Plex cannot be transcoded for playback

Server Version#: 1.41.3.9314
Player Version#:
My PMS runs on Synology, because I can’t directly access some subdomains of Plex in China, so I set proxy rules for some subdomains of Plex to ensure that Plex can be scraped correctly. The specific proxy rules are as follows:

  • DOMAIN-SUFFIX,metadata-static.plex.tv,Ghelper
  • DOMAIN-SUFFIX,metadata.provider.plex.tv,Ghelper
  • DOMAIN-SUFFIX,provider.plex.tv,Ghelper
  • DOMAIN-SUFFIX,analytics.plex.tv,Ghelper
  • DOMAIN-SUFFIX,meta.plex.tv,Ghelper
  • DOMAIN-SUFFIX,support.plex.tv,Ghelper
  • DOMAIN-SUFFIX,forums.plex.tv,Ghelper
  • DOMAIN-SUFFIX,downloads.plex.tv,Ghelper
  • DOMAIN-SUFFIX,clients.plex.tv,Ghelper
  • DOMAIN-SUFFIX,pubsub.plex.tv,Ghelper
  • DOMAIN-SUFFIX,images.plex.tv,Ghelper
  • DOMAIN-SUFFIX,together.plex.tv,Ghelper
  • DOMAIN-SUFFIX,community.plex.tv,Ghelper
  • DOMAIN-SUFFIX,scrobbles.plex.tv,Ghelper
  • DOMAIN-SUFFIX,features.plex.tv,Ghelper
  • DST-PORT,32400,DIRECT
  • DST-PORT,32401,DIRECT
  • DST-PORT,32402,DIRECT
  • DST-PORT,32403,DIRECT
  • DOMAIN-SUFFIX,v4.plex.tv,DIRECT
  • DOMAIN-SUFFIX,plex.tv,DIRECT
  • DOMAIN-SUFFIX,plexapp.com,DIRECT
  • DOMAIN-SUFFIX,plex.direct,DIRECT
  • DOMAIN-KEYWORD,plex,DIRECT

Now I have 2 problems:

  1. Some video files cannot be played, and the web playback interface prompts the error:
    An error occurred trying to play “一条狗的使命”.
    Error code: s1001 (Network)

日志中显示错误为:

  1. In the video that can be played, I must use Original to play. If I transcode to play, an error will be prompted:
    Conversion failed. The transcoder failed to start up.

The error displayed in the log is:

This is my log file:
Plex Media Server Logs_2025-01-13_13-52-50.zip (1.8 MB)

The transcoder cannot handle the subtitle in the file.

Jan 13, 2025 12:40:28.533 [140700551498552] DEBUG - [Req#2bb/Transcode] [Universal] Using local file path instead of URL: /volume2/储存池2/电影/一锤定音 (2017)/一锤定音 (2017) 1080p EAC3.mkv
Jan 13, 2025 12:40:28.533 [140700551498552] DEBUG - [Req#2bb/Transcode/HCl#6e] HTTP requesting GET http://127.0.0.1:32400/library/streams/2223?X-Plex-Token=xxxxxxxxxxxxxxxxxxxx&autoAdjustSubtitle=1
Jan 13, 2025 12:40:28.533 [140700619590456] DEBUG - [HttpClient/HCl#6e] HTTP/1.1 (0.0s) 502 response from GET http://127.0.0.1:32400/library/streams/2223?X-Plex-Token=xxxxxxxxxxxxxxxxxxxx&autoAdjustSubtitle=1 (reused)
Jan 13, 2025 12:40:28.533 [140700551498552] ERROR - [Req#2bb/Transcode] Error configuring transcoder: TPU: Failed to download sub-stream to temporary file
Jan 13, 2025 12:40:28.533 [140700551498552] DEBUG - [Req#2bb/Transcode] Streaming Resource: Terminating session 0x7ff76988f1e8:f9a1j2w38pzppzb7cwgeewzt which is using 14716kbps of WAN bandwidth.  Used is now 0kbps
Jan 13, 2025 12:40:28.533 [140700551498552] DEBUG - [Req#2bb/Transcode] Streaming Resource: Terminated session 0x7ff76988f1e8:f9a1j2w38pzppzb7cwgeewzt with reason Conversion failed. The transcoder failed to start up.
Jan 13, 2025 12:40:28.533 [140700615260984] DEBUG - [Req#2bb/Transcode] Killing job.

Can you try playing without subtitles to confirm everything else is working?
Also , can you try it with Plex/web instead of the Android app?
(Plex/web is easier to debug because more info is written in the server logs)

I play the movie with the web, played in the original code, and turned off the subtitles. But he kept spinning and couldn’t play it. I extracted the log. It can be played with the Mac client.

