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Forum Index : Microcontroller and PC projects : Display mode frame rates
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| capsikin Guru  Joined: 30/06/2020 Location: AustraliaPosts: 341 |
I had also assumed 60 frames per second - I think it would be good for retro stuff - but I don't think that's the default frame rate. What frame rate are the various modes, and is it possible for the program to set 60 fps if it's not the default? (I was just using your post as a prompt for mine, you may be going to run the emulation at 60fps even if the display output is different) Edited 2020-08-24 11:00 by capsikin |
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Sasquatch Guru Joined: 08/05/2020 Location: United StatesPosts: 377 |
According to my monitor, Modes 1 and 9 are 60Hz, All other Modes are 75Hz. Keep in mind that this is the video frame rate that the hardware is sending to the VGA monitor. The actual rate for updating the displayed image is software controlled. -Carl |
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| berighteous Senior Member  Joined: 18/07/2020 Location: United StatesPosts: 110 |
if you change your screen every 1/10 second, you're at 10fps regardless of your refresh rate. |
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| capsikin Guru Joined: 30/06/2020 Location: AustraliaPosts: 341 |
Thanks. Kind of, but it won't be an even 10 fps. Doing 60Hz game updates on a 75Hz screen connection would lose the smoothness of motion you could otherwise get with a 60 or 75Hz frame rate. |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2442 |
i am a little surprised that some modes operate at 75Hz frame rate, my understanding was that many years ago the world had settled on 60Hz. i could see some monitors, both new and old, being unhappy with 75Hz, and indeed did recently strike a monitor that was extremely unhappy with a 75Hz output from a DELL pc via the VGA port. in that case a different monitor attached to one of the DisplayPort outputs worked fine. peter/geoff: is there anywhere a list of ALL modes available on the CMM2, along with: 1. their on-screen resolution 2. their actual resolution (ignoring doubled-up dots or lines) 3. the colour depth 4. the frame rate that the CMM2 uses, 5. other timing information. if it is so, is there any good reason why a 75Hz (or any other than 60Hz) frame rate is used? cheers, rob :-) |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3378 |
My ancient Polaroid monitor flm1511 doesn't handle 75Hz. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| mclout999 Guru Joined: 05/07/2020 Location: United StatesPosts: 490 |
Am I wrong or are people confuing frame rate with REFRESH RATE. Frame rate is a the number of frams you program is able to update during run time(depens on the workload of the procesor). The refresh rate of the mode is just the rate at witch the video circutry is refreshing the immages provided to it by the device. This dose not effect the nuber of frams per second but it does effect the smoothness of the output. In PC FPS gaming a monitores refresh rate is all important as the motion on screen can get very blury and have motion tear effects at lower refresh rates. I spend a lot of money to have at least 120Hz to make fast moveing graphics that don't look like crap. Other have hit on it but I hope this help to clearify it. Tell me if I got this right or not. |
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| capsikin Guru Joined: 30/06/2020 Location: AustraliaPosts: 341 |
I may have used the wrong term, refresh rate is what I was mostly talking about (though also matching frame rate to refresh rate). |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2442 |
ditto - i was referring to "frame rate" in the classic video sense (pre-computers): where a frame consists of two interlaced fields, and the NTSC/american frame rate is 30Hz, while for PAL/european it is 25Hz. as far as i am aware, LCD computer monitors have generally settled universally to 60Hz (non-interlaced) for most of this century (irrespective of country), with 120Hz starting to appear in the last few years for some high-end equipment. a variety of different frame rates (and a mixture of interlaced and non-interlaced) were necessary back in the days of CRT monitors, where the electron beam that 'drew' the picture was moved magnetically by coils that could only have very limited ranges of frequencies fed into them. with LCDs, this constraint (formerly imposed by the magnetic components) no longer exists, but has been replaced with other limitations (including cost-reduction) that have seen 60Hz emerge as the 'standard' frame rate. i guess a less confusing term would be to talk about the vertical sync rate, which would also be 60Hz. cheers, rob :-) Edited 2020-08-25 02:35 by robert.rozee |
