Square pixel video decoders.

I have a bt878 based video capture card. "Selected device: BT878 video (Hauppauge (bt878)) Capabilites: capture tuner overlay clipping scales Device type: 171 Supported sizes: 48x32 => 924x576

" You can completely setup the number of pixels it samples per line - at least under linux, I haven't tried under windows.

Many thanks for your reply.

The Bt878 is a single solution for a PCI card. I really need 8 bit data with embedded SAV and EAV codes etc. Sorry I should have been more specific.

What's wrong with a common or garden 10Mhz 8-10 bit DAC, with a tiny bit of glue in a FPGA?

In reality you'd need 4 or 8 times subcarrier frequency. Then down sample etc to a completely different rate. I would agree in ideal world. Are there any free IP cores which do it all for me? Not sure I'd only need a "tiny amount", mind all things are relative!

In message , Fred writes

Hi Fred,

I'm curious, what is your reference device and price over which the AD decoders have a "price premium"? I recently switched from Philips to ADV7180 and paid less. NB I am a relatively small buyer and not out to save the last few groats, you're maybe in a different league?

I believe the Techwell parts, which are becoming very popular in the CCTV world, do square pixel but require a different oscillator freq for PAL and NTSC (and for 720).

Regards,

The ADV7180 is the target price but isn't square pixel. I'd forgotten about Techwell and have started making enquiries. I see TI do some square pixel variants as well.

Many thanks.

In message , Fred writes

Hello Fred(?),

As they say at the panto "oh yes it is", though I concede it's well hidden in the datasheets.

I'll qualify that, it's not natively square pixel, it scales to square pixel in the backend so that it isn't actually any higher resolution than the 720 capture. For most people I don't think that's an issue and you've already indicated a scaling solution is acceptable.

The AD eval board is very reasonably priced and would let you try this all out. "I'm only a satisfied customer blah blah..." (so far).

Hope this helps,

Regards,

Yes the datasheet does mention 640 pixels but only in one place and without any further reference. I've used this IC and I've learnt not to trust the documentation. It's rather inconsistent in places. I also want 768 active pixels per line.

Philips SAA7114?

Best Regards

Steve Sousa

Many thanks.

It looks like quite a versatile decoder with a scalar but seemingly with a $15 (1000 off) price tag which makes it very expensive.

Fred scrobe on the papyrus:

I think there is a conflict here. By requiring SAV & EAV codes you are implying that you need CCIR656 coding. Unfortunately CCIR656 is an extension of CCIR601 which specifies 720 pixels per active line and

Strictly speaking you are correct. However in practice the SAV/EAV codes are generally available in non CCIR656 formats from many IC vendors. It is something bearing in mind that it's a not a "standard".