Mi blog lah! Το ιστολόγιό μου

5Jun/090

Μαθήματα γλώσσας προγραμματισμού Python στα ελληνικά

Στο φόρουμ του Ubuntu-gr έχουν ξεκινήσει μαθήματα για τη γλώσσα προγραμματισμού Python.

Το πρώτο μάθημα είναι για τη ρύθμιση του περιβάλλοντος Python στο σύστημά σας, οπότε μπορείτε εύκολα να λάβετε μέρος και να παρακολουθήσετε τα επόμενα βήματα.

Μέσω του φόρουμ του Ubuntu-gr γίνεται και η μετάφραση στα ελληνικά ενός οδηγού εκμάθησης της γλώσσας Python, που θα χρησιμοποιηθεί ως ύλη για τα μαθήματα. Η μετάφραση έχει σχεδόν ολοκληρωθεί.

Δείτε τα μαθήματα Python του φόρουμ Ubuntu-gr.

Ο Κώστας Τσακάλογλου αναφέρθηκε στα μαθήματα αυτά πριν λίγες μέρες.

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3Oct/082

The Keyboard Layout Editor

(this entry is a repost, the original was lost in a database mishap.)

As part of the 2008 GSoC program, I worked on a Keyboard Layout Editor for the X.Org Foundation.

The Keyboard Layout Editor (KLE) is an application that allows you to create keyboard layouts for the X.Org server, commonly found in the Linux, OpenSolaris, *BSD, etc Desktops.

My mentor was Sergey Udaltsov, maintainer of xkeyboard-config, the Keyboard Indicator applet in GNOME, supporting libraries for keyboard layouts and much more. I had great help and Sergey was very supportive. Highly recommended mentor for your GSoC’09 project.

The Keyboard Layout Editor showing a layout

The Keyboard Layout Editor showing a layout

The screenshot above shows the main window of the program; a keyboard with blank layout (keys are empty), a section Add to layout with items that can be used to populate the layout, and a section for the description of the layout (Layout details).

There are typically two workflows; first you start off with a blank layout and you add Unicode characters, dead keys, include files, then you save.

The other workflow is to start with an appropriate existing layout as a base, then add more characters, make changes, etc.

It might be strange to talk about different workflows, but in terms of usability it’s important provide assistance for such cases. For example, having tooltips is important when a person starts off with a new layout.

Using the Keyboard Layout Editor

Using the Keyboard Layout Editor

Here we started with a blank layout; we click on Start Character Map, then locate the characters you need, and drag and drop them to the appropriate keys. Each key is composed of four parts, and we number these from 1 to 4. The way we count is quite peculiar,

  1. bottom left, when you press the key as is (key)
  2. top left, when you press the key with Shift (Shift + key)
  3. bottom right, when you press the key with AltGr (AltGr + key)
  4. top right, when you press the key with Shilft+AltGr (Shift + AltGr + key)
Analysis of a key

Analysis of a key

This is my entry to the most engineered diagram competition.

The dead keys relate to diacritic marks such as grave and acute. Since they are too small to see, we present them next to a D letter (D for Dead key). In some cases I could not find a character equivalent to the diacritic mark, so I put ?, therefore it looks like D?. If you put the mouse pointer over the key, you can see the full details in the tooltip.

Including files

Including files

In many cases, there exist layouts/variants that contain most of the characters you want to add. In this case, you add and enable in the Include files section. You can then override any of those characters by dragging and dropping to the layout.

At this stage in the blog post, it is important to clarify the notions of a layout and a variant. The two are quite similar and the distinction is messy when trying to explain to the end-user. The French layout file is fr, which contains several variants (distinct groups of mappings of physical keys to Unicode characters). When you are actually talking about a French keyboard layout, you are actually referring to the default variant of the «fr» file. Oftentimes people refer to the «fr» file as a whole as the French layout. You can also pick a non-default variant of the layout file, and call it your layout.

The way I would like to define layout and variant is this: a layout refers to the default variant of the layout file. This is consistent to the fact that distributions pick the default variant in the settings so it’s what get the most visibility, or when users select a new layout, they are presented with the default setting first. Regarding layouts in general, it is important for different languages/scripts to make effort that the default layout is updated and includes extra useful and relevant characters.

The new Greek keyboard layout

The new Greek keyboard layout

This is the updated Greek keyboard layout, and is the near-final version that we are planning to submit to xkeyboard-config. It adds Greek Polytonic to the existing Greek layout.  It does not make changes to the previous default layout, so users will not be unpleasantly surprised. It also adds all sort of characters that are found in the Greek Unicode block.

