Friday, November 24, 2017

Raspbian Stretch and Cross Toolchain for Linux and Mac OS

Raspbian Stretch is out for Raspberry Pi. I needed a cross toolchain with the same exact version used to build the system so I built my own. As I had my script ready, I also tried to build one for Mac OS and it seems to work for the moment. I tested these cross toolchains for my projects and seemed to be able to build everything that I tried: Qt libs, apps, omxplayer, ffmpeg etc...

Download Linux x64 cross toolchain GCC 6.3.0 for Stretch here.
Download Mac OS cross toolchain GCC 6.3.0 for Stretch here.

NOTE: The Mac OS version requires some packages to be installed from macports.
NOTE: The toolchain is built to crossbuild for armv7-a. I could also build for armv8 but not sure if it also works for armv6.

Have fun! Bye! ;-)

Saturday, June 3, 2017

Mounting Shared Directories on Ubuntu Running on VMWare

This post is mostly for myself :-) This was very simple years ago; actually it was automatic. Now, I have no idea why, but shared directories are not automatically mounted anymore. By searching online it is incredibly difficult to find a proper answer: I tried a million answers but none was working properly. The only one that worked is simply the shortest and the one I never remember for some reason (and also difficult to find) :-):

vmhgfs-fuse /mount/dir

this is how I do it, and it works for me. No idea why the other techniques are not.

Sunday, March 19, 2017

Experimenting with Pi3 optimisations - POT 5.6.0-beta1 with Qt 5.8.0 built for armv8 with GCC 4.9.4

At the moment I still don't want to test custom firmwares or 64 bit arch builds, but I started to test a couple of new features: a new compiler from Linaro (the one provided by the foundation keeps giving me headaches), version 4.9.4 instead of 4.8, and optimised compiler flags for the Rapsberry Pi 3, which is an armv8.
In this build, Qt, ffmpeg and POT are all built with 4.9.4 Linaro toolchain and optimised compiler flags for Pi3. This will only work on Pi3.
You won't probably see much difference in GPU intensive apps, but it is a step on the road of optimisation!

Have fun! Bye! ;-)

Download the toolchain here.
Download POT 5.6.0-beta1 for Raspbian Jessie Lite Pi3 here (md5: 0eec41ef02e9369fc7e569030b8ff868).

Saturday, January 28, 2017

Hardware Decoding in Chromium through QtWebEngine on Raspberry Pi

A few months back I decided to try to implement hardware decoding in WebKit. Unfortunately this task is always pretty long and complex for many reasons. I found the time to draft an implementation for WebKit1, which is pretty useless as WebKit1 in Qt is only used outside QML and JS is executed in the main thread. Unfortunately I never found the time to implement this in WebKit2, which runs in QML and is suitable for more fluid UIs. This was the result:
This is how YouTube was running with this implementation:

Now Qt has deprecated QtWebKit and is working heavily on QtWebEngine, which is built on Chromium, so I wanted to try this road. Unfortunately these kind of things always claim a lot of time, and I don't typically have that much, but I was able to start and get something done already.

Writing a complete solution in Chromium to decode and render video takes much time, so I thought of a shortcut: creating a custom VDA (Video Decode Accelerator) that loads the POT library and reusing its entire codebase to implement decode and rendering with little modifications. This proved to be possible and now I get something on the screen.

So, to summarise: a little patch to Chromium is needed to create a VDA that dynamically loads POT library into memory and uses it with a common interface. Data and calls are translated to POT structures and are sent to POT, which then processes the buffers properly. The result of the decode operation is then sent back to the VDA through the same interface and textures are then sent to Chromium for rendering.

Still many problems remain open, there is much to be done yet as you can see from the video, but something is drawn. Have a look at the demo:

Have fun! ;-)