suggestion on recording P2 video

rjo__

Right now, if I want to record P2 video output, I have to point a camera at the screen.

I found a USB video grabber for less than $20, but it doesn't recognize the P2's composite NTSC.
I am now using VGA and I tried to search for a similar product and can't find one that is reasonably
priced...

Anyone else have any luck with this? Ideas?

Thanks

cgracey

Have you tried capturing the NTSC demos in the FPGA release? I believe they make a perfect NTSC signal.

Phil Pilgrim (PhiPi)

rjo__ wrote:

I found a USB video grabber for less than $20, but it doesn't recognize the P2's composite NTSC.

What?!! After all we've been through, discussing and correcting output levels, impedances, etc., I find this more than a little disturbing. What is it about the P2's NTSC output that precludes simple video capture? By now this should be basic -- second-nature, even.

-Phil

jmg

rjo__ wrote: »

I found a USB video grabber for less than $20, but it doesn't recognize the P2's composite NTSC.

Does this Video grabber work with a P1 signal ?
How exactly does it 'not work' ?
Is it the sync that fails, or the colour side of things ?

cgracey

Phil Pilgrim (PhiPi) wrote: »

rjo__ wrote:

I found a USB video grabber for less than $20, but it doesn't recognize the P2's composite NTSC.

What?!! After all we've been through, discussing and correcting output levels, impedances, etc., I find this more than a little disturbing. What is it about the P2's NTSC output that precludes simple video capture? By now this should be basic -- second-nature, even.

-Phil

There's no way this is anything more than a software issue.

Phil Pilgrim (PhiPi)

cgracey wrote:

There's no way this is anything more than a software issue.

Okay, good. That's reassuring -- on a day that needs reassurance.

-Phil

rjo__

This is what I am using. under Win 8.1 64-bit. Showbiz software from ArcSoft.
It all works fine when I plug an old Quasar camcorder with rca plug out to ezcap rca composite in.

On the P2 side, I have tried both Chip's NTSC sample and a while back a modified version 640x480... which I don't remember at the moment.

I have been assuming that this had something to do with the DAC's on the FPGA board and wasn't particularly concerned about it...now you guys are scaring me:)

cgracey

Does the digitizer have a 75 ohm pull-down? Are you using a Prop123-A9 board?

rjo__

Yes on the A-9... no idea about pull downs ... I'll fiddle with that. Thanks

Phil Pilgrim (PhiPi)

I was wondering about the pull-down, too. Without it, the output will be 2V P-P, instead of 1V P-P. This would be easy to check out with an o'scope. Some digitizers are designed for daisychaining with, say, a monitor. They will usually have a switch or jumper for including -- or not -- the 75-ohm pull-down.

-Phil

rjo__

75ohm ... yes
I also played with scaling the dac output up and down.

rjo__

Phil Pilgrim (PhiPi) wrote: »

rjo__ wrote:

I found a USB video grabber for less than $20, but it doesn't recognize the P2's composite NTSC.

What?!! After all we've been through, discussing and correcting output levels, impedances, etc., I find this more than a little disturbing. What is it about the P2's NTSC output that precludes simple video capture? By now this should be basic -- second-nature, even.

-Phil

I dunno. But let's say there is an issue... what does it mean?

It is an opportunity to sell an add-on circuit. The P2 signal is good enough for every monitor that I have tried... the fact that it isn't good enough for what is probably a knock-off of a knock-off from China can't be that much of a problem....

"If you want to digitize your video with a very inexpensive Chinese digitizer that looks like a well respected product sold by ____,
you are going to need this little circuit, which you can build yourself with spare parts from your ERCO bin.... or PayPal us and we'll send you a completed board in 3 business days"

Silver Linings Inc.

Phil Pilgrim (PhiPi)

rjo__ wrote:

But let's say there is an issue...

I'm confident in Chip's assurance that it's not a hardware issue.

There are two software gotchas I can think of that might prevent some devices from syncing while others work just fine:

1. Lack of serrations in the vertical sync interval. These pulses are necessary to keep the horizontal sync tracking between fields.

2. Identical even and odd fields, instead of the timing between them being offset by half a line.

If you have a scope with video sync capability, you should be able to verify that neither of these characteristics are present.

-Phil

rjo__

Thanks Phil,

I think Parallax needs to start awarding status around here...
If you aren't a full Professor, I'm a Hillary supporter.

Of course I don't have a scope:) I just looked at the one Chip uses....
Holy cow...JESUS. Mother of GOD. Defense Department prices:)

Of course those are 10x what I would need, but I hate to settle.

I have been looking into a VGA frame grabber, but even those prices (for what is equivalent to some ADC's and a bit of memory) seem somewhat unreasonable.

I think my salvation may lurk in the USB work being done here:)

Rich

Publison

rjo__ wrote: »

Thanks Phil,

I think Parallax needs to start awarding status around here...
If you aren't a full Professor, I'm a Hillary supporter.

Careful on the politics.

rjo__

oops... sorry.

jmg

Phil Pilgrim (PhiPi) wrote: »

There are two software gotchas I can think of that might prevent some devices from syncing while others work just fine:

1. Lack of serrations in the vertical sync interval. These pulses are necessary to keep the horizontal sync tracking between fields.

2. Identical even and odd fields, instead of the timing between them being offset by half a line.

If you have a scope with video sync capability, you should be able to verify that neither of these characteristics are present.

-Phil

Even a simpler logic-capture type tool, should be enough to check 1) and 2)
The OP should try a P1 board generating NTSC, and verify that does work on the Capture Card.

Then, differences can be looked for between the P2 and P1 details.

rjo__

I am at the "mansion" right now... my P1 boards with video out are about 5 minutes away, but I'm having a touch of inner ear non-sense, making it interesting to just walk around.

Shouldn't be too long ... I'll get back on this issue.

Roadster

I tested V13 on my A9 board with NTSC output with my USB capture adapter and is working fine
this is the adapter I have
http://www.adesso.com/faq/faq_info.php?id=12&typeid=102

rjo__

Thanks Roadster...

I just tried my cheapo with P1 NTSC and it works fine... I was beginning to wonder.