What rec frame rate & bit rate would u choose ?

will-3 wrote on 4/4/2015, 12:18 PM
When shooting a talking head in studio what Record Mode would you choose for your cam?

1080/60i FX (24 Mbps)
1080/60i FH (17 Mbps)

1080/30p FX (24 Mbps)
1080/30p FH (17 Mbps)

720/60p FX (24 Mbps)
720/60p FH (17 Mbps)

Beyond image quality I guess the issue would be the demands it would place on the editing PC.

For net video why would you need 60 frames per second?
And will anybody be able to see the difference in 24 Mbps and 17 Mbps?
And what about 720 vs 1080 ?

Ditto if in studio and shooting on a chroma key set.

Thanks for any help.

Comments

astar wrote on 4/4/2015, 12:39 PM
Depends on what your output / display format is going to be.

I mostly shoot in 1080p@30fps with the highest bite rate the camera has. Then batch render the trimmed footage to XDCAM-ex for timeline editing. XDCAM has much lower system requirements, and is highly optimized in Vegas when compared AVC.

For the Keying work, search the forum for other posts on the subject. There are plenty of tips and links of things to consider. Shoot the highest bitrate and progressive, and do the compositing from the camera AVC file. If your camera supports uncompressed hdmi out, get a Blackmagic Intensity card or shuttle and capture that route. Bypassing the AVC codec in the camera will give you a cleaner composite edge. You would need to make sure camera is actually outputting uncompressed, and not just feeding the HDMI post compression. Shooting with a camera that has 10-bit or 12-bit color capture would be more optimized.
johnmeyer wrote on 4/4/2015, 12:41 PM
The only way to know for sure is to test. Upload a few clips to whatever online streaming site you are using, and then judge for yourself.

The problem with providing a more concise answer is that when you upload for streaming, the video is re-encoded, and it is really tough to make general statements about what degradation this will do to your video, and whether differences that might be seen before uploading will still be noticeable in the final, streaming result.

As for framerate, a lot of streaming sites don't provide fast frame rates. I often watch ESPN online, and it is quite obvious that their video is, at best 30p.

So, you really have to do your own tests.
will-3 wrote on 4/4/2015, 3:58 PM
Thanks guys. We have decided to go with 30fps for now. 1080p most probably. Highest bit rate probably.

We have already ordered the Blackmagic shuttle and associated stuff. All but the connecting SDI cable will be here Monday I understand.

And John, we will run some experiments

Thanks astar & John as always.


videoITguy wrote on 4/4/2015, 4:21 PM
When you are talking green -screen several exposure processes apply - especially if you are shooting the foreground and background in controlled separate environs.

The rule is open the camera shutterspeed to max without creating motion blur - this could 1/48 sec instead of 1/60. 1/30 sec is probably too much.
will-3 wrote on 4/4/2015, 4:46 PM
We will experiment with 1/48 videoTguy. In the past when we did this (way back) we used 1/60.

farss wrote on 4/4/2015, 5:39 PM
If you're wanting to do a lot of fast turnaround chroma keying I'd also suggest looking at using a complete hardware solution such as BMD offer with their vision switchers and there's also a card from Crystal Vision.

Bob.
musicvid10 wrote on 4/4/2015, 9:15 PM
Talking head doesn't need either a high frame rate or bitrate to maintain optimal quality.
Jerry did some tests below 1.5 Mbps (delivery bitrate) and they were acceptable.