When main-RExt is specified, the constraint flags are either manually specified, or calculated via the other supplied settings.
In addition, the following profiles strings are available: high_throughput_444, high_throughput_444_10, high_throughput_444_14.
When main-RExt or high-throughput-RExt is specified, the constraint flags are either manually specified, or calculated via the other supplied settings.
Compatibility flags are automatically determined according to the profile.
NB: There is currently only limited validation that the encoder configuration complies with the profile, level and tier constraints.