Help! AVCIntra locks up in log and transfer

[Jeremy Garchow]

[David Coleman] “but copying the files to the FW800 drive while the AJA IoHD was connected to the rear FW800 port. “

I wouldn’t blame the ioHD, although it is definitely involved in the case. The other example I linked to is when the PCD20 is daisy chained to a fw800 drive. That doesn’t seem to work either. Keep the PCD20 on it’s own bus, kind of like you would treat an ioHD. You are bound to have less problems as that way the reading and writing from PCD20 to hard drive can keep a one way pipeline instead of overloading the fw800 port. Make sense?

Again, there could be something else going on and I don’t know the nitty girtty technical reasons for sure, so this is my specualtion. Keep the PCD20 and fw800 drives on spearate busses, and let’s hope you have less problems.

And again, you have the PCD20 drivers installed, correct?

Jeremy

[David Coleman]

Yes on the drivers. I see what you mean about having the reader on its own bus, but I’m not sure I agree with your conclusion for three reasons.

1. FW800 is moving data from the card through the computer and back to the hard drive even though it is daisy chained. It isn’t like it has to do it in real time, even though it could, since data rates are <100MB/S. It really shouldn't be an issue. If it is, why do they put two ports on the drive to begin with?

2. I haven't had problems with this hookup until now and the only different variables are the codec--which is smaller than DVCProHD--and the IoHD.

3.It seems to me that the Io is an additional, bidirectional stream that introduces further complexity. I know it polls the FW bus even when it isn't actively carrying video info back and forth. You and others on this site have mentioned that it isn't good to combine it on the same bus with a FW drive and I am sure that is based on experience.

Make sense?

[Jeremy Garchow]

All points well taken.

[David Coleman] “1. FW800 is moving data from the card through the computer and back to the hard drive even though it is daisy chained. It isn’t like it has to do it in real time, even though it could, since data rates are <100MB/S. It really shouldn't be an issue. If it is, why do they put two ports on the drive to begin with? "

Well, that’s the drive. Notice there’s only one port on the PCD20 (same as ioHD) to encourage you NOT to daisy chain it. When the bus is split, the PCD20 is getting read while the writing is happening to a separate instance and bus. When the drive is daisy chained, all the reading writing and traffic info is flowing back and forth all at the same time down the same pipe that could be causing bus conflicts as maybe the PCD20 is maxing out the fw800 bandwdith similar to an ioHD in order to get the absolute wuickest transfer time. Perhaps the PCD20 is not just a passive device, it is actually controlling the bandwdith it uses, like the ioHD (sorry to keep referring to it, but there are similarities). Again, all speculation.

[David Coleman] “2. I haven’t had problems with this hookup until now and the only different variables are the codec–which is smaller than DVCProHD–and the IoHD. “

Perhaps you have been lucky. I don’t think the codec will have much to do with it as it’s just data coming off of the P2 cards. The computer or fw device doesn’t care if it’s DVCPro HD, dv, dv50, or AVC-I 100 or 50. It’s all just bits and codec shouldn’t make a difference, but who knows, maybe it does.

[David Coleman] “3.It seems to me that the Io is an additional, bidirectional stream that introduces further complexity. I know it polls the FW bus even when it isn’t actively carrying video info back and forth. You and others on this site have mentioned that it isn’t good to combine it on the same bus with a FW drive and I am sure that is based on experience. “

It’s based on recommended practices from AJA themselves, starting with the first io, 6 or 7 years ago. The truth is that I don’t know excatly what the PCD20 is doing to the fw bus, but you and the other thread I linked to seem to be having issues when there’s a drive in the middle of itself and the computer. Just drawing conclusions is all.

Jeremy

[David Coleman]

Follow-up: I installed a PCIe Firewire 800 card and connected my FW drive and PCD20 card reader to it. Now the IoHD is on a separate bus. After a few tests I am confident that my problem was overloading the Mac’s FW800 bus. I hope this helps somebody else.

David

[Jeremy Garchow]

Excellent. Thanks for the follow up, David!

Jeremy