weird glitch in my audio after I export at DVinfo.net

Paul Owens · February 9th, 2011, 06:27 PM

I'm really new to all this so i'm sure this is probably me screwing up, but I shot a video of a lecture and have been editing it and cutting it into clips by topic. We're releasing them 1 at a time on the facebook page of the guy that did the talk. I've done 3 so far with no issue but the 4th one (which is longer then the first 3. It's 11ish minutes) when I export it the mov file plays fine but gets to a point where the audio is just all screwed up. It sounds like there's some weird static distortion. It was at 3 minutes. I deleted it and re-exported it and when i play it, it plays fine but the same distortion is at around 7 minutes. I didn't change anything between the first and second export. Any idea what I may be doing wrong or how to make sure my audio comes through?

Thanks!

I should mention... the video was all shot on the same camera in 2 clip using a lavaliere mic and I am editing it in Final Cut Pro. The audio plays fine in the raw footage and in final cut. It's not till I export that there's an issue.

Les Wilson · February 10th, 2011, 05:37 AM

HI Paul, welcome to DVInfo.

I've had this and similar things happen over the years. My gut says there's some corruption in the video data that's throwing the playback software off. The result is that it's playing garbage for audio or video. It could be a bad spot on your hard disk or corruption in the source file that happened during capture. The fact that FCP plays it fine but the QT player doesn't isn't conclusive that the data is fully OK.

Besides restarting your system before exporting, voodoo that has been effective for me is to change things as far up stream as you can. For example, do a Make Offline on the source file but not erase it from the hard disk. If it's on a bad spot, leave it there "covering" that pothole so to speak. Then re-import it from tape or whatever. Another technique is to open the source file in the QT player and Save As (self contained) into a new file. QT pretty much has to traverse the whole file to do this and may silently repair anomalies as it does so. It could be interesting to see if this has any effect on the problem output file. You could also export the capture file from FCP and use that in your timeline.... you get the idea... hope this helps.

Addendum: I once had this problem exporting to an external firewire drive thru a Firewire hub that was going bad. Exporting to an internal drive solved the problem but it came back when I did a copy to the external drive.

Paul Owens · February 10th, 2011, 07:44 AM

Thanks Les,

I'll try some of those things. I really hope it's not the HD. I've only had this computer for 2 weeks. Bought it new from Apple. I also hope I can do it without having to totally recapture. That's not possible. This was my first real shoot and we did things... I wouldn't do again. I didn't have my computer at the time and My buddy has Premier so we hooked up the camera to his computer and captured in real time right to the PC. The thought was to have it on the tape too as a backup, but the camera guy(we're all amateurs) figured we had it ok so he never told the speaker that we needed to change tapes so I don't have the 2nd 2/3rds of the presentation backed up (NEVER DOING THAT AGAIN!) After I got my computer, we transfered the files through ethernet from his computer to mine. They were AVI files. When I imported them into FCP I used the Media Manager to create a working copy and that brings us to where I am now.

Thanks again... I really appreciate your help.

Paul Owens · February 12th, 2011, 08:00 PM

So I got rid of the issue by exporting it as AVI instead of MOV. The quality sucked... but since it was on youtube it was ok.

Thanks for the help.

February 9th, 2011, 06:27 PM	#1
Paul Owens Regular Crew Join Date: Feb 2011 Location: Rochester, NY Posts: 103	weird glitch in my audio after I export I'm really new to all this so i'm sure this is probably me screwing up, but I shot a video of a lecture and have been editing it and cutting it into clips by topic. We're releasing them 1 at a time on the facebook page of the guy that did the talk. I've done 3 so far with no issue but the 4th one (which is longer then the first 3. It's 11ish minutes) when I export it the mov file plays fine but gets to a point where the audio is just all screwed up. It sounds like there's some weird static distortion. It was at 3 minutes. I deleted it and re-exported it and when i play it, it plays fine but the same distortion is at around 7 minutes. I didn't change anything between the first and second export. Any idea what I may be doing wrong or how to make sure my audio comes through? Thanks! I should mention... the video was all shot on the same camera in 2 clip using a lavaliere mic and I am editing it in Final Cut Pro. The audio plays fine in the raw footage and in final cut. It's not till I export that there's an issue.

February 10th, 2011, 05:37 AM	#2
Les Wilson Inner Circle Join Date: Jan 2004 Location: Boca Raton, FL Posts: 3,014	HI Paul, welcome to DVInfo. I've had this and similar things happen over the years. My gut says there's some corruption in the video data that's throwing the playback software off. The result is that it's playing garbage for audio or video. It could be a bad spot on your hard disk or corruption in the source file that happened during capture. The fact that FCP plays it fine but the QT player doesn't isn't conclusive that the data is fully OK. Besides restarting your system before exporting, voodoo that has been effective for me is to change things as far up stream as you can. For example, do a Make Offline on the source file but not erase it from the hard disk. If it's on a bad spot, leave it there "covering" that pothole so to speak. Then re-import it from tape or whatever. Another technique is to open the source file in the QT player and Save As (self contained) into a new file. QT pretty much has to traverse the whole file to do this and may silently repair anomalies as it does so. It could be interesting to see if this has any effect on the problem output file. You could also export the capture file from FCP and use that in your timeline.... you get the idea... hope this helps. Addendum: I once had this problem exporting to an external firewire drive thru a Firewire hub that was going bad. Exporting to an internal drive solved the problem but it came back when I did a copy to the external drive.

February 10th, 2011, 07:44 AM	#3
Paul Owens Regular Crew Join Date: Feb 2011 Location: Rochester, NY Posts: 103	Thanks Les, I'll try some of those things. I really hope it's not the HD. I've only had this computer for 2 weeks. Bought it new from Apple. I also hope I can do it without having to totally recapture. That's not possible. This was my first real shoot and we did things... I wouldn't do again. I didn't have my computer at the time and My buddy has Premier so we hooked up the camera to his computer and captured in real time right to the PC. The thought was to have it on the tape too as a backup, but the camera guy(we're all amateurs) figured we had it ok so he never told the speaker that we needed to change tapes so I don't have the 2nd 2/3rds of the presentation backed up (NEVER DOING THAT AGAIN!) After I got my computer, we transfered the files through ethernet from his computer to mine. They were AVI files. When I imported them into FCP I used the Media Manager to create a working copy and that brings us to where I am now. Thanks again... I really appreciate your help.

February 12th, 2011, 08:00 PM	#4
Paul Owens Regular Crew Join Date: Feb 2011 Location: Rochester, NY Posts: 103	So I got rid of the issue by exporting it as AVI instead of MOV. The quality sucked... but since it was on youtube it was ok. Thanks for the help.