Qt on Linux i.MX 6

i.MX 6 is a good device. Qt runs pretty well on it. Also a plugin for hardware accelerated and zero-copy rendering seems to work pretty well. Simply building Qt for i.MX 6 makes it possible to use the Qt Multimedia plugin. This is the result (on Linux):

I also tested a provided Android port but the result was not as good.

Video with Animations on Android using VLC for software decoding

Again, video with animations: this time video is demuxed and decoded using the awesome VLC library. VLC is provided buffers from Java that are then drawn on a view. The result is pretty good if you think all the decoding runs on the CPU. And I'm sure it can be improved.

Video with Animations on Raspberry Pi and A31s Compared

For many uses, playing video while animations are running is pretty useful and it is also considerably stressful for the GPU. I therefore tested a couple of cheap chips with the same Qt/QML sample app. I created a small demo video comparing Qt on A31s and Raspberry Pi (PiOmxTextures):

In the demo, all the media (video and images) are 720p, and the output is 720p for A31s and 1080p for Raspberry Pi (16bpp). It is pretty hard to tell from the video, but Raspberry seems to still be above A31s.
Bye! ;-)

A Tribute to Qt Portability :-)

The new ports of Qt to mobile systems like Android, iOS and WinRT are getting more and more reliable. I just wanted to have a look at the current stage of development and I therefore wrote a sample app. This is the result:

This is a quick app to test the portability of Qt on desktop, mobile and embedded.

The video shows client/server code, communicating via WebSockets (using the new WebSockets module in Qt), with a server in Qt/C++ running on Pi and with a fluid hardware accelerated interface in C++/QML running on Raspberry Pi, Mac OS X Maverick, Android Phone and Tablet, Windows 8 (Modern UI), Windows Phone 8, iOS and Linux Kubuntu. The server (on Raspberry Pi) stores information about tasks and the client provides a remote interface to manage. A client written using HTML5 canvas and WebSockets from the browser is also shown.

Unfortunately I don't own iOS and Winphone ARM devices, otherwise I'd add those as well :-) Good start anyway: this is really "write once, deploy anywhere".

Using the ports is simple: configure Qt Creator with the correct Qt build, setup the toolchain to use, qmake and build (for iOS and WinRT I preferred Xcode and Visual Studio respectively yet). Your done!
Pretty cool! Bye! ;-)

FFmpeg gstreamer plugin on Ubuntu 14.04

EDIT 02.25.2015: It seems to be missing even in Ubuntu 14.10. But probably the quickest way to install is:

sudo add-apt-repository ppa:mc3man/gstffmpeg-keep
sudo apt-get update
sudo apt-get install gstreamer0.10-ffmpeg


END EDIT

I was trying to develop an application that uses gstreamer 0.10 on Ubuntu 14.04 and I noticed this runtime error message:

"No decoder available for type 'video/x-h264, stream-format=(string)avc, alignment=(string)au, level=(string)3, profile=(string)main, codec_data=(buffer)014d401effe10015274d401ea9181b07bcde00d4040406db0ad7bdf01001000428de09c8, width=(int)854, height=(int)480, framerate=(fraction)24/1, pixel-aspect-ratio=(fraction)1/1, parsed=(boolean)true'."

This is because it seems that the gstreamer 0.10 ffmpeg plugin is missing in 14.04. This also makes my Qt code fail it seems, as it uses 0.10 for the Qt Multimedia module. It used to be sufficient to install ubuntu-restricted-extras until 13.10, but it seems something has changed in 14.04. I really couldn't find that plugin anywhere soI simply built that from the sources here. Luckily it also contains the ffmpeg sources and builds those statically it seems.
Download the package, extract and:

./configure make make install

You'll probably need to install the usual build-essentials, gstreamer0.10, libgstreamer0.10, libgstreamer-plugins-base0.10-dev etc... It may fail with an error on a macro like this:

./libavcodec/get_bits.h: In function 'skip_bits': ./libavcodec/get_bits.h:387:1: warning: variable 're_cache' set but not used [-Wunused-but-set-variable] libavcodec/x86/h264_qpel_mmx.c: Assembler messages: libavcodec/x86/h264_qpel_mmx.c:1294: Error: operand type mismatch for `cmp' libavcodec/x86/h264_qpel_mmx.c:1294: Error: operand type mismatch for `cmp' libavcodec/x86/h264_qpel_mmx.c:1298: Error: operand type mismatch for `cmp' libavcodec/x86/h264_qpel_mmx.c:1298: Error: operand type mismatch for `cmp' libavcodec/x86/h264_qpel_mmx.c:964: Error: operand type mismatch for `cmp' libavcodec/x86/h264_qpel_mmx.c:964: Error: operand type mismatch for `cmp' libavcodec/x86/h264_qpel_mmx.c:964: Error: operand type mismatch for `cmp' make[1]: *** [libavcodec/x86/dsputil_mmx.o] Error 1

If that happens just apply the patch here. Place the plugin libgstffmpeg.so into /usr/lib/x86_64-linux-gnu/gstreamer-0.10, or wherever you have your gstreamer plugins and you're done. Bye! ;-)

Updates on Hardware Accelerated Qt Multimedia Backend on Raspberry Pi (4.15.2014)

For those of you still working on this exciting subject, I did some new changes to PiOmxTextures and it still works pretty good. To have more information on PiOmxTextures refer to this older article. PiOmxTextures is the code behind the creation of a Qt Multimedia backend to provide hardware accelerated video (and software-decoded audio using ffmpeg) decoding and rendering from/in QML scenes on Raspberry Pi. PiOmxPlayer leverages the code from omxplayer. These are the new additions:

1. Imported code from omxplayer to revision 9b0793faf2c12f49b743ae3778ece03e31ed1538.
2. Now using ffmpeg 2.2.
3. Now it can be built using gcc 4.8 using the recent Raspberry Pi Linaro toolchain released in 2014.
4. Tested using Qt 5.3.0 beta.
5. Tested on the most recent Raspberry Pi firmware: it seems Broadcom has made some changes (fixes?) to the egl_render component. Use the new patch to Qt Multimedia and rebuild. The hack I was forced to add to compensate is no more needed.

Everything seems to keep working correctly, both in 1080p and 720p. Enjoy: https://github.com/carlonluca/pi. Bye! ;-)