FS700 , OQ7+, 2K pro-res 240fps aliasing?

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firehawk

Veteran
I've been reading about significant aliasing when shooting 2K.
I originally planned on shooting important footage in 2K ProRes that was intended for 1080P delivery, to allow me to shoot it wider and re-frame. Plus have a master 2K file for archive. Is this a bad idea due to aliasing? Is it really much of an issue?
 
Any aliasing comes from how the camera derives 2K from the 4K sensor. Please note that if you are recording 2K RAW on the Odyssey7Q+ you can get the full 2K frame and shoot at all available frame rates from the camera. If you are recording in Apple ProRes then the mode is 2K RAW HS->HD Apple ProRes, which means that the recordings are in fact in 1920x1080 and the only available frame rates are 100p, 120p, 200p, and 240p. For slower frame rates we recommend shooting 4K RAW->HD.
 
Thank you again, Mitch. You are very helpful and I appreciate it.
I understand aliasing is due to the camera and not the recorder :)
I think I have misunderstood the recording options.

I am interested in recording to compressed formats only and not super massive RAW formats.
If recording in HD, looks like pretty much all frame rate options are possible. BUt can the 7Q+ record 4K or 2K to a compressed codec, and if so, at what frame rates? And if so, will the recording be a bunch of files that have to be pieced together?

Thanks again for taking the time to help. I just recently started reading and learning about the FS700R and 7Q+ obviously.
 
The 7Q+ can record to ProRes (HQ, normal, and LT) in 4K or 2K. As far as frame rates, it can record ProRes to any of the frame rates the camera can produce, but you can choose your setup to optimize your footage for the best results.

For best results:

If recording 60fps or lower - you set your camera to output 4K RAW over the SDI, and then the O7Q+ will either record it in 4K or supersample it down to 2K. This way, you get all the quality of the 4K image, even in a 2K recording. Because the O7Q+ is handling the supersampling, this avoids all the aliasing the camera generates when it outputs at 2K.

If recording 120 fps - you can record the buffered 4K image from the camera to ProRes in the O7Q+. Granted, this only works if you can record in 4 sec chunks, due to the limitation on the buffer in the camera. Again, no aliasing will be introduced by the camera in this mode.

If you want continuous recording at 120 or 240fps, then you'll need to set the camera to output the 2K RAW, which the O7Q+ can record as ProRes. Unlike the two options above, because the camera is doing the downsampling to 2K. this is where some aliasing will be introduced. You just have to weigh your options to see if the 240fps or continuous 120fps is worth a bit of image quality loss.

And finally, you asked about the recording files. On the SSD, the recording will be split up into multiple files, each up to 4GB in size. However, Convergent Design has a free utility that will combine all those files into a single ProRes file for editing. It is an extra step in the workflow, but it doesn't bother me and I appreciate that the file system they use in the SSDs was chosen to maximize the Odyssey's power, stability, and compatibility.
 
Alan has answered quite in depth, but let me make a few additional statements.

Please understand that the difference between 4K v UHD and the difference between 2K v HD is only chopping off some resolution on the sides of the frame. Vertical resolution is untouched.

From the 4K RAW signal the Odyssey can derive Apple ProRes in 4K, UHD, 2K or HD. It can do so at 24p, 25p, 30p, 50p, & 60p.

The FS700 can output a short burst of 4K RAW at high speed, at 100p & 120p. The Odyssey can again record these in Apple ProRes in 4K, UHD, 2K, & HD.

One small correction to Alan's post. From 2K RAW the Odyssey currently only derives Apple ProRes in HD, not 2K. It can do so at 100p, 120p, 200p, & 240p.

One additional correction. The CD ProRes Transfer Tool does not have to be an "additional step." It can be used as the App to transfer files off of the SSD onto your computer. The process takes pretty much the same amount of time as any other way of offloading the files, but the material will all be stitched together in the process so that standard complete clips will result rather than clips being broken into 4G segments.
 
