Alex Ashley authored Jul 05, 2018 and Arun Raghavan committed Jan 11, 2019

ISO 14496-3 defines that audioObjectType 5 is a special case that
indicates SBR is present and that an additional field has to be
parsed to find the true audioObjectType.

There are two ways of signaling SBR within an AAC stream - implicit
and explicit (see [1] section 4.2). When explicit signaling is used,
the presence of SBR data is signaled by means of the SBR
audioObjectType in the AudioSpecificConfig data.

Normally the sample rate is specified by an index into a
table of common sample rates. However index 0x0f is a special case
that indicates that the next 24 bits contain the real sample rate.

[1] https://www.telosalliance.com/support/A-closer-look-into-MPEG-4-High-Efficiency-AAC

Fixes #39