I have recently updated an old (Pre Bullseye) Raspberry Pi video based project environment from P3b, Python 2.7, Buster to Pi4, Python 3.9, Bullseye.
All went well and I am now running as expected on the new platform with one 'deal breaker' exception. I use OMX Player, and yes I have managed to get it installed and working on Bullseye apart from the 'layer' setting function is no longer operational.
I have done much research to try to get to the bottom of this and find a fix, this has been made more confusing due to the mixed semantics used in various posts and articles, 'layer', 'overlay' and 'plane' seem to freely mixed.
So before I give up and revert to Buster (which I am trying to avoid), is this a 100% dead end due to the switch from FKMS in Buster to KMS in Bullseye?
Is it even possible to have multiple layers (i.e. 'z layering display of video planes' with KMS? From what I have been reading suggests not :( This seems like a major loss to the video capabilities of the Pi under Bullseye? I do appreciate for reasons of standardisation it was felt by the Pi foundation the switch was needed but it is a killer for my project and I am sure has caused many other projects major headaches.
I did have seamless, instant switching between multiple video layers via OMX 'layer' function. Now I have no switching as the 'layer' function seems to be ignored by KMS, and FKMS under Bullseye (but not 'FKMAS' with Buster).
In boot\config.txt file I have tried commenting out 'dtoverlay=vc4-kms-v3d' and also tried replacing it with 'dtoverlay=vc4-fkms-v3d' (which is what actually got OMX player running in Bullseye after loads of other hacks) but still no video layer support so I am assuming this is blocked by something else in the chain (DispManx maybe?).
I am 100% certain that, irrespective of setting FKMAS or KMS in config.txt under Bullseye, only a single video stream layer will be created with subsequent requests for new layers being ignored. This has been verified by video layer substitution and 'playing layer analysis' via CLI 'vcgencmd dispmanx_list'.
I have tried VLC but it does not help as that also does not seem to have the layer capability (I think it has overlays but these seem limited to graphics not a video stream) and in general does not offer such flexible and seamless capabilities as OMX player.
Any help would be appreciated, even if it is a 'You 100% can't do layering of multiple video stream planes under KMS OR FKMS with Bullseye' so I don't continue to bang my head against a brick wall.
Thanks
