240hz using the scanout speed of 480hz?
Posted: 12 Feb 2019, 08:44
After I saw Chief talking about the Quick Frame Transport (QFT) from Vesa 2.1 and how it is available today I tried to do a few tests and was able to achieve 576p using the scanout speed of 480hz (by setting 480hz at CRu and then fixing the pixel clock and raising the vertical total until I reach 1201).
Here are the results (Alienware AW2518hf):
The default 576p @ 240hz:
https://www.youtube.com/watch?v=fAiAaNqw7ig
The 576p @ 240hz with VT 1201 (scanout speed of 480hz freq):
https://www.youtube.com/watch?v=EFBP6LFrDJs
Macbook Pro 2017 @ 60hz for reference:
https://www.youtube.com/watch?v=mYToT70hNHg
The video starts and ends at normal speed and then slows down to 960fps in the middle.
What is strange is that at the default the image seems perfectly static at naked eyes while the image at VT 1201 is flickering ultra-fast. In fact I thought the javascript was bugged before I tried to record and thats is perceptible at the start of each video befere the slowmotion kicks in.
Could someone explains this effect and verify if it the scanout is really twice as fast?
Here are the results (Alienware AW2518hf):
The default 576p @ 240hz:
https://www.youtube.com/watch?v=fAiAaNqw7ig
The 576p @ 240hz with VT 1201 (scanout speed of 480hz freq):
https://www.youtube.com/watch?v=EFBP6LFrDJs
Macbook Pro 2017 @ 60hz for reference:
https://www.youtube.com/watch?v=mYToT70hNHg
The video starts and ends at normal speed and then slows down to 960fps in the middle.
What is strange is that at the default the image seems perfectly static at naked eyes while the image at VT 1201 is flickering ultra-fast. In fact I thought the javascript was bugged before I tried to record and thats is perceptible at the start of each video befere the slowmotion kicks in.
Could someone explains this effect and verify if it the scanout is really twice as fast?