Multiband EQ degrades audio on iOS

FMOD Engine
1

I added the multiband EQ DSP to some ChannelGroups in my FMOD-powered iOS music-generating app, but I noticed that the audio quality suffered when I did so.

The following audio files were captured with 0, 1, or 2 multiband EQs in the chain. No parameters were passed to these DSPs, so (I assume) they are totally flat.

No EQ in the chain:

One EQ on the master ChannelGroup:

Two EQs, one on the master ChannelGroup and another on one of the “buses”:

:inbox_tray: Download all three files

I tried the “Three EQ” DSP and it did not have this issue; quality was identical with or without that DSP on the chain. But I was hoping to use the multiband EQ…

Note, I have not tested this out on other platforms.

2

Using the Core API, the default for a multiband EQ is for band A to be enabled and set to a 12dB lowpass with a cutoff of 8kHz and a Q of 0.707, all other bands are off. This is probably what you are hearing.

You can see the defaults for all DSPs in our docs, here are multiband defaults.

3

Ah, I’m sure it is! What a peculiar design choice… anyway, now I know I can just override that band with my own settings. Thanks!