Low delay B frame provide the function of transforming
P frame into low delay B frame which frame type is B, but
only reference predictive frames. This can be used when P
frame unsupported. Especially for P and B both unsupported,
in this case, I and low delay B frame can be encoded in a
stream.
https://bugzilla.gnome.org/show_bug.cgi?id=796984
Creates 2 properties, qp-ip and qp-ib for setting different QP for P/B
frames
and set slice_qp_delta for each frame according to the value provided.
https://bugzilla.gnome.org/show_bug.cgi?id=785923
Users can provide the number of reference frame by this property,
which is exaclty same as h264.
The value of the property will be considered as the number of
reference picture list0 and will add 1 reference frame more to the
reference picture list1 internally if b-frame encoding.
If the value provided is bigger than the number of refrence frames
supported in the driver, it will be lowered.
The maximum value is aligned to the value of the driver supported now.
https://bugzilla.gnome.org/show_bug.cgi?id=783804