In this post I simplified some of the terms/description. If I went a bit too far, please correct me and I’ll update in-place.

Update 8th Sep 08: What are the plans for further development of the layout editor;

  • Increase the user base and get more people trying out the editor. This requires some more cleanup of the code, more instructions on how to run it youselves, and get people to provide feedback. An open-source project without users is not a successful project.
  • Make it easier for developers to contribute on the project. If you use Eclipse, you can install pydev, antlr3ide, mylyn, subclipse, and you can do the full development from within the cozy Eclipse environment. These need documentation.
  • The Issues page at the project has about ten items. This list needs to be reduced.
  • The natural place for users of the layout editor is the http://listserv.bat.ru/xkb/List.html mailing list. We need to promote the editor there, and get examples of users actually using it to maintain layouts.
  • An issue that plagues some users is when they need compose sequences to generate characters that no pre-composed forms exist. If users really need this (mainly Latin and Cyrillic scripts, complex scripts), it can be adapted to the UI.
  • It is technically easy to adapt the editor so that it produces XML layouts. Considering the state of XKB-atkins, this may not be a top priority at the moment. libxml2 comes with the MIT license, so in license terms it would be OK. Not sure if it is OK to link libxml2 to the X.org server. It might actually solve the slow parsing of the configurations files and the issues of xkbcomp.
  • At the moment the default geometry is a somewhat generic keyboard. In addition, I deactivated several keys (such as the function keys), in order not to confuse users (you can activate with a small change in the code). The keyboard can be expanded to a full 105-keys style. A related project would be to figure out an efficient way to edit those geometry files, and make the keyboard customised. If people start creating layouts with the editor, they will certainly love to edit geometry files!
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11Jun/080

ANTLR grammar for XKB, and Relax NG schema (draft)

I completed the ANTLRv3 grammar for symbols/ configuration files of XKB. The grammar can parse and create the abstract syntax tree (AST) for all keyboard layouts in xkeyboard-config.

ANTLRv3 helps you create parsers for domain specific languages (DSL), an example of which is the configuration files in XKB.

Having the ANTLRv3 grammar for a configuration file allows to generate code in any of the supported target lagnuages (C, C++, Java, Python, C#, etc), so that you easily include a parser that reads those files. Essentially you avoid using custom parsers which can be difficult to maintain, or parsers that were generated with flex/bison.

On a similar note, here is the grammar to parse Compose files (such as en_US.UTF-8/Compose.pre). I am not going to be using in the project for now, but it was fun writing it. The Python target takes 18s to create the AST for the >5500 lines of the en_US.UTF-8 compose file, on a typical modern laptop.

I am also working on creating a RelaxNG schema for the XKB configuration files (those under symbols/). There is a draft available, which needs much more work.The Relax NG book by Eric van de Vlist is very useful here.

The immediate goal is to use the code generated by ANTLR to parse the XKB files and create XML files based on the Relax NG schema. I am using Python, and there are a few options; the libxml2 bindings for Python, and PyXML. The latter has more visible documentation, but I think that I should better be using the former.

Update: lxml appears to be the nice way to use libxml2 (instead of using directly libxml2).

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17May/080

Parsing XKB files with antlr

antlr (well, antlr3) is an amazing tool that replaces lex/flex, yacc/bison.

One would use antlr3 if they want to deal with Domain-Specific Languages (DSL), an example of which are the text configuration files.

In our case, we use antlr3 to parse some of the XKB configuration files, those found in /etc/X11/xkb/symbols/??.

Our aim is to be able to easily read and write those configuration files. Of course, once we have them read, we do all sorts of processing.

The stable version of antlr3 is 3.0.1, which happened to give lots of internal errors. It has not been very useful, so I tried a few times the latest beta version 3.1b, and eventually managed to get it to work. If I am not mistaken, 3.1 stable should be announced in a few days.

When using antlr, you have the choice of several target languages, such as Java, C, C++ and Python. I am using the Python target, and the latest version that is available from the antlr3 repository.

