Retaining high bitrate data in XDCAM HD using FCS

Would like to know if the editors here have found a way to guarantee retention of the high bitrate source data that one can get from nanoFlash recorders.

A brief summary of the matter for those unfamiliar.... NanoFlash units are able to capture video source from either HD-SDI and HDMI and record it into (primarily) LongGOP XDCAM HD or iFrame. The problem, as I understand it, is in Final Cut when you have XDCAM HD source data in your sequence that is above 50Mbit it will re-render the altered data into nothing higher than 50Mbit.

My solution to this on a theoretical level is to take the source data from the NanoFlash and convert it with Compressor to Apple ProRes HQ.

What I would like to determine is, does this Compressor conversion actually retain data in a form above the 50Mbit threshold that FCP imposes or is the data in Compressor crunched down to 50Mbit and then simply up-rezed in the process of conversion.

-Andrew

Hi Andrew,

Did you ever solve this problem? We recorded using the Nanoflash at 100 Mbps and would like to retain this quality. We are going to convert the media to Prores for editing since the XDCAM codec has caused some MAJOR crashing issues. I have just become aware of the FCP 50Mbits threshold as being an issue and am curious if you found the answer to your below question.

Also, wondering if you have a suggestion as to the best prores to use to retain the higher data rate.

Thanks,
Jen

Hi Jen,

Converting to ProRes is your solution. If you have a lot of footage and have to do an overnight render, may I suggest you start your edit with your nanoFlash material but just do cutting and then do a reconnect media to the ProRes stuff once you do your overnight render.

Even though it is a lot more space consuming I am using iFrame 220 when I can. If it is long event stuff I don't even both with the nanoFlash for primary recording. I will use it as a backup and record at a lower bitrate. Use ProRes HQ and, of course, set your timeline to render in 10bit and high precision. It makes a huge difference with high bitrate material particularly with transitions, grading, titling, layering, etc. Other simple things like closing down unused sequences and other apps will free up memory. Can mean the difference between a rude computer crash or not.

Cheers,
Andrew

We are planning on converting to ProResHQ - but I am still wondering about the FCP 50Mbits threshold. Does this apply when rendering out a prores sequence or is this specific to the XDCAM codec?

Jen

I have received no word on this. I have posed the question a couple of times to the people who would know (or know the people to ask) and the reply has been silence.

If there is a 50 Mbit cap in FCP (Quicktime) it would be with the XDCAM codec. If you go iFrame it shouldn't have that potential limitation and the workflow is better in my view. The only negative is the file sizes are bigger and you have to go with a higher bitrate to get the full goodness of the 422 color and less artifacts & macroblocking

If you have recorded it in LongGOP XDCAM, I wouldn't loose sleep over it. 422 50 Mbit is good enough for most broadcast outlets, just go for it and convert to ProRes HQ.

-Andrew

There is no bitrate limitation in FCP. Bitrates are determined by the codec. Render to prores, or even better, uncompressed if you can handle the bandwidth and storage requirements. I haven't worked with the iframe codec, but it was created as an in-camera codec that does not use interframe compression. As far as chroma subsampling is concerned, you cannot get better than what you shot, but if you are doing effects work such as blur, rendering to a a less chroma subsampled format would be better, although it also depends on your delivery format.



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Thanks guys - much appreciated.

Do you have an opinion on whether ProRes HQ is overkill for regular EX3 material shot at 35Mbps XDCAM, 4:2:0, 8bits?

Or whether there is any merit in doing a conform to 444 for color grading? I have been told that 444 will allow colorists more latitude when working with the material, but if it was originally 4:2:0 is the difference enough to warrant the time and storage space required?

Jen

>I have been told that 444 will allow colorists more latitude when working with the material

What is your final deliverable? Most video delivery formats is chroma subsampled 4:2:2.



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