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Problem - video duration

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Lex Hiram
Problem - video duration
on Dec 19, 2010 at 12:33:18 am

Hi,

I've screen captured some video at 30fps, sequenced the segments, and pre composed them. The sequence itself adds up to around 20 minutes, so I enabled Time remapping, to shrink it down to ten minutes.

After rendering it out to Mpeg2, my video players all say that it's five minutes long, not ten.

When I open the rendered file in AE, it says that it *is* ten minutes long... I'm confused.

Have I made an error in compression. I left it all at defaults when I selected Mpeg2.

--Lex


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Paul Roper
Re: Problem - video duration
on Dec 19, 2010 at 8:09:50 am

Did you render it out of After Effects as an MPEG2? You'd be much better off rendering it as an uncompressed format, then using a separate compression application such as Apple's Compressor or Sorenson Squeeze to create your MPEG2. You can then check where the weird time stretch is happening - is the uncompressed After Effects render the correct length? If it is, then the problem's in your MPEG2 compression.

Also, you'll be able to experiment with different compression settings without having to re-render your After Effects sequence.

I'm guessing it's for a DVD - that's about the only reason I can think of that you'd use MPEG2 compression. Otherwise, there are better, newer delivery codecs around, such as H.264.


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Lex Hiram
Re: Problem - video duration
on Dec 19, 2010 at 2:17:59 pm

Actually it hadn't occurred to me to render out an uncompressed file and compare the lengths, that's a really good idea.

Although, having said that; I have just tried the H.264 you recommended, and that was far better - thank you. I'd never used it before, and was simply choosing MPEG2 through familiarity, and the fact that MPEG4 wanted to downscale the resolution of my file.

I'll just need to figure out, what are the best target/max settings for H.264...

Thanks again.


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Eric Chard
Re: Problem - video duration
on Dec 19, 2010 at 8:54:08 pm

Did you figure out why AE thought the original footage was short?

++++++++++++++++
"Putting the HARM in 'harmonica' since 2005."
++++++++++++++++


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Lex Hiram
Re: Problem - video duration
on Dec 20, 2010 at 3:53:33 pm

I'm sorry, no.

In AE it seems fine; if I re-import my exported footage, it is the correct length.

I have no idea why the three video players I tried it on all thought it was half-length. I guess, it'll have to stay a mystery for me - I'm really happy with the results I'm getting from the H.264, so won't be going back to MPEG2..

--Lex


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jesus moncada
Re: Problem - video duration
on May 1, 2012 at 7:45:21 am

I hope you have not closed this issue. It is happening the same, with AE-CS5 to export a project to MPEG2 format, the final product is a video with a shorter time to the original project. I have done many tests, the only solution is to use another program to export to this format and this is a cumbersome process.

If you know the solution please tell me


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Paul Roper
Re: Problem - video duration
on May 2, 2012 at 1:43:37 am

The "cumbersome process" you describe is the correct one - After Effects is really not designed for outputting compressed formats; in fact a huge amount of this and other forums' bandwidth could be saved if Adobe removed these formats altogether!

The normal workflow is to output form After Effects, import into an editing program such as Final Cut Pro, Avid or Premiere, edit it into your program, then export the compressed format. Or, as you have found, export an uncompressed format from After Effects then use a specialised compressor to encode it.

- Paul


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jesus moncada
Re: Problem - video duration
on May 3, 2012 at 4:03:44 pm

Paul you are right, is efficient and faster and also helped me with several tests. But when exporting or encoding the video from other software (I tried with several, included 'premiere') and did the same, I could solve this problem by changing the parameters of output with this calculator that i found:
"http://dvd-hq.info/bitrate_calculator.php" for example: I served in one of the tests I did change the 'Rate control' VBR to CBR, he had not taken into account if it were not for the help of that link. I hope that help you all. That worked for me.


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Peter McCormick
Re: Problem - video duration
on Jun 28, 2012 at 11:42:00 pm

Just to confirm my lack of skill here, I realized that AE is indeed exporting to the correct duration. It's when I import the .avi into Vegas that it shortens up to 22 seconds (from 40). Frame rate is the same.

What am I doing wrong?


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