Transcoding issues?

[Jey2024 33]

Hi team,

I downloaded a 4K HDR10 video and streamed it on my Android TV using the Emby for Android app. The issue is that the movie freezes every 5 to 10 minutes for about 3 to 4 seconds before resuming.

Emby logs: https://pastebin.com/SL48tqKy

I started the movie at 2025-08-03 12:45:34.889. We paused the movie several times before I enabled logging at around 17:15. After enabling logging, the movie froze twice. Could you please review the logs to see if there is anything obvious? The server is a very powerful dedicated server, and the processor is capable of handling HDR video transcoding.

Transcoding logs: https://pastebin.com/fhBtn0Ym

Is there anything I can change on the server side or in the Emby settings to make playback smoother? My TV is connected to a 3Gbps LAN, so network connection and latency are not issues.

Edited August 3, 2025 by Jey2024

[Jey2024 33]

The same issue occurred with another movie, this time a 1080p copy. The only common factor between both movies is that they have DTS audio.

Emby logs: https://pastebin.com/u9cJ98Yh

Please check from 18:05 onwards.

[Jey2024 33]

@Lukewhen you have a moment, can you take a look at these logs and let me know if you can see any issues with the transcoding or the freezing issue please? 

[Jey2024 33]

I am not trying to hijack this thread, but @ebr I am facing the same issue while playing a 4K HDR10 HEVC file with DTS-HD MA 7.1 audio. If I play the video file directly on my workstation, it works perfectly fine. However, when streaming via Emby, it lags frequently. I have shared the logs here:

 

[Jey2024 33]

I did the same thing as the OP and replaced the other sequels of this video with 1080p versions to make them work on Android TV.

[Jey2024 33]

I have another set of logs to share with you. The video type is a 4K HDR10 HEVC file with DTS-HD MA 7.1 audio. I started the movie at 8:50 (the time I am referring to matches the log files). At 8:52, I noticed the first lag, which lasted 3 seconds, and at 8:55, I noticed another lag. After that, I let the movie run and did not monitor for further lagging. I let the movie play for 1 hour and am attaching the Emby and transcoding logs here for your review.

embyserver (13).txt ffmpeg-transcode-562b4396-9bb4-482d-9b30-a95741e2149a_1.txt

[Luke 42078]

Hi ,since this is on a remote connection I would try lowering the quality setting and see if that helps. It could just be that the bitrate is too high.

[Jey2024 33]

Hi @Lukeyou're absolutely spot on. I reduced the bitrate to 40, and now I don't see any lagging. However, my impatient side led me to do some ChatGPT searching, and I found something interesting:

 

Potential Bottlenecks/Issues

A. Subtitle Handling

• Warning: "Hardware-accelerated subtitle-overlay is disabled due to diagnostic option"

• Subtitle Overlay: Will be done in software, not hardware. With PGS subs at 4K, this can add significant CPU load.

• PGS Subtitles: The logs show a lot of "Could not find codec parameters for stream..." for all PGS subtitle streams (these are common for Blu-ray but can trip up ffmpeg if not handled efficiently)
  
  B. Transcode Command Analysis

• Emby is:

  Decoding HEVC 4K10bit video (hardware)

  Downmixing/re-encoding audio (software)

  Overlaying PGS subtitles (software)

  Encoding output to H.264 (hardware)

• Segment length: 3s (standard for HLS).

• Bitrate requested by client: ~69 Mbps (matches the file's high bitrate).
   

  Summary: Why You Get Stutter at 8:52 and 8:55

• Most likely cause: Software subtitle overlay for PGS subtitles at 4K.

• Emby (ffmpeg) can't offload PGS subtitle rendering to GPU, so it does this in software. At each subtitle change, a new bitmap must be composited onto the 4K video, briefly maxing a CPU core. At high bitrates and frame sizes, this can easily introduce short stutters if your CPU can't keep up.

 

Is this assessment correct? Will PGS subtitles at 4K cause these types of lags as well? If so, do you have any workaround I should be using?

Thanks Luke.

[Neminem 1518]

4 minutes ago, Jey2024 said:

If so, do you have any workaround I should be using?

You could get .srt subtitles for your movie.

srt subs are text based and can be used by all clients.

[Jey2024 33]

31 minutes ago, Neminem said:

You could get .srt subtitles for your movie.

srt subs are text based and can be used by all clients.

Thanks. What is the reliable way to download srts automatically even though there are inbuilt subs? should I enable hash match?

[Luke 42078]

52 minutes ago, Jey2024 said:

Thanks. What is the reliable way to download srts automatically even though there are inbuilt subs? should I enable hash match?

Hi, I would check out our guide on that:

Automatic Subtitle Downloads

Quote

should I enable hash match?

There are pros and cons to having it enabled or disabled. I would suggest reading the help text underneath the option and then deciding what makes the most sense for you.