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Fix #752, clarification on primary and additional profiles
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sunghee-hwang committed Sep 7, 2023
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11 changes: 4 additions & 7 deletions index.bs
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Expand Up @@ -1840,12 +1840,11 @@ NOTE: This behavior is to allow future versions of this specification to define

This section specifies the conformance points of the simple profile.

Restrictions on the [=IA Sequence=]:
When the [=primary_profile=] field set to 0, the following constraints apply to the [=IA Sequence=]:

- There SHALL be only one unique [=Audio Element OBU=].
- There SHALL NOT be any [=Temporal Delimiter OBU=]s present.
- [=additional_profile=] SHALL be set to 0 to indicate that the [=IA Sequence=] complies with this profile.
- [=primary_profile=] SHALL be set to 0.



Capabilities of the IA parser, decoder, and processor:
Expand All @@ -1858,7 +1857,7 @@ Capabilities of the IA parser, decoder, and processor:

This section specifies the conformance points of the base profile.

Restrictions on the [=IA Sequence=]:
When the [=primary_profile=] field set to 1, the following constraints apply to the [=IA Sequence=]:
- There SHALL be at most two unique [=Audio Element OBU=]s at any one time.
- There SHALL be at most one Channel-based [=Audio Element=] having [=num_layers=] > 1 at any one time.
- There SHALL be at most one Scene-based [=Audio Element=] at any one time.
Expand All @@ -1868,13 +1867,11 @@ Restrictions on the [=IA Sequence=]:
- Scene-based [=Audio Element=] + Channel-based [=Audio Element=] having [=num_layers=] = 1.
- Scene-based [=Audio Element=] + Channel-based [=Audio Element=] having [=num_layers=] > 1.
- There MAY be [=Temporal Delimiter OBU=]s present. If present, the first OBU of every [=Temporal Unit=] SHALL be the [=Temporal Delimiter OBU=].
- [=additional_profile=] SHALL be set to 1 to indicate that the [=IA Sequence=] complies with this profile.
- [=primary_profile=] MAY be set to 0 or 1.


Capabilities of the IA parser, decoder, and processor:
- They SHALL be able to parse an [=IA Sequence=] with [=primary_profile=] = 0 or 1.
- 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).
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