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Audio fades out in video clip for no discernible reason? (Vegas 12.0)

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Terhi Riekkola
Audio fades out in video clip for no discernible reason? (Vegas 12.0)
on Jun 28, 2015 at 9:51:02 am

Hiya,

First of all, apologies if I'm doing something wrong--I only registered because I couldn't find an answer to this topic anywhere. I've been making a trailer-style video clip that's about 30 seconds long with various video tracks and two audio tracks--one with background music, one with various clips of dialogue. Now, when I've rendered my file to .mp4 or .mpg and play it back in MPC or KMPlayer, the audio goes down drastically at 14 seconds in and I can barely hear it. This affects both the dialogue and the music track and lasts until the end of the video. I've checked multiple times and I haven't set an audio envelope over the last half of the video anywhere, nor have I fiddled with the FX of the dialogue clips to take them down (if anything, I had to turn them up because some were so quiet). When I play it back in VLC or in Firefox, it sounds fine, but I expect that's because VLC and my Firefox plugins have something that compensates for the sudden quietness. The audio plays fine in Vegas itself.

And the weirdest thing is that I rendered this same trailer into .mpg, then opened that mpg in Vegas and created a new audio envelope where I turned the audio up like crazy for the last half of the video, then saved that as a new video file, then played that video file back in MPC and the damn thing still went quiet for the second half of the video! I've tried restarting Vegas, restarting my computer but this doesn't work, and I also fiddled with other projects but didn't experience this rendering problem. And needless to say, adding a new audio envelope to turn up the sound in the original project's last half doesn't work either. It becomes so loud it goes into the red in Vegas and hurts my ears, but after rendering (I tried AVI as well), the last half is still muffled in MPC and KMPlayer.

I'm presuming this is some sort of codec problem? Any idea on how I could fix it? Massive thanks in advance.


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Bob Peterson
Re: Audio fades out in video clip for no discernible reason? (Vegas 12.0)
on Jun 28, 2015 at 12:32:48 pm

Since your audio sounds fine in Vegas, VLC, and Firefox, I suspect the problem is in MPC and KMPLayer. However, additional things you could do include;

1. Does the same problem occur with Windows Media Player? I have many, many audio files in WMP and I am quite sure that it does not act like a compressor.

2. Render the audio for your project to a wav file. Import the wav file back into Vegas, and examine the wave form that Vegas displays for audio files. If the wave form shows the same quieting, then the problem is in Vegas. If the wave form shows that volume levels are maintained throughout the clip, then substitute the wav file for all of your existing audio tracks (mute the existing tracks). Now, rerender an mpeg file, and recheck it in Windows Media Player. If it still sounds OK, then recheck it in your other two players.

3. If the problem is shown to be in Vegas in step 2 (above), check the master audio track to be sure that it is not the source of the problem.


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Terhi Riekkola
Re: Audio fades out in video clip for no discernible reason? (Vegas 12.0)
on Jun 29, 2015 at 11:32:03 am

Thanks for the swift response. I tried this and as I expected, the audio looked the same in Vegas, and some of the muffled bits were even louder in the .wav when I played it back in Winamp because of the amount of compensation I had to do earlier. I rendered it into a new file and the problem persists in MPC and KMPlayer. It's probably worth mentioning at this point that earlier versions of the trailer didn't have this problem and I used the exact same audio clips on it, too (and those aren't corrupted)--so I presume it's some glitch that happens during the rendering process and it's some codec issue that certain players just can't handle. The audio sounds normal in VLC, Winamp and Windows Media Player (both the video files and the raw .wav).

Right now, I don't see a way around the problem apart from turning the volume up on the second half on the trailer and don't feel like starting the audio work from scratch, so I guess I'm just going to have to tell whoever downloads it that for some reason it doesn't work on a few players the way it should. It bugs me, though, because I would much rather have a version that played well on all players. I'd also be curious to hear as to whether other people have had problems of this sort, because I've only ever had video problems during rendering before. Or whether there's just some setting I've missed (because there isn't an audio envelope anywhere in there nor have I applied any muffling FX to take down the volume).


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Bob Peterson
Re: Audio fades out in video clip for no discernible reason? (Vegas 12.0)
on Jun 29, 2015 at 4:39:20 pm

I'm not sure what you said, so let me summarize what I think you said.

You rendered the wav file, and imported it back into Vegas. It looked and sounded good with no evidence of reduced volume. It also played fine in one or more media players. When you used the wav file in your render of your video, it sounded fine in Media Player and one or more other players. However, it still had a volume problem in the freeware players MPC and KMPlayer.

The obvious conclusion is that there is not a problem in Vegas or the file it renders. There is a problem in the two freeware players. I would try to follow up with the freeware developers to see if they have a solution. Perhaps a different file format would solve the problem.


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Terhi Riekkola
Re: Audio fades out in video clip for no discernible reason? (Vegas 12.0)
on Jun 29, 2015 at 5:28:24 pm

Yep, that's it. I'm sorry if I sounded convoluted; it's a bit tricky to explain anyhow. I basically did as you suggested and the .wav file was fine, and the versions (one mp4, one mpg) I made of the trailer with just that .wav as the soundtrack gave me the same result as the original--everything worked fine in VLC and WMP and when viewed through a browser. But again, MPC and KMPlayer showed the same strange muffling phenomenon I experienced earlier. Which is why I suspect Vegas fails to render it correctly and those last two players can't compensate for that glitch. My only problem is that I'd just want the trailer to be working perfectly in most video players--especially since it's not just a case of one random player not playing it right, but two fairly popular ones. It really is especially odd as the sound was fine in MPC when I was still testing out earlier versions of the trailer, but I've made so many changes that I can't revert back to the version that worked.

It's like I added something that Vegas just couldn't handle right, but now I've tried removing various clips from the middle just in case they magically screwed up the rendering process somehow and haven't had any luck. The only similar situation I can remember is when I tried to make a video with clips from an old Technicolor movie and the Technicolor parts constantly threw up glitches, like Vegas just didn't understand how to render such rich colours. So I was wondering if there were any idiot-proof sound settings/codecs I could try to smooth this thing out?

Thanks again for your help and again, apologies if I'm explaining these things clumsily.


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