Plex Media Server Logs_2025-01-13_15-57-19.zip (1.8 MB)

May I ask why you’re accessing the server through the public IP address and not from the 192.168.1.x LAN ?

The video you tried to play is not being decoded correctly. Plex can’t tell what it is: (No video stream nor audio stream)

Jan 13, 2025 12:34:20.319 [140700564667192] DEBUG - [Req#f/Transcode/Req#10] It took 0.000000 ms to retrieve 111 items.
Jan 13, 2025 12:34:20.321 [140700564667192] ERROR - [Req#f/Transcode] MDE: video has neither a video stream nor an audio stream
Jan 13, 2025 12:34:20.321 [140700564667192] DEBUG - [Req#f/Transcode] MDE: received PLEX_PROTOCOL_ANY from client, but could not determine best protocol. Defaulting to HTTP
Jan 13, 2025 12:34:20.321 [140700564667192] DEBUG - [Req#f/Transcode] MDE: analyzing media item 866
Jan 13, 2025 12:34:20.321 [140700564667192] ERROR - [Req#f/Transcode] MDE: video has neither a video stream nor an audio stream
Jan 13, 2025 12:34:20.321 [140700564667192] ERROR - [Req#f/Transcode] Streaming Resource: Cannot make a decision because either the file is unplayable or the client provided bad data
Jan 13, 2025 12:34:20.321 [140700640795448] DEBUG - Completed: [36.110.86.162:42687] 400 GET /video/:/transcode/universal/decision?hasMDE=1&path=%2Flibrary%2Fmetadata%2F430&mediaIndex=0&partIndex=0&protocol=http&fastSeek=1&directPlay=0&directStream=0&subtitleSize=100&audioBoost=100&location=wan&addDebugOverlay=0&autoAdjustQuality=0&directStreamAudio=0&autoAdjustSubtitle=1&advancedSubtitles=text&mediaBufferSize=157286&session=66uznocaysga9htl6tmhvjxb&subtitles=auto&copyts=1&Accept-Language=en (2 live) #f TLS GZIP 88ms 497 bytes (pipelined: 2)

What happens when you use some of the internet-standard MP4 test files ?

I use public IP access PMS in my home now,I have a domain name and set up port forwarding on the router. web can’t play,Mac client can play

Synology boxes do not play well with Public IP addresses.

Synology boxes are for home LAN IP ranges and expected to be behind the protection of the modem/router.

If you are going to use it with the 36.x.x.x public IPv4 shown in your logs then you should also consider adding the Syno to that same 36.x.x.x block and not keeping is solely on 192.168.1.125.

You do have IPv6 not did not access it using v6.

Your default transcode buffer length setting is a problem.
You have 120 minutes set.

Jan 13, 2025 15:52:57.218 [140700564667192] DEBUG - [Req#302c/Transcode/JobRunner] Jobs: Starting child process with pid 16245
Jan 13, 2025 15:53:07.218 [140700564667192] DEBUG - [Req#302c/Transcode] Using default transcode duration of 120 minutes
Jan 13, 2025 15:53:07.218 [140700564667192] DEBUG - [Req#302c/Transcode] Started session successfully: z52q5zmdbt4t1upisd5gt2ln
Jan 13, 2025 15:53:07.218 [140700640795448] DEBUG - Completed: [36.110.86.162:60784] 200 GET /video/:/transcode/universal/start.mpd?hasMDE=1&path=%2Flibrary%2Fmetadata%2F432&mediaIndex=0&partIndex=0&protocol=dash&fastSeek=1&directPlay=0&directStream=1&subtitleSize=100&audioBoost=100&location=wan&addDebugOverlay=0&autoAdjustQuality=0&directStreamAudio=1&autoAdjustSubtitle=1&mediaBufferSize=102400&session=z52q5zmdbt4t1upisd5gt2ln&subtitles=burn&Accept-Language=en (9 live) #302c TLS GZIP 10007ms 1083 bytes (pipelined: 9)

You should set it to something far shorter. 2-5 minutes will be more than enough. The default is 2 minutes (120 seconds)

While using a public v4 range in your home is your choice, it makes using Plex much more difficult as Plex expects Private RFC-1918 LAN addresses.

when I play mp4 file in public ip use web client ,The original code can be played, but the transcoding cannot be played.

I do have another question:

How the heck did you hack synology to make an i9-13900 CPU?
They don’t make such a box.

Jan 13, 2025 12:34:15.012 [140700653300536] INFO - Plex Media Server v1.41.3.9314-a0bfb8370 - Synology sa6400 x86_64 - build: linux-x86_64 synology-dsm72 - GMT 08:00
Jan 13, 2025 12:34:15.012 [140700653300536] INFO - Linux version: DSM 7.2.2.72806-2, language: en-US
Jan 13, 2025 12:34:15.012 [140700653300536] INFO - Processor: 4-core 13th Gen Intel(R) Core(TM) i9-13900K

actually Synology is a virtual machine, which runs on unraid.

