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Difficulties rendering WAV audio – Volume
I imported 6 channels of 24-bit 48000 Hz WAV audio files for a 5.1 project. I edited the files in Vegas. The only edits I did was to put a Volume Envelope, and lower the volume for certain parts. The rest of the volume envelope is at the default 0.0db.
I am exporting the files as WAV or W64, 24-bit, 48000Hz.
Everything seems to go fine in the export, but if I reimport them, the audio volume has been significantly raised. In fact, good part of the audio appears as clipped or “maxed out” if I reimport it.
My goal is to output in as “lossless” a fashion as possible – for this I removed all Audio Effects, and left all the volume meters at the default 0.0db.
Any ideas why this is occuring and how I can fix it? If I do the same imports, edits, and exports in Audacity, the exports seem to be 100% identical to the imports except where I made edits. How can I achieve this in Vegas?
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5 Replies
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How’s the master volume look? Are you compressing the final mix?
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The master volume is at 0.0. I am outputting the final mix as 24-bit 48000 W64, so it is totally uncompressed.
I have been playing around with quite a bit today, and have been able to determine what causes the volume change. It only occurs if I render the project when more than one channel of audio is active. If I select “Solo” on a channel, and then render a mono file, it works perfectly. The same happens if I simply delete all channels except for one and then render. As soon as I add a 2nd channel, the waveform on each channel is significanly larger when rendered.
Here is an image of the type of change I am seeing if I have more than one channel. The waveform in both channels is significanly different, and you can see that they are not being mixed together, but Vegas raises the volume on both. The top two are the originals. The bottom two are after rendering. All audio effects are turned off, and all volume meters are at default 0.0db.
If I can’t solve this problem, I will render each channel in “solo” and then render a 5.1 file in Audacity.
I have tried this in 2 different computers with Vegas Pro (8.0c) and both give the exact same results.
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Audio volume is additive and doubling the volume increases the output by 6dB FS. If you’d like to see the effects of this, take a test tone at -32dB and drop it on a track. Play it back and notice that the meters registry -32dB. Now duplicate the track and play it back. The meters should now be 6dB louder and register -26dB. Double those 2 tracks to 4 track and play it back and you’ll see another 6dB jump to -20dB. This is kind of what’s happening with your 5 tracks of surround audio. If each one is at -3dB, adding them together will clip quite easily.
This is the same reason that an orchestra is louder than a single violin. Think about it. No violin is any louder when played along than they are when played together yet they are louder together because volume is additive.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
Oh… I forgot to mentioned that you can change the additive behavior for 5.1 Surround in Vegas (duh!).
For each of the surround channels, right-click on the surround panner in the track header and change the Pan Type from Add Channels (0 dB Center) which is the default… to Balance (0 dB Center). Then Vegas will behave as you expected.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
Just wanted to thank you for taking time to answer my questions. What a great community here.
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