@Former user I tested only with my laptop, not exactly the highest-end either, i5-7300HQ CPU @2.50GHz, Intel HD Gr.630, 8GB RAM GDDR5, Nvidia Geforce GTX 1050 4GB ForceWare v.417.71 (on), QT 7.6.9, Win10H64 1803 (17134.590) and "Automatically create video proxies…" selected in Prefs. Video, PQ Preview (Auto).

Tested again with VP 16b361 and VMSP 16b109, 60 files both. I don't think I can add much to the excellent comments from George the @Eagle Six.

Here is an experiment for JN_ and --A, although there is no difference in my results, I'm thinking maybe it is worth a shot. Bring up your boot drive in Explorer and navigate to Quicktime folder. Leave this window up.

Now start Vegas Pro.

Go back to the Explorer Quicktime folder and change the name of QuickTimePlayer.dll (I use a prefix 'X-', but whatever will work).

Go back to Vegas Pro and add your sample 5D test clip and see if you have an improvement.

If not, try changing the name of QuickTimePlayer.exe (make sure Vegas is already loaded) and see if that does any better.

Testing changing the name of QuickTimePlayer.exe and then QuickTimePlayer.dll one at a time and then changing the name to both.

I don't really need either with the exception if QuickTimePlayer.exe is not there when you start Vegas, later when you try to add the 5D Test Clip, Vegas will throw an error that QT is required. But once Vegas is started is seems it will work without the QuickTimePlayer.exe when you add 5D Test Clips. This is because when Vegas starts it get access to the qt7plug and I assume stores it in memory. So, this may just be a waste of time, but the only other thing I can come up with at this point. I'm guessing you will have the same failed results.

With a bit more pecking around, the qt7plug is in the QTSystem folder and the resource are locked by Vegas and cannot be renamed, so the experiment above will definitely not change the results.

What was "rude"? There was anything rude

Actually, you've already answered your own question. So, in English language,

So, can you upload excatly that working version of QuickTIme for me, especially?

That is quite a reasonable request, in the form of a question, and people would love to help.

So, give me a link to a proper QUickTime wersion to use for me

That is a demand, in the form of a statement, and people would not love to help.

When asking for help, you will catch more flies with honey than with vinegar.

Will you forgive me? I'm a retired educator. Here's a really good book on the subject, in English:

https://www.amazon.com/gp/product/1451612591/ref=dbs_a_def_awm_hsch_vapi_taft_p1_i1

Back to topic, Sorry I can't test for you this time.

I think this is the QT 7.7.6 version I have installed https://drive.google.com/drive/folders/19Aga7zGGez_MaJk-hNGo1XiY-gOerVMt

@Former user I tested only with my laptop, not exactly the highest-end either, i5-7300HQ CPU @2.50GHz, Intel HD Gr.630, 8GB RAM GDDR5, Nvidia Geforce GTX 1050 4GB ForceWare v.417.71 (on), QT 7.6.9, Win10H64 1803 (17134.590) and "Automatically create video proxies…" selected in Prefs. Video, PQ Preview (Auto).

Tested again with VP 16b361 and VMSP 16b109, 60 files both. I don't think I can add much to the excellent comments from George the @Eagle Six.

Ok @vkmast that settles, scratches my machine memory theory anyway, thanks.

So, can you upload excatly that working version of QuickTIme for me, especially?

Sure. Here is the last known truly bulletproof version prior to Magix. Probably not relevant, It may have never seen Windows 10 or a 4k file, so will you let us know if it even loads? With apologies, it's the best I can do besides what has already been offered.

https://support.apple.com/kb/DL762?locale=en_US

This morning I again went to Vegas Pro 13 and loaded up 120 of the sample clips.

And, the computer I was using back then (link to MSZ conversation) was a Core 2 Duo E8400 with 8GB ram.

@Former user@Former user @Eagle Six

Following the lead of Eagle Six, I loaded 120 instances of your clip in VP14, using its resident Magix qt7.dll

Quicktime / iTunes has never been installed on this computer. Maybe that's a clue.

The laptop I chose is an Intel B820 Core2, 4GB DDR3, which is slower than anything you have or ever will see in your life. Takes 5 minutes just to load the wifi adapter!

The Vegas preview is rock solid at 29.97, looping the timeline several times. But at Best / Half (get real, OK?).

So maybe graphics memory allocation is also a factor? Try CPU instead of GPU?

I won't talk about expectations here, because I didn't have any.

So maybe your computer is too new; maybe swap? I'll even throw in $100 as an expression of good faith.

All seriousness aside, you've definitely got a problem.

