What are the possible reasons for jitter on a 30 inch monitor when compared to a 24 inch monitor connected to the same Tera2 Remote Workstation Card?
Problem
In a single workstation environment when comparing a 30 inch monitor at 2560x1600 to a 24 inch monitor at 1920x1600, moving a window containing a running video in the 30 inch screen shows latency and window drag when compared to the 24 inch monitor. Also, additional mouse lag is noticed when moving the mouse within the window of the 30 inch screen.
Cause
Due to the dynamic nature of the PCoIP protocol, a variety of factors can cause display jitter and lag. Listed below are some factors which can contribute to this situation categorized into five different areas: PCoIP processing, Host side, Client side, Network and Bandwidth Management, Application side.
PCoIP processing
- Displays larger than 1920x1200 and faster than 60Hz refresh rates are supported; however, these larger displays may have the Video input decimated (frame rate drops) depending on the amount of change per frame on the display. These frame drops may result in a small degree of jitter. So when comparing a 30 inch monitor (2560x1600) to a 24 inch monitor (1920x1200) in the same environment, the 30 inch monitor may show jitter if more than half of the display is continually changing.
Host side
- Interactions between Video Input interface and Codec.
- Collisions of processing the same area of the screen via the Codec or via the Video input.
Client Side
- Tear reduction - waiting for entire frames to be ready before displaying.
Network and Bandwidth management
- Congestion (Instantaneous bandwidth spikes that fill up internal queues)
- Overall encoded image bandwidth is unable to fit within the network bandwidth
- Variability in encoding codec performance - changes in bits/pixel encoding rate.
Application side
- Some applications which perform image scaling (i.e. the pixel data is duplicated in horizontal lines) interfere with the PCoIP protocol\u2019s ability to detect display motion changes, causing jitter or stuttering.
Note: The stuttering/jittering effect may be further exaggerated if other network issues such as latency or high bandwidth usage are present.
Workaround
It may be possible to reduce the effects of jitter by considering the following actions:
- Lowering the frame rate between the host and client
- Increase the available bandwidth between the host and client
- Consider a different application experiencing the jitter
- Use PCoIP firmware 4.0.3 or newer
- Use Local Cursor and Keyboard in the latest PCoIP Host Software release
See also: