Playing 4K files on 4K Apple TV - pausing

Streaming & Network
1

Hey team…

I’m a long time user of Infuse. For the record here I’m using an Apple TV 4K, connected to a Sony 98” UltraHD screen (4K) and a Sony 8K amp STR-AN1000. Infuse is 8.3.9 (5560) and I’m Pro registered. The apple TV is networked to a Ubiquity UNas Pro. via a couple of gigabit network switches.

This request is for advice on how to diagnose this playback issue:

Couple of instant issues. Take for example - playing Game of Thrones, 720p - we all know the series and its opening title sequence. I cannot get through the title sequence without 4, 5, 6 pauses (seemingly waiting for incoming data). After the title sequence - I can watch the program without it continually stopping.

Game of Thrones S03E07 The Bear and the Maiden Fair.mkv - this is a 4.88GB file.

I’ve also got a 4K Terminator 2 file… yes - it’s ginormous and in the main action sequence, about 35 mins in is where I was testing - it stops every 30 seconds or so. … completely not watchable.

Now… I’ve either got a NAS streaming issue or some form of playback issue and I’m wondering how I can get some concrete details on how to diagnose the fault(s).

Any advise is welcome.

2

One thing that may help narrow things down, run the speed test (let it complete for trouble files) and post the results here with a screen cap of the graph.

What protocol are you using? If it’s SMB you may want to try switching to SMB 2 or Legacy.

3

Confirming it is SMB. I cannot determine at this time if it is SMB 2 or not.
I have discovered that my main switch (where the Unas Pro is connected to is reporting “100 full” - where it should be reporting “1000 full” for gigabit speeds. This is a concern and may well be where the issues are coming from. Ethernet cable replacement is the next item on the action list - I need that port to report 1000 full.

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4

I had an Ethernet cable that went south and it did the same thing. I keep it around as an example of how cables don’t always fail completely.

5

I’ve almost replaced all the networking. I have a GB internet connection (that’s not being used for Infuse, but it’s good for speed testing through the network). I’m now pretty much done with the flat ethernet cables I’ve been using… they don’t seem to be GB capable (I thought they were).

I can see the switch to NAS is GB… and I’ve speed tested from the switch that the Apple TV plugs into is GB connected.

And Game of Thrones still pauses in the startup sequence.

Considering upgrading to 26.4 (Beta RC).

6

Again, running the speed test in Infuse and the graph may give some clues and changing the SMB in Infuse to SMB2 or Legacy may also help.

7

FYI - I’ve ended up running fio against the NAS. Short answer is that it is underperforming and I have logged a ticket with Ubiquity. Below is a ChatGPT’s summary analysis of the 4 different runs.

NAS Throughput Analysis (fio Results)

Summary

Test Throughput Expected Verdict
Sequential Write 22.8 MB/s ~100 MB/s Bad
Sequential Read 12.2 MB/s ~100 MB/s Very bad
Direct Read (no cache) 4.9 MB/s ~100 MB/s Critical issue
Streaming simulation 4.6 MB/s >15 MB/s needed Explains playback issue

UHD Streaming Requirements

  • Typical UHD bitrate: 60–100 Mbps
  • Peak bitrate: ~120 Mbps (~15 MB/s)

Your system:

  • Delivering 4–12 MB/s
  • Experiencing high latency spikes

Result:

  • Buffering
  • Stuttering
  • Playback pauses

Detailed Analysis

Sequential Write

  • 22.8 MB/s
  • Significantly below Gigabit expectations

Sequential Read

  • 12.2 MB/s
  • 99th percentile latency ~3.7 seconds
  • High latency makes streaming unreliable

Direct Read (No Cache)

  • 4.9 MB/s
  • Average latency ~211ms
  • Peaks up to 1 second

This reflects true NAS + network performance.

Streaming Simulation

  • 4.6 MB/s
  • Latency spikes up to 600ms

Conclusion:

  • Cannot sustain UHD playback

Key Finding

Maximum latency observed:

  • Up to 10 seconds per IO

This guarantees playback issues.

Likely Root Causes

  1. Disk subsystem issues

    • HDD spin-down
    • SMR drives
    • RAID overhead or rebuild

  2. NAS limitations (Ubiquiti UNAS Pro)

    • SMB performance constraints
    • CPU limitations

  3. SMB inefficiency (macOS ↔ NAS)

  4. Network issues (less likely)

Recommended Next Steps

  1. Test raw network throughput (iperf3)
  2. Check NAS disk state
  3. Perform Finder file copy tests
  4. Test NFS instead of SMB
  5. Increase concurrency in fio tests

Final Diagnosis

  • NAS cannot deliver consistent low-latency reads
  • Throughput is well below expected levels
  • Severe latency spikes
  • Direct cause of Infuse playback issues
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