FORUMS: list search recent posts

My footage from Canon cam is ingesting at lower bit rate than was shot at. Why?

COW Forums : Canon Cameras

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Vic Noseworthy
My footage from Canon cam is ingesting at lower bit rate than was shot at. Why?
on Feb 17, 2013 at 3:42:39 pm

Hi folks,

I posted this same question in a different forum and didn't get a response. That may be because it's more of a "camera" question than a software question, so I thought I would post here. Here's my question:

I have shot some footage on a small Canon camera (specifically, a Vixia HF M400) and when I ingest (via log and transfer), the footage comes in at about 17Mbs. However, I shot it at a higher camera setting of about 24Mbs. Am I ingesting it incorrectly, or is there something I am not doing. I am using FCP7. Perhaps there's a Log and Transfer setting I don't know about?

Any help/advice you can offer will be tremendously appreciated.
Thanks,
Vic


Return to posts index

David Eaks
Re: My footage from Canon cam is ingesting at lower bit rate than was shot at. Why?
on Feb 17, 2013 at 4:33:24 pm

Log and transfer is bringing in the clips as Prores 422, which is about 17MB/s. Which is exactly what should be happening. You are on the right track, there is no need for a higher quality setting.

Your camera is recording AVCHD at 24Mb/s, log and transfer is making it into Prores at 147Mb/s (or 17MB/s). A matter of big B or little b. Notice that the Prores clips are much larger in file size than the original AVCHD clips.


Return to posts index

Vic Noseworthy
Re: My footage from Canon cam is ingesting at lower bit rate than was shot at. Why?
on Feb 18, 2013 at 6:15:45 am

Hey, David.
Thanks so very much for your help! I'm blown away that ProRes422 ingests footage at 147Mbs (which, as you indicate, equates to about 17MBs). I had no idea ProRes was so much higher in data rate than the Apple Intermediate Codec that I'd been used to. That's an astounding difference!
Many times I have inquired about the difference between AIC and ProRes, and nobody ever indicated such a vast difference in bit rate processing. I was told that I would not see any difference in quality (between the two codecs) because my camera (the Canon Vixia HF M400, which was the only one I had at the time) had such a low bit rate. However, I do a lot of compositing, so I was interested in maintaining as much quality as possible.
And, yes, I surely did notice the difference in file sizes.
So, why does ProRes have such a high bit rate when most broadcast quality cameras are really only shooting at about 50Mbs? (at least, that's my understanding). Is it because ProRes utilizes the much higher bit rate so as to maintain quality during editing/compositing?
Thanks again!
Vic


Return to posts index


David Eaks
Re: My footage from Canon cam is ingesting at lower bit rate than was shot at. Why?
on Feb 18, 2013 at 10:02:26 am

No problem! If I had to pick one thing to explain why Prores is higher bit rate, I'd say because its easier for your computer edit with it. Ever try to edit a 2 hour multicam clip with a few angles of H.264 (in an App that supports it natively)? Not so pleasant. Convert to Prores and its not a problem at all.

The 50 Mb/s cameras you're referring to are recording in a 422 codec, keeping that crucial picture information for grading, compositing etc. For higher end work they bypass in-camera compression via HD-SDI and record 444 or uncompressed externally. But that's getting out of my territory, I'm happy with shooting to Prores LT on my Ki Pro and editing in FCPX.


Return to posts index

Vic Noseworthy
Re: My footage from Canon cam is ingesting at lower bit rate than was shot at. Why?
on Feb 18, 2013 at 5:29:54 pm

Thanks, again, David. I hadn't heard of the Ki Pro, but just looked it up. Awesome, man! Sounds like you've got the gear! I'm gradually getting there, but am relatively new to HD video. Love it, though!
Perhaps you could answer one more question:
When I used to use AIC, my editing went smoothly, consistently. Now that I'm using ProRes, I occasionally get the message, " ...some frames were dropped..." I'm not sure what that means, or why I'm getting that message. I have heard that a computer doesn't have to work as hard with ProRes compared to AIC, so I'd have thought dropped frames would be even less likely.
Any idea why I'm getting this message?
Thank you again.
Vic


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]