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Tools: Topology2: Swap gain and eqiir in DMIC capture
This patch swaps the order of IIR and gain components in capture
pipeline. In IPC4 systems the gain component can only attenuate the
signal, largest gain is 0 dB (pass-through). The IIR component can be
set up to amplify the signal by e.g. +20 dB that is currently default
in many topologies. The gain can possibly distort the signal in loud
environment.
With current "dai-copier -> eqiir -> gain -> module-copier" topology
the user configurable gain (ALSA mixer control) can't prevent clipping
of audio signal in IIR. While with swapped order "dai-copier -> gain
-> eqiir -> module-copier" using attenuation in gain component can be
used to prevent audio signal clipping in IIR. It would be useful in
capturing audio in a very loud environment.
Since the pipeline is 32-bits there is no practical loss of audio
quality even if there would be first attenuation and then gain. Plus
normally the gain control for Dmic0 is set to maximum.
Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>
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