Help troubleshooting low quality HW transcoding

Plex Media Server Desktops & Laptops
1

Server Version#: 1.19.3.2764
Player Version#: Plex Web Version 4.33.1

I am trying to troubleshoot transcoding issues on my server, these issues are common across 90% of everything that is being transcoded.

When there is a lot of action going on in the movie, the quality degrades a LOT.

The source file details are specified here

Annotation 2020-05-11 105520
Annotation 2020-05-11 105520691×392 34.5 KB

The movie is being hardware transcoded to the plex player.

I have quite powerful server:

Dedicated Ubuntu LTS 20, I7 4790K, 32GB ram, ramdisk for transcoding, 4x4TB NAS Drives, dual gigabit network, hw transcoding enabled.

The Plex player is either : Chromecast 4K (wired connection) or Win10 (AC 1600 WiFi, >250 mbit real world speeds)

Processor load is never above 30%

So I suppose the hardware is not the issue? Or maybe is it and I should buy a Nvidia Quadro?

Settings are on Maximum quality

What else should I look into? It’s very frustrating since I spent loads of money in the server and still I cannot get a decent quality out of it.

2

The file is “bitrate-starved”. An average video bitrate of just 3.7mbps for a 1080p/H.264 stream is very low quality to begin with. It should never be transcoded again.
When you feed files such as this into a hardware transcoder, the results regularly look atrociously.

Another idea: Try disabling ‘hardware transcoding’, then play the file again.
If it looks much better that way, you might be hit by a driver issue. Corrupted video output stream with hardware transcoding

3

Also your CPU is quite old, there have been reports that the older generation iGPUs offer a lower quality than the current ones.

4

Hi, yes and thank you, I saw those reports, I just did not want to upgrade my entire architecture. With hindsight that was probably a mistake. :neutral_face:

5

Well you have what you have. You have several options:

  • upgrade CPU (and probably main board)
  • get a gpu
  • live without hw transcoding

Edit: But keep in mind what otto said. You cannot create gold from ■■■■ :smiley:

6

These were also called generation “Haswell Refresh”, which sported only very minor improvements over the original Haswell architecture. The Quicksync chip is the same and has very limited capabilities: Intel Quick Sync Video - Wikipedia

If I had to guess: it doesn’t handle 10-bit color very well, which is used to achieve such a low bitrate in your file.

7

Thank you OttoKerner!

I have now tried with the same movie, same scene but different source, this time it was a 29 GB 4K , and the quality is now perfect , as I wanted it.

Obviously I cannot / will not use 4K source files, since I get other issues with them, so I suppose I am going to try once again with a bigger 1080p file and report back

8

OK, so I suppose a full hardware upgrade is in order… FML. New processor, new MB, new RAM

9

Cheapest option would be to get a decent GeForce (like a 1060 Ti) and run it with the “improved” drivers so you don’t have that session limit that nvidia artificially puts upon the GeForce cards.
Dunno if the 1060 Ti is the best for the job, I just wanted to give an example.

Here is an overview what the cards are capable of:
https://www.elpamsoft.com/?p=Plex-Hardware-Transcoding

10

You are actually very right, I was looking at the cheap NVIDIA Quadro P400, therefore no need to review the entire architecture. That is good!

11

The P400 also has the session limit of 2 parallel transcodes, but this can be probably also circumvented with the improved drivers :wink:

12

Would you please have a link for the “improved” drivers ? I need to learn about them if I go down the route of Video Card Upgrade.

On the other hand , I NEVER ever need more than 2 streams at once

13

You have a PM.

14

The P400 is rightly limited to 2 encode streams, decoding/encoding(transcoding) uses a fair amount of memory bandwidth which the P400 doesn’t have a lot of.

Review this site for possible solution where they tested various Nvidia cards.

15

So I ran another test, same movie, same scene, but the source file this time was a 1080p 30gb file: absolutely perfect, without the issues I had before with 4K (buffering).

This approach however is not very practical with TV Series, since I would need to re-download again entire seasons.

So the solutions are 2:

  1. get better source files (larger 1080p files)
  2. additionally add a capable graphic card for HW transcoding when the source cannot be improved.

Guys, THANK YOU!

16

I checked the site, I am actually still looking for something in that price range, the 1050 is looking good

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