Inkscape Migrated to Launchpad

Yesterday I performed the migration of Inkscape‘s bugs from SourceForge.net to Launchpad. This was a full import of all their historic bug data – about 6900 bugs.

As the import only had access to the SF user names for bug reporters, commenters and assignees, it was not possible to link them up to existing Launchpad users in most cases. This means that duplicate person objects have been created with email addresses like $USERNAME@users.sourceforge.net.

If you are a Launchpad user and have previously filed or commented on Inkscape bugs, you can clean up the duplicate person object by going to the following URL and entering your $USERNAME@users.sourceforge.net address:

https://launchpad.net/people/+requestmerge

After following the instructions in the email confirmation, all references to the duplicate person will be fixed up to point at your primary account (so bug mail will go to your preferred email address rather than being redirected through SourceForge).

Weird GNOME Power Manager error message

Since upgrading to Ubuntu Gutsy I’ve occasionally been seeing the following notification from GNOME Power Manager:

GNOME Power Manager notification

I’d usually trigger this error by unplugging the AC adapter and then picking suspend from GPM’s left click menu.

My first thought on seeing this was “What’s a policy timeout, and why is it not valid?” followed by “I don’t remember setting a policy timeout”. Looking at bug 492132 I found a pointer to the policy_suppression_timeout gconf value, whose description gives a bit more information.

Apparently the timeout is designed to ignore spurious messages from the hardware after a resume — you wouldn’t want to process a left over “suspend” message immediately after resuming from suspend after all. This does bring up a few questions though:

  1. While ignoring “please suspend” messages shortly after performing a suspend makes sense, why ignore “please suspend” messages after an “on battery power message”?
  2. While messages from the hardware might be spurious, surely picking an option from GPM’s menu is not. I guess such suspend requests are being mixed in with hardware suspend requests before the point where the policy timeout is checked.

gnome-vfs-obexftp 0.4

It hasn’t been long since the last gnome-vfs-obexftp release, but I thought it’d be good to get these fixes out before undertaking more invasive development. The new version is available from:

http://download.gnome.org/sources/gnome-vfs-obexftp/0.4/

The highlights of this release are:

  • If the phone does not provide free space values in the OBEX capability object, do not report this as zero free space. This fixes Nautilus file copy behaviour on a number of Sony Ericsson phones.
  • Fix date parsing when the phone returns UTC timestamps in the folder listings.
  • Add some tests for the capability object and folder listing XML parsers. Currently has sample data for Nokia 6230, Motorola KRZR K1, and Sony K800i, Z530i and Z710i phones.

These fixes should improve the user experience for owners of some Sony Ericsson phones by letting them copy files to the phone, rather than Nautilus just telling them that there is no free space. Unfortunately, if there isn’t enough free space you’ll get an error part way through the copy. This is the best that can be done with the information provided by the phone.

Test Suite

As noted in the third point, I’ve started to build up a collection of capability and folder listing XML documents produced by various phone models. This serves a dual purpose:

  1. Ensure that the capability object and folder listing XML parsers don’t regress between releases. It is impractical for me to test gnome-vfs-obexftp against all these phone models since I don’t have the hardware or time.
  2. Give an idea of what information the different phone models provide, which should be useful when planning new features.

If you have an OBEX FTP capable phone that is not already in the test suite, it’d be useful if you could collect the data and file a bug. The information can be collected using the command line “obexftp” program (part of the “obexftp” package on Ubuntu). The following commands will give the capability object and root folder listing:

obexftp --bluetooth $BDADDR --capability
obexftp --bluetooth $BDADDR --list

It’d also be useful to get a listing for one or two other directories. If there is a memory card, it’d be useful to get that folder. For example:

obexftp --bluetooth $BDADDR --list "Memory card/"

It’d be most useful if the transcript of the various commands were included as an attachment. Feel free to censor personal information if you want (e.g. the phone serial number in the capability object, some non-default file names).

In particular, I wouldn’t mind getting information on phones with brands other than than Nokia or Sony to see what info they provide.

