amcvideodec: decoding fails on Mediatek tablet (API level 19)

[Grégoire Gentil]

Hardware decoding fails on this tablet inside amcvideodec as I explained 
in this bug report:

https://bugzilla.gnome.org/show_bug.cgi?id=797149
amcvideodec: decoding fails on Mediatek tablet (API level 19)

I would like to try to debug further this issue which seems to be 
related how Gstreamer handles the hardware decoding.

Can anyone provide any tip how I should investigate further to find out 
the issue?

Grégoire