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Arri Amira


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Anyone else notice a -2 frame offset on the camera is needed to match slate?

 

I had a 1 frame offset on my last Alexa job, and we solved that with no problem (on the 788). Be sure to tell them this is a camera problem due to processing delays in the video. Typically, sound gets ahead because picture is delayed. If it's constant, they should just manually compensate... but there are always assistant editors who whine.  ::)

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I had a 1 frame offset on my last Alexa job, and we solved that with no problem (on the 788). Be sure to tell them this is a camera problem due to processing delays in the video. Typically, sound gets ahead because picture is delayed. If it's constant, they should just manually compensate... but there are always assistant editors who whine.  ::)

is the offset the video processing or the processing of the display panel on the camera? i've heard both tales

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is the offset the video processing or the processing of the display panel on the camera? i've heard both tales

 

My experience is that it's video processing, but it's just my opinion. It never hurts to do a camera/sound test, pull the files out, sync them up on a laptop, and see where the timecode numbers come up. There's camera timecode, the slate timecode in the picture, and then there's sound timecode, so there's at least three ways things can go wrong. All the editors I work with generally understand that if there's just a 1-frame offset, they can compensate for it in their set up and still automatically sync 99% of the takes. They still have to check the claps anyway as standard procedure.

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Huh, the Amira I'm working with seems fine with 0.500v. Can you link the Facebook thread? I'd love to read it.

 

I don't know how to link the FB post, but Gene Martin posted in the Zaxcom group: "New Arri Amira needs to be set at 3v on the ERX time code to really lock on. Was using it at 2v for the first few days, but was getting a sync error occasionally. No issues after the 3v change." 

 

There are over 30 comments, but most stray off topic. His picture is of the modified ERX with the BNC, so it should be a good connection. I don't think anyone responded that had used something like a Denecke or Ambient sync box to see if they were ok with stock settings. 

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I just did a shoot with two Alexas.  They each jammed fine via an ERX.  I believe the output voltages were both set at one volt.  I have also jammed Alexas with Denecke SB3a sync boxes with great success.  My SB3a boxes are around 1.25v RMS.

 

If an Alexa doesn't take a jam, first check all the settings.  If it still doesn't take a jam, make sure that the sensor rate is set correctly -- note the following from the Alexa manual:

 

"Ext LTC    TC is read from the LTC input. Only possible with Mode set to Free Run, and the project fps must match the sensor fps setting!"

 

 

 

 

 

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  • 4 weeks later...

Had a chance to test the audio on a couple of Amira's (Amirae?) a few days back.

While the feature set is very good, I had trouble lining up tone on the camera.

There didn't seem to be enough attenuation on the level controls available to get a 0dBu 1KHz line level tone, to line up at -18dB on the Amira meter.

The result is that the audio was way too hot with insufficient headroom available.

 

Interesting thing is that the two cameras were running slightly different firmware.

On the older firmware, there was a greater level of gain adjustment available and the signal could be lined up properly, whereas on the newer firmware it was not possible.

 

Inputs were set to LINE and both cameras had been reset to factory settings. The audio controls and routing were then configured suitably.

 

The only solution seemed to be to reduce the level of the tone being sent to the camera.

 

Has anyone else encountered this yet?

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Glad its not just me then!

What I found surprising is that the more recent firmware introduces this lack of headroom.

I contacted Arri support about this and they supplied a small post from the engineers in Germany:

"The observation is correct, the available attenuation factor was reduced between the two software packages.

We did this because the camera does in fact only accept levels up to +8dBu. This is a limitation of the current hardware design.

 

SUP 1.0.06 indeed offered to set -18dB through the user interface but the actual attenuation available in the analog part before the DSP is only -6dB, the remaining was attenuated in the digital domain. This left users with the impression that they could safely input 24dBu while the signal in fact was already clipping. If the recording wasn’t properly monitored, the chance of bad results was rather likely to occur.

 

The current setting with SUP 1.0.11/1.0.15 represents the options more accurately. If you intend to feed 24dBu line level into the camera you will need to use a physical attenuator to make sure clipping won’t occur. For 8dBu input level an attenuation factor of -6dB has to be set in the UI to avoid clipping. 0dBu line level leaves you with 8dB headroom."

 

So my interpretation of this is that the choice/design of the hardware was rather poorly conceived and so they are having to compensate via a software/firmware solution.

 

Something for everyone to be aware of. I can't see it changing as it is a hardware problem.

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Glad to see that they stayed with the 5 pin audio inputs (with AES too, although I have only used it rare occasions for camera feeds). At least I don't we don't have to make yet another set of cables!

 

Anything that knocks the RED Epic out of market is a good thing as far as I'm concerned...

 

--S

I've heard that the angle of the 5 pin XLR isn't the same as the Alexa, and those of us that have the 90 degree connector facing up (Remote audio umbilical), won't work on the Amira. 

 

Anyone confirm this?

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