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Alexa Blinking/Flashing Timecode


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Hey all, 

 

 

Getting into timecode and worried about whether I'm totally #$@%i@ things up or not. 

 

Followed and what a few mixers have told me (and searching on JW a bit) have told me that I could jam from the recorder to the camera and that it should be fine. Without a lockit box. However, the Alexa manual is kind of brief and doesn't mention this particular activity of the timecode. 

 

What I want to know is what the blinking Alexa TC means. After I jam from the recorder it (it being the TC numbers/digits) stays solid for awhile, but then goes back to blinking again. 

 

This recent production with the Alexa also had a lockit box, and when I used it it would stay solid generally (although sometimes it would go back to blinking unless I babysat the camera a bit to always make sure it stays solid). The AC was indicating to me the TC staying solid is a good thing. But is he right?

 

 

Anyways, thanks for the help. 

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If you are jamming then you need to double-check that the Alexa TC generator is set to jamsync and NOT in regen mode

Regen mode is used when you have a TC source (Lockit, ERXTCD etc...) constantly connected to the camara.

The problem you describe (TC blinking) happens when you have the camara in regen mode and you pull out the TC source 

Or when in jamsync mode and there has been a frame rate speed change .  

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Eric above is correct. The External timecode mode is now called Regen on the Alexa, according the v7.0 manual (pages 129-130):

 

ArriAlexatimecode_zpse2a2935a.png

 

I've never kept a close eye on it, but I can't recall the display ever blinking in the Regen mode, which is usually what I tell the AC to set it to when I give them a timecode box. Jam sync is only momentary, meaning it ignores the Lockit or SB-T source until it's jammed again. I'm not fond of the idea of just a jam, but I'm told the Alexa is pretty good at holding accurate timecode for a solid 5-6 hours.

 

http://www.arri.com/camera/digital_cameras/downloads.html

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If you are jamming then you need to double-check that the Alexa TC generator is set to jamsync and NOT in regen mode

Regen mode is used when you have a TC source (Lockit, ERXTCD etc...) constantly connected to the camara.

The problem you describe (TC blinking) happens when you have the camara in regen mode and you pull out the TC source 

Or when in jam mode and there has been a frame rate speed change .

It is exactly true as elksound stated above that the TC display blinks when in jam mode after a frame rate speed change,

When TC frame rate is set back to the project's default setting the TC display continues to blink, but in my experience (with current versions of Alexa firmware) the TC will remain accurate as it was previous to changing frame rates,

This has been a concern on shows with frequent frame rate changes, in which an on-board Lockit type device was not desirable,

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Nice to know that even when blinking the TC will remain accurate :-) I have found myself in this situation many times when the DOP tells the AC to change the frame rate and then changes his mind and then go back to projects default frame rate and as always they never tell you anything. Then after a while go back to camera to check if everything is OK and see the TC is blinking in the display  

Never had a complain from post so I assumed that the Alexa was holding it's TC after a frame rate change and the blinking TC is a kind of reminder 

Viva Alexa !

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I'm not fond of the idea of just a jam, but I'm told the Alexa is pretty good at holding accurate timecode for a solid 5-6 hours.

>>>

 

Dear Mark,

 

I did an Alexa shoot (two cams) jamming for six weeks, not a single issue. We jamed each time the camera was turned off though, ignoring this point that the camera keeps TC for about ten min... Jammed in the morning, visual check every now and then to see if the TC is blinking - in jamsync mode as rightfully pointed out it means tc needs to be re-fed. 

 

In six weeks there was not a single complaint from Pic Edit about bad TC... 

 

I initially fed Cantar TC to the GR2 and used it to sync cameras. Later, TC on the Cantar started drifting - 1 frame in 10 hours, so i kept the GR-2 connected to the Cantar and used the Ambient TC slate as 'TC carrier' - it was used to send TC to the cameras every now and then. 

 

-vin

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Here's the thing, with an Arri Alexa there is more than one area that needs attention in respect to frame rate.  Don't feel bad, even a lot of camera people are clueless to this.

 

There is a "Project FPS" setting, and there is a "Sensor FPS" setting.  Both affect several things.  

 

At the Arri's HOME screen, click on INFO, then press the FPS INFO button.  (Try it here on the Alexa Simulator and you'll see what information this displays:  http://www.arri.com/cn/camera/digital_cameras/tools/alexa_camera_simulator/alexa.html ).

 

For most projects we do these days, you'd want to see the Project FPS and Sensor FPS both showing "23.976."

 

As far as the REC OUT and MON OUT frame rates, it depends upon what subsequent devices the camera is feeding.  Those, of course, are not sound department areas.  However, having a mis-matched Project FPS and Sensor FPS does affect us, and it affects time code jamming. 

