Merge pull request #785 from AOMediaCodec/issue_765

Fix #765, Profile clarification regarding channels

index.bs

@@ -1844,6 +1844,7 @@ Common restrictions on the [=IA Sequence=] for all profiles specified in this ve
 NOTE: This behavior is to allow future versions of this specification to define new profiles that support a number of audio elements and/or a number of sub-mixes greater than those recommended in this profile, while still permitting streams compliant with these new profiles to be processed by parsers compliant with the profiles defined in this version of the specification.
 
 - When [=num_layers=] = 1, [=DemixingParamDefinition()=] for demixing MAY be present in the [=Audio Element OBU=] and IA decoders MAY use [=demixing_info_parameter_data=] or [=default_demixing_info_parameter_data=] for (dynamic) down-mixing.
+- The limit on the number of channels, which profiles MAY define, applies to the sum of channels across all [=Audio Element=]s in a [=Mix Presentation=] before mixing.
 - There MAY be [=Temporal Delimiter OBU=]s present. If present, the first OBU of every [=Temporal Unit=] SHALL be the [=Temporal Delimiter OBU=].
 
 
@@ -1878,7 +1879,6 @@ Capabilities of the IA parser, decoder, and processor:
 - They SHALL be able to support the capabilities of the [[#profiles-simple|Simple Profile]].
 - They SHALL be able to parse an [=IA Sequence=] with [=primary_profile=] = 1.
 - They SHALL be able to handle up to 18 channels.
-	- The 18 channels limit applies to the sum of channels across all [=Audio Element=]s in a [=Mix Presentation=] before mixing.
 	- One example is a mix with 3rd-order Ambisonics (16 channels) + non-diegetic stereo (2 channels).
 - They SHALL be able to reconstruct two [=Audio Element=]s.
 - They SHALL be able to mix two [=Audio Element=]s.