0.98.4: Scrolling through .DNGs is very slow

[Hacker]

Hi,

XnView: MP 0.98.4 - 64 bit
OS: Windows 10 20H2 - 64bit

Holding an arrow key to scroll in a list of .DNG images is extremely slow and causes 100 % of one core CPU usage. This does not happen with e.g. .JPG files.

Effect: The scrolling is extremely slow and causes 100 % of one core CPU usage, see video here - https://youtu.be/KVln-l98CDY .

To reproduce:
1. Download a sample .DNG from here - https://my.syncplicity.com/share/grp0u5fzxrmybri/Test .
2. Ctrl-C and Ctrl-V it a few times so you have several identical .DNG files, enough so you can scroll through them (I made 60, but 20 may be enough).
3. Open the folder with the .DNGs in XnView MP and scroll using up / down / left / right keyboard arrows.
Actual behaviour (bug): The scrolling is extremely slow (about two files per second on my system) and the CPU usage goes to 100 % of one core, see video here - https://youtu.be/KVln-l98CDY.

Expected behaviour: The scrolling should be quick, as with e.g. .JPG files.

Thank you
Roman

[xnview]

from what i see, it's DNG decoding

[Hacker]

Hi Pierre,
I am not sure, does this mean you can confirm the bug?

Thank you
Roman

[cday]

Hi Pierre,
I am not sure, does this mean you can confirm the bug?

I don't think it is a bug: some file formats need much more processing to open, and a DNG image in any case has large pixel dimensions, I imagine...

An example is that a file saved with JPEG2000 compression takes noticeably longer to open on a slow computer than the same image saved in JPEG format.

In File > Format settings... you do have the option for camera raw files to view the thumbnail, half size or full size image versions, if that is any help.

[Hacker]

I don't think it is a bug: some file formats need much more processing to open

Well, that might be the case if I was trying to open the .DNG, which, however, I am not.

Roman

[cday]

Scrolling through DNGs in the file browser?

[Hacker]

I am not sure I understand your question. There is a video capture of exactly what I am doing in the first post. It works completely fine in XnView Classic. If there is something not clear about what is happening in the video, feel free to ask.

Thanks
Roman

[xnview]

you can have same behaviour as Classic by changing

Code: Select all

keyDelayedPrev=true

[Hacker]

Hi Pierre,
Thank you, it's a little bit better but it's still much slower than Classic.
This is what happens when I simply keep pressing down, right, up, left in XnView Classic - the cursor moves quickly and exactly as I press the arrow key buttons - see video.
This is what happens in XnView MP - the cursor is unable to keep up with the simple down, right, up, left arrow key presses and skips more than half of them - see video.

The dirs are fully loaded in both Classic and MP, both had plenty of time to cache everything, and the status bar is also displayed in Classic even though it's not visible in the capture.
Again, the cursor works completely fine with .JPG files.

As a side note, what does the setting do, please? Is it documented somewhere?

Thank you
Roman

[xnview]

ok, the delay to start loading is longer on Classic, i'll change it on MP too

[Hacker]

Hi Pierre,
Thank you, looking forward to if it will improve things

As a side note, what does the setting do, please? Is it documented somewhere?

Thanks
Roman

[xnview]

this setting is only to use a delay when you select a new file