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Old November 17th, 2009, 01:01 AM   #1
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Why does Vegas render change CUTS to FADES?

I asked this question once here buried within another thread, but didn't get a satisfactory answer. So I will ask it in its own thread in hopes that someone can address it.

WHY does a render from an HDV project into a DVD Architect Widescreen 24p .mpg file turn CUTS into FADES?

To repeat: when I make the file, it renders some (many) of the hard cuts within the ~70 minute project as quick FADES.

You can SEE the fade being built into the .mpg in the preview file as it renders slowly, and when you view it at speed it gives me this sort of "ghostly" effect where the new is visible for one frame before the cut and then the old frame is visible for one frame after the cut.

First I thought this might be a property of DVD video that I had not noticed before.

However, I examined several commercially released DVDs and found that that this ghostly fade does NOT occur, even when the playback is slowed to 1/10th speed.

Clearly, this fade is some form of compression or way to save space. Is there ANY way to turn this off so that my cuts are clean, as in motion picture film? One image onscreen, CUT, next image onscreen, no fade, no ghost?

EVEN when I render the project as .AVI, or as a 9,800,000 constant bit rate mpg, there is STILL the fading problem!

Any and all help will be appreciated.

Some info.

1) I have just upgraded to Vegas 9.
2) I don't know if this is a codec issue, I have only the codecs that came with Vegas and also quicktime.
3) I am running a fairly decent PC, (twin 3.2GHZ pentium I believe), and my video card is an ATI 256MB X1300 PRO. Is my video card the problem? Do I need to upgrade to a better one to get a fade-free render?

Thanks to all for help. This is a project I have been working on for several years and am finally ready to be "done" with it, however I am unwilling to release the product with this cut-fading problem.

Best,
R Gould
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Old November 17th, 2009, 04:58 AM   #2
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I use jumpcuts frequently and have not experienced this issue, so I cannot know the reason for sure.

You tell us you upgraded to Vegas 9, but you didn't say if the issue was present in Version 8 or not.

If you haven't already: Zero in on the timeline to a cut and make sure you have a clean cut to begin with. Go to the spot in question and hit the up key on your keyboard to zoom in on your cut.

If you look at the images below, in the first image it appears that there is a cut. In the second image magnified you can see there is not a cut, but a fade.

Your issue is most definitely not a graphics card issue. As far as your PC, your pentium, even though it is dual processor, it is seriously dated for HD work, but I doubt that would cause this issue.
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Old November 17th, 2009, 05:31 AM   #3
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TOOLS>QUICKCUT AUTO FADES or something like that I forget exactly - turn it off and that should take care of it.
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Old November 17th, 2009, 05:37 AM   #4
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In addition to Jeff's suggestions, make sure you DON'T have "Quantize to Frames" disabled (first listing under the Options menu) as this will mess things up.
To see if it was disabled, zoom in to a cut, place your cursor on the cut point and use the arrows to move left and right.
The cursor should ALWAYS end on the cut point.
If it doesn't, you'll have to re-trim every single edit to ensure that each clips starts/ends on a frame boundary.
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Old November 17th, 2009, 07:26 AM   #5
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If you create a "cuts" project, it will NOT just change it to "fades". As Mike said, make sure "Quantize to frames" is turned ON. Then, zoom in on the timeline and make sure you don't really have a small crossfade. If you do... get rid of it. It's quite possible you have an extremely small crossfade that you can't see at your zoom level.
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Old November 17th, 2009, 10:10 AM   #6
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I suspect Don might be referring to Options/quickfade audio edits. Under options there is a auto crossfade option, but you likely want to leave that on.
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Old November 17th, 2009, 11:56 AM   #7
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yep, it was way tgoo early in the morning to be replying to anything. I was still waiting for the coffee to brew :-( Thanks Jeff.
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Old November 17th, 2009, 12:44 PM   #8
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On the contrary, thank you Don. I didn't know about the audio thingy, and I hated when I cut audio tracks and a fade was automatically...so thanks to you I now have it shut off!
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Old November 17th, 2009, 01:02 PM   #9
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Robert also asked this question on the Cow Vegas forum and here's the response from John Rofrano. It's totally different from anything suggested here which is why I'm adding it as it made me think that maybe we're off base with our responses :-).
Anyone care to comment?


What you are seeing is the way that MPEG2 compression works. It is assembled in a Group of Pictures (GOP) that contains 15 frames. The first is an I-frame and it contains a complete image. The next 14 frames are composed of B-frames and P-frames which are delta frames and predictive frames. These only contain the information that has changed since the last I-frame. If you make a hard cut on a B or P-frame, the encoder will probably not give you enough bits to represent an entire frame so you watch that frame fill in over several frames. This is the nature of the MPEG2 GOP.

