/**
* Parse MPEG-4 systems extradata from a potentially unaligned GetBitContext to retrieve audio configuration.
* @param[in] c MPEG4AudioConfig structure to fill.
* @param[in] gb Extradata from container.
* @param[in] sync_extension look for a sync extension after config if true.
/**
* Parse MPEG-4 systems extradata from a potentially unaligned GetBitContext to retrieve audio configuration.
* @param[in] c MPEG4AudioConfig structure to fill.
* @param[in] gb Extradata from container.
* @param[in] sync_extension look for a sync extension after config if true.