On 2015-05-23 11:24, Mark J. Blair wrote:
> In the middle will be some FPGA to perform any necessary magic. I've been > looking at a prohibitively expensive ($115) one that has enough dual-port RAM > blocks to support a frame buffer. I need to see if I can push the frame > buffer out into external RAM in order to move to a cheaper FPGA. It would be > ideal if the video parameters could be figure out automagically, but I have a > feeling there will be a need for user-adjusted parameters, and possibly even > loading up different FPGA programming to handle some odd-ball signal. > > Output would be HDMI, at 1080p. Are other interfaces and/or resolutions > desirable? I'd like to keep it as feature-simple as practical. OMG, stop. Google "Composite to HDMI" and you will find hundreds of low cost boxes that do this. Hopefully one of them will work for you. I was going to do your idea for C64s long ago until I realized there's no way I can do it nearly as cheap as Mr. Wong in his apartment in Shenzhen, Guangdong. However if you really want to pursue your idea "because it is fun for you", I suggest looking at the Lattice XO2 Control Development Kit (novel idea of OpenLDI in/out + LPDDR2), the Digilent Atlys board (Spartan 6 + dual direct TMDS in&out), or NeTV (Marvell SoC + Spartan 6 w/ dual direct TMDS) as starting points. You don't even need a full frame buffer if you need to scale. If the frame rates match, you can just store one line if you need to horizontal stretch and/or line-double, or three lines if you want to perform multi-tap vertical scaling. All HDMI TVs (at least in North America) support 480i however you generally have to pixel double per the CEA-861 standard to have enough clocks in the HBI/VBI to pass audio. -Alan
