About

Michael Zucchi

 B.E. (Comp. Sys. Eng.)

  also known as zed
  & handle of notzed

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Saturday, 20 July 2019, 16:49

Not quite a new computer!

Well I decided I'm sick of piss farting about thinking about a new computer so I would just go and buy the bits to build one. And I was looking forward to having something to do on the weekend.

intel outside logo

But for various reasons I wanted to pay cash and of course an online shop-front doesn't have that option, so I email the retailer regarding the list of items i'd arrived at. Do they have them on hand, are they compatible, that sort of thing.

But alas, still no reply two days later.

So that bummed me out.

Then I looked at another retailer in another state, but they don't sell a single 32GB memory kit that's present in tested memory list for the only suitable motherboard they have. I'm after an itx board so that severely limits the options.

So that bummed me out further and I decided I'd just walk in to the first shop I tried and just go buy it in person. Unfortunately I ran into a mate who I haven't seen in yonks so I just ended up catching up with him all afternoon and never made it.

And now i've got a hangover and what was really just an impulse buy has turned into a hassle and so I guess it's off the table for this weekend at least. Maybe next week.

I'll probably still just end up going to them if i've still got a pocket full of cash because the retailer options are so limited in this tiny city. If they're still in business anyway, they don't seem to be too keen on making money. The chips will only get better althgough RAM is volatile so who knows there.

For what it's worth this is what I came up with:

The motherboard is the only ITX available that I can find here (or really, anywhere in the whole country in ready supply), but at least this shop says the BIOS is already upgraded. I've already got a power supply. The aim would be to build a case ... but it's a bit involved so I may never get around to it and i've got some old shit lying around I can use in the mean time. GPU is a bit of a pain, really I just want a short 1 or 2 slot AMD card (for the proper free software linux drivers). Rare as fucking hens teeth here though, the shop I was going to has had no AMD graphics cards at all for months until the 5700 came out and now that's all they have. No one else local has anything below RX 580 nor any of the workstation line which would do, if a little pricey. I have an old HD 5770 that i'll use to start with. It's a double pain if i build my own case as I need to make sure whatever i end up with will fit. And if i get a new one it may as well be the latest design. I'll probably have to order online, whatever I decide.

Tagged biographical, rants.
Tuesday, 16 July 2019, 22:50

Primary Tool Upgrades

I've been looking for a new keyboard for a while. My venerable old (old!) litetouch honeywell keyboard has finally worn itself out. I tried cleaning it but that probably just damaged the contacts further. It's a really amazing design, no screws in the whole thing, the contacts are just printed on a thin plastic sheet that folds over itself, and the springs are just a single silicone overlay which sits over it. Virtually silent and yet the keys have a very positive bump action. Each row of keys is a single injection moulded piece - almost like the way a plastic aeroplane model comes - that clips off the base. You can just unclip them all and chuck them in the dishwasher!

It still works but the left quarter is a bit finicky if you don't press hard enough. Many of the clips which are part of the injection moulded parts have snapped off. Some for example held down the contact between the keyboard sheet and PCB which houses the MCU and LEDs so the contact isn't as solid as it used to be.

I actually semi-retired it some years ago, i've just been using it on a secondary machine here.

Spot the emacs user. left-ctrl completely obliterated. right-shift is from all the C/Java language symbols. Not much left of the cursor keys. N and M were very early victims of AmiWM - which I haven't even used for years! No fucking windows keys and a proper bloody space bar!

Real pity, just comparing the key feel now it's still amazing for the keys that still work, but C and A mis-firing often enough to become obnoxious and it just can't be repaired. I can't even remember how I ended up with it or even when, I certainly didn't buy it. I think I got it through a mate (Jamie) who collected piles of computer shit. It seems to have been made in 1991! I was still using a C64 in 1991, my first year at uni.

Anyway i looked around a bit and didn't bother doing anything about it for months until last Friday when I ordered a couple of "ducky one" keyboards online. Only one shop in Australia seems to sell them, albiet in 600km away (i.e. the nearest next town). Locally you can only get microsoft keyboards or some RGB "gamer" monstrosities at exhorbitant prices.

