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Old 25th November 2004, 15:13   #1  |  Link
lancer
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Location: leeds england
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wav to dolby 2.0 encode question

I'm going to have a crack at extracting my original wav recording and turn it into a 5.1 or at least a surround track in vegas.

I've seen the guides on the forum here but a question occured to me.

when I originally recorded the sound in virtualdub_sync, I recorded it as a straight 48khz 16 bit stereo wav file. as per the offered choices on vdub.

at the time I ignored all other options, but looking at vdub today, (two years after the capture was made)I notice further down now that there is the option for PCM. as I recorded wav stereo, would this suggest that there is nothing for me to extract to make it a surround track, or would it still be embedded in there somewhere?

when I pipe it through my speakers and select and surround 2.0 dolby pro logic I do get some rear surrounds. is that the PCM at work? am I right in assuming that PCM info is embedded in stereo tracks or would I have to rerecord the audio?
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Old 25th November 2004, 16:00   #2  |  Link
ursamtl
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Hi lancer,

Short answer: PCM is simply a way of digitally storing the sound data, but it has no direct bearing on the information needed to produce stereo or surround, so if your source file is real, 2-channel stereo, you should be ok.

Explanation: Stereo to surround conversions basically fall into two categories (or a combination of the two):

1. Those that extract existing audio spatial information
2. Those that impose artificial audio spatial information

All you need to do the first is a stereo track. The spatial information is stored in a signal that is derived by "subtracting" one channel from the other (inverting the phase of one channel and combining it with the other. Sounds that are the same cancel each other out; those that are different remain).

As for the second approach, this amounts to adding artificial effects processing such as reverb. In this case, your source could even be mono and you'd be able to come up with some sort of surround.

Steve.
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Old 25th November 2004, 17:05   #3  |  Link
lancer
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thanks for that, I thought that might be the case, I really didn't want to have to re-record the sound again.
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