 

I first discovered this on a shoot that galloped into action without proper time for setup of either of the two Alexas.  I asked about frame rate and both ACs assured me that the cameras were set correctly, which was 23.976.  I tried a couple of quick runs at doing a proper time code jam, but I only had about five-to-ten seconds (literally, I'm not exaggerating), and each time neither camera would accept the jam. 

 

Finally, when we (the ACs and I) had a five minute chance to go into the menus, I discovered that the "Project FPS" and the "Sensor FPS" did not match.  We set the Sensor FPS to match the Project FPS rate, and things worked fine from then on. 

 

As far as the issue of a time code reset following a power cycle, here's a short section from one of the Alexa supplements: 

 

"Timecode int. free run is lost when running off-speed and swapping battery
With asynchronous recording, i.e. "Project frame rate" NOT EQUAL to "Sensor fps" and timecode set to INT FRERUN, the timecode will be reset to 00:00:00 after reboot."

 

It actually gets even more complicated than this as there are settings that can allow the Sensor FPS to follow other settings, but hopefully the bit of information above can help us better understand the simple world of digital (well, there were many people who proclaimed how much simpler workflow would be once everything changed to digital -- so this MUST be simpler, right?). 

 

Perhaps it's time we redefined the word "simpler." 

 

If anyone can add more clarity to the above (not speculation, clarity), please do so.

 

 

 

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I initially fed Cantar TC to the GR2 and used it to sync cameras. Later, TC on the Cantar started drifting - 1 frame in 10 hours, so i kept the GR-2 connected to the Cantar and used the Ambient TC slate as 'TC carrier' - it was used to send TC to the cameras every now and then. 

 

1 frame in 10 hours is great! I've encountered AC's who insisted on jam mode, and others who would voluntarily go to external, and it worked both ways. One of them was wary of external because they were sure the camera would glitch if we disconnected it or the cable got bumped. We tested it, and (this was a couple of years ago) my memory is that the camera kept chugging along and just updated the timecode on its own. I've had zero problems with TC on an Alexa, with the only exception that it sometimes goes to 00:00:00:00 right after a speed change. I believe Arri eventually caught that bug and fixed it. 

 

This also follows the "Project Timecode" and "Sensor Timecode" note from John above. The Red Epic/Scarlet is another camera that has a "project" timecode and then a separate frame-rate. Several times, I've run into flashing TC windows, all because the AC wasn't aware that if the project and frame rate were set differently, 23.976 could be regarded as varispeed. 

 

I believe the Alexa can now do a speed ramp (continuous varispeed from 48fps to 23.976), but I think all bets are off for sound sync -- it'd have to be manual. 

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  • 2 weeks later...
  • 1 month later...
However, the Alexa manual is kind of brief and doesn't mention this particular activity of the timecode. 

 

What I want to know is what the blinking Alexa TC means. After I jam from the recorder it (it being the TC numbers/digits) stays solid for awhile, but then goes back to blinking again.

 

The Alexa manual is actually reassuringly thorough in its explanation of jamming: have you looked at the section titled 'Using Timecode' (under 'Operation of the Camera'), or are you just looking at the section that covers the Timecode menu...?

 

The TC flashes while the camera is jamming. It stops flashing when it is jammed. If it flashes again, that is because it is attempting to rejam (for various reasons, e.g. an external source is connected or the camera has lost sync). When the TC stops flashing, you should remove the external source. If it flashes after that, there is a problem.

 

There's normally extra information available on the Info screen - press the Info button during the process and the camera will tell you if it's jamming, jammed etc.

 

When people say that a jammed Alexa will drift 1 frame in 8 hours (as per the manual), it needs to be borne in mind that this inaccuracy is in addition to the inaccuracy of the sync box or audio recorder. E.g. if a Nomad (1 frame in 6 hours) and an Alexa (1 frame in 8 hours) are jammed, then the 'drift' could clearly be over 2 frames in 8 hours (if they drift in the opposite direction from one another!). So if you want to stay within a frame, you should plan on a mid-morning and mid-afternoon jam as well as post-breakfast, post-lunch (at least every 3-4 hours with the equipment in this example).

 

In actual use, most people get away with jamming less often than that with no ill consequences since the maximum specified drift on both units in opposite directions will only happen occasionally. There's already a degree of innacuracy implicit in feeding external TC without Genlock, but if you want to be as tightly sunk as possible (and depending on the manufacturer, the 1 frame in x hours spec might be a best case scenario rather than a worst case scenario), one jam after breakfast, one after lunch is inadequate.

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