Specific advise on codec and bit rate

[Steve Kalle]

Originally Posted by Ron Little

Dan, I just wanted to check back in to let you know that the green screen shoot at 100mbps went well. It was the easiest key I have ever pulled. It is 100mbps from now on.

The Nanoflash is a great product but your service is above and beyond.
Thanks Ron Little

Hi Ron,

With an EX1, greenscreen & Rycote wind muff, I have spent countless hours testing and comparing the 35Mb SxS to the nanoFlash recording at 50 & 100 L-GOP and 220 & 280 I-frame (using AE CS5 and Keylight). I did not see any difference in quality between all formats but the amount of noise was certainly higher in the 100 L-GOP and both I-Frame formats. Also, the keying was not any easier in any format. The key to keying (pun intended) is lighting (my Kino's really make a difference).

PS Anyone using Premiere Pro CS5 should be careful with nanoFlash footage due to PPro's memory leak which has been documented by me and others in prior threads. Also, PPro and AE CS5 can handle all MXF HD formats/bitrates from the nanoFlash.

[Dan Keaton]

Dear Steve,

Hasn't the memory leak in CS5's After Effects been corrected in later releases?

[Steve Kalle]

Originally Posted by Dan Keaton

Dear Steve,

Hasn't the memory leak in CS5's After Effects been corrected in later releases?

Hi Dan,

I'm running the latest version of CS5 (5.0.3) and I still must close and re-open PPro when importing more than 10GB of nanoFlash files. I remember testing CS5.5 a long time ago and I think it worked but I had another issue (I can't recall what, but I dropped 5.5 because of all the problems overall).

[Dan Keaton]

Dear Steve,

Thank you for the update.

What camera are you using as the source for comparing 35 Mbps SxS (4:2:0) and our 50 Mbps or higher 4:2:2 files?

Also, if the difference is not visible, how are you monitoring the images?

And are the image comparisions from still images, or is there motion in the images?

[Ron Little]

Hi Steve, thanks for your 2 cents worth. I found the 100mbps to be a lot easier to key than the 50 mbps clips. All clips were shot on the same screen and the 50 mbps clips took more fiddling to get the same results. I got good results with both and the clients were happy, I got paid so I was happy. For me the 100mbps was an improvement.

[Steve Kalle]

You got paid - definitely what matters :)

What camera are you using with your nano?

[Ron Little]

Sony V1, it has served me well. It is being replaces with a Nex-FS100.

[Ron Aerts]

Ron, did you work with progressive or interlaced recording?
Dan, When does one choose for I frame and when for LongGOP? is there some kind of base rule?

[Dan Keaton]

Dear Ron:

Here are my recommedations:

For low bit-rate needs:

35 Mbps Long-GOP (which is 4:2:0)

For broadcast origination quality: (all of the following are 4:2:2)

50 Mbps Long-GOP

Then in order of increasing quality or extra insurance to handle lots of detail or movement:

80 Mbps Long-GOP

100 Mbps Long-GOP

Then, above 100 Mbps, I recommend I-Frame Only

140 Mbps I-Frame Only
180 Mbps I-Frame Only
220 Mbps I-Frame Only
280 Mbps I-Frame Only

Please note that 100 Mbps Long-GOP is very good.
There is a law of dimminshing returns as one uses bit-rates higher than 100 Mbps.

Please note that older versions of Avid support both 50 Mbps Long-GOP and all of our I-Frame Only flavors, but not Long-GOP over 50 Mbps.

[Ron Little]

I use progressive all the time unless, a client request something else.
For green screen progressive is the way to go.

[Ron Aerts]

I'm in recordings of a feature movie and people tell me to use the highest possible. I'm using 280 I frame. But it slows down the workflow, specially in backing up etc. There will be done some serious grading, Which I'm not so familiar with the results. Other thing is that there will be quite some nightshoots and other dark environments, using only lightsources of the surroundings. A lot of attention for careful use of max lattitude range.
I discovered the 100GOP sweetspot a time ago and guts tell me this would do the trick as well. Also quite some steadicam work.
still a bit tricky to decide what to do.

[Steve Kalle]

Originally Posted by Ron Aerts

I'm in recordings of a feature movie and people tell me to use the highest possible. I'm using 280 I frame. But it slows down the workflow, specially in backing up etc. There will be done some serious grading, Which I'm not so familiar with the results. Other thing is that there will be quite some nightshoots and other dark environments, using only lightsources of the surroundings. A lot of attention for careful use of max lattitude range.
I discovered the 100GOP sweetspot a time ago and guts tell me this would do the trick as well. Also quite some steadicam work.
still a bit tricky to decide what to do.

What camera are you using? This makes some difference because high noise cameras and >100Mb L-GOP do not work well together due to the way the noise gets recorded. However, all of the I-frame bitrates work great with noisier cameras like the EX1/3. Also, with low noise cameras like the FS100 & F3, you don't see any benefit from very high bitrates. I have read about a fellow DVInfo'er that he used the 80Mb/s L-GOP with 10+ F3's for a concert which was a great combination of higher bitrate with low enough size that backing up at the end of the night wouldn't take forever.

[Ron Aerts]

That must have been Allister C. I'm using the PMW F3. Hard to find any noise, even at +12dB gain.
Although it's the grading I'm worrying about