Massive amounts of latency when using h264 at 120fps with Sunshine

[andy013]

Moonlight Version

1.6.25

Device Type

webOS TV

Device Model

50QNED816RE

Device OS

webOS 23 / 8.4.0-2202

Host OS

Windows

Host Software

Sunshine

Host Setup

Intel Core i7 12700k, Nvidia GTX 970, 32GB DDR4, 240hz Monitor, Windows 11 Pro 23H2

Bug Description

I recently started using Sunshine in place of GameStream. Sunshine (v2024.1115.143556) is running on my pc and streaming to the LG TV.

Everything is working fine apart from h264 120fps. When I try this I start getting massive amounts of lag; multiple seconds of delay which makes it impossible to use. Even using menus in games is difficult because of how bad the lag is. It seems like the stream is falling further and further behind as time goes on. This is not an input issue as my controller is connected directly to the PC.

h264 at 60fps or 90fps works fine with minimal latency. h265 at 120fps also works fine.

All settings in Sunshine are left at defaults. The UI in Moonlight does not show any massive increase in latency for encoding or decoding. I tried reducing the bitrate but it doesn't make any difference.

H264 at 120fps was working fine using GameStream and this app, however I tested Sunshine with my phone using the android Moonlight app and the same settings work fine there, so I think it could be a problem with how this app is interacting with Sunshine.

Reproduction Steps

1. Set codec to h264
2. Set frame rate to 120fps
3. Stream from pc running Sunshine
4. Notice huge amounts of latency

Expected Behavior

Using 120fps and h264 should work with minimal latency just like HEVC.