Subtitles causes transcoding - burn in setup has to be chenged between diferent combinations of formats

Plex Players Streaming Devices
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Server Version#: 1.18.4.2171 QNAP S-453Be-8G
Player Version#:7.26.0.14578(eaeeea5c) - shield TV 2017 and shield TV PRO 2019

Hi,

i am having issue with different formats of subtitles, “burn in subtitles” setup and transcoding on server.

    • burn in setup - automatic - PGS subtitles & 1080p h265 tv show plays correctly without transcoding - GREAT
    • burn in setup - automatic - ASS subtitles & 1080p h265 tv show transcodes to h264 on server - NOT GOOD
    • burn in setup -only image formats - PGS subtitles & 1080p h265 tv show transcodes and is unwatchable - QNAP NAS cannot process this fast enough
    • burn in setup -only image formats - ASS subtitles & 1080p h265 tv show - plays correctly without transcoding (loosing some advance formating is not an issue, this if totaly fine).

→ so, if i want to watch show with ASS subs, i have to switch to burn in - only image format and if i want to watch PGS subs show, i have to switch setup again…
Can you please extend this setup so automatic wont transcode ASS subs ? or allow some more customization of burn in setup ?

Also PGS subtitles with 4k HDR does not work without transcoding → is some fix comming for this issue ?

Thank you :slight_smile:
Vojtech

2

Shield Pro 2019

  1. Has hardware in place to do PGS overlay (Image on Image)
  2. HEVC (H.265) is an expensive codec. Plex does not have license for it. Transcoded output will be H.265.

QNAP:

  1. PGS subtitles must be processed by the CPU. No dedicated hardware. VA-API does not yet provide image merging in hardware
  2. Text -> Image conversion via onboard GPU is possible but (per #1) does not have image merge capability.

Possible solution:

  1. Put the server on the Shield Pro 2019, let it pull the source media from the QNAP
  2. Let it do everything on the Shield.

(I just acquired a Shield Pro 2019 and this does work exceptionally well; even with 60 FPS 2160p video)

3

Hi Chuck, i was quite busy, so i had time to test shield as server today… Picture and subtitles works fine on shield (it has enough power to transcode) but shield is unable to play sound correctly - it is transcoding eac3 5.1 instead of passthrought it to reciever. When it is not transcoding subtitles (disabled subtitles) sound works correctly…

Isnt it just possible to extend burn subtitles setup to allow us to choose single setup which wont cause either ass or pgs to transcode :(?

Edit— sry, i am idiot… Its vobsub subtitles, not pgs, pgs works mostly fine
So request is allow ass subtitles not to be transcoded on automatic settings :slight_smile:

4

Can you recreate that for me and capture the logs?

I only need about 20 seconds of each playback to see what’s happening.

Please verify DEBUG logging is enabled and VERBOSE logging is diabled.

  1. Start session 1
  2. Play 20 seconds
  3. Stop
  4. Start session 2
  5. Play 20 seconds
  6. Stop
  7. wait 30 seconds for logs to quiesce
  8. Download ZIP and attach here.

This is very interesting because I can passthrough to the Onkyo without issue.

5

Sure, i will do that i few days, when i will have some free time :slight_smile: i will also add log from qnap server, which has OK sound :slight_smile:

Show quoted text

6

A lot of Android devices don’t have AC3 support, so this actually makes sense.

If you check the Shield TV website:

You can see the audio codecs it supports. For stuff like DTS/Atmos the support is pass-through which means you need something like a soundbar that can handle EAC3. Otherwise it has to be transcoded.

So it sounds like:

If you playback on the TS-453be (which I also have), Plex has to transcode the video because it doesn’t have hardware that can independently handle PGS subtitles, which aren’t actually text. They’re images. Similar to vobsub files.

Whereas according to Chuck on the Shield TV (which I also have, twins!) it has hardware that can handle PGS subs without transcoding, BUT it doesn’t have built-in AC3/EAC3 support, so it will have to transcode the audio if you’re like me and your TV doesn’t have AC3 support.

So neither piece of hardware does all of what you want.

What confuses me is that on my QNAP I’ve found that PGS subtitles always have to be transcoded, no matter what my settings are, but you said if you use automatic they don’t. ChuckPA, are you able to clarify if that’s possible on the QNAP? How would that work, theoretically?

