Re: Open hardware AV to digital conversion

From: silverdr_at_wfmh.org.pl
Date: Mon, 12 Jan 2015 20:43:14 +0100
Message-ID: <54B423D2.4010106@wfmh.org.pl>
On 2015-01-10 13:50, smf wrote:
> If you create a 624 line frame, made up of two fields that are 312 lines
> each then it's not a valid PAL signal and no tv will think it's interlaced.
>
> To make it interlaced you have to alternate between vsync happening at
> the end of the last line and in the middle of the last line. To keep the
> speed right you'd be alternating between 311.5 & 312.5 lines, which
> isn't valid PAL either and so may work better or worse than the standard
> c64 signal based on what equipment you are using.

Unfortunately you may be right... if the final frame rate differs 
because of this (I can imagine it not differing despite the half-line 
difference) then that would be a show-stopper. Altering clocks is out of 
question - it would kill all communication stuff that is timed based on 
cycle counting for example.. and possibly some other things.

I am tempted to check the idea Ingo wrote about. I mean the waveform 
generator that would give us a chance of generating the interlaced 
output as you describe above or generally experiment with different 
modifications of the original C64 signal.

-- 
SD!

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Received on 2015-01-12 20:00:55

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