Here is the tree of the gb layout file,

tree = (SECTION (MAPTYPE (MAPOPTIONS partial default alphanumeric_keys xkb_symbols) (MAPNAME “basic”)) (MAPMATERIAL (TOKEN_INCLUDE “latin”) (TOKEN_NAME Group1 (VALUE “United Kingdom”)) (TOKEN_KEY (KEYCODEX AE02) (KEYSYMS 2 quotedbl twosuperior oneeighth)) (TOKEN_KEY (KEYCODEX AE03) (KEYSYMS 3 sterling threesuperior sterling)) (TOKEN_KEY (KEYCODEX AE04) (KEYSYMS 4 dollar EuroSign onequarter)) (TOKEN_KEY (KEYCODEX AC11) (KEYSYMS apostrophe at dead_circumflex dead_caron)) (TOKEN_KEY (KEYCODEX TLDE) (KEYSYMS grave notsign bar bar)) (TOKEN_KEY (KEYCODEX BKSL) (KEYSYMS numbersign asciitilde dead_grave dead_breve)) (TOKEN_KEY (KEYCODEX LSGT) (KEYSYMS backslash bar bar brokenbar)) (TOKEN_INCLUDE “level3(ralt_switch_multikey)”))) (SECTION (MAPTYPE (MAPOPTIONS partial alphanumeric_keys xkb_symbols) (MAPNAME “intl”)) (MAPMATERIAL (TOKEN_INCLUDE “latin”) (TOKEN_NAME Group1 (VALUE “United Kingdom – International (with dead keys)”)) (TOKEN_KEY (KEYCODEX AE02) (KEYSYMS 2 dead_diaeresis twosuperior onehalf)) (TOKEN_KEY (KEYCODEX AE03) (KEYSYMS 3 sterling threesuperior onethird)) (TOKEN_KEY (KEYCODEX AE04) (KEYSYMS 4 dollar EuroSign onequarter)) (TOKEN_KEY (KEYCODEX AE06) (KEYSYMS 6 dead_circumflex NoSymbol onesixth)) (TOKEN_KEY (KEYCODEX AC11) (KEYSYMS dead_acute at apostrophe bar)) (TOKEN_KEY (KEYCODEX TLDE) (KEYSYMS dead_grave notsign bar bar)) (TOKEN_KEY (KEYCODEX BKSL) (KEYSYMS numbersign dead_tilde bar bar)) (TOKEN_KEY (KEYCODEX LSGT) (KEYSYMS backslash bar bar bar)) (TOKEN_INCLUDE “level3(ralt_switch)”))) (SECTION (MAPTYPE (MAPOPTIONS partial alphanumeric_keys xkb_symbols) (MAPNAME “dvorak”)) (MAPMATERIAL (TOKEN_INCLUDE “us(dvorak)”) (TOKEN_NAME Group1 (VALUE “United Kingdom – Dvorak”)) (TOKEN_KEY (KEYCODEX BKSL) (KEYSYMS numbersign asciitilde)) (TOKEN_KEY (KEYCODEX AE02) (KEYSYMS 2 quotedbl twosuperior NoSymbol)) (TOKEN_KEY (KEYCODEX AE03) (KEYSYMS 3 sterling threesuperior NoSymbol)) (TOKEN_KEY (KEYCODEX AE04) (KEYSYMS 4 dollar EuroSign NoSymbol)) (TOKEN_KEY (KEYCODEX LSGT) (KEYSYMS backslash bar)) (TOKEN_KEY (KEYCODEX AD01) (KEYSYMS apostrophe at)))) (SECTION (MAPTYPE (MAPOPTIONS partial alphanumeric_keys xkb_symbols) (MAPNAME “mac”)) (MAPMATERIAL (TOKEN_INCLUDE “latin”) (TOKEN_NAME Group1 (VALUE “United Kingdom – Macintosh”)) (TOKEN_KEY (KEYCODEX AE02) (KEYSYMS 2 at EuroSign)) (TOKEN_KEY (KEYCODEX AE03) (KEYSYMS 3 sterling numbersign)) (TOKEN_INCLUDE “level3(ralt_switch)”)))

When traversing the tree, we can then pretty-print the layout at wish:

partial default alphanumeric_keys xkb_symbols “basic” {
name[Group1] = “United Kingdom”;
include “latin”
include “level3(ralt_switch_multikey)”
key <AE02> = { [ 2 , quotedbl , twosuperior , oneeighth ] };
key <AE03> = { [ 3 , sterling , threesuperior , sterling ] };
key <AE04> = { [ 4 , dollar , EuroSign , onequarter ] };
key <AC11> = { [ apostrophe , at , dead_circumflex , dead_caron ] };
key <TLDE> = { [ grave , notsign , bar , bar ] };
key <BKSL> = { [ numbersign , asciitilde , dead_grave , dead_breve ] };
key <LSGT> = { [ backslash , bar , bar , brokenbar ] };
};
… snip …

The code is currently hosted at code.google.com (keyboardlayouteditor) and I intend to move it shortly to FDO.

