Ive left the office for the week, ill post full details on Monday when I'm back at my work computer.
Edit: M 8_21 I've loaded the same program up on a different phone (Samsung Galaxy S7) running Android 7.0 API 24. When trying to get a local file to play the following appears on the logcat screen filtered for warnings.
The problem doesn't seem to be linked to file types as it not only affects hls streams and .mp4 local files but also occurred when playing a .mkv. As with the other files only sound was playing, there was no video.
Log Pastebin: https://pastebin.com/5SXhvivM
I'll post my relevant code within the next few minutes to show how I was intending to use exoplayer2, I was mainly attempting to replace the code from the previous version of exoplayer in place inside of the gvr-360video project from the samples for GearVRf.