A Ducky One `ten-key-less', with the all-black tops. I got the cherry-mx brown switches.

I don't really know anything about them, or what appears to be a whole computer sub-culture regarding 'mechanical' keyboards.

But I liked the idea of a keyboard with no markings, i've worn a few off over the years so this should be immune to that at least! Actually from a sitting position you can read the front face of the keys not covered by your hands anyway. It was also a bit cheaper. I also really liked the idea of the `ten-key-less' design - I've always found the numpad a fucking pointless desk-waster.

The description of the `brown' switches are soft but with a bump - but they're not quite as positive as the litetouch was though, and definitely much louder particularly when they bottom out. If my sister ever types on it she'll make a racket as she really thumps the keys and types like she's on a mechanical typewriter (on which she learnt).

A Ducky One Two `ten-key-less', with the Horizon colour scheme. I also got the cherry-mx brown switches here.

And this one really just because I liked the colours. It's quite pretty! This is a newer design and feels a little softer and quieter but i haven't used it much yet.

They both come with a couple of extra key caps in contrasting colours (pink for the black one), although a few of the keys are for the non-existent numpad. They're both fairly heavy and very solid, basically no flex in the body.

I'm still getting used to the tiny differences even though the layout and dimensions are identical to the keyboards I was using. Probably the main difference is that the very top of the key is slightly smaller so they have larger gaps in between, it just throws out my touch enough but it wont take long to get used to them. Oddly I end up not making typos so much as typing a completely different word? I mostly type on my work laptop anyway, whose keyboard isn't fantastic but it's adequate.

My desks are always full of shit so the smaller size is handy as well.

I wouldn't have minded a bit more of a positve feedback on the key presses, but I guess I will get used to it and they aren't squashy at least. I suppose i'd better, the pair of them cost $250, but given the amount of time I spent on the damn machines it's justifiable. I only really needed one but this saves more desk space, and maybe i'll take one to work if i ever spend enough time there.

Another tool looking to be upgraded is my home machine. I'm thinking of getting a ryzen 3K system at some point, but i'll probably umm and ahh over that for months more yet - or just spend on a whim. The X570 boards are just too overpriced and there's basically no ITX boards to be had either.

Update 21/7/19: Short mini-review. I've been using the D1-2 (the blue one) on my home machine enough to get used to it. In a word: very good. I was at work using a keyboard that I thought was ok before (a HP workstation keyboard, one of the flat square-keyed ones) but it felt like typing on soggy bread - although this was the project managers keyboard and not my pc of the same, and well, he eats at his desk.

Tagged biographical.
Sunday, 14 July 2019, 12:41

Improved post navigation links

I've made a minor improvement to blogz so that when viewing a single post the navigation links at the bottom of the post show the title of the next/previous post rather than just saying 'Older' or 'Newer'. This was something I had intended to add when I got the database backend working but that is still in limbo. Actually most of the code for the blog output is done, I just can't decide on relatively unimportant details like the serialisation format for the metadata records. The other issue is adds a whole mass of potential complexity to creating posts rather than just editing a file on a shell login. Like an order of magnitue of complexity. It doesn't require this complexity but it enables it.

I made some other minor changes to the stylesheet mostly to do with inline figures (photos and captions), justified the text of posts, and messed about with the About box.

Tagged blogz, zedzone.
Saturday, 13 July 2019, 12:52

Reading multi-stream high-depth videos in octave (and matlab)

So I discovered recently that octave and matlab support direct calling out to Java. We had a need to read both multi-stream and high bit-depth videos from them, and using jjmpeg seemed a lot easier than writing some mex shit. The native video format support in matlab is abysmal and it simply has no capability for reading multi-stream videos either.

Anyway, i've just commited some stuff to jjmpeg in contrib/octave. It consists of a simplified multi-stream VideoReader and a small set of octave.m files which ease it's use and make it portable. And a Makefile to compile this using a Java 8 JDK because those tools are so wildly out of date.

Here I am testing my patches for ffmpeg+kinect as discused in some recent posts. This shows the 3 streams recorded by that tool; colour 8-bit mjpeg from camera, infra-red 16-bit raw and depth 16-bit raw losslessly encoded using jpegls.