Unraid?

There are a ton of transcoding problems right now with Unraid kernels.
You’re using the 6.1.x kernel?

I mean synology runs on unraid,PMS run on the synology

Umm, you’re making it WAY more complicated than it should be.

  1. Unraid provides storage management just as DSM does
  2. You can run PMS on Unraid a lot easier than putting PMS on a Synology VM on Unraid.

Can you simplify this? Do you have another computer you can do a test installation of PMS on?

If anything, I’d run native XPEnology on that CPU and then run PMS on the XPE box.

note: I need sign off for now. I will be back in the morning


I see trancoder default buffer is 60 seconds,not 120 minutes

Jan 13, 2025 12:42:05.821 [140700545170232] DEBUG - [Req#456/Transcode] Using default transcode duration of 120 minutes
Jan 13, 2025 12:42:05.821 [140700545170232] DEBUG - [Req#456/Transcode] Started session successfully: gmske1igzyczhm9pt3itopbp


I don’t know where is 120 minutes,it’s 60 seconds in my setting - Transcoder

Now I use Win 11 System(LAN IP 192.168.1.30) access PMS (LAN IP192.168.1.25) on web.
When playback .mkv files in original ,It’s still can not do it.


when playback .mkv files in transcode ,it’s not work

When playback .mp4 files in original,it can playback

When playback .mp4 files in transcode , it’s not work too.

so I guess this problem ,It has nothing to do with access from public network IP or intranet IP access.

this is the new logs:
Plex Media Server Logs_2025-01-13_17-53-25.zip (2.5 MB)

I have some new information
When I don’t let PMS use proxy, the .mkv file can be played normally using the original code.


It is also normal to transcode playback.

It’s normal for me to turn on the subtitle transcoding and play it instantly.

.mp4 file can also be played normally, whether it is transcoded or the original code.

So I guess the above problem is related to the http proxy, but if I don’t open the proxy, I can’t scrape. Sometimes it prompts that the codec cannot be downloaded during transcoding.

When the http proxy is turned on, the scraping is normal, but there is the above problem in playback.

this is the proxy rules:

  • DOMAIN-SUFFIX,metadata-static.plex.tv,Ghelper
  • DOMAIN-SUFFIX,metadata.provider.plex.tv,Ghelper
  • DOMAIN-SUFFIX,provider.plex.tv,Ghelper
  • DOMAIN-SUFFIX,analytics.plex.tv,Ghelper
  • DOMAIN-SUFFIX,meta.plex.tv,Ghelper
  • DOMAIN-SUFFIX,support.plex.tv,Ghelper
  • DOMAIN-SUFFIX,forums.plex.tv,Ghelper
  • DOMAIN-SUFFIX,downloads.plex.tv,Ghelper
  • DOMAIN-SUFFIX,clients.plex.tv,Ghelper
  • DOMAIN-SUFFIX,pubsub.plex.tv,Ghelper
  • DOMAIN-SUFFIX,images.plex.tv,Ghelper
  • DOMAIN-SUFFIX,together.plex.tv,Ghelper
  • DOMAIN-SUFFIX,community.plex.tv,Ghelper
  • DOMAIN-SUFFIX,scrobbles.plex.tv,Ghelper
  • DOMAIN-SUFFIX,features.plex.tv,Ghelper
  • DST-PORT,32400,DIRECT
  • DST-PORT,32401,DIRECT
  • DST-PORT,32402,DIRECT
  • DST-PORT,32403,DIRECT
  • DOMAIN-SUFFIX,v4.plex.tv,DIRECT
  • DOMAIN-SUFFIX,plex.tv,DIRECT
  • DOMAIN-SUFFIX,plexapp.com,DIRECT
  • DOMAIN-SUFFIX,plex.direct,DIRECT
  • DOMAIN-KEYWORD,plex,DIRECT

This is a log that can be played normally when http proxy is not used.
Plex Media Server Logs_2025-01-13_18-19-18.zip (2.3 MB)

That is an interesting result.

So you’re experiencing partial block from the government,

-and-

As expected, running your own proxy for plex.tv connections fail.
(PMS → Plex.tv must be a direct connection. You cannot proxy it

I’ve seen where folks will have inbound proxy to their domains → PMS
but never seen successful outbound

For outbound, the most successful I’ve seen is a captive VPN which will also support Remote Access.
(I’ve seen others use this technique in countries where their governments also heavily restrict / mostly block Plex )

Can you help me find a way to make scraping and playback work normally at the same time?

There isn’t anything we can do on our end because it’s a government / ISP block.

There are folks who’ve found ways to make some things work.

One main thread is here.

My only thought is to try a captive VPN while the server gets all the metadata.
Once everything is loaded, return to normal operation.