Smooth scrolling at 50hz via HDMI

antonvaltaz · 11 July 2015, 21:03

I wonder if anyone can give me advice...

I have a Sony Vaio laptop with an Intel Graphics HD 3000 graphics chipset, which I am trying to connect to my Toshiba 'HD Ready' TV (its native resolution is only 1366x768 but it can accept a 1080p signal which it scales down) so that I can emulate Amiga games at 50hz for smooth scrolling.

The laptop's native resolution is also 1366x768, and if I connect via VGA then I get a pretty sharp picture but I can only display at 60hz.

If I connect via HDMI then I get a 50hz option, but the laptop insists that it should output via the TV's 'native' resolution of 1920x1080, only for the TV to actually scale it down again to 1366x768. Even if I set the laptop's resolution to that, I think the picture is getting upscaled then downscaled.

The end effect seems to be that vertical scrolling remains a bit jerky (I use SWIV as my test case). Am I screwed unless I buy a new TV, or is there anything I could be doing to improve matters?

BigFan · 12 July 2015, 11:47

Quick guessing:
1366 is not truly 16:9. If intel driver gets suspicious over that, it switches to next higher vertical 16:9 resolution that is capable of displaying 768 lines and that is 1080.
Try 1280:720 if driver accepts it.
1366 might be vga only. Any hints on that in tv documents?

60 Hz can't be forced to any thing but 60 Hz. That's the refresh rate of the matrix.
The internal transcoder will add missing pictures mostly.
Your 50Hz is what the input allows be sent as the lowest vertical frequency. This is independent from frame rates.
This is quite opposite to the specs and behaviour of CRTs.

Emulation is not effected by this. The video should be as smooth as on my LG (at 60Hz).

lordofchaos · 12 July 2015, 15:27

SWIV doesn't scroll at 50fps so maybe not a good test case, how about trying pinball dreams, it has a super smooth text scroller at the start..

antonvaltaz · 13 July 2015, 08:11

Thanks both for your helpful comments, I'll have a bit of an experiment when I'm back home.

11 July 2015, 21:03	#1
antonvaltaz Registered User Join Date: May 2009 Location: Oxford, UK Age: 43 Posts: 511	Smooth scrolling at 50hz via HDMI I wonder if anyone can give me advice... I have a Sony Vaio laptop with an Intel Graphics HD 3000 graphics chipset, which I am trying to connect to my Toshiba 'HD Ready' TV (its native resolution is only 1366x768 but it can accept a 1080p signal which it scales down) so that I can emulate Amiga games at 50hz for smooth scrolling. The laptop's native resolution is also 1366x768, and if I connect via VGA then I get a pretty sharp picture but I can only display at 60hz. If I connect via HDMI then I get a 50hz option, but the laptop insists that it should output via the TV's 'native' resolution of 1920x1080, only for the TV to actually scale it down again to 1366x768. Even if I set the laptop's resolution to that, I think the picture is getting upscaled then downscaled. The end effect seems to be that vertical scrolling remains a bit jerky (I use SWIV as my test case). Am I screwed unless I buy a new TV, or is there anything I could be doing to improve matters?

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12 July 2015, 11:47	#2
BigFan Registered User Join Date: Feb 2014 Location: Germany Posts: 261	Quick guessing: 1366 is not truly 16:9. If intel driver gets suspicious over that, it switches to next higher vertical 16:9 resolution that is capable of displaying 768 lines and that is 1080. Try 1280:720 if driver accepts it. 1366 might be vga only. Any hints on that in tv documents? 60 Hz can't be forced to any thing but 60 Hz. That's the refresh rate of the matrix. The internal transcoder will add missing pictures mostly. Your 50Hz is what the input allows be sent as the lowest vertical frequency. This is independent from frame rates. This is quite opposite to the specs and behaviour of CRTs. Emulation is not effected by this. The video should be as smooth as on my LG (at 60Hz).

12 July 2015, 15:27	#3
lordofchaos TinkerTailorContentMaker Join Date: Nov 2009 Location: Bedfordshire Age: 45 Posts: 1,205	SWIV doesn't scroll at 50fps so maybe not a good test case, how about trying pinball dreams, it has a super smooth text scroller at the start..

13 July 2015, 08:11	#4
antonvaltaz Registered User Join Date: May 2009 Location: Oxford, UK Age: 43 Posts: 511	Thanks both for your helpful comments, I'll have a bit of an experiment when I'm back home.

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