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Lessons learned the hard way

Filed under: General — Thomas @ 13:05

2007-04-20
13:05

According to /etc/security/limits.conf, nproc controls the "max number of processes".

In reality, it counts a thread started by a process as a process.

This makes the setting orders of magnitude less useful. And, since it goes through pam, and thus gets decided at start time, also a little painful to recover from changing this setting to a higher value to account for threads.

moap release

Filed under: moap,Releases — Thomas @ 22:59

2007-04-17
22:59

A new moap release is out ! This release adds support for Darcs to the moap changelog prepare/commit/diff and moap ignore commands, and generation of iCal data based on the releases in DOAP files.

I've been wanting to add iCal and RSS feed generation based on this for a long time, so I can automatically update feeds when I do a release of any piece of software. RSS feeds are an excellent way to keep updated about project releases. And I like seeing the GNOME iCal spread all over my Evolution calendar.

Now, with Dates getting better on my N800 with every release Opened Hand is rocking out on, I wanted to get the GStreamer releases on there too. It was pretty hard to figure out why Evolution was refusing my ics files when subscribed to on the web. Importing them worked fine. In the end, it turned out I was missing a UID field for each VENTRY. And evolution-data-server-1.8 was telling me so ... on its stdout.

(Sure, it is nice for Evo to be all component-based and stuff, but if the end result is that your code is writing to stdout without anything being connected to stdout - because you are some background server process - then you need a better way to get warnings to the main application. Now the components in eds just litter silly output to stdout, showing that nobody ever sees that stuff because nobody bothers keeping it clean. Like I really need to know what memory pointer the currently selected calendar uses ? Enough ranting though.)

Anyway, now I have lovely Dates showing lovely GStreamer releases. Maybe now I should actually make some !

HELP

I am looking for people interested in making me a nice image or icon. Hey, it works for the Opened Hand guys, why can't I use the intarweb to shake down for icons ?

I am also looking for people to package moap for their favourite distro. Come on Gentoo hackers - be agile ! Come on Ubuntu people - care about maintenance !

Shed bike

This is your opportunity to bikeshed ! I have a quick-and-dirty implementation of an RSS feed feature ready to get commited using templating with Cheetah. Users will want to customize their RSS feeds so allowing them to template the feed makes a lot of sense. I am also planning to get the release mail be templated, and do atom support ,and possibly more stuff.

Cheetah was easy to get started with, in about an hour I had the meat of the feature programmed. I am also going to look at Nevow, just because I am ridiculously reverent of anything Twisted - even though it seems Nevow is more suited for XML-like output.

Here's your chance to bike shed ! Which (Python) template system should I use and why ? Bear in mind that I want to be able to generate at least plain text, HTML, RSS, and Atom. Answers on a post card or in the comments !

Cats and bags

Filed under: Life — Thomas @ 21:45

21:45

Today was the press release, so I'm finally allowed to make it public.

A big congratulations to my girl for being selected out of over thirty people to be the new Ketnet-wrapper ! Vanilla Ice need not worry for a sudden dip in sales - the wrapping Kristien will be doing consists of livening up the screen inbetween shows. For those of you who are geographically challenged, Ketnet is the TV channel for kids run by the Flemish national television here in Belgium.

It was her first screentest ever, and she was chosen out of a bunch of people who all had more experience. Her first time on television is May 1st, Labour day - no bad jokes please. Anyone back home care to record it for me ?

I'm sure she will now finally come to appreciate the hours and hours of practice I have given her - for free,  I might add - dealing with kids.

It's going to be fun having all my friend's kids become old enough to watch and see how they react to someone they know from TV. Of course I'm very excited about this opportunity for her, but I am left with one small worry. Young children have young dads. I remember how some of my friends used to comment on the hotness of wrappers, so I'll have to watch out. I am relying on my posse to keep a watchful eye.

All you docbook experts

Filed under: General — Thomas @ 19:23

2007-04-16
19:23

Dear lazyweb,

oasis.org is having spurious problems for the last week, hanging on about 1 out of 25 downloads.  This uncovered a bug in the docbook-dsssl setup on Fedora/Red Hat machines - in ideal situations the docbook toolchain should be set up such that local catalogs resolve the system id's to local files.

On FC6 I drilled down the relevant jade command line used by docbook2html to

 jade -G -t sgml -i html -d /usr/share/sgml/docbook/utils-0.6.14/docbook-utils.dsl#html -V paper-type=A4 -V %use-id-as-filename% /usr/share/sgml/xml.dcl test.xml

where test.xml is the most simple docbook/xml file you can make:

 <?xml version='1.0'?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<book id="index">
</book>

strace'ing it shows that it's contacting oasis.org

A similar jade line on Ubuntu manages to process the docbook file completely locally.

So, question time:

  • does openjade/opensp offer ANY facilities AT ALL for debugging the resolving process, and the replacement of system id's with local copies of files ?
  • Anyone else who has seen similar problems with the oasis site ?
  • Can anyone figure out how ospcat works ? The short help and man page conflict each other, I cannot find a single example of its use, and none of the lines I tried produced any output whatsoever.
  • Is there any simple way to verify if my catalogs are set up correctly ?
  • Is there any way to tell openjade that it cannot use the network, ever ? xsltproc has -nonet, for example.
  • Are there tools comparable to "docbook2html" (which, you know, does the sensible thing - take a docbook file and output html) that wrap around xsltproc and do all the nasty bits like figuring out where the xsl stylesheets are ?

Thanks in advance.

Coming up

Filed under: Flumotion,Hacking — Thomas @ 03:44

03:44

I couldn't get to sleep, so I got up again and did some hacking. I've been working on reviving our Flumotion RTSP code the last few weeks in my spare time. This is code that was written more than a year ago, at the time when cell phone streaming was supposedly the Next Big Thing. I felt it was a waste to leave that code (which is in beta quality) to rot in our private repository.

The actual impulse for getting back to this is the work we've sponsored with Fluendo on RTP specs for Vorbis and Theora. They're close to finished, and the payloaders and depayloaders have already been implemented in GStreamer.

Anyway, back to the point - I hacked in a quick UI not too different from the http-streamer UI tabs:

Flumotion Admin with RTSP

And that screenshot is the actual result of starting up the Flumotion stream, actually clicking on the URL and having Totem start up and start playing this stream. No cheating besides the hacks in the code :)

Some notes:

  • As you can see on the right, there's also an HTTP streamer running. It serves the same stream as the RTSP streamer, but (obviously) muxed. Producers and encoders can be reused for both types of streaming.
  • Totem and Flumotion need HEAD of core, base and good for various tweaks and fixes to a bunch of elements to get RTSP running reliably.
  • The RTSP code is not public yet, but will be soon after some cleanup and stabilizing of the RTP specs.
  • GStreamer isn't yet sending any signs of life to the RTSP server - no RTCP, or RTSP channel pings. Wim is planning to work on that, so the stream keeps running for half a minute (until the RTCP server times the client out)
  • The page says there are two clients connected, even though it's just me - in RTSP-land each substream is separate, and thus right now watching audio and video is counted as two clients. To be cleaned up in the future.
  • The mime type is a hard-coded lie - again, there are two substreams, and not muxed, so it should probably show audio/x-vorbis, video/x-theora
  • The code can still handle H263, AMR, MPEG-4, ... and still works with cell phones.  Too bad there are no phones out there with Theora/Vorbis support (yet ?)

Anyways - let's see if this puts me to sleep ...

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