#apertus IRC Channel Logs

off to bed now ... have a good one everyone!

irieger_: do you have any documentation about this? To be sure I understand what you are talking about ;)

if you refer to that

its a mammoth project we will try to work on in the future

1080p 12bit RAW would be a bit easier... but still

1920 x 1080 x 12bit = 2.966 Mbyte for one raw image

so over gigabit ethernet we get a theoretical maximum throughput of 125Mbyte/s

so that would mean we could get around 40 FPS with a raw stream

maybe quite a big challenge for the first task to get warm with the camera

se6astian: I suspected the sarcasm! Just that I still don't know what is done, what is still to be done and furthermore what are the references used in the project

For instance, are there like academic papers that you use at some point in the project? Or is every existing thing closed?

I'm just nuts for the highest quality possible and "rawest" we can possibly get ;-)

may be a dumb question, but why cannot the images be slightly compressed, somehow (losslessly, I mean)?

Is it because it would take too much time?

Don't know about the full capabilities of the FPGA but from the HDMI point: To be maximum compatible the best is to pack into a valid HDMI stream which means (afaik) have a image with RGB 8,10 or 12 bits or 422 (YCrCb) with alternating Y+Cr or Y+Cb per pixel with 10 bits (I think 8 may also be allowed)

ok

morning folks!

the problem is not to generate a valid HDMI stream containing raw data, the problem is more to make it a steam suited for a non raw recorder :)

well, if the recorder does lossy compression for example, you need to produce an image which "looks" like a "normal" one, otherwise the compression will mangle your data heavily

so the decoder assumes it has some kind of image

i.e. first image is R/G1/B

they will look like "normal" images but have the spatial information from the bayer matrix

bayer matrix?

problem there: duplicating the values reduces the amount of data that can be packed.

second row: GBGBGBGB ...

Bertl: this is what you call the bayer matrix, right?

eliemichel: https://en.wikipedia.org/wiki/Bayer_filter

irieger: but on the other hand, the fact that always two consecutive frames are _very_ similar (only the green value changes so slightly) makes it easyy for the codec to compress

and how do people "usually" do?

Bertl: And why are the Reds and blues in the second frame better?

Meaning 422 already debayered of course.

sure, not a problem if there is only intra-frame compression

Bertl: you know any recorders that do inter-frame?

Haven't seen any yet. Only recording devices doing H264 or so I know are all usb capture devices but no real recorders

So I was asking: are they devices with raw 1080p 12bit RGB packing or something?

high end recorders are capable of recording raw data

I mean, there seem to be some challenge here, which is to record that much data

have this very challenge already been addressed?

for example, if you take full HD at 36 or 48 bit (RGB)

you have 9331200 or 12441600 byte per frame

let's assume 12bit now, and you get 18874368

the problem is partially to get the data out of the AXIOM Beta at resonable frame rates and to have a recorder which doesn't mess with the "raw" data

you need to divide it by eight to get the bytes

ok it's getting much clearer in my mind =P

let's put it this way: there are many more options with a camera like the AXIOM, where you can control what data is generated and how

you can choose between them and that's it

ok and then compression are mode-specific?

yes, although the methods are quite similar regardless of the modes

in reality, you will be able to compress the data by 1/2 without losing any data (i.e. lossless)

or, to record losslessly

yes, I'm talking about the recording itself not the transport to the recorder

it might make sense if you transport data over e.g. gigabit ethernet though

I don't have the orders of magnitude in mind

se6astian was talking about GB ethernet

"the plugin side"?

you can plug in two of them already, and we plan to do a 3xHDMI dual slot plugin module as well

meant 50/60p, not 50/560p of course

Yep, haven't thought about this...