[polo_joe]

I tried both settings together and each alone.
No change.

mmal half works.

mmal advanced at HD triggers a boost to 300MHz (of v3d clock).
The half version doesn't need the boost, nor does automatic (which uses bob for hd).

So my guess is that 300MHz v3d is not working on your Pi.
However with default config.txt settings (i.e. no v3d_freq or gpu_freq specified) and with disable_auto_turbo=1 you should still be running at 250MHz.

When running with default config.txt settings + disable_auto_turbo=1 and when getting the artefacts can you run:

Code:

vcgencmd measure_clock v3d

If it is zero then run a few times until you see a non-zero value and report what it is.

With this settings 300MHz v3d works, but still artefacts with mmal advanced:

OpenELEC (unofficial) Version: devel-20150901235445-#0901-g494f51d
OpenELEC git: 494f51dfa4508753ff7ab804094306b5f9499bf7
OpenELEC:~ # vcgencmd measure_clock v3d
frequency(43)=300000000
OpenELEC:~ # paste /flash/config.txt
http://sprunge.us/eJUF
OpenELEC:~ #