The underlying driver need not support B frames - since they are enabled
by default for some codecs, it is better to disable them rather than
returning an error in this case.  This makes the default settings usable
for low-power encoding on Intel platforms.
Signed-off-by: Haihao Xiang <haihao.xiang@intel.com>
Signed-off-by: Mark Thompson <sw@jkqxz.net>