big 4 second video

[Gary Adcock]

[Dennis Couzin] “My “None” file will have 25 full frames per second. Won’t QT display 25 full frames per second?”

No. but how would you know if it did.
without a 3rd party video card, there is nothing to force FCP or QT to act “professionally” so there is no guarantee that your content will playout with specific timing, RASTER SIZE or frame rate, since you are telling the computer that you did not need it to play with accuracy.

This is the main reason that I always talk about the hardware output, since the the software and the OS do not always tell the truth to the user.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Check out
https://www.aja.com/kiprotour/

Inside look at the IoHD
https://library.creativecow.net/articles/adcock_gary/AJAIOHD.php

[Dennis Couzin]

This is the FCP board. Nothing is quite “professional” in FCP and Mac OS-X. And now I add three dangerously undocumented elements between the image file and its display: QuickTime v.7.6; vidia 7300GT; Samsung 305T. They can do anything at all to the images. As you say: “you are telling the computer that you did not need it to play with accuracy”.

Yes, the consumer-grade player, graphics card, and monitor can sometimes amaze us with their engineering crudity, even perversity. But they are just concoctions of men. We can study their behavior and learn to work around their weaknesses as they would affect our use. The examples you cite don’t seem to apply to my visual experiment. My “None” file will have 25 full frames per second, and I do expect QT will display 25 full frames per second. A stopwatch will show if it plays at 25 fps rather than, say, 24 fps. I don’t care if it is playing at, e.g., 24.99 fps — such small errors aren’t visually relevant. I can make a simple animation of a dot taking 100 frames to make a circle and look for any irregularities in the display. This will show that the frames are presented regularly. I can mask off a small part of the screen in order to see an individual dot tachistoscopically and verify that it is sharp as it should be. Even “professional” equipment must be verified before use in a scientific experiment. The difference is that if I find that I don’t get 25 full frames per second displayed, if for example, the graphic card asserts itself by interpolating additional pixels, I can’t complain to Nvidia.
Your other example, raster size, is also simple to verify. When I set QT to play “actual size” there are very nearly the true number of pixels displayed on the monitor. I haven’t counted the 1500 and 2000, but I can. It doesn’t matter to the experiment if QT crops off a row or column at an edge, but I can check this too. I mostly care that QT doesn’t scale, that where my bitmap image fills exactly N pixels of height the screen does the same. I will definitely check this. (There might be workarounds to tease it back to scaling factor 1.000.)

[gary adcock] “This is the main reason that I always talk about the hardware output, since the the software and the OS do not always tell the truth to the user.”

I fully agree, but believe that frame rate and raster size are the (managable) tip of the iceberg.
I am more concerned that the display be pixel-by-pixel with no spatial or temporal dithering.
(The luminance in the display of pixel P in frame F should depend only on the value of pixel P in bitmap F.)

[Gary Adcock]

[Dennis Couzin] “I am more concerned that the display be pixel-by-pixel with no spatial or temporal dithering.”

Then you should be using REAL tools that will supply and test in a scientific manner whether as a test generator or more accurate equipment , which I do not believe you are doing. You seem to be relying on what ever the computer tells you, without external verification, from your statements above.

How can you accurately judge something if you are not using analytical test equip? You seem to be saying that you trust your eyes? I would never do that if I was expecting accuracy with the tests.

You editorialize on how it needs to be accurate, but it seems that you are not using tools ( hardware or software) to confirm that what you are sending out is handled in the manner you described for testing, so I do not understand what kind of outcome you expect, since you are not using the most accurate method for your “analysis”.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Check out
https://www.aja.com/kiprotour/

Inside look at the IoHD
https://library.creativecow.net/articles/adcock_gary/AJAIOHD.php