Allow me to tag your previous reply as a solution

Please do, looks like all is working as it should now.

Glad you figured it out; here's the "for the record" part which should help those reading this post the first time for guidance:

• First of all, your original video -- in addition to the Handbrake version, should open in Vegas. The trouble may be, it wants to open with s04. Try this first, before converting:

https://www.vegascreativesoftware.info/us/forum/avc-xavc-s-issues-in-vp15-try-disabling-so4compoundplug-dll--108345/

Should you still need the Handbrake conversion, keep these points in mind:

• MP4 and M4V wrappers are identical and should be interchangeable in all respects and all operating systems as of a decade ago. Used to be, Quicktime Player would only read Apple chapter markers in M4V, but that was then.
• MP3 was never intended as audio for video; a lot of people and rogue codec developers use it because it has a familiar name and it is practically unlicensed. Some players will open it, Vegas will probably not. The de facto standard for audio delivery with AVC video is AAC.
• AAC has better high frequency retention and bitwise efficiency than the older MP3, so there is no reason to use MP3, other than superstition.
• When rendering in Handbrake, be sure to set "Constant Frame Rate" and "Same as Source" in the video properties.

Best of luck, and welcome to the discussions.

That's good information, I'd just assumed that .mp3 would be the most compact "chunk" of audio to go with my video, but I understand now that I would likely be best advised to always leave the audio in AAC format in order to avoid frustrating complications such as I had to deal with earlier.

"When rendering in Handbrake, be sure to set "Constant Frame Rate" and "Same as Source" in the video properties."

Another possible mistake I was making, I noticed the two options, and thought that maybe if I left it as variable frame rate, it might mean that the program would know where the video was not changing very much, or something to that effect, and so would automatically lower the frame rate since a higher rate was not needed, and this would ultimately result in a more efficient and compact file.

Reasoned thinking based on insufficient knowledge doesn't lead to proper conclusions it is obvious to see.

*****

"First of all, your original video -- not the Handbrake version should open in Vegas. The trouble may be, it wants to open with s04. Try this first, before converting"

Well as I kept trying to figure out these issues, eventually I realized that indeed, the original file did load, I'd forgot. The problem was that the original file was playing in Vegas at half speed, or something similar, so the video and audio were both playing too slow, so I decided that if I converted it through Handbrake, I might be able to solve the problem with the file.

From the information in this thread, does anything explain why the original file was playing back slowly in Vegas?

Slow computer?

Change preview to preview/auto and if that doesn't help, right click on the media and "create video proxy".

I tried to upload the small video capture file here, but it won't seem to upload, so uploaded it to imgur.com: https://imgur.com/a/xkb9yGz

This is what happens when I try to preview this file in Vegas. It plays perfectly in VLC, nothing to do with slow computer though...

Playing back in editing software and in VLC or another media player are very different things. The player can take shortcuts to preserve the framerate.

Anyway looking at the video it's hard to understand what's going on. There is no audio and playback seems to start and stop. Under display it appears locked at 29.970fps so Vegas is able to play it back smoothly at full frame rate.

If this videos was ripped from somewhere I'd experiment with other methods of downloading the video that might work better in editing software.

Anyway looking at the video it's hard to understand what's going on. There is no audio and playback seems to start and stop. Under display it appears locked at 29.970fps so Vegas is able to play it back smoothly at full frame rate.

There is audio, hard to say where you will see the unmute, on my browser, the unmute is upper-right.

That is the first file that gave me this problem, and off hand, I don't remember where I downloaded it from. If it keeps happening, I'll have to figure out what the problem is, but fingers crossed, this one video file might have been an outlier.

Thanks, I found the mute button. Wow. I've worked with Vegas for a decade and have never seen a file play back like this before!

It's definitely an outlier and I encourage you to figure out a better way of downloading videos that will work well in Vegas. Ripping video is a bit of an art in and of itself (and not one I have much experience with personally).

Reasoned thinking based on insufficient knowledge doesn't lead to proper conclusions it is obvious to see.

That is a more articulate statement of truth than I have been able to express through years of periodic consternation. It's going verbatim on my studio wall.

From the information in this thread, does anything explain why the original file was playing back slowly in Vegas?

Yes, and it's becoming more common. People are unknowingly downloading third- and fourth-generation "Frankenfiles," where the reported metadata is garbage, no attention having been paid to the original file parameters. Naming an orange as an apple does not change its flavor; it may just evoke a different appearance.

A nondestructive remuxer like VideoRedo can "occasionally" correct problems like this without re-encoding, but often they are baked in and can't be unbaked. A player such as VLC often ignores the bad metadata, which as a nonlinear editor Vegas is unable to do, because it does not "play" the file -- it must unpack it to raw bits first partially based on the metadata. In this case it may be a misreported audio sample rate in the file itself.

It is a familiar situation to this troubleshooter, and it's getting worse.

Reasoned thinking based on insufficient knowledge doesn't lead to proper conclusions it is obvious to see.

Naming an orange as an apple does not change its flavor; it may just evoke a different appearance.

For me, both quotes go on my studio wall 😉👍

It is so refreshing when there are still people who are capable of healthy, humorous self-criticism.
For the most part, we often hear insults in this forum that only point at the product - and then, after many postings, it usually comes out that the main problem was sitting between the armchair and the keyboard.

@N1755L Theres a link, via my signature, to util “Copies video, converts audio to AAC”. Maybe a fallback for any future audio codec issues.

I just installed Vegas Post 19 and am getting the prompt to install Quicktime when I launch Effects. I already have Quicktime installed and just re-installed it. I still get prompted to install it.


EDIT:
Nevermind I got it to work by completely uninstalling QuickTime and reinstalling it again. No more prompt.