16 BIT v 24 BIT VIDEO SAMPLE RATE?

[Kevin Camp]

i have a feeling he is getting confused with 8 bit-per-channel and 24-bit images.. those are actually the same. 8 bpc (commonly called 8 bit in after effects circles) is 8 bits per rgb channel which makes a 24-bit image — 8 bits of red + 8 bits of green + 8 bits of blue = 24-bit image (a 32-bit image has an additional 8-bit alpha channel included).

any 8 bpc renders are in 24 bit color, or ‘millions’ in the render settings.

your 16 bpc renders (if rendered to a codec that supports 16 bpc) are in 48 bit color, or ‘trillions’…

note that there are not a lot of codecs that support trillions of colors. apple’s lossless in only 8 bpc. some image sequences, like tiff support 16 bpc (tif supports 32 bpc too). avid’s dnxhd is a free one that supports trillions, although it is a lossy codec. hopefully, one day, red giant will release digital anarchy’s microcosm codec which was lossless and 16 bpc, but it’s been a year now since they bought da, and they still haven’t released it.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Jessica Robbins]

Here is his email:

“Also, just curious but I’ve created some avi’s that have a frame rate of 29.97 & Video sample size of 24 bit instead of the 30 and 16 you have on yours. It seems as though mine are a little more crisp, can set up yours with those specs? I would think there would be any noticeable difference between the 29.97 & the 30 frame rates, but figure there is between the 16 & 24 Video sample size.”

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This is for a outdoor display sign that requires a 280 x 512 sq pixel size and only take uncompressed AVIs. I sent the client several tests and the only one that works “satisfactorily” is the render I make in after effects and then encode via quicktime pro to AVI (uncompressed). The manual itself only states in must be in 29.97/30 fps and uncompressed AVI. I even spoke to the manufactuered to see if there were in bitrates to stick to- and thay of course said “i dont think so.”

This client is just one of those that really thinks he knows things about video and make me second guess myself. He says his images are “crisper” and I only assume they are crisper becuase they are rendered out on a PC>PREMIERE>AVI instead of what i do (MAC>QT PRO>AVI). I am also guessing that they are perfectly fine- as I see them on my computer here and they play great.

He has premiere and plays around with things. The manufacturer sent him this file and he opened it in premeiere and took a screen grab
(335_avifilespec.jpg.zip) See how it says “depth 24” (which from the above comments means it is 8 BIT? correct?

If you guys have any more advice on this subject- that would be great. I think it might come down to diplomatically explaining this to the client. And taking out my frustration on a punching bag.

[Jessica Robbins]

Thanks Dave and Kevin- wish me “luck” and thanks for the help as always.

[Kevin Camp]

i don’t have qt pro to test your method, but have you tried to ‘export’ the render via file>export>avi in ae.

if you do this you can click the avi settings and choose ‘none’ for the compressor and set the color to ‘millions’ (which is 24-bit color — i did notice that mine defaults to ‘thousands’ which is 16-bit color) and uncheck the audio output.

send that to him and see if that gives him 24-bit in his info panel.

it may be that qt pro has a similar export avi setting and that is what is converting your renders to 16-bt color when creating an avi.

also, just to correct dave (not disrespect him), a 24-bit image is an 8 bpc image without an alpha channel. a 32-bit image is an 8 bpc image with an alpha channel 😉

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Alan Lloyd]

That’s the standard .avi file output for PPro – I know, because that’s what I cut with.

You can output a regular uncompressed .avi file from After Effects and that’s what you’d get.

Also, the only way to be certain your client’s file output (or yours, for that matter) is “crisper” is for both of you to export the identical file from your respective applications of choice and compare them both, side-by-side, in two viewer windows on the same monitor. And make very certain it’s a monitor you can trust.

[Alan Lloyd]

As I think about it (and you’re very welcome, by the way!) a compressed file may look “crisper” under some circumstances, because of some type of edge (or other) artifacting, where an uncompressed file may be seen as softer because it’s actually smoother/cleaner.

I have not tested this – as I said, side-by-side on the same monitor with the same file from different applications is the only real way to know for certain. Just a thought on re-reading things.