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| capsikin Guru Joined: 30/06/2020 Location: AustraliaPosts: 341 |
Would they also support lower frame rates? VGA and HDMI both support lower frame rates as well as higher. Unfortunately VGA 50Hz support doesn't look like it's standard though. I found "Graphics Programming on the CMM2" has quite a bit of information on the older resolutions (mode resolutions 1-5). I haven't seen the info for the modes in the new betas compiled into a list, and I don't remember how much info was in the beta announcements. Colour depth would have the same options as the old modes. (8, 16 or 12 bits, with 12 bits having an alpha channel and 2 pages used as layers). |
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panky Guru Joined: 02/10/2012 Location: AustraliaPosts: 1114 |
Peter is still doing quite a bit of developement in the MODE area so I am waiting a bit for the dust to settle and with Peter's help/approval, will update all the new MODE features that have appeared in recent betas. Doug. ... almost all of the Maximites, the MicromMites, the MM Extremes, the ArmMites, the PicoMite and loving it! |
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| capsikin Guru Joined: 30/06/2020 Location: AustraliaPosts: 341 |
I was mistaken about the colour depth always having the same options. From https://www.thebackshed.com/forum/ViewTopic.php?TID=12438&P=5#153217 "[mode] 9 = 1024x768 (NB: 12-bit colour depth not available in this mode)" Other info from the thread: |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2442 |
bear in mind, i don't have a CMM2. my interest is purely academic. for each mode, i take it there are up to three variations: 8-bit, 12-bit, and 16-bits. not all modes support all three. between 8/12/16 there may be timing differences, as different quantities of data is being shuffled around - although if there is a lookup table involved, this may negate the differences. some/several of the lower resolution modes double up pixels and/or lines, yes? so they are effectively a quite different resolution to that observed on-screen. what i am interested in is the timing set (including front and back porches) for each of the mode and colour depth combinations, in part to look at what the resulting dot-clock is. i am curious about the shimmering some see, the cure for the problem (a crystal block), and that some monitors seem quite unhappy with some modes, while others have displacements that can not be adjusted out. cheers, rob :-) |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10315 |
Not sure why we need to keep repeating this. There are three resolutions used 640x480 @ 75Hz, 800x600@60Hz and 1024x768@60Hz. See here for the full details. All modes other than 1 and 9 use 640x480 and the timings are exactly as per the reference in all cases |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4044 |
I think modes are: 1 = 800x600 2 = 640x400 3 = 320x200 4 = 480x432 5 = 240x216 6 = 256x240 7 = 320x240 8 = 640x480 9 = 1024x768 (NB: 12-bit colour depth not available in this mode) John |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2442 |
peter, john: much appreciate the info. may i ask why 75Hz is used for modes based around 640x480? cheers, rob :-) |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10315 |
More stable - less shimmer of flicker. Freq can be produced precisely |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6283 |
And while 60Hz was around in the early days, it is not VESA compliant and would be likely to cause more compatibility problems than it solved. Jim VK7JH MMedit |
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| MikoKisai Newbie  Joined: 10/07/2020 Location: GermanyPosts: 6 |
Are you sure about that? I find this rather curious, because according to their specifications, neither of my monitors support 640x480@75... only 640x480@60. It's also listed as an "industry standard" on the timing page that Peter linked to, which isn't the case on any of the other modes. (It may be the case that they do support it in practice - but I don't have my CMM2 yet to test.) I also see 640x480@60 listed in a copy I found of the VESA monitor timing standards, suggesting that it would be commonly expected to work. Edited 2020-08-26 08:19 by MikoKisai |
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| TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6283 |
I used this as a reference: "VESA and Industry Standards and Guidelines for Computer Display Monitor Timing (DMT) Version 1.0, Rev. 12 November 17, 2008" It lists 640x480 60Hz as Either way 75Hz is a standard and any modern monitor should be able to display it. Jim VK7JH MMedit |
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