My 4K movie that was direct playing with srt subtitles suddenly has to transcode

[tchit]

Hello

Yet another issue with 4K and srt transcoding on LG WEBOS. Except that behavior changed in 1h timeframe and no change in my settings whatsoever.

Was watching a 4K HEVC vidéo direct playing from my Synology with Srt : direct play was working perfectly.

Made a pause in the middle of movie to get to eat. Stopped my projector. Started again 1h later and now, no way to direct play with srt files. Absolutely nothing changed, same network, same video, same server, same srt. But now it’s transcoding.

Any reason and solution to that?

Thanks a lot

Attached pictures with and without srt.

[BigWheel]

what are you subtitle burn in settings set to. Do you have auto adjust quality enabled?

[tchit]

Hello,

@BigWheel

what are you subtitle burn in settings set to. Do you have auto adjust quality enabled?

I have set to burn subtitles only when necessary and original quality with direct playback.

[FordGuy61]

Check the settings in the Plex LG app. Make sure Direct Play is enabled.

The movie needs to be direct playing.

Direct streaming + SRT subtitles results in a video transcode when using the Plex LG app.

Edit:

See post below for additional details. The thread mentions what you are experiencing, but in the context of transcoded audio. It is essentially the same, since when Plex transcodes the audio the video will be direct streamed (see Partially-Transcoded Direct Stream).

Are custom profiles dead?

You’re running into the limitations of the Plex LG app (Samsung behaves similarly). I have an LG B7 OLED. The limitations are one of the reasons I purchased a Nvidia Shield for myself and give Amazon FireSticks to my family/friends as birthday/Christmas gifts. The Plex Android TV app direct plays PGS, VOBSUB, and SRT subtitles even if the video or audio is transcoding (reference). ASS subtitles still result in a video transcode and subtitle burn, but I’m not aware of any Plex client that h…

[BigWheel]

if you enable playback info it should say why it is transcoding

[tchit]

@FordGuy61

Check the settings in the Plex LG app. Make sure Direct Play is enabled.

The movie needs to be direct playing.

Direct streaming + SRT subtitles results in a video transcode when using the Plex LG app.

Edit:

See post below for additional details. The thread mentions what you are experiencing, but in the context of transcoded audio.

Hi, is there a difference between direct playing and direct streaming? [Edit: read the article, will try disabling direct streaming then!] Because I didn’t change a thing. Usually I have no trouble reading 4K HEVC movies with SRT subtitles as long as I select a compatible audio track. The movie played with absolutely no issue for 1h until I turned the projector off and then turned it back on and opened Plex again and pressed resume. Meaning that since it worked the first time, video and audio format are compatible. I tried different srt files but got the same transcoding result.

[FordGuy61]

@tchit

will try disabling direct streaming then

Don’t.

Disabling direct streaming does not result in direct playing. It may result in additional transcoding.

Plex tries to direct play first. It falls back to direct streaming if it cannot direct play.

@tchit

The movie played with absolutely no issue for 1h until I turned the projector off and then turned it back on and opened Plex again and pressed resume.

Not sure why the movie would switch from direct play to direct stream.

It should not matter, but maybe something to do with resuming vs starting from the beginning?

Does the problem happen with multiple movies?

Can you re-create it?

If so, see if you can capture it in the log files.

1. Set server for debug, not verbose, logging.
   Settings → Server_Name → General (not Plex Web → General).

2. Set the LG Plex app to log to the server at the debug level.
   Note: This times out after 8 hours.

3. When the problem occurs, let it run for at least a minute. Then stop playback.

4. Wait at least one minute for the server to log everything.

5. Pull the server log files (Settings → Troubleshooting → Download Logs)

6. Attach the entire ZIP file to the thread.

Hopefully the log files will show what is happening.

[zplosion]

I literally just ran into this problem.

OttoKerner said on a previous thread that this is intentional to prevent the subtitles desyncing.

