Exoplayer failing when playing an 8 channel audio file in Android 8.0

### Issue description
Exoplayer is failing when playing audio files, mp3 or ogg, with 8 channels, in Android 8.0, in some specific Samsung phones.

By "failing" I mean it plays the audio as if it was in very slow motion, not in a smooth way, in those specific devices.

It plays well in other devices tested so far, Samsung and other brands. It even plays well in a Samsung S7 with Android 8.0.

### Reproduction steps
1. modify file media.exolist.json to play one single ogg file
2. place this ogg file in the assets directory
3. modify method initializePlayer() within class PlayerActivity, replacing following code line:
player.prepare(mediaSource, !haveResumePosition, false);
by code lines below, in order to play in loop mode:
LoopingMediaSource loopingSource = new LoopingMediaSource(mediaSource, 100);
player.prepare(loopingSource, !haveResumePosition, false);
4. Play the demo

### Link to test content
Audio sample file sent by e-mail to dev.exoplayer@gmail.com.

### Version of ExoPlayer being used
2.8.1

### Device(s) and version(s) of Android being used
Samsung S9 SM-G9600 and A5 SM-A520F, both running Android 8.0.0.
I have noticed also that both of them have the Octa-core chip. It may be a coincidence or not.

### A full bug report captured from the device
There is no abnormal message shown in logcat when testing.