Can I adjust the video-out frequency of my CPC464?

[mr_lou]

According to my new XRGB-Mini Framemeister, my CPC464 is outputting a 50,08hz signal.

Is there any way I can adjust this, in order to hit 50hz?

[arnoldemu]

According to my new XRGB-Mini Framemeister, my CPC464 is outputting a 50,08hz signal.

Is there any way I can adjust this, in order to hit 50hz?

The frequency is defined by the CRTC parameters set by the game or firmware.

To correct this you would need to patch the game.
But, 50.08 and 50hz is a difference of 32us of the whole frame, and it's not as simple as removing one scanline from the frame, that would remove 64us. So making a perfect 50hz on CPC I think would be very difficult.

Is the Framemeister dropping frames or repeating them?

[mr_lou]

Is the Framemeister dropping frames or repeating them?

The Framemeister is excellent.

The 50,08hz signal gets converted to a 720p 50fps stream.
But because of the additional 0,08 hz, I lose a frame every 13th second or so.

The Framemeister can fix this simply by setting SYNC_MODE on. And then all is fine.... My TV displays the stream fine, and everything is smooth.

The problem is with the Hauppauge HD PVR Rocket device that I'm using for recording.
As soon as I turn on SYNC_MODE on the Framemeister, then the Hauppauge HD PVR Rocket device doesn't recognize a signal anymore. Apparently it's not happy with a 720p 50,08fps stream.

I've written Hauppauge about this, but even if they care to do something about it, it'll take months.

[arnoldemu]

Interesting.

Is it possible to change settings in the Framemeister to double up to 100hz and repeat every frame 2 times?
Maybe the Hauppauge would sync to that?

[mr_lou]

Is it possible to change settings in the Framemeister to double up to 100hz and repeat every frame 2 times?
Maybe the Hauppauge would sync to that?

No I don't think that's possible with the Framemeister.
And according to the website, the PVR Rocket won't accept that either.

Looks like my only hope is a new firmware for the Rocket - or another game-capture device that doesn't mind a 50,08 fps stream.

[gerald]

Using a GX4000 with its 39.90MHz oscillator would give you 49.95Hz, not sure it will be better accepted by your recorder.
You need an unobtainium 39.936 oscillator 
An other possibility would be to use a VCO to generate this frequency, but this is not a simple solution.

[Bryce]

Using a GX4000 with its 39.90MHz oscillator would give you 49.95Hz, not sure it will be better accepted by your recorder.
You need an unobtainium 39.936 oscillator 
An other possibility would be to use a VCO to generate this frequency, but this is not a simple solution.

Or open the crystal and file a bit off the side

Bryce.

[gerald]

Or open the crystal and file a bit off the side

Wait, is the JustPlus bare PCB already available ? 

[PulkoMandy]

The issue is a bit more complex than it appears.
The 50.08Hz signal is perfectly normal for the CPC. The slight difference is because the CPC output is not a proper interlaced video signal, but instead a progressive one.


For an interlaced signal, there is an extra half-line at the end of each frame. You could tell the CRTC to do this, but:
1) Nothing will have the correct timings anymore and apps will do strange things
2) Your signal will still not be completely correct, because the Gate Array cannot generate the correct composite sync from the CRTC outputs in that case.
3) It does not work the same way for each CRTC type (they all have different bugs in interlaced mode).


The 50.08Hz frequency is the same thing you get on any microcomputer with progressive video output (Amstrad, Amiga, Atari ST, ...), and probably most game consoles as well. So, it is a bit surprising that your hardware can't sync to it.

[mr_lou]

The 50.08Hz frequency is the same thing you get on any microcomputer with progressive video output (Amstrad, Amiga, Atari ST, ...), and probably most game consoles as well. So, it is a bit surprising that your hardware can't sync to it.

Yes well, best case scenario is that Hauppauge will reply my mail with: "We will fix this right away. Expect a new firmware available tomorrow!"