Specific advise on codec and bit rate
 

With my nanoflash I ususally shoot I-Frame Only @ 220 mbps. I prefer I-Frame above LongGop for my workflow. Shortly I will be on an expedition with no access to mains and I will dump my footage on Nexto devices. I want to keep data rate lower during this trip and consider two options:

- Shoot LongGop @ 50mbps and transcode to Prores in post
- Shoot I-Frame @ 100mbps and work with this files in post

I understood well that quality of LongGop @50 should be better than I-Frame @100, but am not sure if that will still be the case when transcoded to Prores afterwards.

Does anyone have advise on which will give the best end result quality wise?

Re: Specific advise on codec and bit rate
 

Hello Cees,

What NLE are you using to edit your footage?

Best Regards

Re: Specific advise on codec and bit rate
 

Dear Cees,

Personally, I never recommend 100 Mbps I-Frame Only.

I would shoot 50 Mbps Long-GOP over 100 Mbps I-Frame Only.

140 Mbps I-Frame Only is ok to use.

100 Mbps I-Frame Only should be reserved for very unusual situations.

Re: Specific advise on codec and bit rate
 

My feeling is that if you have enough cards, go with 100Mbps Long-GOP. The picture will be that much better, and then Xfer to pro-res if you need to. Start with the best image you can afford! The nano at 100/LongGOP is excellent!

Re: Specific advise on codec and bit rate
 

If you are on expedition with a limited space on the Nexto, 100Mb/s maybe be risky. 50Mb/s is good (approved for broadcasting by BBC) but you may think that you haven't the best possible quality for your project. So the good compromise seems to be Long-Gop 80Mb/s! :)

You may also adapt the data rate during the shooting: 50Mb/s for interview, 100Mb/ for complex shots in nature with a lot of movements for instance…

Re: Specific advise on codec and bit rate
 

Thanks all. It seems 50-100 mbps LongGop is the way to.

Andy, I use Final Cut Pro 6.

Cees

Re: Specific advise on codec and bit rate
 

Dear Cees,

For Final Cut Pro, for you situation, 50 to 100 Mbps Long-GOP should work great.

If you have scenes with an excessive amount of detail, or excessive movement, then 100 Mbps is preferred.

If you were editing it older versions of Avid, then 50 Mbps Long-GOP would be preferred.

Re: Specific advise on codec and bit rate
 

Hello Cees,

Any Bit rate would work fine for Final Cut Pro,

Everyone has mentioned very good advice,

Thanks Everyone,

Best Regards

Re: Specific advise on codec and bit rate
 

I'd go the 80mbps long GOP, noticed a worthy jump in quality from 50, and you save space over 100. But at the end of the day, the size of your field back up will determine everything..

Re: Specific advise on codec and bit rate
 

I just finished a music video shot on green screen. I went with 50mbps long gop. Would 80 mbps be better for green screen?

Re: Specific advise on codec and bit rate
 

Dear Ron,

50 Mbps Long-Gop may work fine for you, for green screen work.

I would normally recommend 100 Mbps Long-GOP, unless one is editing in older versions of Avid.

Re: Specific advise on codec and bit rate
 

Thanks Dan. I have another green screen job coming up. I will give the 100mbps setting a try. I guess I should test it with CS5 before the job just to make sure I can edit it.

Re: Specific advise on codec and bit rate
 

Dear Ron,

That is always a good idea.

Re: Specific advise on codec and bit rate
 

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

Re: Specific advise on codec and bit rate
 

Dear Ron,

Thank you very much for your kind comments.

We try hard to provide world-class service 24/7.

Re: Specific advise on codec and bit rate
 

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.

Re: Specific advise on codec and bit rate
 

Dear Steve,

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

Re: Specific advise on codec and bit rate
 

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).

Re: Specific advise on codec and bit rate
 

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?

Re: Specific advise on codec and bit rate
 

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.

Re: Specific advise on codec and bit rate
 

You got paid - definitely what matters :)

What camera are you using with your nano?

Re: Specific advise on codec and bit rate
 

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

Re: Specific advise on codec and bit rate
 

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?

Re: Specific advise on codec and bit rate
 

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.

Re: Specific advise on codec and bit rate
 

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

Re: Specific advise on codec and bit rate
 

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.

Re: Specific advise on codec and bit rate
 

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.

Re: Specific advise on codec and bit rate
 

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