There are two ways that I can think of to fix this. One thing you can try is rendering with the 2-pass option. This will allow the encoder to be smarter and use a higher bit-rate for the frames that need it for these cuts. The other is to only make cuts on I-frames which gives the encoder the entire frame to represent the cut. To accomplish this, you could try setting your timeline ruler to Frames. Then only make cuts on frames that are evenly divisible by the GOP length (15).

I have not tried either of these to fix this problem so let us know how it works.
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Old November 17th, 2009, 03:04 PM   #10
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Quote:
Originally Posted by Mike Kujbida View Post
Then only make cuts on frames that are evenly divisible by the GOP length (15).
.
Wow, isn't there a simpler way than dividing every cut by 15 to see if you're safe?

Presumably if you had a Cineform timeline you needn't worry about any of this?
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Old November 17th, 2009, 08:17 PM   #11
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Quote:
Originally Posted by Mike Kujbida View Post
Robert also asked this question on the Cow Vegas forum and here's the response from John Rofrano. It's totally different from anything suggested here which is why I'm adding it as it made me think that maybe we're off base with our responses :-).
Anyone care to comment?


What you are seeing is the way that MPEG2 compression works. It is assembled in a Group of Pictures (GOP) that contains 15 frames. The first is an I-frame and it contains a complete image. The next 14 frames are composed of B-frames and P-frames which are delta frames and predictive frames. These only contain the information that has changed since the last I-frame. If you make a hard cut on a B or P-frame, the encoder will probably not give you enough bits to represent an entire frame so you watch that frame fill in over several frames. This is the nature of the MPEG2 GOP.

There are two ways that I can think of to fix this. One thing you can try is rendering with the 2-pass option. This will allow the encoder to be smarter and use a higher bit-rate for the frames that need it for these cuts. The other is to only make cuts on I-frames which gives the encoder the entire frame to represent the cut. To accomplish this, you could try setting your timeline ruler to Frames. Then only make cuts on frames that are evenly divisible by the GOP length (15).

I have not tried either of these to fix this problem so let us know how it works.
That advice would have been accurate 5 or so years past, but not anymore. NLE's can cut MPEG long GOP on any frame because they work with it as all I frame in the background. When the sequence is rendered, the GOP is re-conformed if going back out as MPEG.

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Old November 17th, 2009, 11:24 PM   #12
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I use cuts frequently on many projects and have not encountered this issue ever.
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Old November 18th, 2009, 07:02 AM   #13
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I have been working on this problem for nearly all of the last 24 hours. I think I have finally cracked it.

The problem seems only to occur when I have .veg project files NESTED within other project files. When I try to render out of that, the ghost cuts appear. When I don't have any nesting project files, they do not appear.

Does this ring a bell with anyone?

I obviously cannot say whether this is a problem with processor, my copy of Vegas, my graphics card, or a bug with Vegas in general. But that appears to be what causes it and when I remove the nested projects (instead rendering the content of the sub-project as an .avi and dropping it back into the main project) the problem disappears.

I would be interested to see if anyone can test this to find if they can replicate this problem on their copy of Vegas. Or, can you suggest something I may have done wrong (project settings, Vegas settings, system settings) that may lead to this problem when nesting projects?

I will submit a more detailed report on this when I know more.
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Old November 18th, 2009, 09:15 AM   #14
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It would have been helpful had you mentioned that you are using nested files to begin with. Many use them regularly with no problems, but they offer potential for a myriad of issues.

I avoid them. I vaguely recall they render more slowly as well, though I could be wrong.

For my workflow, I create projects in segments. When they are completed I simply select all and copy and paste them together. It is tricky at first with multiple lines of video/audio, etc., but eventually you learn which line to click on the timeline when pasting so that you do not create a mess. For example, I usually end up pasting to the top line.

This might not be a solution for you, but it really works well for me.
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Old November 18th, 2009, 09:24 AM   #15
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Thank you, Jeff, you're right, I should have mentioned the nested files at the beggining. I've been so tunnel-visioned on this project over the last couple of years that it didn't even occur to me that using nested projects was an unusual thing, let alone a problematic one. Now I know.

At this point, rendering the individual projects as DV AVIs, then putting all the AVIs end to end and rendering all of that out as a DVD Architect File seems like my best bet. This required a bit of gordion knot untangling as I have 10 main project files with an average length of ~7 minutes each, and some of THOSE project files have projects nested within them (for complex effect shots and composite masking stuff), so I've been up all night rendering, trying stuff out, putting it back in, etc.

Is there any disadvantage to rendering my individual projects as DV AVIs before I dump to .mpg? I understand there's compression when I go to DV, but since it's going to MPEG-2 in the end this DV compression is probably irrelevant, correct? The other way that I can think of would be to put everything into uncompressed AVI first, then stick it all together and render to MPEG. I would have to go buy about 1TB more hard drive space to handle that, I believe, and I somehow doubt the quality gain is consequential. Thoughts, Jeff, others?
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