Before someone jumps all over me for my measly HD display, is it worthy to check yours out instead, since I have no issue?

https://www.vegascreativesoftware.info/us/forum/faq-how-can-i-make-my-video-preview-play-smoothly-in-vegas-pro--104624/

Following the lead of Eagle Six, I loaded 120 of your clips in VP14, using its resident Magix qt7.dll

Quicktime / iTunes has never been installed on this computer. Maybe that's a clue.

@Musicvid Awh man......your older laptop computer is better than my older desktop computer. The plot thickens!

If I change the name of the installed Quicktime, simulating it isn't installed, I cannot get the test clip to load in any version VP13, VP15, and VP16......and wouldn't you know, the version I do not have is Vegas Pro 14!!!

Well Ive also got VP8 and the clip loads black. Will check out MSP;13 when I feel like it, but the patient is definitely not dying!

Oh, the drama....

Two small points of interest, on my PC where I can load at max 39 clips on the timeline, with all 50 clips in project properties.

1) I can load hundreds of clips either continuing on the same single track or on multiple tracks, tried up to 6, total of 234. The catch is all the loaded clips can only be clips 1 to 39.

2) When I check in the project properties media by type as video type, only 39 video clips are available, not the 50. This explains item 1) above as vegas cannot load any more video clips to the timeline as it doesn’t see that they exist, even though they are all in project properties.

I later noticed that all 50 video clips do show in media by type = video, but as they are added to the timeline it reduces to 39.

I'm not suggesting that any of this is of significance.

I have at last tested with proxies also, same difference, none.

I got hold of QT 7.76.80.95, and installed, it made no difference. My previous version was a more recent version .. 7.79.80.95.

For various reasons I couldn’t download the ones pointed to by @Eagle Six and @Musicvid.

Thats it I think.

@vkmast @Musicvid @Eagle Six (A) Can I take it that you are all using for example 45 or more real files on disc, each one a copy of the single original file and then loading them into vegas, and then putting these say 45 or more real clips onto the timeline?

Or did you do this ... (B) had only one file on the ssd/HD, loaded it into VP then made the copies in VP, not on the Hard drive?

If (A) then ok, if (B) then its not a proper test.

My reason for this query is point 1) above in my earlier post.

If (B) I can make available later today a much smaller file, a few seconds in duration.

@Former user (Disclaimer: I did only what @--A suggested here. (Another: off to sleep for awhile. It's almost 3 am here.)

I was literally switching off the lights and heading to bed also, 12:55 here. Goodnight.

@vkmast @Musicvid @Eagle Six Can I take it that you are all using 45 plus real unique files on disc and loading them into vegas, then putting these say 45 plus unique clips onto the timeline?

@Former user No can do! I don't have any unique source media from a 5D. I have the sample file that --A provided. I can make 40 copies of that, each with a unique name and bring them into the Project Bin, then add them to the timeline and it works.

I can try more on Monday, but know I am leaving out of town and will not be back until late Sunday.

@vkmast @Musicvid @Eagle Six My previous post may not have been very clear, using the word unique was misleading, i’ve changed it a bit.

Can I assume that you all have only one file on disc? Then you made the copies in vp, not on the Hard drive?

i.e. item (B) in previous post.

@Former user my previous attempts were as per @--A's suggestion. I now made copies on the hard drive (files named *1.mov, *2.mov. etc.). The limit of 41 files happened. (Prefs. video proxies setting on or off)

Thanks @vkmast. I'm just putting together a 2 second 5D Mk IV test .mov file. If anyone else wants to test and don’t have a smaller file it'll be easier. I'll post a dropbox link later.

I couldn’t quite decipher @Eagle Six's response, which way he did it.

I'm going out the door, but wanted to get this last post in. @Former user I make unique copies on the 5D Test clip in Explorer, then brought them into the Project Media bin, then on to the timeline. When I get back I wil download your sample as well and try a few different ways to get my system to fail. Hope you guys have a great weekend.

Ok thanks @Eagle Six.

@Eagle Six @Musicvid @vkmast This is the dropbox link below for anyone that cares to test this issue ...

This a a two second C4K .mov 5D MK IV clip.  If you are so inclined you can use the included batch file(s) to create a total of 50 clips. Then load them into VP to see if it can display more than 40.  Best to load into project properties first then add to the timeline in stages, saving as you go.  Loading 50 at once may cause a crash.  The total download size is only about 138 mb.

The batch file with the hyphen added can be more easily modified (in two places) to create up to 999 clips.

If you’r happy just testing 50 then use the one without the hyphen. They are both set initally to just create 49 extra clips, giving a total of 50.

https://www.dropbox.com/sh/cebefr9ru6a3pfv/AADB9T-zWztN0pPijMLgIFBka?dl=0