Hypothetical question: 1.85 / 2.35 letterbox

[george su]

I'm currently in prep for a feature to be shot with my af100. In talking with the director about aspect ratio, we decided on 2.35:1 framing. Of course, the director liked the idea of "not baking that in" and "changing his mind in post".

Which got me thinking: I miss the dvx100 letterbox option. Bake that frame size right in, I say.

So, I have 2 questions:

1) would you all want to have a 1.85 and 2.35 letterboxed aspect ratio option in the af100?

and

2) if the af100 did have that option, would the compression not assign information to those black bars, and thus free up more bitrate to apply to the image within that letterbox? Or in other words, would a 2.35 letterbox increase the image quality?

Best,
George

 

[Barry_Green]

1.85 wouldn't make much difference, as you'd be talking about such a minor change in frame size. It's 1920x1038 vs. 1920x1080, so it'd only be 21 pixels off the top and bottom.

2.35 would be a much more substantial difference, obviously, as now you're talking about 1920x803 (for 2.39:1), which represents somewhere around 25% of the total image area. And I do believe that you would see notable compression efficiency from the black bars, as AVC is a very smart codec and wouldn't waste any noticeable bandwidth encoding black bars. I believe you would see a slightly higher-quality, less-compressed image in that scenario.

 

[george su]

Thanks for the response, Barry. I had assumed that compression could be more efficient, thanks for answering that!