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30Jan/084

Improving input method support in GTK+-based apps

When a bug report gets long with many comments, it gets more difficult for someone to get the full picture of what is going on. I’ll attempt to summarise here what’s being said in Bug 321896, Synch gdkkeysyms.h / gtkimcontextsimple.c with X.org 6.9/7.0.

GTK+-based applications use by default the GTK+ Input Method in order to let users type in different languages. Some scripts are very complex (such as SE Asian scripts) and in this case SCIM is used, replacing the GTK+ Input Method. One can even disable GTK+ IM altogether and use the basic X Input Method (XIM) which is provided by the Xorg server, by setting GTK_IM_MODULE to xim. However, the majority of the users have GTK+ IM enabled.

Between GTK+ IM and XIM, the keyboard layouts are being managed by the xkeyboard-config project and Sergey Udaltsov. A keyboard layout is simply a mapping of keyboard keys to Unicode characters, but you can also have compose sequences for some characters using what we call dead keys. When you press a dead key nothing appears on screen but when you press a letter immediately afterwards, you can get an á. This functionality is common to add accents, and there is a big table for these compose sequences (1.3MB) and what Unicode characters they produce.

If you change your keyboard layout (System/Preferences/Keyboard/Layout) to something like U.S. English International (with dead keys), then the ‘ key on your keyboard becomes dead_acute, and the compose sequence

<dead_acute> <a>  : "á"   U00E1 # LATIN SMALL LETTER A WITH ACUTE

works when you press ‘ and then a.

There is an issue with compose sequences and input methods; XIM maintains the official upstream version of the compose sequences, and projects such as GTK+ and SCIM carry their own copies of that table.

The issue with GTK+ regarding the compose sequences is that it has a very old version compared to what is available upstream. This is what Bug 321896 is about.

The bug would be have been resolved much much earlier if it wasn’t for the insistence of the GTK+ maintainers to cut the fat and reduce the size of the table (~6000 entries) with clever optimisations.

Tor suggested a clever optimisation; a good number of compose sequences (which looks like <dead_acute> <a> : “á”) resemble the decomposed form (a la Unicode) of those characters. Thus, we can let the user type what she wants, and we can try Unicode normalisation to see if the sequence is composed to a single Unicode character. Lets demonstrate in Python,

$ python
>>> import unicodedata
>>> sequence=[65, 0x301]     # That's 'a' and acute
>>> result = unicodedata.normalize('NFC',"".join(map(unichr, sequence)))
>>> result
u'\xc1'
>>> print len(result)
1
>>> print result
Á

That long line above takes the array, applies the unichr() function on each member so that they become Unicode characters and then joins them in a single string. Finally, it normalises the (decomposed) string to a single character. The fact that the resulting string has length 1 (single character) is key to this optimisation. Over 1000 compose sequences can be removed from the compose table through this optimisation. This includes a big chunk of the Latin Unicode blocks, about a few dozens of Cyrillic characters, all of modern Greek and Greek polytonic, some Indic languages (are they actually used?) and other misc sequences.

Matthias laid out the requirements for the optimisation of the remaining compose sequences; ① it has to be static const so a single copy is shared all over the place, ② the first column (out of six) is repeated too often, thus use subtables, and ③ each row ends with a varying number of zeroes, so cut on those zeroes as well. This also required the automatic generation of the optimised table using a script.

The work has not finished yet, and requires testing of the patch. The high priority testing is that keyboard layouts do not get any regressions (that is, compose sequences with dead keys must continue to work along with any new sequences).

With an updated compose table in GTK+, one can write things like ⒼⓃⓄⓂⒺ and all variations of accents on characters, in an easier way.

I’ld like to thank Matthias and Tor for their support in this work. And Jeff for adding this blog to Planet GNOME!

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16Jul/070

GUADEC Day #2

(see http://www.guadec.org/schedule/warmup)

At the first presentation, Quim Gil talked about GNOME marketing, what have been done, what is the goal of marketing. He showed a focused mind on important marketing tasks; it is easy to get carried away and not be effective, a mistake that happens in several projects.