Investigating OBEX over USB

I’ve had a number of requests for USB support in gnome-vfs-obexftp. At first I didn’t have much luck talking to my phone via USB. Running the obex_test utility from OpenOBEX gave the following results:

$ obex_test -u
Using USB transport, querying available interfaces
Interface 0:   (null)
Interface 1:   (null)
Interface 2:   (null)
Use 'obex_test -u interface_number' to run interactive OBEX test client

Trying to talk via any of these interface numbers failed. After reading up a bit, it turned out that I needed to add a udev rule to give permissions on my phone. After doing so, I got a better result:

$ obex_test -u
Using USB transport, querying available interfaces
Interface 0: Nokia Nokia 6230 (null)
Interface 1: Nokia Nokia 6230 (null)
Interface 2: Nokia Nokia 6230 (null)
Use 'obex_test -u interface_number' to run interactive OBEX test client

With the change, I was also able to access the phone using the obexftp command line client. This seemed enough to start investigating a bit further. The OpenOBEX API for setting up USB connections goes something like this:

  1. The app calls OBEX_FindInterfaces(), which returns a list of obex_interface_t structures that represent the different discovered interfaces.
  2. The app picks one of the discovered interfaces (based on the manufacturer, product and serial number strings), then connects to it using OBEX_InterfaceConnect().

There are a number of issues with this interface though.

  • If the phone doesn’t provide a serial number via its USB interface (like my 6230 doesn’t), the obex_interface_t structure is not enough to identify a particular phone.
  • If the phone exposes multiple OBEX USB interfaces for some reason, OpenOBEX lists it multiple times. In the obex_test output shown above, there was a single phone attached – not three.
  • There is no way to tell when phones are connected or disconnected. While HAL can do that job for us, there is no way to map from the device information provided by HAL to one of the discovered interfaces provided by OpenOBEX.

To sum up, it shouldn’t be difficult to hack support for USB connections into gnome-vfs-obexftp with URLs like obex://usb-N/ (where N is the number of the discovered interface), but there are a number of features I’d need to provide a good user experience:

  1. The ability to ask OpenOBEX to connect to a particular USB device, rather than having to deal with its discovery interface.
  2. A good set of udev rules to grant the needed permissions on common phones so they don’t need to find out why things only work as root.

TXT records in mDNS

Havoc: for a lot of services advertised via mDNS, the client doesn’t have the option of ignoring TXT records if it wants to behave correctly.

For example, the Bonjour Printing Specification puts the underlying print queue name in a TXT record (as multiple printers might be advertised by a single print server). While it says that the server can omit the queue name (in which case the default queue name “auto” is used), a client is not going to be able to do what the user asked without checking for the presence of the record.

Rather than thinking of TXT records as optional data, it is better to think of them as “stuff that is can not be used to perform searches”. In the printer example above, the fact that you can’t search by print queue name is not a problem because users instead pick a printer based on the human readable service name which is exposed as a DNS name.

In your example of including session and machine identifiers in TXT data, it would be enough to tell a client that two services belonged to the same machine or session, but it wouldn’t let you do searches like “find all the card game servers belonging to the same session as the guy I’m chatting with”.  For that you’d also need to advertise DNS names that include the machine identifier or session identifier.

gnome-vfs-obexftp 0.3

I’ve just released a new version of gnome-vfs-obexftp, which includes the features discussed previously. It can be downloaded from:

http://download.gnome.org/sources/gnome-vfs-obexftp/0.3/

The highlights of the release include:

  • Sync osso-gwobex and osso-gnome-vfs-extras changes from Maemo Subversion.
  • Instead of asking hcid to set up the RFCOMM device for communication, use an RFCOMM socket directly. This is both faster and doesn’t require enabling experimental hcid interfaces. Based on work from Bastien Nocera.
  • Improve free space calculation for Nokia phones with multiple memory types (e.g. phone memory and a memory card). Now the free space for the correct memory type for a given directory should be returned. This fixes various free-space dependent operations in Nautilus such as copying files.

Any bug reports should be filed in Launchpad at:

https://bugs.launchpad.net/gnome-vfs-obexftp/

Stupid Patent Application

I recently received a bug report about the free space calculation in gnome-vfs-obexftp. At the moment, the code exposes a single free space value for the OBEX connection. However, some phones expose multiple volumes via the virtual file system presented via OBEX.

