Polarity inversion

[Alandbush]

(05-01-2021 04:12)koslowj Wrote:  Hi, I'm new here, since I'm looking for exactly this feature. Has anything changed since 2015? I'm presently streaming via MPD from an SOTM sms 200 ultra neo, which comes with the option of using minim-server. The music library is on a local NAS. Unfortunately, my DAC+Amp (Lyngdorf TDAI 2170) does not have a dedicated polarity switch, as do some other amps, and I'm looking for a software solution. (The Lyngdorf is capable of handling 32 bits at 384 MHz via USB.)

Apparently, Roon does have this feature, but first I would like to explore Minimserver/-streamer. The majority of material is encoded as FLAC, a few DSD-files are streamed via dop, as my DAC doesn't accept that format natively. If needed, Minimstreamer might be used to transcode to FLAC beforehand.

The option of switching polarity on the fly would help enormously in deciding which files are inverted, before fixing them offline, at least the FLAC-files

In order to offload the work from the SOTM sms 200, I could also try to move Minimserver and Minimstreamer to a dedicated Odroid N2.

-- Jürgen

P.S. In case you have difficulties hearing a difference when flipping the polarity, you may have 2-way or 3-way speakers, where the polarity is already flipped for some frequency ranges, but not for others.

You might like to try the following with Minimstreamer:-

stream.options

Code:

convOut=-af aeval=-val(ch):c=same

together with

stream.transcode

Code:

flac:wav;

For more detail refer to the ffmpeg filter aeval.

Basically, the negative (-) sign performs the reversal to all the channels. So, you could simply include/exclude this sign to compare the effect.