Why is this movie not playing on my TV?

[frobineau_gmail_com]

Server Version#: 1.18.8.2527-740d4c206 (Ubuntu)
Player Version#: 2.2.0 (updated 17/03/2020)

I have a movie that’s not playing on my LG TV (LG oled65c9pla), and I don’t understand why. When I try to start the movie, it shows the movie title with the loading spinner, and that’s it.

In the Plex dashboard, the movie appears to be playing (but nothing actually plays on the TV):

I also notice an initial burst of network activity, then pretty much nothing:

However, if I force transcoding (e.g. turning on PGS subtitles, or changing the quality/bandwidth setting to something other than “Original”), then the movie plays just fine.

I have other 4K movies that play just fine as well. Why doesn’t this one work?

Here is the media info for that file:

Media

Duration 2:13:57
Bitrate 46234 kbps
Width 3840
Height 1608
Aspect Ratio 2.35
Video Resolution 4K
Container MKV
Video Frame Rate 24p
Audio Profile ma
Video Profile rext
Part

Duration 2:13:57
File Rogue One A Star Wars Story (2016).mkv
Size 43.26 GB
Audio Profile ma
Container MKV
Video Profile rext

Codec HEVC
Bitrate 43418 kbps
Bit Depth 10
Chroma Subsampling 4:2:2
Coded Height 1616
Coded Width 3840
Color Primaries bt2020
Color Range tv
Color Space bt2020nc
Color Trc smpte2084
Frame Rate 23.976 fps
Height 1608
Level 5.0
Profile rext
Ref Frames 1
Title Rogue One: A Star Wars Story 4K
Width 3840
Display Title 4K (HEVC Rext HDR)

Codec DCA
Channels 8
Bitrate 1536 kbps
Language English
Audio Channel Layout 7.1
Bit Depth 24
Profile ma
Sampling Rate 48000 Hz
Title English DTS-HD Master Audio 7.1
Display Title English (DTS-HD MA 7.1)

Codec AC3
Channels 6
Bitrate 640 kbps
Language Français
Audio Channel Layout 5.1(side)
Sampling Rate 48000 Hz
Title French AC-3 5.1
Display Title Français (AC3 5.1)

Codec AC3
Channels 6
Bitrate 640 kbps
Language Español
Audio Channel Layout 5.1(side)
Sampling Rate 48000 Hz
Title Spanish Latino AC-3 5.1
Display Title Español (AC3 5.1)

Codec PGS
Bitrate 12 kbps
Language English
Header Compression true
Display Title English (PGS)

... (more PGS and SRT codecs, elided for clarity)

[FordGuy61]

It is probably the HEVC RExt video with 4:2:2 chroma subsampling.

There are many posts in the forum with people having trouble playing such video.

[frobineau_gmail_com]

Thanks! Is it possible to convert the video to 4:2:0 chroma subsampling without re-encoding the whole video?

[JuiceWSA]

No - it is not.

[frobineau_gmail_com]

Noted, thanks! Off to Handbrake I am…

[JuiceWSA]

Bring your lunch.

[FordGuy61]

FYI, Handbrake does not preserve HDR info. It has an internal 8-bit pipeline, even when choosing HEVC 10-bit or 12-bit output.

You may want to look for another encoding method or a native 4:2:0 source (I believe commercial Blu-ray UHD HDR movie discs have 4:2:0 video).

Handbrake Forum: Notice posts at end by members of Handbrake team
https://forum.handbrake.fr/viewtopic.php?f=6&t=39004

Handbrake Github: Notice posts at end, from last week, regarding timeline (there isn’t one):

Add better HDR support and 10bit pipeline

[frobineau_gmail_com]

Oh wow, thanks for the heads-up! Do you know of any free (as in free beer) software capable of doing this correctly?

[frobineau_gmail_com]

Found this, will give it a try directly with FFMpeg: https://medium.com/@yllanos/how-to-encode-a-4k-hdr-movie-using-ffmpeg-while-maintaining-selected-auio-tracks-intact-from-source-d1e2f6a16162

[FordGuy61]

I do not. I have not tried transcoding HDR material. Was going to suggest looking at ffmpeg.

Google search for “transcode hdr to hdr” kicked out this: https://forum.doom9.org/showthread.php?t=175227

[g000phy]

Have same problem. Discovered that given same codec (both audio and video) the LG app can play MKV but have the described problem with both m4v and mp4. The LG TV app definitely needs fixing. My guess is that mp4 and m4v have interleaved audio and video samples.

It interleaves the audio and video samples, and puts the “MooV” atom at the begining of the file, restoring the Quicktime “fast-start” (also known as “pseudo-streaming”) ability of the file.

Mac app can play any of the filetypes even with interleaved samples…

[OttoKerner]

@g000phy

My guess is that mp4 and m4v have interleaved audio and video samples.

Every file format that is able to be streamed is employing the same technique. You can expect major performance issues when trying to play a file that is not using interleaving.

There can be mp4 files with and without interleaving, btw. But if an app is producing files without interleaving, I consider it faulty.

[g000phy]

Just remuxed the same file into mp4 without interleave. Plays fine on LG app. while same file with interleaved samples doesn’t play.

did I discover a bug after all?

[g000phy]

Just discovered, that removing subtitles from mp4/m4v also makes them playable.