Shortening the length of a long track by a tiny fraction

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Shortening the length of a long track by a tiny fraction

Permanent link to this post Posted by DMG » Wed Apr 24, 2013 9:33 am

HI All,

I have a two hour wav file, which I need to shorten/compress by about 8 frames. (I am backing up my VHS copies of Empire Strikes Back. One copy has near perfect picture, but a bit of crackle on the audio, and the other tape has a worn-out picture, but near perfect audio. I am using the best bits of both tapes, and to be honest, was surprised and impressed that the difference in track length was only 8 frames over the whole length of the movie... 8 frames is about a third of a second, so it's too big a difference to ignore.)

I have tried the 'shorten' filter, but it appears to only work for two decimal places. I need to shorten the audio by exactly 0.99995555555555555555555555555556
The shorten filter seems to abbreviate this to .99, which is over a minute.

Are there other simple options for reducing the length of a track by a teeny-tiny amount, or should I just go through the whole audio, and trim tiny bits out here and there to keep it in sync? I have the audio from both copies in wav format, so I could work with the poor-quality-but-in-sync version visible to use as a guide for aligning the good-quality-but-out-of-sync version.


Thanks for any suggestions,

Derek
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Re: Shortening the length of a long track by a tiny fraction

Permanent link to this post Posted by Damienb » Wed Apr 24, 2013 12:52 pm

Can you use the timer down the bottom of the main window? If you click the arrow you can select different time formats. Then you can just type in the time you require? It should then select the track by the amount of time you typed in.

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Re: Shortening the length of a long track by a tiny fraction

Permanent link to this post Posted by steve » Wed Apr 24, 2013 4:08 pm

You have posted in the "legacy" section. If you are really using an old (obsolete) version of Audacity you should upgrade. The current version is available here: http://audacityteam.org/download/

The following instructions assume a recent version of Audacity (not tested on obsolete versions).

You could try changing the track sample rate just a little.
To do that, Click on the name of the track, then from the drop down menu select "Set Rate > Other". Set the new sample rate a little higher to make the track a fraction quicker (shorter). For example, of the current sample rate is 48000, setting it to 48002 will reduce the length of 1 hour to 59:59.850. The sample rate must be a whole number, but that may be close enough, and it is quick to do.

When you export the track back out from Audacity, the audio will be resampled to the "Project Rate" (bottom left corner of the main Audacity window). The Project Rate should match what you need for the video (usually 48000 or 44100).
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Re: Shortening the length of a long track by a tiny fraction

Permanent link to this post Posted by DMG » Thu Apr 25, 2013 3:29 pm

Thanks for the replies guys.

Steve - I don't use audacity a lot, so I haven't bothered to upgrade for quite a while. I probably should. I'll have a go at altering the sample rate, see if that does the trick.

Thanks,

Derek
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