The .jar file and octave scripts are portable to matlab. Althhough the license means they cannot be distributed, I think.

Since the freenect2 indev patches were not accepted into ffmpeg I will add them and probably the kinect2 indev patches to jjmpeg/contrib as well. At some future point in time.

Tagged code, hacking, java, jjmpeg.
Sunday, 07 July 2019, 12:21

ZedZone sitemap.xml

I've added a sitemap.xml to the site. Maybe that'll make google consider adding it to it's index as it's only indexing 130 odd pages out of 1K+. bing is probably a lost cause, it's only indexed 10 pages.

It's a patch to blogz which generates both the short (id only) and long (date-title) urls as well as a sitemap for the few plain html articles which mostly cover the project home pages.

I also noticed some very old url's were being accessed so I added a redirect from /blog?post=xx to /post/xx. Huh now i think of it /blog?post=xx was blog by date, but no matter, it's good enough. Been a bit sick and not really on top of it the last few days.

Tagged blogz, code, hacking, zedzone.
Saturday, 06 July 2019, 16:22

incremental javac, make

I've been looking into incremental javac compilation again. I had most of the code for one approach done weeks ago but it never really got to the point of doing anything useful.

The goal is to simplify a GNU make based Java build system while ensuring consitent and complete builds.

javac -m <module> comes very close to what I want but the main problem is that it doesn't remove stale files. These come about for the same reasons that might occur with C development, for example the .java file is renamed or deleted. But there are many more cases that occur regularly in Java, for example an inner class or anonymous inner class is removed or renamed. And in C these aren't such an issue since a link line or whatever is just going to ignore any stale files anyway but with Java you can't easily calculate all the possible .class files (without recompiling the source) so you just grab all the files in the directory when creating a jar or module, so you don't want stale ones lying about.

So far i've created a tool called ijavac that uses the --module-source-path only to automatically find all source files that need recompiling. It optionally supports per-module mode where it restricts processing to in-module classes. It also automatically removes all stale files before they are recompiled. It works by parsing all the existing .class files, matching them up with their source based on --module-source-path and checking timestamps. The parsed .class files are used to create the full set of down-stream dependent classes, then match them to the corresponding set of .java files, and then invoke javac with this set.

In per-module mode it isn't quite as fast as using javac -m, but it's close and it ensures stale files are removed. Because it's only performing file-level dependencies it can recompile more than is necessary. In whole-project mode it depends on what was changed and how many files could need recompiling. However i'm not sure I can fit this in with my build system as I want to support generated files which may require a per-module build order.

There are also cases where module mode fails, regardless of whether the stale files are removed or not. For example:

// module a
public class Bob {
    int x;
}

// module b
public class Foo {
    Bob bob;

    int baz() {
        return bob.x;
    }
}
  

If x is renamed in class Bob then a per-module rebuild will only rebuild Bob.class. Subsequently running a dependency-aware module build on module b will not recompile Foo.

The whole-project mode will catch this case succesfully assuming a per-module build hasn't already updated Bob.class independently. Although if you have a deeply dependent object (that is used widely in a project) it's about the same speed just to delete all the classes and rebuild them all together.

The main reason is that the per-module mode restricts it's view to only in-module classes and sources. I guess it should be able to handle cross-module checks with some additional work.

Another idea i'm toying with is creating a cleanup routine that is run as a post-process after javac -m. Becasue this only needs to match each .class with a .java it doesn't have to worry about building the whole dependency graph and can get away with only parsing the Source attribute. I'm not sure why javac -m doesn't expunge stale files but alas it does not.

I also have the code to generate the module-level dependency lists which is what would go into a makefile. The makefile wouldn't track .class files as one would with C.

But for now i'm not sure I really got anywhere so I guess it'll just go on the backburner again.

Apparently 'best practice' using maven is just to delete and rebuild every time which is nonsense.

Tagged hacking, java.
Wednesday, 03 July 2019, 15:39

Kinect2 device for FFmpeg, Microsoft Kinect for Windows SDK 2.0

So further on the previous post about Kinect for Microsoft Windows v2 support in ffmpeg ...

