[Rock-dev] compressed video streaming module

[Peter Nemeth]

Dear All,

TL;DR: I'm looking for suggestions for creating a good structure for 2
modules that manage compression/serialization and
deserialization/uncompression of video frames.

===

In project RIMRES, we have a system (for the payload items) that
contains a Gumstix Overo board with an E-con camera attached to it.
This should supply a continuous video stream that is accessible from
any computer on the network running Orocos. Naturally, both speed and
quality of this stream are important, and the Gumstix board has
mediocre resources for this task only.

Initially, I've used the interfaces provided by frame.h and
frame_helper to pass UYVY raw frames from the Gumstix to any desktop
PCs, but the fps was very low due to the huge size of these frames.

Now, we got the Gumstix Overo Fire boards instead of the old Gumstix
Overo Air ones. The main difference is that the Fire boards have a DSP
chip, which can be used for on-the-fly video compressing. At the
moment I have managed to squeeze out two formats from it - H263 and
MP4. This operating with the DSP can be used with Gstreamer, which has
an API for C.

I recently had a talk with Alex Duda, and we agreed that pushing a
compressed video frame into an "orocos frame" - although possible - is
illogical for several reasons. It would make more sense to create
two new modules for this task. The first one (on the Gumstix, in my
case) would be responsible for grabbing the video with Gstreamer,
compressing the video and serializing the buffer object for use in the
second module. The latter module (on any "desktop PC") would
deserialize this object, uncompress the video and push it to an orocos
frame, allowing any functionalities that the frame interface offers as
well.

As other projects might benefit from these modules as well, I would
like to ask whether you have any ideas or suggestions concerning the
buildup of these libraries/modules, in terms of structures or extra
functionalities. Please let me know as soon as possible, as I would
like to start developing it already this week.

Thank you,

Peter

-- 
--
Peter Nemeth
Space Robotics

DFKI GmbH
Robotics Innovation Center
Robert-Hooke-Straße 5
28359 Bremen, Germany

Phone: +49 (0)421 178 45-0
Fax:   +49 (0)421 178 45-4150
E-Mail: robotik at dfki.de

Weitere Informationen: http://www.dfki.de/robotik
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