Is that the case with ANY video with PGS subtitles, where it doesn’t transcode? Or is it possible some videos have smoother playback than others so you don’t notice it?

Since AC3 is a way more common audio track on Blu-rays than AAC, I’ve settled for using the TS-453be instead of the Shield TV. To work around the performance hit when transcoding PGS subs I use something like Subtitle Edit and “Tesseract” to OCR the PGS subs into an SRT file, which Plex+TS-453be handles beautifully (because it’s just a text file with timestamps).

Or you could convert your EAC3 audio into AAC, but I’d rather have as close to the original audio as possible more than a few typos here and there in my OCRed subtitles, so that’s why I didn’t go that route (although it’d probably be easier).

If the TS-453be can handle PGS without transcoding with the right settings, I’d definitely be curious to give it a try.

7

pgs
pgs980×500 368 KB

PGS

alpha
alpha980×500 368 KB

ASS

nosubs
nosubs980×461 337 KB

None

Whether I’m using Automatic, Always, or Only Image Formats, .ass and .pgs are always transcoded.

I can’t remember where else in the forum I saw it, but I do have a weird issue of when I use HW transcoding everything is garbled:

hw
hw930×538 196 KB

Where if I don’t, it’s fine:

nohw
nohw930×538 78.1 KB

Logs:
Plex Media Server Logs_2020-01-21_16-32-30.zip (25.2 KB)
Plex Media Server Logs_2020-01-21_16-35-20.zip (26.7 KB)

The logs are from testing via Firefox, but the exact same behavior was reproed on my Roku 3 and TiVo Bolt.

(The .ass subs aren’t actually in Japanese of course, I just set it like that so it was easier to tell which subtitle was which when selecting them.)

Plex version is latest stable, and QTS version is 4.4.1.1146 (latest stable, essentially). Device is the TS-453be.

8

Found it, knew I saw it somewhere:

But all the transcoding stuff still applies. .pgs and .ass always result in transcoding.

So definitely, if there’s magic trick or secret sauce to not transcoding PGS, I’m curious. But since they’re literal images I don’t see how that’s possible on the TS-453be.

9

You can see the audio codecs it supports. For stuff like DTS/Atmos the support is pass-through which means you need something like a soundbar that can handle EAC3. Otherwise it has to be transcoded.

→ I have Yamaha reciever which supports everything except for Atmos → EAC3 is working when using Qnap server even with transcoding, i is not working on shield server while transcoding

So neither piece of hardware does all of what you want.

What confuses me is that on my QNAP I’ve found that PGS subtitles always have to be transcoded, no matter what my settings are, but you said if you use automatic they don’t. ChuckPA, are you able to clarify if that’s possible on the QNAP? How would that work, theoretically?

Is that the case with ANY video with PGS subtitles, where it doesn’t transcode? Or is it possible some videos have smoother playback than others so you don’t notice it?

→ I am using only shields as players (well done insanely expansive SONY TV, which cannot play almost anything) → playback of PGS works fine on automatic setup, it transcodes when burn in setup is “only image formats” - i will post screens when i arrive at home

So only final issue are ASS subtitles, which forces transcode on shield client, while it is capable of direct play them on burn only image subtitles (i dont realy care about loosing advance formating from ass).

I will post screens and logs when i find some time to prepare it :slight_smile:

ALL QNAP Server screens
whis transcodes on automatic setup, plays directly on “only image subtitles”

image
image548×401 77.1 KB

this plays directly on automatic, transcodes on only image subtitles

image
image529×379 56.5 KB

this plays directly on automatic, transcodes on only imafge

image
image512×460 87.9 KB

i will add more info when i arrive home

I can’t remember where else in the forum I saw it, but I do have a weird issue of when I use HW transcoding everything is garbled:

hw
hw930×538 196 KB

i have same issue, fix was deleting new video driver in plex media server folder on QNAP
leave only this one (stop plex server, delete file, start server)

image
image605×207 48.8 KB

you have to do this everytime you update your server to new version

10

Ahhh, okay. That makes more sense.

I actually tried this and it didn’t work, so I gave up and downgraded. As long as HW transcoding is working I haven’t been making much use of features from newer versions so I figured it was easier than trying to figure out why the above method didn’t work.

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