Tuesday, 8 July 2014

Odroid U3+

Odroid U3+

Not a very good picture but what you are seeing is an Odroid U3+ in it's
case sitting on a tangle of wires which is my desktop. The Odroid is made
by Hardkernel, it is a Quadcore ARM device as used in Galaxy Smartphones.
It is a lot faster that other ARM devices I have been experimenting with and
is well supported with an inhouse magazine and hardware accelerators for the

Currently with DATV-Express there are 2 main development strands. Firstly
I am adding support on the PC platform for analogue video capture and encoding
in software using libavcodec.

On the ARM platform I am trying to get the code fast enough to handle low
bandwidth DVB-T. I have moved from using fftw to do the iFFT to
av_fft which can be found in libavcodec. The new iFFT uses single precision
maths and on the ARM platform has special modules that use the NEON SIMD
instructions available on later ARM devices. The combination of these two
features means the code should run a lot faster.

Thanks to a suggestion by Ron W6RZ (who has ported my DVB-S2
implementation to GNURadio) I have managed to optimize part of the S2 code
to knock around 5% off the CPU load. I am sure further optimizations can be found.

Finally I have been reading a book on OpenCL called "Heterogeneous Computing
with OpenCL" One of the chapters gives an example of using it to do real-time
graphics processing and it has sent my mind racing as to the possibilities.

OpenCL for those that don't know is a framework based on the C language that
allows you to harness both CPUS and GPUS (graphics cards) in a parallel
processing environment. So far I have installed the Intel OpenCL SDK and
compiled and run a few pieces of example code. I have a NVIDIA card on my
Linux machine and the NVIDIA drivers now include the bits needed to work
with OpenCL.

What I am thinking of doing is taking the video capture code I have already
written for DATV-Express, run that on the CPUs to capture up to 4 video
channels. Then pass the video frames to the GPUs for manipulation and then
back to the CPUS for MPEG compression using libavcodec. The resultant
transport stream would then be sent to DATV-Express. I can then get rid of the
old Analogue video mixer / effects unit I have. The video mixer cost me
about the same amount as a dedicated PC would.  

Till next time!

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