Key Questions To Consider When Purchasing 4K Storage

4k Storage. What you need to know about 4K header

So, you want to purchase 4k storage? Storage requirements vary considerably depending on key decisions made in the preproduction process. What will be the standard frame rate? Bitrate and Depth? Is it a multi-cam shoot, with how many cameras?  How many hours of footage?  What codec?  Does the camera create proxy media on capture?  Answering these questions is crucial to any shoot. But, does shooting 4K mean you simply multiply the storage by 4x? Not necessarily.

Many codecs exist to edit in 4K – but they are not created equal. 4K RAW and uncompressed formats take up more storage and require faster drives with faster connections. A Codec means Compressed 4K will take up less storage and bandwidth, but the computers or graphics cards inside need to be much more powerful to handle the image decoding. In addition, multi-camera edits require pulling multiple video streams from your storage- which becomes much more of an ask with shared storage for multiple editors.  We decided to look at the top questions people should consider when choosing 4K storage.

What is the best way to determine the amount of storage required for a 4K shoot?

Some content distributors are requiring specific acquisition frame sizes and bit depth, which pre-determines your starting point.  On other projects, before making the decision for resolution needed, it would be wise to first calculate the total GB or TB of storage size required. The good news is our partner AJA created an app, called AJA DataCalc, that can calculations for you.  Remember, storage requirements grow rapidly depending on bit depth & codec choices made for acquisition or post.

If you’re dead set on manually figuring out the numbers, it’s not hard either.

Here’s an example of the formula: Approx. bit rate / 8) x 3600s = KB per hour / 1000 = GB (Gigabytes) per hour Explained: Approx. bitrate / 8 (converting Megabits to MegaBytes) x 3600s (seconds in an hour) = KB per hour / 1000 = GB (Gigabytes) per hour GB per hour x hours of operation per day (count all cameras!) =GB per day GB per day x requested period of storage = Basic RAW storage required (*+40%)

*Notes: render files, built-in proxy and other associated media will increase your storage needs. If your storage is RAID formatted for protection or speed, some of your raw storage sizing may be unavailable due to the protection RAID formatting offers. Lastly, many storage solutions see performance dips if more than 80% of your storage is full. Key Code Media recommends that using the above formula still requires an additional 40% extra storage space above what the math tells you Before figuring out the numbers it’s best to find answers to the following questions:

  • Number of cameras
  • Amount of hours cameras will be recording
  • Frames per second recording
  • Image resolution (HD, 2K, UHD, 4K, 6K, 8K.)
  • Image bit depth (8bit, 10bit 16bit)
  • Video compression type used: RED RAW, DPX, XAVC, ProRes, DNxHD,etc.
  • How long data must be stored for editorial use
  • Offline / online workflows will require additional storage for the proxy media.

We highly recommend using the AJA DataCalc App when first estimating the amount of storage space needed on a project. DataCalc is able to estimate storage needed factoring in the number of hours, video resolution, audio formats, and codecs being used. Did we mention it’s free?

Is it possible to edit 4K in a shared storage environment?

Absolutely possible!  There are a few things to figure out how best to make this work. Traditional creative editorial departments rarely edit only in uncompressed or lightly compressed camera formats, such as uncompressed, DPX, and RAW. The additional expense in storage solutions to edit this way tends to far exceed the benefits.  Instead, most folks end up keeping a high-res master (& LTO tape back up), then do all the editing in a lower-res proxy.   This offline/online workflow has been around since the first NLE, and will no doubt be essential to many workflows for the foreseeable future.  In feature films,  the dailies process delivers the editorial media in the desired format to your door or drive- and that typically has been an HD frame size,  in the 36 Megabit range.  Also, if your editorial systems only have monitors in HD frame sizes,  you’ll only ever see a resized version at this point-  working in larger frame sizes should have a benefit-  you should weigh this decision in an offline/online workflow.

The addition of Avid’s DNxHR and ProRes RAW, as resolution independent codecs, will allow people to edit in resolutions above HD – including UHD and 4K, and paves the way to edit in even higher resolutions inside your offline NLE.  These codecs are compressed, relieving storage space, but may require more GPU processing from the editing workstation.

If you are looking to edit an entire project with uncompressed or lightly compressed media, even the most high-end storage currently limits editors to 1, and rarely 2 streams of uncompressed/raw. That means, only one editor will be able to access high-res media from the system. This is a big reason why new compressed codecs, such as DNxHR & these new flavors of ProRes, will be so important to editing 4K and beyond.   Even if you don’t edit the entire project at these sizes, they do come back into use in the Conform, Color and Deliverables processes-  the Online part of the workflow.

Do I need SSD, or Flash, or NVME to edit 4K?

Drives that don’t have spinning platters certainly offer far greater speeds for boot drives & project drives and offers fantastic speeds for media playback.

Solid State storage – SAN and NAS included can be more expensive per unit than traditional spinning hard drives.  They tend however to require less “spindles” or individual drives to get to the desired speed and stream counts.   This makes them perfect for the editorial process but not so cost effective for keeping media at rest for longer periods of time.

What are the minimum storage requirements for 4K editing?

Be aware of minimum requirements to consider when choosing shared 4K storage, such as throughput, connection, etc. For example, choosing incorrect spindle speed could leave your editor with a very unpleasant editing experience. Here are some bare minimum requirements to consider:

Shared  Storage Connection – 1GigE minimum. 10GigE or 4/8/16 Fibre recommended  

NLE/Finishing Support – Your NLE needs to handle the codec you are onlining and/or offlining with.  If a finishing system, the system needs to handle the EDL or AAF  from your NLE.  The NLE also has to allow media to be utilized from shared storage.  

Speed – 7200rpm (rotational speed) at the bare minimum!   Stay away from green drives, or other power saving drives. These drives can spin down to conserve power but can cause playback issues within your NLE.

Throughput – (Your codecs data rate/8) x amount of concurrent tracks with video in your NLE = MB(MegaBytes) per second. This number must fit within the speed provided by your Ethernet or fibre connections. Key Code media recommends a 25% overhead to account for real-world throughput values.   Once you have this number,  multiply by the number of systems that will be using a shared storage setup-   Don’t forget about data I/O stations, and systems that only produce deliverables.  They count in the totals!

How many streams of 4K can be pulled from my storage?

The number of streams that can be pulled from a shared file system is heavily dependent on what file formats you’re using.  Using DPX, RAW, or uncompressed? You’ll get fewer streams of these formats than compressed streams.   These formats typically have huge file sizes and require lots of bandwidth.

How much more does 4K storage cost?

Numbers can vary wildly –depending on the quality of the drive, if it’s meant for enterprise or home use,  if it’s an off the shelf single drive, or provided by a storage manufacturer. If we look at drives which are rated for professional use, the rule of thumb for storage cost is $1.20/GB for SSD and $0.75/GB for a spinning disc. While 4K media does not necessarily mean 4x cost of HD, there is an increase in your cost of storage.  Factoring in RAID for speed or protection and shared file systems makes the cost to benefit values change.

According to Videomaker, ” One hour of standard definition DV footage requires approximately 12.7GB of storage; approximately 217MB per minute. By comparison, one hour of RAW 4K content requires close to 110GB of storage; approximately 2GB per minute.” Assuming that’s correct, you’re looking at around $1 per minute, per camera. With hundreds of vendor and product choices, it becomes easy to get lost in all the various technical details when selecting video production storage.   Feature choices like volume locking or file locking, SAN or NAS, and RAID types will likely shape the way your 4K video production operates.  Learn more about how Key Code Media can partner with you on possible workflows to allow your storage to say YES to 4K.