Caution—ProRes corruption on power loss

[Trevor Meier]

A caution if you're recording ProRes alongside R3D: In doing my battery testing I let the camera run until the batteries completely died. This would lead to multiple Quicktime files (they max out at 4GB, like the R3D files). Generally, the first Quicktime clip was fine, but whatever Quicktime was being recorded when the power died was corrupted and unusable. This was not true of the R3D files—they were usable.

Just a fair warning in case you run into this situation!

 

[Kristopher Colavecchio]

Appreciate the heads up!

 

[Nick Morrison]

This makes sense.

Most QT's need to finish "writing" in order to be playable/usable - whereas the R3D's seem to build/save sequentially in smaller bits, making them pretty robust.

We had an Epic Dragon surprise us with a power fail recently (battery wasn't as full as we thought), and though we went down mid take (a 10min interview), we lost NOTHING.

The mag wasn't playable in camera.

But it was recoverable later on the DIT station, and media was totally usable.

We were very, very impressed.

 

[Matthew Quinn]

I gotta say. the prores thing is amazing

 

[Marc Wielage]

It's too bad the camera can't sense the lack of power coming and just write an end of file marker, close out the file, and then shut down.

 

[Nick Morrison]

It's too bad the camera can't sense the lack of power coming and just write an end of file marker, close out the file, and then shut down.

Don't most Prores cameras have this issue though? I was always under the impression this was a very hard thing for Prores recordings todo...

 

[Matt Bass]

It must be a Pro Res thing because Arri cameras totally kill ProRes clips if the battery dies. Its a HUGE HUGE bonus that the RED R3D files are recoverable, you can always make a ProRes file from the R3D.

99% of the time I have seen the RED warn you that the power is going to shut down in 30seconds, again another HUGE bonus. The only time I have seen the camera just shut off in low power was because the actually battery was faulty or near the end of its lifecycle, perhaps that battery needs to be replaced.

 

[Phil Holland]

Don't most Prores cameras have this issue though? I was always under the impression this was a very hard thing for Prores recordings todo...

Yep. This is actually more due to how ProRes is written while rolling.

It's too bad the camera can't sense the lack of power coming and just write an end of file marker, close out the file, and then shut down.

Possible. Something with auxiliary power or a hot swap solution is nice (DSMC2 REDVOLT Expander comes to mind). But even in the case where the camera itself has some sort of small battery to help protect from this occurring it's still possible.

The way it works right now is if the camera is up and power is draining to dangerous levels it will stop your recording and shutdown.

If you yank on the tail or slap off a battery, that's where the concern is specifically with ProRes and DNxHR.

 

[Patrick Tresch]

Thanks for your test Trevor!

This could be adressed by writing small batches of Prores files every 10sec up to the moment it reaches a 4gb block and then start over again.

This could be a major problem for those who shoot RED in "Prores only" mode.

Pat

 

[Filipe Abreu]

I use the Convergent design when writing Prores, and every time i have a power down problem, when the recorder has power again it finishes the Prores file. I never ever had a corrupt prores file. So i think Red can do the same thing. I am not a programmer, but i think it can be done.

 

[Nick Morrison]

99% of the time I have seen the RED warn you that the power is going to shut down in 30seconds, again another HUGE bonus. The only time I have seen the camera just shut off in low power was because the actually battery was faulty or near the end of its lifecycle, perhaps that battery needs to be replaced.

I don't think we've ever seen that warning - is that only for batteries with RED communication protocols?

I use the Convergent design when writing Prores, and every time i have a power down problem, when the recorder has power again it finishes the Prores file. I never ever had a corrupt prores file. So i think Red can do the same thing. I am not a programmer, but i think it can be done.

Good to know!

 

[Scotty Kunkel]

If Blackmagic can do it, Red should be able do it =P

 

[Trevor Meier]

In this case, I'm running with batteries that don't report their info, just a voltage level (Bebob). So the camera didn't stop the recording before shutdown like Phil says, hence the corrupted ProRes files. Not a big deal - it's behaviour I would expect - but just good to be aware of.