Jittering on Playback - Trying to Find Bottleneck

[noahajac 0]

Hi everyone!

I was watching a movie the other day and started getting jittering during playback. The stream would freeze for a few seconds then continue. This was a remote stream so I initially thought it was a connection issue, but I tried again at home and had similar problems.

This is a 4K HEVC file being transcoded to 4K H264. I was initially watching on an Android TV device, but the logs below are from my testing on the web browser. It's definitely related to transcoding. When I play this file on a Windows device that supports HEVC, it streams perfectly fine with Direct Play.

I can see in the settings menu that the transcoding progress bar lags just slightly behind the playback bar.

I have Emby running in Docker which is running in an LXC container on Proxmox. The container is allotted 12GB of RAM, and given access to all 24 cores of the dual Xeon E5-2630's in my R720. Additionally I have a GeForce 750 Ti passed through to Emby.

The media is being served to Emby over a network share, but I have no problems at all with Direct Play so I do not think this is the cause.

I understand that this is some older hardware and its 4K footage. But while streaming my utilization stays well below 100%. My GPU hovers between 20-60% and CPU 30-70%. Thermals are more than fine too. There has to be a bottleneck somewhere causing poor transcode performance but I'm having trouble finding it. Would upgrading the GPU to something more modern likely solve this problem, or is it time for a full platform upgrade to a newer CPU?

Thank you for your time and any assistance.

embyserver.txt ffmpeg-transcode-ed07496c-4fc8-4c4c-9bd6-827a8058a57c_1.txt

[Luke 42077]

Hi, as a test, if you disable hardware transcoding, how do things compare?

[noahajac 0]

1 hour ago, Luke said:

Hi, as a test, if you disable hardware transcoding, how do things compare?

For the same 4K file, it doesn't even play with hardware transcoding disabled. The logs show error "ProcessRun 'StreamTranscode 1adbae' Process exited with code 137 - Failed" which appears to be ffmpeg being killed for consuming too many resources.

If I try comparing with a 1080p file, the CPU will be pegged around 70%-80% without hardware encoding and around 40-50% with hardware encoding.

[Luke 42077]

On 5/19/2024 at 11:00 PM, noahajac said:

For the same 4K file, it doesn't even play with hardware transcoding disabled. The logs show error "ProcessRun 'StreamTranscode 1adbae' Process exited with code 137 - Failed" which appears to be ffmpeg being killed for consuming too many resources.

If I try comparing with a 1080p file, the CPU will be pegged around 70%-80% without hardware encoding and around 40-50% with hardware encoding.

@noahajaccan you please provide log examples from doing that? Thanks !

[noahajac 0]

On 5/23/2024 at 3:34 PM, Luke said:

@noahajaccan you please provide log examples from doing that? Thanks !

@LukePlease see attached. I rebooted Emby between gathering the logs so they are easier to tell apart. Thanks for the help!

embyserver_4K_no-hw-transcode.txt embyserver_1080p_no-hw-transcode.txt embyserver_1080p_with-hw-transcode.txt ffmpeg-transcode-4ab88b8a-0d2e-479f-9aa7-fff27b098bfa_1_1080p_no-hw-transcode.txt ffmpeg-transcode-9f7bc6bd-5393-484c-a7f5-225c9e060d39_1_4K_no-hw-transcode.txt ffmpeg-transcode-84c7c9cf-07c8-4eea-99eb-2e62c984b436_1_4K_no-hw-transcode.txt ffmpeg-transcode-a34a8e9b-fe1c-47c5-bcbd-28fcad5c608f_1_1080p_with-hw-transcode.txt ffmpeg-transcode-dd80d145-6402-40a5-886b-a6b57943a891_1_4K_no-hw-transcode.txt

[Q-Droid 989]

When you're trying to transcode 4k HEVC to 4k h264 your system can't keep up with the workload. The bottleneck is old CPUs and old low end GPU, neither of which can support HEVC in HW. It's seems to get by with 1080p and you might be able to stream 4k downscaled to 1080p. A GPU upgrade could help and the Intel Arc cards are cheap but you'll have to make sure your old system can support them. They have certain PCI/BIOS/UEFI requirements.

[noahajac 0]

On 5/27/2024 at 8:25 AM, Q-Droid said:

When you're trying to transcode 4k HEVC to 4k h264 your system can't keep up with the workload. The bottleneck is old CPUs and old low end GPU, neither of which can support HEVC in HW. It's seems to get by with 1080p and you might be able to stream 4k downscaled to 1080p. A GPU upgrade could help and the Intel Arc cards are cheap but you'll have to make sure your old system can support them. They have certain PCI/BIOS/UEFI requirements.

Thank you! I'll have to start looking into upgrading my hardware. I've been looking for an excuse to get a newer server anyway.