Weird video stability problem.

[Dougie]

So far, I've just used Videopad to create 30~45 second videos. Yesterday I edited about three minutes of video. it played back smoothly on both Videopad and Win Media Player after being saved as an mpeg4 avi file. So far so good.

 

Today, I added about two more minutes of video to this file. On playback the newly added footage is fine, BUT, the footage preceeding it (from yesterday) is jerky!! Not every second, but enough to make the video basically useless.

 

it's jerky (just that first half) in Videopad, WMP, anything I try it on. This is a single file I'm talking about in which the first half was saved one day, then the next day opened up and more video edited on, then saved again. That is why I think this is weird! Only the first half is jerky (hummm...the half that has been saved twice). Thinking it just a fluke, I redid the whole thing; delibertly saving the first half and closing. Then opening it up again to add the second half. Same odd results. First half jerky! The computer has never done this before with any editor or video file, and it plays hour long YouTube videos smooth as silk. The problem started suddenly.

 

The computer is a fast dual core with a ton of memory. Any Ideas??

[borate]

So far, I've just used Videopad to create 30~45 second videos. Yesterday I edited about three minutes of video. it played back smoothly on both Videopad and Win Media Player after being saved as an mpeg4 avi file. So far so good.

Today, I added about two more minutes of video to this file. On playback the newly added footage is fine, BUT, the footage preceeding it (from yesterday) is jerky!!

 

Try this: Instead of saving the first-half as an mpeg4, instead save the project (a .vpj file). Then open the project, add the new material, and save the extended project under another name.

Lastly, produce your mpeg4 movie.

[Nationalsolo]

Hi

This jerkyness may be a problem of the mpeg4 format and how VP deals with it. In the videos output by VP, objects moving across the frame (like traffic) seem to move in short spurts 2-3 times per second but here's what I found....

 

I usually shoot MPEG4 1280 x 720 H246 format and I so shot some traffic moving at right angles to the camera as a test with these settings.

 

The resulting video clip played OK with WMP, and VLC. The traffic moved from left to right quite smoothly with no jerks.

 

I then opened VP and loaded the clip to the sequence line and previewed it. The traffic now jerked across the frame, both in the sequence preview, the clip preview and the main preview. So the first question is why? What is VP doing to the MPEG4 to cause this?

 

I then saved the clip as another MPEG4 (Native) with VP and then viewed the copy with WMP and VLC the traffic jerked across the frame just like it did in VP in both of these players. Why should a straight copy behave like this? I noticed it had been compressed. 19.6 megs down to 8.6 megs

 

Choosing H246 made no difference even with the quality slider set reasonanbly high (at 1.0 it was useless!)

 

Any comments regarding how to keep the original raw video quality and Is 3.02 different to 2.41 in this respect?

 

Nat

[Dougie]

Nat wrote (while speaking about mpeg4 video) > "In the videos output by VP, objects moving across the frame (like traffic) seem to move in short spurts 2-3 times per second but here's what I found...."

 

Nat,you pretty much described my problem. Sometimes it will play fine for several seconds before doing this. Today I added a few minutes more to my project (what you might call a third days worth, or part three) and now on playback (any player) the first AND second parts are jerky, with the new stuff quite smooth!! That part of it (old stuff jerky-new stuff smooth) is the most confusing part of all this. But it does offer a clue because it's the clips that have been saved only once that play back smoothly!

 

So it seems that, for me anyway, it is only after re-saving finished parts of a project (making them multigenerational) that the jerkiness comes into play (by the way, I also tried saving this project as an mpeg2 avi file, and got the same results, so it doesn't seem to be just mpeg4.

 

I also tried borate's suggestion with no changes. Since I'm not the only one here experiencing this, we may need to make NCH aware of it before they come out with the new version.

[borate]

So, you're confirming that you created part one of your movie, saved it as a PROJECT (,vpj file), then produced it as an AVI (mpeg4) and it played fine.

 

You reopened the PROJECT (not the AVI), added more clips to the timeline and once again produced (outputted the now longer movie) as an AVI...

but now the part-one clips jerk during playback, even though they have not been previously saved, re-rendered or converted?

[Dougie]

No, I'm not confirming that. Originally I did not save it as a project but simply produced it as an avi, because I was not aware of the problem at that time. After that one saved, it played fine. The next day, I put that avi on the time line, and added added some clips to the end of it. I re-saved it as an avi and played it back. This is when the oddness started: the first part suddenly playing jerkly and the newest stuff playing fine. Unacceptable from any video editor!

 

This was all done before your suggestion. Today (after reading your suggestion) I opened the avi file and saved it as a project (which, of course included the jerkiness, but was all I could do since the original clips are gone). I re-started the computer and loaded the project file. I made an avi from the project, which of course played with the jerks.exactly where they were in the avi.

 

In my mind, there are two ways to save your work if you can't finish it in one sitting. Save as a project file, or save as a master video. Both should work without problems and I rarely use project files. But that should be no excuse for the jerkiness!

[Nationalsolo]

Hi

 

Borate is correct when he says to save your completed work as a .vpj file......i.e. Save it as a project file. When you continue to work on it, this file reconstructs your project from the original film clips***.

 

Reconstructing it from any saved MPEGs or avis you have made may not be the same. I have already noted that saved mpg4 files are considerably smaller than the original camera mpeg4 files which may have some effect if they are used again. (But only guessing)

 

The point I am making is that the ORIGINAL MP4 H246 test clip I made of traffic downloaded from the camera plays perfectly OK and smoothly on both the WMP and the VCL player whereas once loaded to VP it plays with a regular jerky motion most evident when the image pans or the objects move across the frame from one side to the other.

 

More annoyingly, irrespective of the output file type, this jerkyness remains visible in any saved files created by VP. (Even DVDs.)

 

When playing the original clip it's interesting to note the movement of the progress pointer with these players. With VLC (which plays smoothly) it moves in regular spurts which makes me think it is perhaps buffering the video stream as it plays it in some way, hence the smooth output. With WMP the movement is less jerky but the video is still quite smooth.

 

This jerkyness created by VP is an annoying effect particularly as it remains in the finished video.

Furthermore, is it something that can be addressed by NCH?

 

Nat

 

*** Or does it? The .vpj file certainly uses the cache file created by VP and the cache does seem to contain copies of the video clips used. Perhaps these are are already jerky having been created by VP. Its difficult to say with certainty as the only clips that definitely play without jerks are those downloaded from the camera.