The next session was by Tomas Frydrych (Open Hand – I have their sticker on my laptop!) on memory use in GNOME applications. Many people complain that XYZ is bloated. However, this does not convey what exactly happens; pretty useless. In addition, the common tools that show memory use do not show the proper picture because of the memory management techniques. That is, due to shared libraries, the total memory occupied by an application appears very big. A tool examined is exmap. This tool uses a kernel module that shows memory use of applications by reading in /proc. It takes a snapshot of memory use; it’s not real-time info. It comes with a GTK+ front-end (gexmap) that requires a big screen (oops, PDAs). However, it is not suitable for internet tablets and other low-spec devices. Therefore, they came up with exmap-console which addresses the shortcommings. It has a console interface based on the readline library.

Here are the rest of my notes. Hope they make sense to you.

. exmap –interactive
. ?: help
. Head: quite useful (dynamic allocation)
. Mapped:
. Sole use: memory that app is using on its own (rss?)
. “sort vm”
. “print” or “p”
. “add nautilus”
. “clear”
. “detail file” (what executables/libs loaded and how much consume)
. “detail none”

Sole use
. valgrind, to analyse Sole Use memory?
. “detail ????”

Lots of small libraries: overhead

Looking ahead
. Pagemap: by Matt Macall
. http://projects.o-hand.com/exmap-console/

Python
. Sole use: ~18MB ;-(

Tomas was apparently running Ubuntu with the English UK locale. The English UK translation team is doing an amazing job at the translation stats. Actually, most messages are copied, however with a script one can pick up words such as organization and change to organisation. The problem here is that, for example, the GAIM mo file is 215KB (?), however for the British English translation the actual changes should be less than 2-3KB. Messages that are missing from a translation mean that the original US English messages will be used. I’ll have to find how to use msgfilter to make messages untranslated if msgid == msgstr. Where is Danilo?

After lunch time (did not go for lunch), I went to the Accerciser session. Pretty cool tool, something I have been look for. Accerciser uses the accessibility framework of GNOME in order to inspect the windows of running applications and see into the properties. A good use is to identify if elements such as text boxes come with description labels; they are important to be there for accessibility purposes (screen reader), as a person that depends on software to read (text to speech) the contents of windows.

The next session was GNOME accessibility for blind people. Jan Buchal gave an excellent presentation.

My notes,

. is from Chech republic, is blind himself. has been using computers for 20+ years

. from user perspective
. users, regular and irregular ;-)
. software
. firefox 3.0beta – ok for accessibility other versions no
. gaim messenger ok
. openoffice.org ok but did not try
. orca screenreader ^^^ works ok.
. generally ready for prime time
. ubuntu guy for accessibility was there
. made joke about not having/needing display slides ;-]
. synthesizer: festival, espeak, etc – can choose
. availability of voices
. javascript: not good for accessibility
. links/w3m: just fine!
. firefox3 makes accessibility now possible.
. web designer education, things like title=”", alt=”" for images.
. OOo, not installed but should work, ooo-gnome
. “braillcom” company name
. “speech dispatcher”
. logical events
. have short sound event instead of “button”, “input form”
. another special sound for emacs prompt, etc.
. uses emacs
. have all events spoken, such as application crashing.
. problems of accessibility
. not money main factor, but still exists.
. standard developers do not use accessibility functions
. “accessor” talk, can help
. small developer group on accessiblity, may not cooperate well
. non-regular users (such as blind musician)
. musicians
. project “singing computer”
. gtk, did not have good infrastructure
. used lilypond (music typesetter, good but not simple to use)
. singing mode in festival
. use emacs with special mode to write music scores (?)
. write music score and have the computer sing it (this is not “caruso”)
. gnome interface for lilypond would be interesting
. chemistry for blind
. gtk+
. considering it
. must also work, unfortunately, on windows
. gtk+ for windows, not so good for accessibility
. conclusion: free accessibility
. need users so that applications can be improved
. have festival synthesizer, not perfect but usable
. many languages, hindi, finnish, afrikaans
. endinburgh project, to reimplement festival better
. proprietary software is a disadvantage
. q: how do you learn to use new software?
. a: has been a computer user for 20+ years, is not good candidate to say
. a: if you are dedicated, you can bypass hardles, old lady emacs/festival/lilypond
. brrlcom, not for end-users(?)
. developer problem?
. generally there is lack of documentation; easy to teach what a developer needs to know
. so that the application is accessible
. HIG Human Interface Guidelines, accessible to the developers
. “speakup” project
. Willy, from Sun microsystems, working on accessibility for +20 years, Lead of Orca.
. developers: feel accessibility is a hindrance to development
. in practice the gap is not huge
. get tools (glade) and gtk+ to come with accessibility on by default
. accessibility
. is not only for people with disabilities
. can do amazing things like 3d interfaces something

These summaries are an important example of the rule that during presentation, participants tend to remember only about 8% of the material. In some examples, even less is being recollected.