A/V desync, close enough. https://forums.plex.tv/t/buffering-with-subtitles-on-lg-smart-tv-plex-app-only-works

Edit: never mind me, that’s not your issue.

[tchit]

Thank you for your help. I will try what you ask and upload the log files. Can’t do it now as it’s bed time.
I tried playing from beginning instead of resuming, but got the same issue.
Also in my Plex Dash app, I can see that it starts without transcoding but immediately switches to transcoding.

Thank you very much for your help. Really curious to understand what changed between the 2 times. I know that I played another video on Plex iOS during lunch. And I use a Bluetooth device for audio. Can’t see any other parameters.

[tchit]

@FordGuy61

Can you re-create it?

If so, see if you can capture it in the log files.

1. Set server for debug, not verbose, logging.
   Settings → Server_Name → General (not Plex Web → General).
2. Set the LG Plex app to log to the server at the debug level.
   Note: This times out after 8 hours.
3. When the problem occurs, let it run for at least a minute. Then stop playback.
4. Wait at least one minute for the server to log everything.
5. Pull the server log files (Settings → Troubleshooting → Download Logs)
6. Attach the entire ZIP file to the thread.

Hello, me again!
Not only was I able to reproduce the bug, but I even got it to work without the bug at the first try (direct play with SRT, no transcoding). Then I stopped the playback, changed subtitles from English to French and the bug started again (transcoding). Tried again with previous English subtitles and same issue, it’s transcoding…

Here is the ZIP file with the logs. Thanks a lot, I hope we can find what happens!

log.zip (7.1 MB)

[tchit]

@BigWheel

if you enable playback info it should say why it is transcoding

Hi, without subtitles it’s direct streaming. With subtitlers it’s transcoding and it says “ServerRender” for the subtitles decision.

[FordGuy61]

Thanks for the log files. Still looking them over, but one thing immediately stands out.

You’ve some serious network instability. See below.

In Plex Media Server.log, These messages repeat 11,000 times between 04:45 and 15:55, when you pulled the log files. There are similar numbers going back to March 10 in the rollover files (.1, .2 etc).

Shutdown the DS716+.
Check / replace the Ethernet cable connected to the NAS.
Restart any switches, routers, etc in your network.
After the rest of your network is back online, start the DS716+.

After the NAS is online and Plex Media Server has been running for a few minutes, check the log files or look in Settings → Console.

The messages started within two minutes of Plex starting and repeat roughly every 2 - 3 seconds, so they’ll be easy to spot.

Mar 12, 2022 04:45:04.575 [0x7fd507751b38] DEBUG - NetworkInterface: Notified of network changed (force=0)
Mar 12, 2022 04:45:04.576 [0x7fd507751b38] DEBUG - Network change notification but nothing changed.
Mar 12, 2022 04:45:04.576 [0x7fd507751b38] DEBUG - NetworkInterface: received Netlink message len=148, type=RTM_NEWLINK, flags=0x0
Mar 12, 2022 04:45:04.576 [0x7fd507751b38] DEBUG - NetworkInterface: Netlink information message family=7, type=1, index=1440, flags=0x1003, change=0x0
Mar 12, 2022 04:45:04.576 [0x7fd507751b38] DEBUG - Network change.

[FordGuy61]

The logging from the LG shows what happens.

Plex tries to direct play the video with French subtitles. The player has an error and switches to direct stream. This results in Plex transcoding the video, due to the previously mentioned limitations of the Plex LG app.

Given that the English subtitles play OK, I’m wondering if the problem is with the subtitle file.

Open the subtitle in a text editor (Windows Notepad, Notepad++, etc).

Make sure the subtitles really are in SRT format and not mislabeled ASS or other such format (which would result in a transcode). There should not be any information regarding text color, position, etc.

Here’s a SRT example:

Summary

1
00:00:29,612 --> 00:00:31,280
(THEME FROM JAWS PLAYING)

2
00:01:28,462 --> 00:01:30,590
MAN ON INTERCOM: The white zone is
for immediate

3
00:01:30,673 --> 00:01:33,301
loading and unloading of
passengers only.

