Aliased compressed AAC bytes are almost certainly not meaningful SBR
data. In the wild this causes harsh artifacts switching HE-AAC streams
that don't have SBR headers aligned with segment boundaries.

Turning off SBR falls back to a default set of upsampling parameters
that can function as a sort of error concealment. This is consistent
with how the decoder handles other sorts of errors.

Bug-Id: 1047
CC: libav-stable@libav.org
Signed-off-by: Sean McGovern <gseanmcg@gmail.com>