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6Jul/06Off

Multimedia support in Ubuntu Linux 6.06

With Ubuntu Linux 6.06, it is much clear how to install those codecs in order to get broad multimedia file support.

In Ubuntu, the multimedia infrastructure is handled by GStreamer; you install GStreamer plugins and any application that uses GStreamer can immediately benefit from the new codec support.

A typical installation of Ubuntu will bring in the free and open-source codecs by default. This includes the base gstreamer plugins package, gstreamer0.10-plugins-base that covers

  1. /usr/lib/gstreamer-0.10/libgstadder.so
  2. /usr/lib/gstreamer-0.10/libgstaudioconvert.so
  3. /usr/lib/gstreamer-0.10/libgstaudiorate.so
  4. /usr/lib/gstreamer-0.10/libgstaudioresample.so
  5. /usr/lib/gstreamer-0.10/libgstaudiotestsrc.so
  6. /usr/lib/gstreamer-0.10/libgstcdparanoia.so
  7. /usr/lib/gstreamer-0.10/libgstdecodebin.so
  8. /usr/lib/gstreamer-0.10/libgstffmpegcolorspace.so
  9. /usr/lib/gstreamer-0.10/libgstogg.so
  10. /usr/lib/gstreamer-0.10/libgstplaybin.so
  11. /usr/lib/gstreamer-0.10/libgstsubparse.so
  12. /usr/lib/gstreamer-0.10/libgsttcp.so
  13. /usr/lib/gstreamer-0.10/libgsttheora.so
  14. /usr/lib/gstreamer-0.10/libgsttypefindfunctions.so
  15. /usr/lib/gstreamer-0.10/libgstvideo4linux.so
  16. /usr/lib/gstreamer-0.10/libgstvideorate.so
  17. /usr/lib/gstreamer-0.10/libgstvideoscale.so
  18. /usr/lib/gstreamer-0.10/libgstvideotestsrc.so
  19. /usr/lib/gstreamer-0.10/libgstvolume.so
  20. /usr/lib/gstreamer-0.10/libgstvorbis.so

With a properly encoded multimedia file, you can play music or video with subtitles. Such good codecs are Ogg, Vorbis and Theora. You can also rip CDs; cdparanoia is also there.
By default you also get the good package, gstreamer0.10-plugins-good
It contains

  1. /usr/lib/gstreamer-0.10/libgst1394.so
  2. /usr/lib/gstreamer-0.10/libgstaasink.so
  3. /usr/lib/gstreamer-0.10/libgstalaw.so
  4. /usr/lib/gstreamer-0.10/libgstalpha.so
  5. /usr/lib/gstreamer-0.10/libgstapetag.so
  6. /usr/lib/gstreamer-0.10/libgstavi.so
  7. /usr/lib/gstreamer-0.10/libgstautodetect.so
  8. /usr/lib/gstreamer-0.10/libgstcacasink.so
  9. /usr/lib/gstreamer-0.10/libgstcdio.so
  10. /usr/lib/gstreamer-0.10/libgsteffectv.so
  11. /usr/lib/gstreamer-0.10/libgstgoom.so
  12. /usr/lib/gstreamer-0.10/libgstid3demux.so
  13. /usr/lib/gstreamer-0.10/libgstlevel.so
  14. /usr/lib/gstreamer-0.10/libgstefence.so
  15. /usr/lib/gstreamer-0.10/libgstmulaw.so
  16. /usr/lib/gstreamer-0.10/libgstossaudio.so
  17. /usr/lib/gstreamer-0.10/libgstrtp.so
  18. /usr/lib/gstreamer-0.10/libgstrtsp.so
  19. /usr/lib/gstreamer-0.10/libgstsmpte.so
  20. /usr/lib/gstreamer-0.10/libgsttaglib.so
  21. /usr/lib/gstreamer-0.10/libgstudp.so
  22. /usr/lib/gstreamer-0.10/libgstvideobox.so
  23. /usr/lib/gstreamer-0.10/libgstvideoflip.so
  24. /usr/lib/gstreamer-0.10/libgstwavenc.so
  25. /usr/lib/gstreamer-0.10/libgstwavparse.so
  26. /usr/lib/gstreamer-0.10/libgstauparse.so
  27. /usr/lib/gstreamer-0.10/libgstdebug.so
  28. /usr/lib/gstreamer-0.10/libgstnavigationtest.so
  29. /usr/lib/gstreamer-0.10/libgstalphacolor.so
  30. /usr/lib/gstreamer-0.10/libgstcairo.so
  31. /usr/lib/gstreamer-0.10/libgstflxdec.so
  32. /usr/lib/gstreamer-0.10/libgstmatroska.so
  33. /usr/lib/gstreamer-0.10/libgstvideomixer.so
  34. /usr/lib/gstreamer-0.10/libgstcutter.so
  35. /usr/lib/gstreamer-0.10/libgstmultipart.so
  36. /usr/lib/gstreamer-0.10/libgstflac.so
  37. /usr/lib/gstreamer-0.10/libgstjpeg.so
  38. /usr/lib/gstreamer-0.10/libgstpng.so
  39. /usr/lib/gstreamer-0.10/libgstspeex.so
  40. /usr/lib/gstreamer-0.10/libgstgconfelements.so
  41. /usr/lib/gstreamer-0.10/libgstshout2.so
  42. /usr/lib/gstreamer-0.10/libgstvideobalance.so
  43. /usr/lib/gstreamer-0.10/libgsticydemux.so
  44. /usr/lib/gstreamer-0.10/libgstximagesrc.so
  45. /usr/lib/gstreamer-0.10/libgstannodex.so
  46. /usr/lib/gstreamer-0.10/libgstgdkpixbuf.so
  47. /usr/lib/gstreamer-0.10/libgsthalelements.so
  48. /usr/lib/gstreamer-0.10/libgstdv.so

