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HD Link Pro Audio Issue
I’ve been a longtime BMD user and promoter and the cards have been working smooth for me.
I’m now helping the Weinstein Co. with a new HD suite and I recommended the Decklink cards as usual.
Unfortunately, we’re having some very gremlin-like situation that is very hard to trouble shoot due to its random nature. Yeah, I know, it’s always like that, ain’t it?!Here’s the deal: HD link Pro card with dual HD-SDI support for PCI-e, HD link box to an Apple 23″ Cinema display (standard stuff), Quad Core Intel Mac Pro w plenty of RAM, FCP 5.1 and all the online updates. We captured BMD HDTV 1080p 23.98 PsF DVCPRO-HD for our offline.
The Audio keeps randomly making a noise as if the digital clock lost its sync or when you’re playing and forwarding a DAT tape. It makes that hollow phase shifted noise exactly like when cueing a DAT tape or if the audio clock lost its sync ref momentarily. If you’ve heard it you know what I mean. The visual graphic of the waveform is fine. And if I stop right when I hear one of those distorted sections and play it again right from that place, the audio is fine. But when I hit play again and let it go for about 30 sec to a minute it comes back.
The situation has gone from slightly embarrassing to very mysterious.
If this is a known issue, please inform me as to what the correct fixes are. If not, we have either a bad card or a bad HD link box.
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7 Replies
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Hi Erik,
This is not a known issue.
Can you please try monitoring your audio via a different method and then listen for the distortion? For example, if you always monitor your audio via the RCA analog audio outputs of the HDLink box, try using the analog or S/PDIF output of the DeckLink card to monitor audio and let us know if the distortion can be heard.
If you output audio via the Mac’s built-in speaker, can the distortion be heard?
These tests will help to determine if the problem is with the DeckLink card or the HDLink box or something else.
Regards,
Luke Maslen
Blackmagic Design -
I tried monitoring via the built in audio ports of the Mac and it’s fine. Tomorrow morning (LA time) I will bring in my DAT deck and monitor via the SPDIF to see if it’s the card or the HD link box that twists the audio.
I’ll keep you posted and let you know tomorrow.
Thanks for your quick response.
Erik -
Hi Erik,
That’s great as you’ve determined that the source material is OK so presumably there is an issue with the card or the HDLink box. That could be software or hardware so it will be good to know if you can hear the distortion in the S/PDIF audio to help further narrow down the problem.
Regards,
Luke Maslen
Blackmagic Design -
Hi Luke,
I hooked up the DAT deck and connected the SPDIFs directly and there’s no bad audio anymore. So logic tells me that the HD Link Box is bad somehow.What’s troubling beyond this particular instance is that this is the 3rd HD link box we had to replace. The other two had picture issues. Must be a bad batch due to glitchy components.
This is just information. Pass it on to who can make a difference.Thanks for your always quick help.
Erik Lundmark -
Hi Erik,
Thank you for your information. I’ve spoken with a HDLink engineer and it sounds as though this is probably fixable with a firmware update and we’re intending to release an update in about a month. We’ll need to replicate the problem in order to fix it and I think your original posting has all the details we’ll need to replicate it. We’ve got your email address so we can seed you a fix when it is ready to see if it helps with your HDLink.
Thanks for testing out the problem and narrowing it down to the HDLink audio. That’s a great help and we hope to have a solution for you very soon.
Regards,
Luke Maslen
Blackmagic Design -
I too am having a VERY similar problem. My HDLINK is one of the earlier ones. This product is fully up to date with the latest firmware etc and worked flawlessly for over a year. I now get garbled phase type distortion every 5-10 mins or so (sounds like an aphex twin remix). It lasts around 3-5 seconds and then clears. This is very annoying and not good when doing client previews. I have isolated to the hdlink box as I connected it from a deck to an amp only. The amp works fine with any other source and has been tested by an electrical engineer. I am glad I am not the only person with this issue. Any advice on this would be greatly appreciated.
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I hear you. My old box started doing it too.
And I thought it only was an issue with new boxes. Those were the ones I was installing at a post facility. My only thought is that the DA converter loses sync suddenly for some to me unknown reason. And since the old boxes are acting up as well as the new ones it must be some updated (changed) software that is causing the noise.
Needless to say, my clients are very dissapointed. I need to find another view-out solution as this one is too hard to trust.
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