Re: [Avid-L2] timecode offset double-system jam sync

I don't know, Jay. I've owned and used Sound Devices products for 15 years or so, and their timecode-equiped recorders for close to 10. I also work with but don't own recorders from Zaxcom (the makers of the DEVA and other recorder/mixers, and some pretty cool wireless systems) for about as long. In my experience Sound Devices provides great tech support, acknowledges and fixes problems, and goes out of the way to keep customers working; think AJA or Marianna. My Zaxcom-based buddies say the same about Zax.

There are some real differences between the companies and their products. And both Zaxcom and Sound Devices products do occasionally break or screw up
(and a few over-excited users of each company's products slags the other for sport). But in my experience, and that of soundies in my circle, timecode on both is stable and reliable. The same cannot be said for most cameras, Arri Alexa excepted (btw- IIRC, both the Alexa and all Sound Devices recorders use TC technology from Ambient). As for the metadata around that timecode, and NLEs' interpretation of that metadata…we'll get to that.


So what prompted Jay's sync problems? Got me, but here are a few guesses:

**Perhaps the Sound Devices 788T is broken.
I doubt it, but a quick call to Sound Devices will help determine that; and SD has a loaner program that can keep your mixer rolling while his recorder gets repaired.

**Perhaps there's some 788T firmware problem that's been fixed.
You can read about and download the latest here:
http://www.sounddevices.com/products/788t/downloads/

**Perhaps as Mark and Bouke suggest, there's some feature that can be triggered in such a way as to cause TC problems.
Haven't bumped into one myself, but could be.

**Perhaps there's some issue with the way the 788T writes metadata or the way MC reads that metadata (FCP has its own issues).
Here are two different (and long and not recently re-read by me) discussions on the exact same occurrence of such an issue issue (in this case with Zaxcom playing the bad guy, iirc):

Avid users discussion:
BUG: Match alternates out of Sync to AAF
http://duc.avid.com/showthread.php?p=2094420

Location sound discussion:
Conformed original BWAVs are out of sync by up to a frame compared to the AAF
http://jwsoundgroup.net/index.php?/topic/19496-conformed-original-bwavs-are-out-of-sync-by-up-to-a-frame-compared-to-the-aaf/

**Perhaps the guy using the Sound Devices 788T sent only TC to the camera, but not sync. So while the camera recorded the SD TC somewhere, it used its own crappy clock to "lock" its frames…and then during battery changes or other power downs, the camera came back with its own TC that inconsistently varied from the SD TC. And perhaps the mixer using a Zaxcom Deva sent TC and genlock so the camera used the Deva's TC to regulate its own clock throughout the day.

Like all of us, I occasionally see production and post both dodging responsibility for issues that really are their's to avoid and/or fix. And I occasionally screw up. But seems like this issue should be addressable in the field. I don't think abandoning Sound Devices equipment is the key step.

I could be totally misreading or misunderstanding Jay's issue. But based on my limited knowledge, this is what I think.


On Jun 26, 2014, at 11:21 PM, Michael Brockington brocking@sfu.ca [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

> They did another test, which looks more reasonable. After turning camera and sound recorder off for an hour, there's about a 3 frame timecode offset. After re-jamming, that drops to 1 frame. Not clear why such a drastic change, but at least its getting better...


Hmmm. Glad the situation's improved. One frame isn't so bad for a Sony camera…but I don't know if I'd expect the difference to remain the same from hour to hour. If it were my production, I'd want a box sending TC and sync attached to that camera. But it's not my production. Good luck.


That's more than enough from me. Back to work...

jim feeley
pov media
word image sound





On Jun 26, 2014, at 12:41 PM, Michael Brockington brocking@sfu.ca [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

