Thanks for the help Harald, much appreciated.
On Wed, Feb 9, 2011 at 8:44 PM, Harald Gustafsson email@example.com wrote:
OMX main purpose is to handle multimedia hardware and offer an interface to that HW that looks identical indenpendent of the vendor delivering that hardware, much like the v4l2 or USB subsystems tries to do. And yes optimally it should be implemented in drivers/omx in Linux and a user space library on top of that.
Thanks for clarifying this part, it was unclear to me. The reason being that it seems OMX does not imply userspace/kernelspace separation, and I was thinking more of it as a userspace lib. Now my understanding is that if e.g. OpenMAX defines a certain data structure, say for a PCM frame or whatever, then that exact struct is supposed to be used by the kernelspace/userspace interface, and defined in the include file exported by the kernel.
It might be that some alignment also needs to be made between 4vl2 and other OS's implementation, to ease developing drivers for many OSs (sorry I don't know these details, but you ST-E guys should know).
The basic conflict I would say is that Linux has its own API+ABI, which is defined by V4L and ALSA through a community process without much thought about any existing standard APIs. (In some cases also predating them.)
By the way IL is about to finalize version 1.2 of OpenMAX IL which is more than a years work of aligning all vendors and fixing unclear and buggy parts.
I suspect that the basic problem with Khronos OpenMAX right now is how to handle communities - for example the X consortium had something like the same problem a while back, only member companies could partake in the standard process, and they need of course to pay an upfront fee for that, and the majority of these companies didn't exactly send Linux community members to the meetings.
And now all the companies who took part in OpenMAX somehow end up having to do a lot of upfront community work if they want to drive the API:s in a certain direction, discuss it again with the V4L and ALSA maintainers and so on. Which takes a lot of time and patience with uncertain outcome, since this process is autonomous from Khronos. Nobody seems to be doing this, I javen't seen a single patch aimed at trying to unify the APIs so far. I don't know if it'd be welcome.
This coupled with strict delivery deadlines and a marketing will to state conformance to OpenMAX of course leads companies into solutions breaking the Linux kernelspace API to be able to present this.
Now I think we have a pretty clear view of the problem, I don't know what could be done about it though :-/
Yours, Linus Walleij