Are WAV Files "Smart Rendered"?

Shredder wrote on 1/14/2003, 9:41 AM
Hi,

I just want to verify that i'm not lessening the quality of my audio files with minor edits.

If I start with a 32 kHz, i6 bit, Stereo PCM wav file, drop it into a vegas project with the same audio properties, and then simply trim the beginning and end and remove a bit of the middle, and then "Render As" exactly the same format 32/16/S, is the resulting audio simply "copied" to the new file without being re-rendered (as happens with DV AVIs in VV3), or is it actually resampled again etc. (and does that lessen the quality?)

If anyone could verify this i'd appreciate it.

If it is being resampled, anyone know of a tool i can use to trim large 2GB/4.5hr wav files without altering the data stream?

Thanks,

Jon

Comments

bgc wrote on 1/14/2003, 11:06 AM
If you only do what you're saying and don't insert any signal processing in the chain and leave all the faders at 0dB you'll get the same samples back that you put in. You can test this by lining up the original track with a portion of the rendered file and invert the phase of one. If they're the same (in the areas that they're supposed to be the same) then you'll hear nothing (they'll perfectly cancel each other out).
bgc
SonyEPM wrote on 1/14/2003, 11:35 AM
From the vegas engineering team:

"The quick answer is that, so long as you apply no volume or pan changes, a rendered 16 or 24 bit audio file of the same bit depth and sample rate as the original media will be indistinguishable from the original media.

The long answer is that there is no resampling going on for the type of situation you describe. There is one potential gotcha when doing this, and that is to make sure you have your track pan-type set to "Add Channels (0dB Center)" or "Balance (0dB Center)". Other pan types apply an attenuation to the signal when set to the center position that will reduce the effective bit-depth to a small degree, and result in the loss of some information. Internally the audio data is converted to 32 bit floating point but this is more than enough to ensure that the conversion back to 16 or 24 bit results in an identical copy.

Because of this conversion, it would probably be faster if you simply trimmed your long media in a product like Sound Forge - since Forge will do a simple copy of the part you want when you save."
Shredder wrote on 1/14/2003, 12:44 PM
Awesome! -- Thanks for the info.

On last question.
By default, a new audio track has 3 track FX plugins applied: "Track Noise Gate" "Track EQ" and "Track Compressor" -- Assuming I don't change any of the default settings (which seem to be null) -- will these have some effect on the processing anyway. I'm just going to delete those FX anyway, I just want to know if i need to.
SonyEPM wrote on 1/14/2003, 2:15 PM
No need to delete the default track fx- they won't screw with your files in the default state.

You can delete them if you want to, and you can also change them- right click on the track header and choose "set default track properties".
riredale wrote on 1/15/2003, 3:47 PM
I got rid of my default FX audio track properties, because they seemed to be slowing down the render speed, even if unchecked.