> Thanks for clarifying that. It looks pretty rare for you to see it
> slipping by more than 13 perfs (~3 frames). So it does sound like the
> 12 frames of slippage I'm seeing are likely due to some other factor.
>
> Thanks,
> --Michael
>
> On 2014-06-26, 12:02 PM, Jay Mahavier jay_mahavier@earthlink.net
> [Avid-L2] wrote:
>> Ok, let me start by saying I totally screwed up when I said frames. I never should have said frames. It's all perfs that things are off by. I'm very sorry about that, but that being said.
>>
>> it's kind of goofy. The average will usually drift greater and greater over the day, and they re-jam after lunch. But from take to take it will still bounce around a perf or two, but then you will get the oddball that is like 4 extra perfs out, or even an adjustment the other direction. So following is a list an actual day of shooting in day order with the amount of slip I had to apply for each sync clip.
>>
>> -5,- 9, 0, 0, -7, -7, -4, 0, -5, 0, 0, 0, -7, -6, -6, 0, 0, -6, -7, -6, -4, -6, -9, 0, -7, -6, -5, 1, -14, -7, 0, -5, 0, -5, -5, -2, -3, -5, -13, -4, -3, -12, -6, -4, -6, -12, -7, -10, -7, -12, -7, 0, 0. -3, 0, 0, -4, 1, 0,
>>
>> Ugh!
>>
>> and then the day we used the Deva recorder
>>
>> 2, 0, 0, 0, 0, 0, 1, 0, 2, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 1, 0, 0, 0, -1, 1, 0,
>>
>> I prefer the Deva.
>>
>> Jay
>>
>>
>>
>>
>> On Jun 26, 2014, at 12:42 PM, Michael Brockington brocking@sfu.ca [Avid-L2] <Avid-L2@yahoogroups.com> wrote:
>>
>>> Thanks for chiming in, Jay. When you say it bounces around, will it
>>> change that much from 1 take to the next, or will you have a continuous
>>> string of takes with, say a 8-frame offset, then another string with a
>>> 12-frame offset later in the day?
>>>
>>> Thanks,
>>> --Michael
>>>
>>> On 2014-06-26, 10:14 AM, Jay Mahavier jay_mahavier@earthlink.net
>>> [Avid-L2] wrote:
>>>> I think the problem is that they are using a product from Sound Devices. They set mixer we have worked with for the last few years uses a Sound Devices product. The 788 I believe. I have never had good luck with getting that thing to jam TC. I don't know what the problem is but it sucks. We have jammed our cameras to the Sound Devices machine both by jamming their internal to the SD box and also using Clock-Its. And it's always all over the place. Anywhere from 2 to 12 frames on any given take, but it bounces around. Usually about 5 frames off.
>>>>
>>>> On the other hand, on those occasions that our regular guy is not available, we have used a couple of other people who use Deva recorders and those things are solid on the TC. When I get my audio from a Deva box it's about a quarter of the clips that I usually end up perf-slipping 1 perf. And of those about a quarter get slipped 2 perts. But 3 perf slips are rare if the audio is from a Deva box.
>>>>
>>>> So all I can say is avoid the gear from Sound Devices if you can. Use Deva gear if you can.
>>>>
>>>> Jay
>>>>
>>>> On Jun 25, 2014, at 5:18 PM, Michael Brockington brocking@sfu.ca [Avid-L2] <Avid-L2@yahoogroups.com> wrote:
>>>>
>>>>> I have a test that was shot for me, audio recorded on a sound
>>>>> devices 633, wirelessly transmitted to a F55. Timecode from the 633 was
>>>>> used to jam sync the F55. Timecode on the first audio clip starts at
>>>>> 12:08:50:00.
>>>>>
>>>>> Problem is when I line up the audio waveforms, the timecode on the
>>>>> 633 audio is 15 frames ahead of the camera timecode. This was a test,
>>>>> so there was no great amount of time elapsed between jam-syncing and
>>>>> recording. The total time of the test is about 8 minutes, with the
>>>>> camera and audio recorder starting and stopping twice. Sync appears
>>>>> solid over the 8 minutes, and the 15-frame gap in timecode is consistent
>>>>> from head to tail.
>>>>>
>>>>> Any guesses as to what might be going wrong, here? Doesn't look
>>>>> like an obvious timecode rate mismatch between the 2, for instance.
>>>>>
>>>>> Thanks,
>>>>> --Michael
>>>>>
>>>>>
>>>>> ------------------------------------
>>>>> Posted by: Michael Brockington <brocking@sfu.ca>



------------------------------------

------------------------------------


------------------------------------

Yahoo Groups Links

<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/Avid-L2/

<*> Your email settings:
Individual Email | Traditional

<*> To change settings online go to:
http://groups.yahoo.com/group/Avid-L2/join
(Yahoo! ID required)

<*> To change settings via email:
Avid-L2-digest@yahoogroups.com
Avid-L2-fullfeatured@yahoogroups.com

<*> To unsubscribe from this group, send an email to:
Avid-L2-unsubscribe@yahoogroups.com

<*> Your use of Yahoo Groups is subject to:
https://info.yahoo.com/legal/us/yahoo/utos/terms/