Data rates and FCP ..?

[Phil Beaton]

Hi, I'm newly registered although a long time lurker.

I'm working on my first broadcast spec video, aiming to deliver a file that can pass BBC1 / MTV etc standards and be transferred to digibeta tape. I shot using an EX1 with a NanoFlash set to 100mbs i-frame. I've just got a few worries regards editing in FCP (version 6.05 on a G5).

If I drop one of the nano files onto a new sequence, it sets itself to "XDCAM HD422 1080p25 (50 Mb/s)", but I shot at 100 Mb/s. Quicktime player's movie inspector says the data rate is 102.29 Mb/s. Should I be concerned about this? Also, in the FCP browser window, the nano clips are all listed as 12.2 Mb/s in the Data Rate column. What's going on there?

Is it safe to send clips to Shake from this timeline, or am I losing loads of Mb/s?

I opened a clip directly in Shake and exported it as "Uncompressed 10 bit 4:2:2". That's now showing up in FCP's browser window as 131.8 Mb/s.

Confused. Can anyone shed any light please? I really scared about screwing this job up.

[Piotr Wozniacki]

Hi Phil, and welcome to the board!

I'm not an FCP user (not even Mac - I'm editing on a PC using Vegas Pro), but out of the bitrate readings you quoted, only the Movie Inspector's 102.29 Mbps and FCP's "XDCAM HD422 1080p25 (50 Mb/s)" one looks "normal" to me (like many NLEs, FCP will report your nanoFlash clips as closest to what is handles natively).

The others I can't comment one, but I would pay too much attention to them anyway.

Happy nanoFlashing!

:)

[John Richard]

FCP incorrectly labels all nano and XDR files as 50mbps. If you look at the properties, the data rate tells you they what the original files really are.

The real problem with editing these high data rate files is when you apply any effect other than a simple cut, then the data rate gets knocked down.

There are several threads discussing how to deal with this editing. One way of dealing with editing other than simple cuts only is to start from the beginning of a project that is going to involve dissolves, color correction, etc. with setting the project up as a Pro-Res job. There are other methods as well that you should probably read in the various threads.

And it is annoying to see the mis-labeling of nanoFlash and XDR Flash files ... but then FCP really hasn't been kept up by it's maker :>{

[Ryan Johnson]

Hi, Phil

FCP only 'officially' supports up to 50 Mb/s, but will accept all of nanoFlash's video formats. But because of this, 50 Mb/s is the maximum number it will display. You do not loose any quality.

Quicktime player is displaying the data rate correctly. The extra 2.29 Mb/s contains the audio and the timecode.

In the FCP browser window, the clips are listed and measured in MB/s (Mega Bytes) as opposed to Mb/s (Mega bits). This is correct. If you multiply this number by 8, you get your data rate in mega bits per second. (8x12.2 roughly = 100). This is just how final cut displays the data rate in the browser window.

When you open a clip directly in shake and export it as uncompressed 10 bit 4:2:2, it does indeed export as uncompressed. But remember, in the FCP browser window, data rates are displayed in Mega Bytes per second as opposed to Mega bits per second. (Again, 8 x 131.8 MB/s = 1054.4 Mb/s which is uncompressed)

You have not lost this much quality, you have simply confused Mega bits (represented with a lower case 'b': Mb/s) with Mega Bytes (represented with an upper case 'B': MB/s). All is well.

[Phil Beaton]

Thanks folks, that's a huge relief.

I'll see if I can find those threads, but presumably Uncompressed 10-bit is overqualified here and I should render and export my finished file using a ProRes 422 sequence?

[John Richard]

Thanks Ryan for a far better explanation.

For normal editing in FCP (dissolves, color correction, effects, etc.) what work flow do you recommend to maintain as much original data rate quality with the various CD formats out of the nano and XDR files?

[Ryan Johnson]

Other editors on the forum may know better than I do about various editing strategies, but we have generally found that it works very well to use the XDCAM HD 422 Easy Setup for the timeline, then set the effects rendering to Apple ProRes (under User Preferences->Render Control). Then make sure that 'recompress all frames' is unchecked upon export.

The other option would be to transcode the video into your favorite CODEC for ease of editing and familiarity, but then again, that introduces another compression cycle which can slightly impact quality. It's really a game of trade-offs which is left up to the individual editor to decide.

-Ryan

[Ronald Jackson]

Does anyone know whether this "50Mb/s" apparent limitation applies also in FCP X?


Ron

[Gary Nattrass]

If you are going to digibeta then everything will be Ok at 50mbs anyway.

I don't think that is true regarding the 50mbs limitation as I am loading 100mbs AVC Intra 100 P2 material into FCP in native format and it comes out at pro res HQ at around 200mbs.

Note also that the mpeg 2 bit rates are different to mpeg 4 intra frame rates and as a rule 50mbs on mpeg 2 is the equivalent to 100mbs on mpeg4 intra frame.

[Piotr Wozniacki]

I don't know about FCP, but FWIW Vegas Pro up to version 9.0 "understood" the real bitrate and could smart-render to e.g. 100 Mbps output clips.

he current version is limited by the XDCAM HD 50 Mbps cap, and cannot render to anything higher...

Piotr

[Andy Mangrum]

Hello Everyone,

To maintaing the Quality of the originally recorded nanoFlash files this can be done in Final Cut, regardless of what bit rate is recorded or Codec (I-Frame or Long Gop).

Simply import your footage into a timeline, make necessary changes, and then Export as a Self Contained Movie and make sure "re compress all frames" is not selected, your output will reflect you original bit rate, such as 280Mb, or 100Mb. Simply whatever was recorded with the nanoFlash.

Also with the Addition of Final Cut Pro X, there is currently not an option to Export files as Self Contained Movie without re compression, so whatever codec is selected at the begging of the project Final Cut X will then render the files to, for Example Pro Res, XDCAM (50Mb), etc. at least these are the Option's at this present time.

Hope that Helps

Best Regards