Slightly Different Render Depending on Format?

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ctheiss
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Slightly Different Render Depending on Format?

Post by ctheiss »

Hi there,

I've been experimenting with syncing audio and video in a precise way (something like http://www.youtube.com/watch?v=dBVA0kyXX4k#t=2m20s), and have found that in every output format except "MPEG Optimizer...", the sync is a little off... or at least different than the preview.

Through experimentation, I have found that you can be off by one frame and not really notice, but two frames and things look "amateurly" synced. Given that there is one frame leeway, I figured that rounding due to frame rate differences are accounted for, but this is not the case.

In some cases, I have also noticed transition and F/X changes, depending on the output format. For example, I have an image of a statue with "AutoSketch" applied. In the preview, everything looks wonderful. In HD MP4 output, the statue is drawn top to bottom, then the base of the statue disappears and is re-drawn. In DV and WMV format, the drawing is noticeably different, even though the resolution is the same.

What gives? If we can't count on the output to be like the preview, then all that time spent making a killer sync is just wasted :(
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Black Lab
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Re: Slightly Different Render Depending on Format?

Post by Black Lab »

A couple of important points are missing:
1. What version of VS are you using?
2. What are the properties of the clips you are trying to render?
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ctheiss
Posts: 8
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operating_system: Windows XP Pro
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sound_card: onboard
Hard_Drive_Capacity: 80GB

Re: Slightly Different Render Depending on Format?

Post by ctheiss »

I am using VideoStudio Pro X3. As to the clips, they are varied. But the problem is reproducible using jpegs with no transitions. Just make sure that the images change right on the beat of a song, and you'll see that in most output formats, the image change is a little off (and more importantly, different than the preview).

Upon further testing, I have noticed that the video seems to be bang on... it's the audio that becomes un-synced. In some formats, a frame or two of blank audio gets added or taken away from the start. It is possible to compensate for this behaviour: if you want the audio to be as synced as the preview,
  • remove the first frame before rendering to AAC
  • add two frames before rendering to FV
  • etc...
As for the transitions, I haven't yet figured that one out.
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