New article - Linux multi-seat
It has been a while since I wrote an article, so here is a new one: Demystifying Linux multi-seat.Comments - Edit - Delete
1080p video playback on cubox-i
I have been experimenting with hardware acceleration for video playback on i.MX6 (cubox-i), that came with Freescale BSP. The most recent released for Freescale BSP is version 3.10.17, for their kernel GA 3.10.17.Hardware acceleration of anything is a fickle thing, because there are non-standard ways of doing things (one may disagree and says that there are too many standards to choose from: vdpau, vaapi, openmax, gstreamer, and others). In the end, different hardware vendors supports their hardware with different libraries.
Freescale chooses to use gstreamer to support video playback acceleration. It comes are a set of open-source gstreamer plugins, which links to closed-source VPU* and IPU* libraries, for gstreamer 0.10. Yeah that's the old version but it still works. Freescale has a newer (semi-official?) "community"(?) gstreamer 1.0 libraries but the support is not identical with 0.10 libraries.
[*Note: VPU is Freescale's hardware video processing unit, and IPU is Freescale's hardware Image Processing Unit]
The 0.10 libraries are purely VPU/IPU based and does not depend on a working GPU. It has a few plugins: a demux plugin ("aiurdemux") that recognises certain common formats like AVI, MKV, WEBM, MP4 and others, a VPU-assisted video decoder ("vpudec") and a video renderer (sink) that is IPU-assisted (mfw_v4lsink), among others.
If this sounds like alien language, let me translate it for you: "demux" is the one that splits a media file into its video and audio component (so they can be routed and processed by different components). "video decoder" is the one that decompress the video file and outputs raw video data, and "video renderer" is the component that takes that raw video data and display it on screen (possibly converting the formats in between).
Together they form a hardware accelerated video playback pipeline that can play 1080p video effortlessly with less than 10% CPU usage. As a comparison, even the quad-core i.MX6Q cannot play 1080p video smoothly using only its ARM cores alone.
There are just a few hiccups. The plugins apparently can't rotate the playback when you launch it using gst-launch (e.g see here - although if you use the gplay tool it would work), and if you try to use the plugin to play video on a rotated display (rotated using xrandr etc), then video playback gets totally wrong. This is mainly because certain parts of plugin follows X coordinate orientation, while other parts of it are stuck with real CRTC coordinates (that is, they aren't rotated).
I've done some fixes on that and the gstreamer plugins can now play video in any orientation (even from gst-launch) as well as in any display orientation. As a bonus, I have the code that makes video playback rotated following the display rotation automatically. Of course, because the final rendering is done by IPU, this is only possible if the size of the video output is not more than 1024x1024 pixels - this is an IPU limitation which isn't easily bypassed.
Combined with this: gstreamer npapi plugin, one can make an alternative video player plugin that provides accelerated video playback (compared to xine-plugin or vlc-plugin, for example); and when built with the "fixed" version, the video will play correctly on any display orientation. I know that, I've built one myself. It runs nicely on FatdogArm :)
Comments - Edit - Delete
Fatdog64 700 beta1 is released.
This release is mostly for bug fixes and some package updates.Forum announcement: http://murga-linux.com/puppy/viewtopic.php?p=799326.
Release notes: http://distro.ibiblio.org/fatdog/web/700b1.html.
Get it as usual from ibiblio or one of its mirrors: aarnet, uoc.gr, and nluug.nl.
Comments - Edit - Delete
Xscreenshot updated
Add "delayed" snapshot function to Xscreenshot accessed by Shift-hotkey). This is useful when you want to capture open menus etc. The usual way of pressing hotkey to capture won't do because as soon as press a key, the menu is closed."Delayed" snapshot avoid this by you pressing the hotkey first (to trigger the capture), and it giving you the chance to open the menu, and after a while it will do the capture behind the program's back.
Get it from here.
Comments - Edit - Delete
aufs - please support Mr. Okajima
Aufs filesystem is a full-featured, full-fledged layered filesystem for Linux, created by Mr. Junjiro Okajima. It is an alternative to "unionfs", Unlike unionfs, however, aufs is actively developed, and actively supported. Unlike other alternative Linux layered filesystems like "overlayfs", aufs is feature rich and has a lot of options. Aufs is mature and stable software, it is about 10 years old by now.I don't know how extensive aufs is used in the field, but I have a suspicion that many "live" OS systems (with support for persistence) will use aufs in form or another. I also think that aufs would be widely deployed in the embedded world, where one needs to have "writable" rootfs while still having the base OS in ROM. What I *do* know is that aufs is used in Fatdog64, FatdogArm, Puppy Linux and its multiplicity of derivatives, Slax, AntiX, and perhaps many others.