Also, make sure they are in UTF-8 format, not UTF-8 with BOM or any other format. This will be displayed in the lower right corner of the editor window (Notepad).

If it is in another format, save it as UTF-8, then refresh the metadata for the movie so Plex will pick up the changes.

---

Here’s the log entries:

Select French subtitles:

Mar 12, 2022 15:50:28.934 [0x7fd50716fb38] INFO - [Plex for LG] [tchit:by5kmxlaf4e06iv70jqa6uy5]   subtitleStream: {
  "id": 45059,
  "streamType": 3,
  "selected": true,
  "codec": "srt",
  "index": 5,
  "bitrate": 0,
  "language": "Français",
  "languageTag": "fr",
  "languageCode": "fra",
  "displayTitle": "Français (SRT)",
  "extendedDisplayTitle": "Français (SRT)"
}

OK to Direct Play
Mar 12, 2022 15:50:28.934 [0x7fd50716fb38] INFO - [Plex for LG] [tchit:by5kmxlaf4e06iv70jqa6uy5] [MDE] Server decision, directPlay: true, directStreamVideo: true, directStreamAudio: true

Beginning playback:
Mar 12, 2022 15:50:28.934 [0x7fd50716fb38] DEBUG - [Plex for LG] [tchit:by5kmxlaf4e06iv70jqa6uy5] [PlaybackSessionController] Opening playback

Error:

Mar 12, 2022 15:50:28.934 [0x7fd50716fb38] WARN - [Plex for LG] [tchit:by5kmxlaf4e06iv70jqa6uy5] [Player] A critical HTML media error occurred: 3 (Décoder); the player cannot recover
Mar 12, 2022 15:50:28.934 [0x7fd50716fb38] INFO - [Plex for LG] [tchit:by5kmxlaf4e06iv70jqa6uy5] [PlaybackSessionController] playback state changed to: stopped
Mar 12, 2022 15:50:28.934 [0x7fd50716fb38] ERROR - [Plex for LG] [tchit:by5kmxlaf4e06iv70jqa6uy5] Playback error occurred. Reason: Unknown, An unknown player error occurred. code: 3, message: Décoder

Retries playback, switching from Direct Play to Direct Stream, which results in a video transcode since subtitles are enabled.

Mar 12, 2022 15:50:28.934 [0x7fd50716fb38] WARN - [Plex for LG] [tchit:by5kmxlaf4e06iv70jqa6uy5] [PlaybackSessionController] able to retry playback, {
  "metadataSourceUri": "server://e0c30694ab00daa410d4b5fc41a7ea5e023ff29a/com.plexapp.plugins.library/library/metadata/8402",
  "retries": 1,
  "allowDirectPlay": false,
  "allowDirectStream": true
}

[tchit]

@FordGuy61

You’ve some serious network instability. See below.

Thank you I was unaware of this issue. I will try changing cables but I wonder if it will be enough to fix it. In practice my network has been rock solid. No issues to access from remote or anything else…

@FordGuy61

Given that the English subtitles play OK, I’m wondering if the problem is with the subtitle file.

I have tried everything possible with subtitles. The error happens whatever the subtitle file and if subtitles are internal or external. The English or French srt play ok the first time but not the second. I’ve discovered that if I restart PMS or wait long enough (1 or 2 days) then the direct play for this movie apparently works again, but only once. Then it wants to transcode again.

[Heffalump_NgoroNgoro]

I just started having the exact same issue! from one day to the other. no additional files were added to the library, no network setup was changed. seems to affect all h.264 movies.
have you found a solution?

[tchit]

Hi, fortunately for me and to my knowledge that affects only that specific HEVC file, so we may not have exactly the same issue. In my case I wasn’t able to find a solution (apart from replacing the movie file) and I believe there is a bug, either in Webos or Plex (or both). I see no reason for the player to choose to direct play the first time and then not direct play the second time. I suggest you create a new topic with detailed informations about your issue!!