2009 Rear DVD Systerm infrared frequency

Hi, I am palnning to purchase two pairs of IR headphones for my rear DVD system.
I have a 2009 X5.

But, not sure about the frequency SPEC of X5 infrared.

Here is the SPEC of the headphone I am checking, which has two channels.

A channel: 2.8MHz frequency for right channel; 2.3 MHz frequency for left channel.
B channel: 3.8MHz frequency for right channel; 3.2 MHz frequency for left channel.

Does anybody know what is the infarred frequency of the orginal 2009 X5 rear DVD systerm?
Does these compatible?

Does anybody try "sound via via speakers" function?

Thanks
Bo