  1. My patch to ffmpeg-devel was completely ignored. Not even the courtesy to say it wasn't welcome due to it being obsolete hardware or any other comment whatsoever.
  2. My patches to libfreenect2 also seem to have been simply ignored.
  3. I couldn't get libfreenect2 to work on microsoft windows 10. It compiles and in some cases detects the camera but bulk transfers always timeout. I tried everything!
    • Using the libusb.dll in the binary download. This detects but transfers timeout.
    • Using visual studio to compile the libusb.dll. Doesn't work at all.
    • Using visual studio to compile libfreenect2 and a very basic capture program but uses the libusb.dll from libfreenect2 distribution. This only works if i put a couple of Sleep() calls in the right place. Otherwise it also fails.
    • Adding Sleep() calls in the ffmpeg module just times out.
  4. So I wrote a C dll to wrap the microsoft sdk so it could be called from gcc compiled code as c++ has no ABI so there it can't call it directly.
  5. Then I wrote another simple ffmpeg device 'kinect2' which uses this C dll to capture on a microsoft platform.
  6. Due to delays in processing this locked up the capture when trying to record all streams so I needed to use a capture thread and dump copies of the frames to a limited-size write queue.

This works and is stable but is microsoft platform only. The colour signal comes through as YUYV so it needs to be recompressed for saving vs the libfreenect2 indev which supported raw jpeg capture, so it takes considerably more cpu resources using a software codec. Also the C dll can only be compiled with visual studio as the Kinect headers (apart from being an auto-generated unreadable mess) are are not standard C or c++ compatible. But ffmpeg is still cross-compiled from a proper development system.

The c++ kinect sdk isn't too bad - apart from all the COM overheads and unredable headers. The documentation is abysmal. This is the first time iv'e ever used visual studio for C or c++, and hopefully the last, it's pretty pants.

Given my shitty experience with ffmpeg-devel I probably wont bother even submitting a patch for it there. If I decide to publish it at all I might send a link to ffmpeg-devel just to get some exposure.

I've found that it's almost impossible to find this site with any search engine even if you look for something specific so it's pretty pointless publishing it here anyway. Yesterday I was forced to login to bing and google's search consoles to find out what the hell was going on. bing has only indexed about a dozen pages and google has indexed the site but barely ever shows anything, and some of what it shows (10+ pages in) is dead links from previous iterations of the blog software. A few months ago I added jjpeg and zcl (at least) to the GNU Free Software Directory ... and even there the jjmpeg entry has been sitting at 'not approved' ever since and doesn't show the anything unless you dig further.

I've seen people asking on the microsoft developer forums for a piece of software which does exactly this - mostly from academic users - but if they can't find it what's the bloody point?

Tagged hacking, jjmpeg.
Monday, 03 June 2019, 10:48

Kinect2 device for FFmpeg, libfreenect2

I've been working on a kinect2 device backend for FFmpeg the last few days. Actually it's only about a day's work so far and i've got the code talking to the c++ (sigh) libfreenect2, building, and most of the glue written - I just haven't tested it with the hardware yet. I hope it should be quite straightforward but FFmpeg is a fairly complex library and there are a lot of details that could be wrong.

One feature it has is that the jpeg frames are not decoded; which means cheaper recording and no loss of capture quality. I had to make some minor modifications to libfreenect2 for this to be possible.

It exports 3x streams: the RGB data as jpeg, the IR data as grey16, and the depth data as grey16. I have options to enable various subsets of these streams, so for example depth+ir decoding can be skipped as it requires a good amount of flops. Cameras are referenced by serial number or index. Device queries work as do some basic capture settings. I'm also considering other options which libfreenect2 provides such as streams with the depth/rgb aligned to each other.

Once I have it at a working state and ported to git head (FFmpeg git was down when i started working on it) I will see if FFmpeg is interested in it. The fact that it requires c++ and a patched libfreenect2 might be a downside but there is already a c++ device in the source tree. Otherwise i'll just upload it to code.

This was going to be for work but they decided they'd rather use some junk matlab (ffs) on a shit platform (fffs) so i'm a little annoyed about the whole thing. While it should be possible to get this to work on their chosen shit platform as well it's a bit more involved.

Tagged hacking, jjmpeg.
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