Well, ‘no’ may not be the best answer to the question from soix.
I2S most definitely will use any standard HDMI cable to transport the clock and data signals between two compatible I2S interfaces. I use I2S all the time with standard HDMI cables.
The question should be, is the output from the OPPO truly I2S or standard HDMI? The specs I read indicate a standard HDMI audio/video out from the OPPO, no mention is made of I2S.
So, while you certainly can use HDMI cables for I2S to I2S, you won’t get any signal from a standard HDMI out to I2S.
Hope this helps.