[gmpi] Re: on mutliple sample types (OT, but let's finish?)

  • From: Chris Grigg <gmpi-public@xxxxxxxxxxxxxx>
  • To: gmpi@xxxxxxxxxxxxx
  • Date: Thu, 18 Dec 2003 12:49:14 -0800

 >>>
Say I want the following insert plugs (all hypothetical) on a DP
audio track, some running native and some running on a PowerCore, in
the following order, with all operating as first-class plugs as far
as I the user am concerned:

        Slot 1 - Para EQ (native)
        Slot 2 - Waveshaper (PowerCore)
        Slot 3 - Envelope Following Filter (PowerCore)
        Slot 4 - Bit Decimator (native)
<<<

I don't think you even need subgraphs to solve this problem.  Just use
baton-passing for the data buffers, where the baton is an abstraction that
lets the buffer be polymorphic.

IOW, a float based host produces batons that are naturally float.  If the
float wants to support other sample data types, it needs to provide converts
from float->whatever.  Each slot fetches the raw data by asking the baton
for data in its native (profile) type.  The host intercedes in this fetch to
convert as necessary.

If 2 plugins in the chain happen to be different sample types than the host,
then they can freely pass the baton without the host getting involved.

Right, and that's fine with me as far as it goes, but as people have been pointing out, for performance you don't want to make the DSP card pass every output buffer back into host address space. It would be great if GMPI used concepts that would do away with those unnecessary transfers.


-- Chris G.

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