Proof of concept OSD code.

[rdoeffinger]

It works for displaying a usable OSD in MPlayer at full screen
resolution and even if using hardware decode, but is far
too slow for fullscreen use for example.

Signed-off-by: Reimar Döffinger Reimar.Doeffinger@gmx.de

[rzk]

Awesome! But may I ask, how slow is "too slow"? Just a user question, would be great to know some data about what formats and on what resolutions work good with OSD. If this is is the only OSD solution possible, it might be even needed to add info to the wiki for users to know what to expect.

[jemk]

I added a branch of my idea for OSD support. It is far from optimal too, but at least it's pretty fast and I have many optimizations in mind. Seems like we doubled some work, sorry for not pushing this earlier.

[rdoeffinger]

I think it's not exactly duplicated code.
Note that the speed issues is mostly due to me choosing a stupid design because I wanted to test the idea.
The only non-fixable issue is that proper alpha blending is not possible.
I have to admit that I kind of really do not like having a hard dependency on another, independent hardware feature like G2D. My approach only needs colorkey support.
I wonder what your opinion is on how feasible/sensible it would be to possibly support both?
just to be clear: I don't mean this as an attempt to push my solution (who knows if I'll have time to ever finish it), just sounded like a nice idea in my head.

[jemk]

No, of course not duplicate, only vdp_output_surface_put_bits_indexed()

Well, it doesn't strictly depend on G2D, this could be done in software too. It even needs to get some software fallback for SoCs without G2D. But most sunxi SoCs have G2D, so why not use it.

The main difference is that my version puts a second disp layer over the video with real alpha blending. I'm still not quite sure if this is really better than using X (a little bit more optimized). It will be necessary to support "both", as a second alpha blended layer makes it impossible to use color key, so no window overlapping. I had many ideas how to do all this, but not much time to try.

[ssvb]

Hi guys. It's great to see some progress with the OSD feature support. We talked about this with @jemk some time ago on #linux-sunxi irc, and in my opinion the xorg ddx driver has the best control over what part of the window is visible at any time. So that it may handle fully visible or partially overlapped windows in the most optimal way.

On a technical side, we can implement some basic DRI2 support for libvdpau-sunxi in https://github.com/ssvb/xf86-video-fbturbo and get it nicely integrated. The dri2 workflow is that the the clients may do two things:

1. request the dri2 buffers (the dri2 buffers are created on the x server side)
2. request to swap dri2 buffers

This may look rather invasive. Except that we may treat "dri2 buffer" as not a real buffer with pixels, but as just some sort of a unique token. The cedar kernel driver can be extended with some new ioctl to support storing data by token and retrieving data by token. So the workflow may look like this:

1. The VDPAU client asks the X server for a new dri2 buffer (DRI2GetBuffers)
2. The X server generates a unique token and returns it to the client
3. The client does whatever it wants with its own memory buffers and then calls the cedar driver ioctl to store data with the detailed information about the video frame using this token as a unique handle
4. The VDPAU client asks the X server to DRI2SwapBuffers
5. The ddx driver in the X server uses the dri2 buffer token to retrieve the detailed data about the video frame (the addresses of the video surface, the bitmap surface and anything else) via the cedar driver ioctl.
6. Then using the frame data, the ddx tries to present it on the screen in the most optimal way possible. If the window is fully visible - configures the sunxi disp layers. If the window is partially overlapped - uses a software rendering fallback or g2d fallback.

Does this look reasonable? I was actually intending to implement some sort of prototype, but just did not have much free time lately. Still I hope to be able to do something useful during the upcoming Christmas holidays.