This includes generic AVI support, access to digital video and Firewire devices, visualisers, the Matroska codec, access to shoutcast servers, the speex audio codec, the flac codec and many more.

At this point, you can install Pitivi, a gstreamer-enabled video editor written in Python that helps you create your own movie. Make sure you install gstreamer0.10-gnonlin which enables non-linear editing in gstreamer.

Up to here you got free and open-source software.

You can continue with more codecs by installing the package gstreamer0.10-plugins-ugly. This package is not part of the official Ubuntu distribution; you need to enable the Universe repository. Use System/Administration/Synaptic Package Manager to install these additional packages.
Ugly are the plugins and codecs that may have distribution problems in some countries.

Ugly includes

  1. /usr/lib/gstreamer-0.10/libgsta52dec.so
  2. /usr/lib/gstreamer-0.10/libgstasf.so
  3. /usr/lib/gstreamer-0.10/libgstdvdlpcmdec.so
  4. /usr/lib/gstreamer-0.10/libgstdvdread.so
  5. /usr/lib/gstreamer-0.10/libgstdvdsub.so
  6. /usr/lib/gstreamer-0.10/libgstiec958.so
  7. /usr/lib/gstreamer-0.10/libgstmad.so
  8. /usr/lib/gstreamer-0.10/libgstmpeg2dec.so
  9. /usr/lib/gstreamer-0.10/libgstmpegaudioparse.so
  10. /usr/lib/gstreamer-0.10/libgstmpegstream.so
  11. /usr/lib/gstreamer-0.10/libgstrmdemux.so
  12. /usr/lib/gstreamer-0.10/libgstsid.so

This package will bring in, among others, DVD playback and subtitle support, ASF file support, MP3 support (MAD package) and MPEG2 video playback.
You can also get MP3 support if you install the gstreamer0.10-fluendo-mp3 plugin which is available from Universe as well. This package is probably free to use in any country thanks to the efforts of the Fluendo team.

It appears that if you install ugly, it is good to install gstreamer0.10-ffmpeg so that you get support for

FFmpeg plugin for GStreamer

This GStreamer plugin supports a large number of audio and video compression
formats through the use of the FFmpeg library. The plugin contains GStreamer
elements for encoding 40+ formats (MPEG, DivX, MPEG4, AC3, DV, …), decoding
90+ formats (AVI, MPEG, OGG, Matroska, ASF, …), demuxing 30+ formats, and
colorspace conversion.

