Speed up Transcoding

[Justus 8]

Hello everyone,

I've been dealing with a perplexing issue on my Emby Media Server and would love to get your thoughts and suggestions.

Setup: My Emby Server at Version 4.8.8.0 runs on a Windows 11 system on a CSL Narrow Box Premium, 32GB RAM, and Intel UHD Graphics. Normally, this configuration provides solid performance until now.

Problem: Recently, I've noticed inconsistencies in transcoding performance that I can't quite figure out. For example, I streamed "Game of Thrones" Season 7, Episode 1 (GOT S7E1) on two PCs and networks.

Details: all logs attached

• PC 1: i7-11700k, 32GB DDR4 RAM, RTX 3080, 50MBit/s LAN. Started the stream at 11:30 and the transcoding was relatively quick.
• PC 2: Similar specs to PC 1 but with a 100MBit/s internet connection. Started the stream earlier at 11:21, yet the transcoding was much slower, with stuttering and lag during playback.

At this time, these were the only two streams running, although the server usually struggles only when four or more streams are transcoding.

Questions:

• Has anyone experienced something similar or have any ideas on what might be causing these performance variations?
• Are there specific settings or optimizations in Emby that I should check to enhance performance?
• Could it be related to network settings or hardware configuration that despite similar conditions there are such big differences in transcoding speed?

Any help or insight would be greatly appreciated, as this issue significantly affects the streaming experience. Thanks in advance for your support!

ffmpeg-transcode-da458bce-4d1a-48fa-a593-ba98c6882e30_1.txt ffmpeg-transcode-fdeb449a-82d8-4329-8c22-84ddaed5ded3_1.txt ffmpeg-transcode-035207d7-57bc-4cb9-ac6e-14ad0b5f2915_1.txt embyserver (2).txt ffmpeg-remux-9d394b7e-c21f-4fa8-92f5-a6a1b60d1ee6_1.txt

 

 

Edited September 4, 2024 by Justus

[GrimReaper 4740]

13 minutes ago, Justus said:

Any help or insight would be greatly appreciated, as this issue significantly affects the streaming experience. Thanks in advance for your support!

ffmpeg-transcode-da458bce-4d1a-48fa-a593-ba98c6882e30_1.txt 24.66 kB · 0 downloads ffmpeg-transcode-fdeb449a-82d8-4329-8c22-84ddaed5ded3_1.txt 664.01 kB · 0 downloads ffmpeg-transcode-035207d7-57bc-4cb9-ac6e-14ad0b5f2915_1.txt 14.61 kB · 0 downloads embyserver (2).txt 1.94 MB · 0 downloads ffmpeg-remux-9d394b7e-c21f-4fa8-92f5-a6a1b60d1ee6_1.txt 161.79 kB · 0 downloads

 

Those examples are not comparable, as first one is DirectStreaming (only audio remux required) whereas second one is full Transcode (both video and audio need converting). 

Direct Play vs Direct Streaming vs Transcoding

As for your exact examples, all three sessions are transcoding due to unsupported subtitles:

Quote

TranscodeReasons=SubtitleCodecNotSupported,DirectPlayError&allowVideoStreamCopy=false

TranscodeReasons=SubtitleCodecNotSupported,DirectPlayError&allowVideoStreamCopy=false

TranscodeReasons=SubtitleCodecNotSupported

Burn-in of graphical subs is very CPU-heavy process and your server simply cannot keep up/is underpowered:

Quote

11:21:37.239 elapsed=00:00:10.91 frame=  145 fps= 13 q=16.0 size=N/A time=00:00:05.95 bitrate=N/A throttle=off speed=0.545x    

11:52:09.534 elapsed=00:30:29.90 frame=30087 fps= 16 q=20.0 size=N/A time=00:20:54.91 bitrate=N/A throttle=off speed=0.686x

You need a speed >1.0x as absolute minimum for real-time transcoding. 

You can somewhat mitigate playback issues for those items by disabling graphical subtitles or obtaining external text-based subs. 

[Justus 8]

Ah, thank you for the clarification. That's good to know. Now, I'm facing the issue of needing to check each MKV file to see if it contains PGS subtitles and possibly replace them with ASS subtitles. Does Emby have an option to disable graphical subtitles from being displayed? What would be the smartest solution here?

[GrimReaper 4740]

Just now, Justus said:

Does Emby have an option to disable graphical subtitles from being displayed?

Not currently. 

Just now, Justus said:

What would be the smartest solution here?

Either remove all internal subs with some batch-tool (like Tdarr, @JayceDKmight have a hint or two there) or download text-based subs (Emby has automatic subtitles download feature), in which case (with all conditions being equal) those would have priority over embedded subs during subtitle pre-selection/can be selected manually if subtitle mode is No subs. 

[seanbuff 1318]

1 hour ago, Justus said:

Are there specific settings or optimizations in Emby that I should check to enhance performance?

You might also try avoiding using web browser clients as they don't always support all formats. You could try using the desktop Emby Theater to see how it compares.

[Luke 42079]

52 minutes ago, Justus said:

Does Emby have an option to disable graphical subtitles from being displayed? What would be the smartest solution here?

Hi, no, but you could just not select them.