Thank you Alan and Mitch,
Very helpful!
So the separate/stitching of files occurs on any formats once size exceeds 4GB, regardless of whether you are recording to ProRes or to RAW?
So the 2K continuous 120fps and 240fps can currently only be recorded in the RAW format, right? And not to a compressed format?

Sounds like it's best to shoot everything in 4K mode and let the O7Q+ then process it to whatever size you need, since it will yield better results than having the camera do any downsampling. The only exceptions are the high frame rates in 2K where the camera will have to do the downsampling and thus introduce aliasing.

I'm excited about the ability to record to HD a superior downsampled 4K image that is better than if I just shot and recorded in HD normally without the O7Q+.
I see several real benefits and I think it's great the help I'm getting here.
Thank you
 
firehawk said:
Thank you Alan and Mitch,
Very helpful!
So the separate/stitching of files occurs on any formats once size exceeds 4GB, regardless of whether you are recording to ProRes or to RAW?
So the 2K continuous 120fps and 240fps can currently only be recorded in the RAW format, right? And not to a compressed format?

Sounds like it's best to shoot everything in 4K mode and let the O7Q+ then process it to whatever size you need, since it will yield better results than having the camera do any downsampling. The only exceptions are the high frame rates in 2K where the camera will have to do the downsampling and thus introduce aliasing.

I'm excited about the ability to record to HD a superior downsampled 4K image that is better than if I just shot and recorded in HD normally without the O7Q+.
I see several real benefits and I think it's great the help I'm getting here.
Thank you
Click to expand...

File stitching works for all recording formats. In fact we have several programs designed for the use of different recording formats.

2K continuous 120p & 240p only available in RAW. HD continuous 120p & 240p available in Apple ProRes. 2K = 2048x1080, HD = 1920x1080. 64 pixels chopped off on each side.

Setting the camera to 4K RAW yields the best quality output the camera can offer. The Odyssey7Q+ can then generate many recordable formats.
 
On the other hand, the prores transfer tool is often several extra steps since it rarely works and requires lots of troubleshooting in my experience. Sometimes it requires finding the right version of Java and installing the application and then troubleshooting why it won't work. Usually it just needs aa computer restart or a versions downgrade or java upgrade but the latest issue was that none of the current or previous versions work with Windows 10... Support sent me a newer version that isn't released yet but that was after hours of troubleshooting that I didn't have time for. Still can't imagine why 1tb media should be using a filesystem from 1996 when 32GB partition and 4GB file size limits seemed as immense as exFAT's 128PB do now.
 
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Mitch Gross said:
The CD ProRes Transfer Tool does not have to be an "additional step." It can be used as the App to transfer files off of the SSD onto your computer. The process takes pretty much the same amount of time as any other way of offloading the files, but the material will all be stitched together in the process so that standard complete clips will result rather than clips being broken into 4G segments.
Click to expand...

This is actually exactly what I do - transfer with the tool, then check the log to double-check for any issues (rarely happens). "Additional step" was a poor choice of words on my part. I usually just hear that kind of comment from people who are used to just drag and drop transfers... some might consider having to use a specific program as an annoyance, but I would not agree with those people in this case.

Mitch Gross said:
2K continuous 120p & 240p only available in RAW.
Click to expand...

Oops, I didn't realize the 240p was only HD. Thanks for correcting - glad to know that.

nyvz said:
On the other hand, the prores transfer tool is often several extra steps since it rarely works and requires lots of troubleshooting in my experience.
Click to expand...

That's unfortunate - I haven't had too many problems except once, and that's because I was using a Beta OS. Though, I am on a mac, so I can't speak to the stability of the Windows version.
 
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Maybe my issues are with common usb controllers but it seems like every time I install the tool on a dit/data manager's computer it lags or won't start copies and needs a system restart to start working both on Mac and Windows.
 
nyvz said:
Maybe my issues are with common usb controllers but it seems like every time I install the tool on a dit/data manager's computer it lags or won't start copies and needs a system restart to start working both on Mac and Windows.
Click to expand...
I would caution that we have seen issues with various brands of USB3-SATA adapters to connect the SSDs to the computer. Sometimes even expensive ones have issues. This is why we sell our own, a model that we know works well.
 
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