up as /dev/sdh). The command fdisk -l is quite helpful here particularly as we use that next.

Once you find the iPod’s device, use that to display the partition table using fdisk :-

# fdisk /dev/sdh
# fdisk /dev/sdh
Note: sector size is 2048 (not 512)

The number of cylinders for this disk is set to 22506.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
 (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p

Disk /dev/sdh: 240.1 GB, 240057409536 bytes
84 heads, 62 sectors/track, 22506 cylinders
Units = cylinders of 5208 * 2048 = 10665984 bytes
Disk identifier: 0x20202020

 Device Boot      Start         End      Blocks   Id  System
/dev/sdh1               1          13      128394    0  Empty
Partition 1 does not end on cylinder boundary.
/dev/sdh2              13       22507   234302542    b  W95 FAT32

Command (m for help): q

Here we use the “p” command to list the partition table, and “q” to quit. The key bit of information we are looking for are the number of cylinders, heads and sectors per track (22506, 84, 62). For the number of cylinders, we need to subtract the number of cylinders used by the first partition … or perhaps easier the value of the cylinder that the second partition starts on (13). This gives the values we use for mformat to format the filesystem.

Next we need to create a “drive letter” (!! – why doesn’t mtools allow you to specify a device to work with in the proper Unix fashion?) by editing /etc/mtools.conf and adding a line at the end like “drive z: file=”/dev/sdh2″”.

Finally we need to use mformat to create the filesystem :-

mformat -t 22493 -h 84 -n 62 -S 4 -M 2048 -F -v FATBOX -N deadcafe z:

The “-v” and “-N” options are unnecessary, but at least the “-v” option is kind of handy to allow the iPod to be automatically mounted in an appropriate place. And I usually take every opportunity to assign some funky hex value 🙂

Gender Differences In Photography

 Photography, Politics  No Responses »
Dec 062009
 

I have just read this article on whether men and women take different photograph. Without going into too much detail, the overall impression is of confusion with some people saying yes and others no.

This is going to be very short. Whilst there may be gender-based differences in the way that we make photographs, these are likely to be overwhelmed by the simple differences between us that are down to us all being individuals. Most of us are far too keen to jump on the obvious differences (gender) and assume that these explain everything.

Or to put it another way, why did Robert Capa and Henri Cartier-Bresson make images that were so different when they are both men ? That’s right, because they were individuals and so was Gerda Taro. That she was a woman adds to her individuality, but being a woman didn’t make her any more of an individual or any less of an individual than Robert Capa was.

MSN Robot Has A Bug ??

 Computing  No Responses »
Dec 052009
 

So a few days ago I was idly looking at the “StatPress” page on my site to look how few people were visiting to see something rather surprising :-

Graph of accesses

What was happening here ? Have I been slashdotted ? Is my income from those silly ads down the side going to shoot through the roof to a level worth letting a certain company send me the payments ?

No. Nothing so exciting. All (well, the overwhelming majority) were from an MSN robot – presumably indexing this site. Well fair enough, but why so many accesses ? It is not as if my site has much on it – nowhere near the nearly 100,000 page fetches they tried. A closer look at the Apache logs shows that the msn robot repeatedly fetched many pages including one page 1,300 times!

Sounds like Microsoft has a bug somewhere.

Creating A Date-Based Photo Repository & Examining Results

 Computing, Photography  No Responses »
Nov 282009
 

Because of a little “issue” with Bibble which causes that software to cease responding when navigating the browser whilst it is updating the icons, I had to come up with a different way of storing my raw images. Or at least a different “shadow view” that would allow Bibble to work more reliably. I had been thinking on what would be the best way (for me!) of doing this for a while now, and this morning spent about 45minutes knocking up some code to do what I wanted.

I chose to use the “date” contained within the Exif information within each file to produce a directory structure along the lines of “/some/place/YYYY-MM-DD/original-name-of-file” with the file at the bottom level being a symlink back to the original file. I chose not to move any files around as I could more easily fix things if the code I had written did Something Stupid. I chose not to copy any files, as I did not want to duplicate some 100Gbytes of RAW files if I did not need to — and I did not as symlinks can do the job perfectly well.

As for the choice of the date format, well I have long preferred the ISO date format in places where a conventionally human readable date was not necessary or would be inconvenient. The ISO date format is useful in that it is not subject to misinterpretation as date formats such as “DD-MM-YY” and “MM-DD-YY” are, and it happens to sort easily with the ls command – which is much more useful than you would think. If it looks a little odd, just start using it and get used to it.

The code itself is available here if you really want to get hold of it (I wouldn’t bother if I were you – it’s just something knocked up in a rush that works ok for me).

The interesting thing about the new “repository” was that it was easy to produce a table of dates and the number of photos taken on those dates :-

cd /media/photos/raw.dated
for i in $(echo *)                        
do
  echo -n "$i "; ls $i/* | wc -l
done

The output is long enough and boring enough (for anyone other than me) that I will not include it here. But it is relatively easy to turn this into a graph using ploticus :-

ploticus -prefab chron \
  -o photos.png \
  -png \
  data=dates.dat x=1 y=2 \
  datefmt=yyyy-mm-dd \
  color=blue \
  echodata=no \
  xinc='1 year' \
  stubfmt='MMM YY'

This produced a graph similar to :-

Photo Frequency

I seem to be taking more photos over time.

Lessons On Domestic Abuse

 General  No Responses »
Nov 262009
 

It seems that the government is planning on teaching children from the age of 5, that domestic abuse is wrong. And about time too! There is an absolutely horrific level of domestic abuse in the UK, which may or may not be better than elsewhere, but that is not what this is about.

Some parents are complaining that it is their job to teach their children about such things. Well obviously not all parents are doing their job properly, or the figures for domestic abuse would be far better! So this is a good initiative, or is it ?

Apparently the lessons are to emphasise that boys are to treat girls with respect and that girls are to expect respect. The reason for this sexism ? Because the overwhelming number of victims of domestic abuse are women. Well that is certainly true; the BBC article claims that in 2008/9 there were 293,000 incidents of domestic violence reported in England and Wales with 77% being against women. That leaves 23% being against men giving a total of 68,000 incidents.

Let us change the sex of those 68,000 victims of domestic violence to women. Would 68,000 female victims of domestic violence justify these lessons ? I would say so, so surely the lessons should also teach that abusing men is also wrong?

Another thing about those statistics is that it is known that domestic abuse is subject to a huge level of under reporting. With that in mind, and bearing in mind that women have been encouraged to report domestic abuse, it is perfectly possible that the statistics given above are inaccurate not just in the size of the problem, but in the ratio of victims – it may well be that men are as likely to be victims of domestic abuse as women! Perhaps you do not agree, but we simply do not know.

If we teach children the lessons exactly as expressed, children will learn a second lesson from them – that whilst girls should have respect, boys do not need be given respect. It is a short distance from that to accepting domestic abuse against men.

Domestic abuse against anyone is unacceptable.

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