I recently had the pleasure of working directly Mr. Okajima.
I had problems with kernel oops with FatdogArm on cubox-i. Researching the problems, I found that kernel oops was a known common problem in the official cubox-i kernel and there were some solutions - but they didn't seem to work for me. My oops symptoms were quite different, too - the kernel didn't immediately crashed; but all filesystem operation failed, which lead me to suspect that the problem may have had to do with aufs (the other popularly Linux distros on cubox-i - Arch, Ubuntu - they all don't use aufs as far as I'm aware).
I escalated the problem to Mr. Okajima through the public mailing list and to my pleasant surprise, found that he was all courtesy, and very responsive. Mr. Okajima is very knowledgeable person - not only he helped me to troubleshoot the problem, but he actually solved it. This is despite the fact this was his first time looking at problems in ARM systems (and the problem required looking at ARM code dissasembly to find the cause); and the fact that he didn't have any ARM boxes whatsoever to reproduce the problem. One rarely encounters this kind of support and talent - even in the commercial world.
I'd encourage those who beneftis from aufs - especially commercially - to support the work of Mr. Okajima in whatever means that they can. Donation link is here (this goes straight to Mr. Okajima - not to me).
Comments - Edit - Delete
Fatdog64 700 alpha1 is released
Two years after the debut of Fatdog64 600, and five (5) months in the making, Fatdog64 700 finally gets its first public release - the first alpha release.Fatdog64 700 is built from scratch, using modified build recipes from LFS (Linux From Scratch) and BLFS, version 7.5 (the latest as of today). It features a brand new base: kernel 3.15.5, glibc 2.19 and gcc 4.8.2, and the latest or at least recent libraries of all the basic libraries, bringing Fatdog64 back to the contemporary world.
Fatdog64 700 left its PET legacy package management inherited from Puppy and switch to Slackware-style packages, using the excellent slapt-get and gslapt from http://www.jaos.org.
Forum announcement: http://murga-linux.com/puppy/viewtopic.php?p=791980#791980.
Get it from ibiblio or one of its mirrors: aarnet, uoc.gr, and nluug.nl.
Comments - Edit - Delete
Xscreenshot
Xscreenshot is a simple program to take a screenshot of a selected area in your desktop.You can run it in single-shot for multiple-shot mode; in multiple-shot mode you can use it to take successive screenshots of different area of the screen - very useful when capturing screenshots for documentation.
Xscreenshot is packaged as part of Xannotate.
Comments - Edit - Delete
Xannotate updated
If you've got the first released version of xannotate yesterday, you should get it again.The new version (dated 2014-07-27) now supports three pens, eraser, and support for alpha transparency (if you're running a compositing manager) which makes it run faster.
Comments - Edit - Delete
Xannotate, a desktop annotation tool
I like gromit, but unfortunately it is not working for me. The code itself is good, the bug is probably due to the subtle changes of GDK/GTK behaviour over the years.Anyway, I decided to write my own, and call it xannotate; because it does "annotation" and it only depends on Xlib.
Here's a shot:
More details (with download links) here.
Comments - Edit - Delete
FatdogArm on Cubox-i - update
FatdogArm now runs with Cubox-i i2w and i4p; supporting all features of FatdogArm plus i.MX6-specific hardware acceleration (vivante video driver, VPU, gstreamer, ALSA hardware resampler). Cubox-i is the *the only* ARM platform I have where you xrandr works correctly and you can change resolution on the fly. Kudos to Freescale to make this happen.On the other hand, the only thing currently not working on Cubox-i is the GPU (OpenGLES stuff). I have an open thread in the forum here: http://www.solid-run.com/community/post9713.html#p9713. All my other ARM platforms have their GPUs running, this is the only platform which it isn't (you've got Xorg hard lockups when trying to run any OpenGLES programs with GPU acceleration).
Comments - Edit - Delete