Finally, there is a package gstreamer0.10-plugins-bad with plugins of potentially suboptimal quality. It includes

  1. /usr/lib/gstreamer-0.10/libgstbz2.so
  2. /usr/lib/gstreamer-0.10/libgstcdxaparse.so
  3. /usr/lib/gstreamer-0.10/libgstdtsdec.so
  4. /usr/lib/gstreamer-0.10/libgstfreeze.so
  5. /usr/lib/gstreamer-0.10/libgstgsm.so
  6. /usr/lib/gstreamer-0.10/libgstmms.so
  7. /usr/lib/gstreamer-0.10/libgstmodplug.so
  8. /usr/lib/gstreamer-0.10/libgstmusepack.so
  9. /usr/lib/gstreamer-0.10/libgstqtdemux.so
  10. /usr/lib/gstreamer-0.10/libgsttrm.so
  11. /usr/lib/gstreamer-0.10/libgstspeed.so
  12. /usr/lib/gstreamer-0.10/libgstswfdec.so
  13. /usr/lib/gstreamer-0.10/libgsttta.so
  14. /usr/lib/gstreamer-0.10/libgstvideo4linux2.so
  15. /usr/lib/gstreamer-0.10/libgstwavpack.so
  16. /usr/lib/gstreamer-0.10/libgstxingheader.so
  17. /usr/lib/gstreamer-0.10/libgstneonhttpsrc.so

With bad you get GSM audio codec support, MMS support, QT playback support for some formats, Flash (SWF) playing support, Video4Linux2 support, MUSEPACK support and a few more.

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4Dec/04Off

Ελληνικά στην αλληλογραφία, μέρος πρώτο

Πρέπει να λαμβάνετε γράμματα / ανακοινώσεις από μερικούς δικτυακούς τόπους όπου η κωδικοποίηση για τα ελληνικά δεν είναι σωστή, είτε στο σώμα του μηνύματος, είτε στην κεφαλίδα (From: “Ανακοίνωση” ).

Συγκεκριμένα, δεν καθορίζεται η κωδικοποίηση οπότε είναι θέμα εξ ορισμού ρυθμίσεων του παραλήπτη για να δει το αποτέλεσμα.

Ας δούμε πως μπορείτε μέσα από μια εφαρμογή PHP να στείλετε αλληλογραφία με ελληνικά. Το ίδιο μπορεί να γίνει και από άλλες γλώσσες, όπως Perl και Python.

<?php
include(‘Mail.php’);
include(‘Mail/mime.php’);

$from = “From: \”" . mb_encode_mimeheader(‘Όνομα Αποστολέα’) . “\” < αποστολέας στο gmail τελεία com>“;
$to = mb_encode_mimeheader(‘Όνομα Παραλήπτη’) . ” < παραλήπτης στο gmail τελεία com>“;
$subject = ‘Θέμα γράμματος’;
$body = ‘Περιεχόμενο του γράμματος.’;

mb_send_mail($to, $subject, $body, $from);
?>

Το γράμμα που θα παραχθεί θα μοιάζει με

Από: Όνομα Αποστολέα < αποστολέας στο gmail τελεία com>
Προς: Όνομα Παραλήπτη < παραλήπτης στο gmail τελεία com>
Θέμα: Θέμα γράμματος

Περιεχόμενο του γράμματος.

Απαιτεί την εγκατάσταση του πακέτου php-mbstring που το έχουν όλες οι καλές διανομές Linux. Διαφορετικά είναι δυνατόν
να έχετε το ίδιο αποτέλεσμα αλλά θα κάνετε τα παραπάνω χειρωνακτικά.

Ακόμα, πρέπει να ρυθμίσετε το /etc/php.ini με τα παρακάτω:

[mbstring]
; language for internal character representation.
; Neutral σημαίνει Unicode
mbstring.language = Neutral

; internal/script encoding.
; Some encoding cannot work as internal encoding.
; (e.g. SJIS, BIG5, ISO-2022-*)
mbstring.internal_encoding = UTF-8

; http input encoding.
mbstring.http_input = UTF-8

; http output encoding. mb_output_handler must be
; registered as output buffer to function
mbstring.http_output = UTF-8

; enable automatic encoding translation accoding to
; mbstring.internal_encoding setting. Input chars are
; converted to internal encoding by setting this to On.
; Note: Do _not_ use automatic encoding translation for
; portable libs/applications.
mbstring.encoding_translation = On

; substitute_character used when character cannot be converted
; one from another
; σημαίνει ότι στην μετατροπή αν κάτι πάει στραβά, θα εκτυπώσει των κωδικό U+xxxx του χαρακτήρα.
mbstring.substitute_character = long;

Αν είστε χρήστης της εφαρμογής phplist, ενημερώστε τη σελίδα αυτή.

Σημείωση: Όλα τα παραπάνω είναι σε κωδικοποίηση utf-8 (Unicode).

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