Saturday, May 7, 2011

Technical Specs of the EPIC: File Sizes

A few clients have asked what filming on the EPIC will look like on their hard drive—i.e., how big are the files? In the interest of providing an objective answer we ran some quick and dirty tests this morning. Not everyone will care about this, but some are curious.

Executive Summary: If you don't care to read the details, here's the scoop. EPIC footage is larger than that of the RED One, but not a whole lot. Based on our tests, EPIC footage at 5K is about twice as large as shooting with the RED One. BUT, you can dial down the bitrate and get files even smaller than the "old" 4K footage. Bottom line: the Epic is very flexible.

The Details
(For the geekier amongst us):
Keep in mind Redcode is a variable bitrate codec. Our tests were not particularly good for pushing the codec, but we wanted to have each test be somewhat repeatable. Your results may vary from these numbers, but they will give you a sense of what is involved with shooting EPIC.

To begin with a frame of reference, a 4k file from the RED One (non-MX) at 16:9, 23.98 timeline, 24 fps, is as follows:

Redcode 28 = 1.88 GB/min*
Redcode 36 = 1.57 GB/min*

(* Our other cameras were out this weekend, so we used iSee4K space calculator to generate these numbers. We hope to get the other cameras tested to see how the MX’s compare.)

We filmed two scenes with the EPIC. The first was a static exterior shot, and the second was of a focus chart. No audio was recorded.

Scene One: Each test clip was shot for 5 seconds at 5k, 16:9, 23.98 timeline, 24fps, no HDR:

18:1 = 115 MB = 1.38 GB/Minute
15:1 = 142 MB = 1.70 GB/Minute
10:1 = 214 MB = 2.57 GB/Minute
8:1 = 254 MB = 3.05 GB/Minute (Default setting)
5:1 = 410 MB = 4.92 GB/Minute
3:1 = 720 MB = 8.64 GB/Minute

Scene Two: To vary things a bit, we used a focus chart, panning back and forth for one minute (not the best way to push the variable bit rate, but at least it was somewhat repeatable).

18:1 = 1.48 GB/Minute
15:1 = 1.77 GB/Minute
10:1 = 2.65 GB/Minute
8:1 = 3.34 GB/Minute (Default setting)
5:1 = 5.26 GB/Minute
3:1 = 8.70 GB/Minute

Very much in line with what the static exterior shot normalized to one minute produced.

As you can see, the default setting of the EPIC (8:1) is about twice that of the RED One at 4K. We might try running actual tests using the MX cameras at 4.5K, with the additional Redcode 42 setting available. Presumably HDR would at most double again the file sizes, since it shoots a second frame under for the highlights.

So, if file size is a concern for you, shooting the EPIC at around 12:1 or 15:1 should give you what you're used to with the RED One at 4k. If you've shot with the MX, I would guess that 10:1 or so will give you what you're used to. The default of 8:1 is probably not a bad compromise as a default setting. Hopefully we can update this comparison shoot at a later date.

1 comment:

  1. PPerfect info!
    Just what I was looking for.

    Have you any info on what the different compressionsrates does for realtime playback?
    Is it more CPU intense to debayer and play a 18:1 compared to 3:1?
    Is one RedRocket enough?