Fixing AAC Playback with Amazon FireTV (Gen1)

tl;dr: If you want to skip the background and want the fix: click here

The Background

I’ve got a first generation Amazon FireTV that I use as my media playback device. It’s connected to a Yamaha RX-V675 via HDMI. It’s served me well over the years and I rarely have to fiddle with it. So much so that recently I decided to take on the endeavour of updating the version of Kodi that was currently installed on it, which turned out to be a version 16.0 - from 2016.

If it’s not broken, why fix it? Because eventually you get that itch to break perfectly reasonable things to learn a bit and update old components. Also, updating Kodi has been on my weekend to-do list for quite sometime.

Following the install directions provided on the Kodi wiki went smooth without any sort of problems and upgraded me to 18.7.1 (armeabi-v7a). Once installed, I started up Kodi and went off to playback some Media. The first few files I attempted to play had no issues. All of these media files were encoded with Dolby Digital or Digital Theater Systems (DD/DTS). However, I noticed that there was some media that would not play any audio - the video was fine. I checked with other devices and the audio tracks were valid, so the problem must be something to do with with the way the AFTV and the A/V Receiver interacted.

On closer inspection, the troublesome media all were encoded with AAC2.0:

Digging through the spec sheets for the Gen1 AFTV shows that it supports various AAC codex:

1
2
3

**AAC-LC Up to 96kHz, 6 channels, 16-bit and 24-bit
HE-AACv1 (AAC+). Up to 96kHz, 6 channels, 16-bit and 24-bit
HE-AACv2 (enhanced AAC+). Up to 96kHz, 6 channels, 16-bit and 24-bit

The problem doesn’t seem to be on the AFTV side. Next up was to look at the spec sheet for the RX-V675, which showed that it doesn’t support AAC.

This led to many Google searches, reading all over the place, and eventually some since-lost-hints that maybe I needed to rethink the configuration on number of channels in Kodi.

The Fix

After a lot of reading, pondering the issue while I went about the rest of my weekend, and since the problem was only with AAC2.0 audio, it seems I needed a way to force transcoding of the audio. Here’s how I managed to do it, and in doing so solve my audio issues.

In Kodi’s Settings -> System -> Audio it looked like the following for me:

What I needed to do was match the number of speakers, 5.1, to the number of channels. In addition to that setting, I also needed to enable “Stereo Upmix”:

And just for completeness this is what the rest of the settings on the Audio page look like:

Once all of these were set, I went back to the troublesome media files and the audio started playing with no problems. Additionally all of the other content seems to play back without any issues as well.