Hi,
I just got my MiSTer Pi and suffer from major problems regarding the HDMI out (sync) in several different setups. My current conclusion is that MiSTer might not be the best choice as long as you don´t use the analog crt output.
Two stories here.
1st:
After having setup the MiSTer, I connected it to my main monitor, a BenQ EW3270U - it is an (older) FreeSync monitor (just 40Hz-60Hz) rated quite good for it´s SDR mode (compared to the HDR mode), but I know that it has some quirks - there must be a reason for the low price...
When starting the C64 or the Minimig core (Amiga) and having the resolution set to 1080p50, scrolling text is not smooth. I tried everything to get rid of it: disabling vsync, all other vsync options, enabled and disabled game mode, enabled and even disabled VRR - no chance.
Same with an "AVerMedia Live Mini" capture hardware - no fluent horizontal movement at 50Hz. I know that most people prefer Elgato hardware, and I cannot ensure that the hardware itself does not an internal conversion to 60Hz even though it should not - there must also be a reason for it´s low price compared to Elgato products...
I also tried R-Type (Arcade) with it´s 55Hz. The monitor clearly states that 55Hz have been detected and output, but there is visible judder.
As a comparison, I already used this BenQ monitor with RetroArch, and it worked on Windows and Linux (Batocera) - but it was DP/USB-C in this case, not HDMI, so there might be a problem with the sync via HDMI even though it states to have detected 50Hz/55Hz/60Hz/70Hz.
But as it also does not work with vsync and VRR disabled (as written above), I currently don´t see a way to get it working. Maybe using an HDMI-DP adapter?
Then, I checked the same with an (older) LG non-freesync monitor - no problems, suprisingly even not with the 55Hz. I did the same with my Panasonic TV, connected via an Onkyo Dolby Atmos amplifier in my living room - no problem, smooth animation, even with low lag settings. However/of course: 55Hz R-Type does not work on the consumer TV, the screen stays black.
2nd:
Then, by coincidence, I discovered Zaxxon for the Atari VCS/2600 on the Atari 7800 core. On my TV as well as on my BenQ monitor, I get desyncs (i.e. TV and monitor do permanent mode changes) as long as vsync is enabled (any of the modes).
I tried other cores as well - there were desyncs e.g. after every scene change in Gran Turismo on PSX - which is ok because I know that there are a lot of resolution changes in the original game, but it was stable in-game. Same with N64, Saturn, NES, SNES etc.
Summary:
- To me, it looks like MiSTer does some "strange" things regarding the HDMI output sync. Maybe the Atari Zaxxon is one great example that might show that it has some kind of "dynamic" frequency management that might go beyond what certain monitors/TVs might accept?
- It looks like that I cannot use the MiSTer Pi on my BenQ monitor and the capture hardware as long as I don´t play 60Hz games.
- In the VCS/2600 example, I would have to add a special entry to the mister.ini that disabled vsync for this core.
Questions:
- Are there known general issues with the HDMI timing that cause my problems with certain displays or capture hardware (from certain manufacturers)? Anyone with the same experience and maybe another solution for it apart from editing the mister.ini (which apparently does not seem to help)?
- Is there a way to "blacklist" resolutions, e.g. the 55Hz for R-Type on my consumer TV? I would have expected that this frequency is not allowed at all on my TV because EDID might not list it as valid frequency. Setting the arcade cores all to 50Hz or 60Hz also sounds wrong to me (because slight deviations like 59Hz vs. 60Hz will work).
- The option to set R-Type to 50Hz in the core settings itself is no more visible and thus accessible after I have startet the game. Can I change this setting before starting R-Type without editing the config files manually?
- Is there a possibility to change the resolution "on-the-fly" in case I turn off the vsync completely for all cores? Currently, it looks to me that I have to always reboot the system and change the mister.ini to switch between 50Hz and 60Hz - or add an appropriate entry for the 50Hz cores.
- MiSTer is all about eliminating the lag. What is the point of using MiSTer via HDMI when turning vsync off and then, as a result, adding a lag of 1-2 frames (according to the documentation)? It might then come close to RetroArch/Denise with read-ahead enabled. This sounds like a critical comment, and indeed, most cores worked even with low lag enabled and vsync on, but when low lag/vsync don´t work, you might end up with disabling it to not get suprises during gameplay...
Thanks in advance for your insights/tipps!