The existing implementation of the Player from 2012~2015 inclduded
an additional differentiation by media channel (for multichannel media)
and would build a separate CalcStream for each channel.
The in-depth analysis conducted for the ongoing »Vertical Slice« effort
revealed that this differentiation is besides the point and would never
be materialised: Since -- by definition -- all media processing has
to be done by the engine, also the generation of the final output format
including any channel multiplexing will happen in render nodes.
The only exception would be when only a single channel of multichannel
media is extracted -- yet this case would then translate into a
dedicated ModelPort.
Based on this reasoning, a lot of complexity (and some contradictions)
within the JobTicket implementation can be removed -- together with
some further leftovers of the fist attempt to build JobTickets always
from a Mock specification (we now use construction by the Segment,
based on an ExitNode, which is the expected actual implementation
for production setup)
...by defining a new scheme for access to custom allocators
...and then passing a reference to such an accessor into the
JobTicket ctor, thereby allowing the ticket istelf recursively
to place further JobTicket instances into the allocation space
--> success, test passes (finally)
Up to now, a draft/mock implementation was used, relying on a »spec tuple«,
which was fabricated by MockJobTicket. But with the introduction of
NodeGraphAttachment, the MockSequence now generates a nested ExitNode structure,
and thus the JobTicket will be created through the "real" ctor, and
no longer via MockJobTicket.
Thus it is possible to skip this whole interspersed »spec tuple«,
since ExitNode *is* already this aggregated / abstracted Spec
PROBLEM: can not implement Spec-generation, since
- we must use a λ for internal allocation of JobTickets
- but recursive type inference is not possible
Will thus need to abandon the Spec-Tuple and relocate this
traversal-and-generation code into JobTicket itself
Use another unit-test (FixtureSegment_test) to guide and cover
the transition from the existing fake-implementation to the
actual implementation, where the JobTicket will be generated
on-demand, from a NodeGraphAttachment
