Vegas 4.0c adding audio clicks/pops during rendering.

Elizabeth Lowrey wrote on 6/26/2003, 1:50 PM
I'm in quite a jam, trying to get a project out the door ASAP that I've been working on at various stages for weeks. This is my first project with Vegas, so it is the first time I've done renders longer than a few seconds for testing purposes.

Because the project is so long (2.5 hour recital with 3 cameras), I split it up in sections with the intent of rendering out one section when fully edited, deleting the associated media for the underlying Vegas project, and moving to the next section, assembling the 4-5 rendered sections at the end for the final result.

It was during playback of the first completely rendered section (brought into a blank, brand new Vegas project for that purpose) that I noticed audio clicks and pops SUDDENLY appearing. Each time I heard one, I immediately replayed the section several times to make sure it wasn't a realtime playback problem, and each replay revealed the pop to be in exactly the same place with exactly the same character, i.e., was now part of the rendered file. This was also verified by taking the rendered AVI into Premiere and playing back through DVStorm, comparing to my notes about where the pops were observed in Vegas playback.

I know from endless playback of the underlying media files in the Vegas project from which the renders were taken that there were NO audio anomalies in the component media files or even in the initial audio previews. The project included several tracks at standard DV audio spec (though rarely playing together) with some noise reduction and EQ and occasional inclusion of 44.1 audio from a music track.

The clicks occur randomly throughout the 13-minute render, some in places where there were a couple of active audio tracks, others in places where there was only one active audio track. All were observed in passages with voice over or speech where "space" and volume level permitted obseration. The clicks, if present during sections where the music track was playing alone at full volume, must be masked. So it's definitely not a sample rate conversion issue.

I can't for the life of me think of any reason why Vegas is adding these pops during RENDERING -- a non-realtime, software process of assembling and mixing all the elements at best quality -- or why previewed audio with all its realtime stressors and chores doesn't exhibit this problem.

Any help much appreciated.

Elizabeth Lowrey

Amore Productions

Comments

mfhau wrote on 6/28/2003, 6:57 AM
I have seen this type of thing happen when using 12 bit audio using othe NLE software - mind you Vegas was my saviuor and didn't exhibit this behaviour when the other software did.
just a suggestion

mark
Randy Brown wrote on 6/28/2003, 8:08 AM
Hi Elizabeth,
There have been other people here having pops in a render (using the c version). For me it doesn't happen very often and seems to be random; or is it random? I hardly ever use noise redution (about as often as I hear pops in my render); when you mentioned using noise reduction, it made me wonder if it could have something to do with it.
Randy
JJKizak wrote on 6/28/2003, 8:26 AM
I have encountered clicks and pops in the playback on the timeline since
I went to the 5.1 drivers in the Audigy soundcard but they do not show up in the
render. Also when capturing there are many echoes in the sound but they are not
in the captured clips. Don't know if this will help.

JJK
Elizabeth Lowrey wrote on 6/28/2003, 9:19 AM
The problem was apparently the intentional introduction of "garbage" into the render from the NR program, which was a demo that I'd downloaded to test the program while doing this project. It played fine in realtime previews, but a SoFo rep specifically told me that it will add junk to the render.

This caught me way off guard because the download site says nothing about such a limitation. In fact, since "timing out" after a week was the ONLY limitation listed, downloaders are left with the distinct impression and expectation that renders will be unmolested.

I suggested that this very substantial limiation be made conspicuous on the download site not only to avoid others reporting the same problem but because it could seriously impair one's impression of the quality of the NR program on trial. It's not an obvious interference or sabotage -- like say with a constant or intermitent tone or severe limitation on the permissible length of renders. The pops and clicks are mostly mild and not terribly frequent. So someone demo-ing that software, if they caught on to the fact that the pops were only present when NR was on, might come away with the impression that the plugin is junk, not that it is intentionally inserting junk in renders.

In any case, the clicks are gone, for which I am very grateful, and I'm very happy that SoFo tech support worked so swiftly and efficiently to solve it.

And thanks to all who replied.:-)

Elizabeth Lowrey
Amore Productions
Randy Brown wrote on 6/28/2003, 9:20 AM
Thanks JJK, but I think the sound card has been ruled out as the rendering process does not go through the sound card. It's not a "playback" issue, the pops are definitely in the file (even though we can't see them).
Thanks again,
Randy