Dear Piotr,

When we fill up one file, we start another, and then while we are writing the video and audio to the new file, we go back to write the large index to the old file.

If the card is not fast enough to keep up with this double writing, then the level of the FIFO will increase.

If the FIFO buffer level then goes down before before the second file is finished, then you are ok.


Please understand that you need to perform a recording, to your card under test, until the card is full.

But has this issue always been there or is it something new with this build?

Peter,

You misunderstood one of my previous posts on this - the audio drift used to be even longer with previous firmware releases (I don't know about the 1.6.29, though - as I skipped that).

So if I mention the 4 milliseconds now is because I appreciate it's improving, but still not quite there yet:)

Piotr

Piotr,

You are obviously very technically adept and clearly you strive for excellence in your productions - as we all should. I come from a telecommunications and telemetry background and from all the training I have done, the 4 ms delay you are worried about would be absolutely imperceptible to the average punter.

You know its there because you have the means to test it. The viewer, on the other hand, probably hasn't a clue. I have copied and pasted a paragraph (below) from a paper about the subject (which as you will know is commonly just referred to as lip-synch problems).

Quote:

From time to time, standards committees in various countries have addressed the problem
of audio to video timing errors, and have set standards or guidelines for the maximum
allowable amounts of these errors. For the most part, these standards or guidelines are in
agreement that lip sync errors start to become noticeable if the audio leads the video by 25
ms to 35 ms, or if the audio lags the video by 80 ms to 90 ms."

End quote

The paper was authored by:

J. Carl Cooper
Mirko Vojnovic
Chris Smith

and can be viewed here:

http://www.pixelinstruments.com/pdf/...c%20Errors.pdf

Honestly, whilst I think it is admirable that you are striving for perfection in everything that you do, I think Dan probably has a lot more to worry about than trying to correct things that simply don't matter to the end-user of the recordings.

Cheers

Russ

Thanks Russ for your comments, and the link to some interesting reading.

I'm not ranting - to the contrary; the delay used to be almost half a second when I first got my nanoFlash, and now it has been greatly reduced. But still - and I'm sure Dan understands me well - the matter is two-fold:

1. From purely technical viewpoint, I don't see a reason for any discrepancies between nano and native recordings. Of course, there is some latency to any type of connection, including SDI - so I have no problem with the fact that the nano clips start a couple of frames later than the native ones. But, inside the SDI stream, the picture is spot-on with the TC - why not the audio?

2. As to what is noticeable and what's not - I can assure you that if a guitarist's fingernail, pulling a string, is more than 5 ms off in relation to the sound, it will be noticeable (especially on 50+ inch screen's closeups). So, 4 ms is just barely tolerable (I agree that for the lip-synch, even 25 ms may be OK; also some other instruments might pose much lesser demands in this regard than the guitar does).

Cheers

Piotr

PS. I've just noticed you're located in Australia - if you are in touch with Bob Grant, you might ask him about the amount of effort I put into editing that particular guitar recital; he also is in possession of the DVD I produced....

G'day Piotr,

sorry if you got the impression that I thought that you were ranting, because I certainly didn't intend for you to interpret it that way. I think that the point about the audio/video being out of synch is being laboured a bit, not ranted about.

Anyway, hopefully the team at CD have got their teeth into the problem by now, although there will be a limit to how much they will be able to achieve. As you pointed out yourself, there are latency issues, and many other issues that are not even the nano's fault, so I don't think that perfection will be achieved. Time will tell.

I do correspond with Bob, and although we live on opposite sides of the country, I hope to catch up with him next year when I go to Sydney, even if it's just for a coffee (or beer.)

Cheers

Russ

Just curious, at what stage of the beta firmware does CD recommend downloading the new firmware?

Thanks

Dear Anthony,

1.6.226 is a Public Beta. Thus, we encourage our users to download and load this version on their nanoFlashes so that they can test it.

After they have finished their testing, then we recommend re-installing 1.6.29 for production work.

And, of course, if you have any quetions or problems with the firmware, please contact us.

We have had very few reported problems with 1.6.226, thus I would expect that we will issue Production Level firmware fairly soon.

Looking good then Dan.

Thanks.

I can confirm that the newest Beta is the best nanoFlash firmware ever - no doubts about it. A real milestone, and very stable, too.

Piotr

Thank you Piotr, I think I will download it and try it.

Thanks.

I personally would never do a job with Beta FW.

Try it, help debug it. But if you have an important job go with the latest official version.

I think that is what CD wants you to do. You don't want to find a bug while on a job. Just my opinion.

Thanks Olof.

MPG recording audio sync seems fixed
 

Hi all,

We've been testing the audio sync when recording lower bitrate MPG recordings (as viewing copies).
used to be 4 frames out, but now seems to be dead on and a lot more stable.

Still testing, but looking good for that improvement.

Thanks guys.

Regards

Dave

Dear Olof,

Exactly, thank you for making that clear.

Our Public Betas are to allow others to test the upcoming release.

While our testing is very exhaustive, we may miss something, and we do not have every camera in our lab.

And others may use the nanoFlash or Flash XDR differently than we do.

After testing the nanoFlash, for production we recommend going back to the Production Level releases.

Our next step is to release Production Level releases.