Final video 'pulses' when playback speed is slowed...?

jakobkraft · Post by **jakobkraft** » Tue May 08, 2007 5:43 pm

I just finished my first video of a trip to India, and as I was editing I did notice that certain clips pulsed in the Preview window whenever the playback speed was changed to a slower speed. Since a lot of the effects seen in the preview window don't show in the final video, I didn't worry about it.

Unfortunately, the final video DOES pulse, or become intermittently blurry, for clips whose playback speed was changed to a slower one (not even that much slower, maybe 80 or 90).

Is there any way around this, as I really do need to have slower playback on some clips...
any help would be greatly appreciated.

Thanks in advance:)

Black Lab · Post by **Black Lab** » Tue May 08, 2007 10:27 pm

What are your clip and project properties?

jakobkraft · Post by **jakobkraft** » Wed May 09, 2007 1:57 am

Project Properties:

NTSC DVD, 4:3
Video data rate: 9200 kbps, Constant
Quality 100
DVD-VR Compliant (checked)
29.97 frames/second
Frame type: Upper Field First
Frame size: 720x480
Perform non-square pixel rendering (checked)

Dolby Digital Audio, 2/0 (L,R)
Audio frequency 48000 Hz
Audio bit rate 384 kbps
Audio channels: Stereo

Is there anything here I should change?

Black Lab · Post by **Black Lab** » Wed May 09, 2007 3:55 pm

You gave us the project properties, but we need the clip properties too. Right click on a clip and post them here.

jakobkraft · Post by **jakobkraft** » Wed May 09, 2007 6:15 pm

Actually, I figured it out; I changed the 'Lower Field First' setting to 'Frame-based' and afterwards, perfect picture:)

My only grievance now is with music that is played at a slower speed. If it's a loud song, it generally sounds okay. But if it's an instrumental track, then I get a lot of pops and click, some distortion but it's mainly just very audible pops and clicks.

Is there anything I can do for that? Maybe a third-party app that can stretch out a track with minimal distortion and clicks?
Thanks in advance...!

Black Lab · Post by **Black Lab** » Wed May 09, 2007 7:59 pm

What sort of file is the music track (mp3, wav, etc.)?

Are you altering the playback speed of the music track. If so, VS does tend to distort the sound if you alter it too much. VS is a fine video editor, but not such a great audio editor. A third party app (such as the free Audacity) might do the trick.

jakobkraft · Post by **jakobkraft** » Wed May 09, 2007 9:14 pm

It's an mp3 file...

Someone else suggested Audacity, and I downloaded it but couldn't figure out for the life of me how to use it to stretch out a track.

Can you maybe give me a quick rundown on how to do that? It seems like a capable app. but the interface has my head spinning...

Post by **Ken Berry** » Wed May 09, 2007 9:23 pm

I am more worried by the fact that your project properties are set to Upper Field First; yet you later also mention changing Lower Field First video to Frame Based. If all this is to go into one video project, then no wonder you had problems with the final output.

It is a major no-no to mix Field Orders in one project. That is why we wanted your original captured clip properties. If video starts life as Upper Field First, you must maintain that in the project settings and also the properties you use to burn the final disc. Ditto with video which started out as Lower Field First.

Generally, video captured from an analogue source is Upper Field First, while from a digital source it is usually Lower Field First.

Now the one exception is Frame Based where a slideshow of still images can be produced using Frame Based because still images are not interlaced.

But Frame Based may look good on your computer monitor, because that is what it is meant to look good on. But you might find that your final DVD is not performing correctly in a stand-alone player because parts of the video on it is using the wrong field order.

Black Lab · Post by **Black Lab** » Wed May 09, 2007 9:25 pm

First of all I will tell you that some people have problems with MP3s. You may try converting it to a wav file, but you may still have problems with the distortion if you are adjusting the time.

As for Audacity, click File > Open to import your audio. Then click Edit > Select > All. That will allow you to apply effects. Click on Effect and choose whatever you like (Change Speed or Change Tempo in your case). Then Export As (WAV is my preference).

jakobkraft · Post by **jakobkraft** » Wed May 09, 2007 9:31 pm

Ken Berry wrote:I am more worried by the fact that your project properties are set to Upper Field First; yet you later also mention changing Lower Field First video to Frame Based. If all this is to go into one video project, then no wonder you had problems with the final output.

It is a major no-no to mix Field Orders in one project. That is why we wanted your original captured clip properties. If video starts life as Upper Field First, you must maintain that in the project settings and also the properties you use to burn the final disc. Ditto with video which started out as Lower Field First.

Generally, video captured from an analogue source is Upper Field First, while from a digital source it is usually Lower Field First.

Now the one exception is Frame Based where a slideshow of still images can be produced using Frame Based because still images are not interlaced.

But Frame Based may look good on your computer monitor, because that is what it is meant to look good on. But you might find that your final DVD is not performing correctly in a stand-alone player because parts of the video on it is using the wrong field order.

Sorry, I got confused when referring back to my project properties - I'm at work and not in front of my machine. It originally was set to 'Upper Field' first, NOT 'Lower Field', like I said in my second post -- my mistake.
But thanks for the info; all of that's good to know:)

And thanks, Black Lab, for the Audacity info - can't wait to get home!!

Post by **Ken Berry** » Wed May 09, 2007 9:34 pm

My comments still apply if the video you changed to Frame Based was actual video and not a slideshow of still images...

jakobkraft · Post by **jakobkraft** » Wed May 09, 2007 10:35 pm

It was actual video, shot from a JVC Everio GM77U 30GB. It's the second movie I've made with this camera which, despite some negative reviews, I think takes very nice-looking videos. I didn't have any problem at all encoding and finalizing my first movie, but I didn't mess with the playback speeds on that one.

For my India movie, there's just so much stuff for which I have to adjust playback speeds; it was only then that I started to see this 'pulsing' effect.

I didn't make a final DVD of it but I did encode a MPEG-2 video with the Frame-Based setting and when I played it back in PowerDVD & WinDVD it looked great...

I'll let you know what the final DVD looks like with the Frame-Based setting...

Black Lab · Post by **Black Lab** » Wed May 09, 2007 10:57 pm

It will look fine as frame-based on a pc because pc monitors are not interlaced. If your DVD will be played on interlaced TVs you will have problems. If your DVD will be played on a new progressive scan (LCD) TV then frame-based will be ok.