Archive for August, 2014

High Priority Libav Projects Revisited

Sunday, August 10th, 2014

More than two years ago I’ve posted what I considered should be high priority Libav projects. Let’s see what has been finished, what’s left and what should probably be added.

User tools

  • Working avserver — fixed in the clean way (by removing it completely);
  • Proper filter system. When I say “proper” I mean the one that allows dynamic reconfiguring, handles errors and works for arbitrary inputs and outputs — some claim it’s been fixed;
  • libswscale replacement. The one that doesn’t sap sanity when you look at its code. Maybe with a nicer API too. And better pixel format support.

RealMedia support

  • Improve RM demuxer or maybe rewrite it from scratch — there’s a demuxer reimplementation from scratch is in the works, hopefully it will succeed;
  • Add proper support for multirate RM streams — hopefully will be handled;
  • Add IVR format demuxer — noone cares;
  • Add ClearVideo decoder (that’s the last codec in RM that we don’t support, hopefully not for long) — noone cares and I lost interest too.

Other Intel codecs support

  • Improve Indeo4 decoder (it still has some features lacking) — B-frames support was added, transparency support is still not there;
  • Improve Intel Audio Coder decoder — fixed too.

On2 codecs support

  • On2 VP7 decoder (we still can implement it faster than certain Baidu rival releases its source code) — nothing to say except “many thanks, Peter!” and “Baidu, I’ve not expected anything else from you”(and indeed we got what we expected, i.e. total lack of support);
  • On2 VP4 decoder;
  • On2 AVC decoder (that stands for “Audio for Video Codec”) — done.

Micro$oft (screen) codecs support

  • Add M$ Screen Codec 1 decoder;
  • Add M$ Screen Codec 2 decoder;
  • Add M$ Expression Encoder Screen Codec decoder;
  • Add beta Windows Media Video 9 interlaced decoding — maybe it’s better left unfixed.
  • Fix beta Windows Media Video 9 P-frames decoding — again, it’s unlikely to ever happen because there are not so many people who can RE intended behaviour and even less people who can RE libavcodec/vc1dec.c to put the fix there.

QuickTime codecs support

  • Add Rottenfruit Intermediate Codec decoder;
  • Add any other codec decoder — noone cares about Pixlet, noone cares enough to add QDesign Music 1 etc..

Other codecs

  • Add GoToMeeting 2-4 decoder — GoToWebinary aka G2M4 is done, the rest is permanently stalled (and I’ve passed stalling duties to Diego);
  • Add more screen codec decoders — someone asked for FIC Video and got it;
  • Add more game format decoders (especially Discworld Noir BMV) — I should return to it;
  • Add more audio (especially speech) codec decoders — Opus decoder is enough.

So, if the tast was moderately interesting it was done, fringe stuff was not taken, serious stuff was not taken either (most people I know agree that swscaler should be replaced yet noone wants to work on the replacement).

And what high priority projects for Libav do I see in the future? None really. Just none.

Posted in Uncategorized | 3 Comments »

KBS 743

Friday, August 1st, 2014

I’ve not written anything about one of the crucial topics of this blog since ages, so here’s the long-awaited update.

Today I’d like to talk about probably the most interesting railway in Germany — Wutachtalbahn or Kursbuchstrecke 743 (Waldshut-Immendingen). It was build as a route to the South border of Germany that does not go on Swiss territory (the line along the Rhine it connects to goes through Basel and canton Schaffhausen).

Now, what makes it so interesting?

Despite being rather unimportant line nowadays and being about only 60km long (and there are no branches either!), it is operated by three different rail companies:

  1. northern part (Immendingen — Blumberg-Zollhaus) is operated by SWEG
  2. central part (Blumberg-Zollhaus — Weizen) is operated by WTB
  3. southern part (Weizen — Lauchringen — Waldshut) is operated by DB

Plan of the central part from Wickedpedia
(Image shamelessly stolen from Wickedpedia)

So you have three different companies running trains on approximately 20km tracks. Is it the same rolling stock? Of course not!

SWEG runs class 650 (aka Stadler RS1) diesel unit, Deutsche Bahn employs class 641 diesel unit and WTB runs a steam locomotive (Württembergische T.14 or class 52.80 or something similar) with bunch of outdated carriages from various places (like Switzerland).

And for unknown reason it’s nicknamed “Pig’s Tail Railway” (see the map above, I have no clue why) and the name somehow appeals to me.

I’ve visited it in three parts: one year I saw the middle part, next year I saw the north parth and later I saw the last part too. Curiously, while DB runs the most modern train the route itself seems the most outdated: the rails are uneven so you can get a bit seasick, the signal system is implemented by driver’s assistant with a red flag who stands on the crossing while the train passes it and it does not stand on the Weizen station for long because it has to give room to the WTB train (in result it comes to the station, waits a bit and cowardly retreats back to the track and waits there till the WTB train is gone).

In general I’d recommend visiting it if you happen to be there. If you want to see something better — go to Sweden and try Uppsala-Lenna railway, it’s the best (now I want to visit it again — oh wait, I wanted that before too).

Posted in Railways | Comments Closed