Plex Refresh Rate Switching forces Remux / Transcode on FireTV

Plex Players Streaming Devices
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When turning on refresh rate switching in Plex, all videos are remuxed (audio & video).

Videos with AAC still direct play, but any with AC3 or EAC3 audio are remuxed.
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DETAILS:
I have a 2nd gen FireTV Cube as client, and Win10 machine as server.

Direct playing SDR, HDR10, DoVi videos works perfectly. However, turning on refresh rate switching in the Plex client (and FireOS settings), causes nearly all videos to be remuxed. Most videos will get audio and video copied rather than transcoded. But there are a few videos that trigger a transcode too.

This appears to be related to audio codecs. Any video with AC3 or EAC3 triggers a remux when refresh rate switching is on. Videos with AAC audio will direct play. In all instances, the TV refresh rate is switched to 24Hz when the content is 24fps. When the video is 30fps, the TV refresh rate remains at 60Hz. I’m assuming this is intentional, but may also be another bug.

The remuxing triggered by this bug, results in the Dolby Vision layer being lost, resulting in a purple & green tint. So DoVi content is unwatchable while refresh rate switching is on.

I’ve included the client log from one DoVi video with EAC3 audio that is remuxed, to give the Plex team an example. This should be very easy to reproduce, I went through over 20 videos and it was 100% consistent.

Server Version#: 1.24.5.5243-8dcc73a59
Player Version#: 8.27.0.29827

Plex.zip (19.2 KB)

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I recall something that sounds roughly ~similar with the Shield. When Refresh Rate switching was enabled, the player couldn’t probe the Dolby Vision capabilities of the new resolution.

Dolby Vision Refresh Rate Switching? - #8 by KCX

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Thank you for the link. On reviewing that thread, I don’t think these are related issues. The FireTV issue I’m encountering happens with all videos, not just Dolby Vision. It’s just that the forced remuxing makes Dolby Vision especially problematic because it drops the DoVi layer in the remux. I should add that the TV still detects that the video is in DoVi, and switches the picture mode to DoVi, but the video is tinted purple and green after the remux, as though the DoVi layer is not being received by the TV.

Refresh rate switching on the TV works in all cases of 24fps videos (both SDR and HDR), with the TV going from 60Hz to 24Hz.

The question is why is Plex remuxing all videos (except those with AAC audio) when refresh rate switching is turned on?

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@OttoKerner any chance you can comment on this? I’m not sure what the proper way is to report a bug to the Plex team.

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I’ve just noticed the exact same issue with my Fire TV cube as well.
I’m sure it was working fine previously so assume it broke in a recent update.

As soon as you turn off refresh rate switching, it will happily play with Direct play again.

I’ve tried with the fire tv cube plugged direct into my Samsung TV and with the cube plugged into an AV receiver.

Latest plex app on the firetv is 8.27.1.29871

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