Video volume drops Facebook app

[g3m1nn1]

hi all,
I was wondering if anyone else is having similar problems:

When i watch a video on facebook app on iphone 6 the video starts with normal volume but then randomly drops and slowly returns to previous loudness, i searched around but couldn't find any answers.

On my IPad 2 the latest video i am having problems with plays without volume drops

I am using ios 8.4 on iphone and 8.3 on ipad 2.

Now i am wondering could this be ios version problem and should i reset all settings on iphone.

 

[C DM]

Does it happen when you touch the screen or do anything like that?

 

[g3m1nn1]

no, it happens by it self without me touching the screen, I click play ...

yesterday i update iOS to 8.4. on ipad 2 and replayed the video, volume was ok, checked on iphone ( v 8.4. ) volume ok,
but like i said sometimes its ok and sometimes it drops.
weird i know. was wondering if it could be hardware problem. but since this doesn't happen for example when i am playing music via music app, i doubt it.