It turns out my own phone does this, which was useful for testing. The Nokia 6230 can store things on the phone’s memory (named DEV in the OBEX capabilities list), or the Multimedia Card (named MMC). So the fix would be to show the DEV free space when browsing folders on DEV and the MMC free space when browsing folders on MMC.

Doing a bit of investigation, I found that the information I wanted was in the folder listings:

<?xml version="1.0"?>
<!DOCTYPE folder-listing SYSTEM "obex-folder-listing.dtd"
 [ <!ATTLIST folder mem-type CDATA #IMPLIED> ]>
<folder-listing version="1.0">
    <folder name="Memory card" user-perm="RW" mem-type="MMC"/>
    <folder name="Images" created="19800101T000008" user-perm="R" mem-type="DEV"/>
    ...
</folder-listing>

I took a look through the OBEX specification, and this mem-type wasn’t defined. So it looked like a Nokia extension. Doing a quick search, the closest I came to a describing it was US patent application #20060095537.

So Nokia is effectively trying to patent an XML attribute. I’d seen a lot of bad patents, but this seemed particularly weak. The patent application even comes with a useful diagram explaining the invention:

Figure 2

As far as I can tell, using the information returned from the phone wouldn’t be covered by the patent (if it gets issued, that is). So it should be fine to use the information to calculate free space more accurately.

FM Radio in Rhythmbox – The Code

Previously, I posted about the FM radio plugin I was working on. I just posted the code to bug 168735. A few notes about the implementation:

  • The code only supports Video4Linux 2 radio tuners (since that’s the interface my device supports, and the V4L1 compatibility layer doesn’t work for it). It should be possible to port it support both protocols if someone is interested.
  • It does not pass the audio through the GStreamer pipeline. Instead, you need to configure your mixer settings to pass the audio through (e.g. unmute the Line-in source and set the volume appropriately). It plugs in a GStreamer source that generates silence to work with the rest of the Rhythmbox infrastructure. This does mean that the volume control and visualisations won’t work
  • No properties dialog yet. If you want to set titles on the stations, you’ll need to edit rhythmdb.xml directly at the moment.
  • The code assumes that the radio device is /dev/radio0.

Other than that, it all works quite well (I’ve been using it for the last few weeks).

Development

I developed this plugin in Bazaar using Jelmer‘s bzr-svn plugin. It produces a repeatable import, so I should be able to cross merge with anyone else producing branches with it.

It is also possible to use bzr-svn to merge Bazaar branches back into the original Subversion repository through the use of a lightweight checkout.

For anyone wanting to play with my Bazaar branch, it is published in Launchpad and can be grabbed with the following command:

bzr branch lp:~jamesh/rhythmbox/fmradio rhythmbox

FM Radio in Rhythmbox

I’ve been working on some FM radio support in Rhythmbox in my spare time. Below is screenshot

At the moment, the basic tuning and mute/unmute works fine with my DSB-R100. I don’t have any UI for adding/removing stations at the moment though, so it is necessary to edit ~/.gnome2/rhythmbox/rhythmdb.xml to add them.

FM Radio Tuners in Feisty

I upgraded to Feisty about a month or so ago, and it has been a nice improvement so far. One regression I noticed though was that my USB FM radio tuner had stopped working (or at least, Gnomeradio could no longer tune it).

It turns out that some time between the kernel release found in Edgy and the one found in Feisty, the dsbr100 driver had been upgraded from the Video4Linux 1 API to Video4Linux 2. Now the driver nominally supports the V4L1 ioctls through the v4l1_compat, but it doesn’t seem to implement enough V4L2 ioctls to make it usable (the VIDIOCGAUDIO ioctl fails).

To work around this, I ported the tuner code in Gnomeradio over to V4L2. The patch can be found attached to bug 429005. I don’t know if this patch will go in as is though, since it only works for drivers supporting V4L2. Perhaps it’d be worth supporting both APIs, using V4L2 if both are supported.