Why does audio file show "flatline" when video has sound?

[virg]

While working on a family video project, I discovered one of my DVDs has a bad spot on it. I have searched & searched through the forum archives, looking for a post with the same issue. While I have found similar occurrences, none seem to match the problem I'm having.

In an attempt to explain the problem further, here is a link to YouTube, showing what we see.
https://www.youtube.com/watch?v=saNtYVF ... e=youtu.be

The bad spot occurs at approx. :11 of the YouTube clip. You'll notice, the video freezes for a few frames, and then jumps & skips ahead a little, and then most of the picture is covered in lime green pixels. That's when the audio drops off & "flat lines" on the Sound Mixer bar. Even after VS X9 skips ahead past the bad area & seems to resume playing both video & audio normally, the Sound Mixer bar still shows a "flat line" instead of sound waves. There is another small bad spot (green pixelated video) at the transition from this current clip to the next clip. Audio seems to be okay, but the Sound Mixer bar continues to show nothing.

At 1:11 of the YouTube video, I use the scrubber to slowly go through the frames, showing the skips & pixels. I then run thru the "flat line" audio portion, to where the Sound Mixer picks up sound waves again. It occurs right in the middle of a clip.

Properties of my video file are displayed at 2:20.

I understand the raw footage may be damaged, and a portion of the video cannot be recovered. Ideally, I would like to be able to cut out the small section where the frames freeze, and the audio first disappears (approx. :11 - :22). It seems the section that begins at :23 is okay. That is, the video frames look okay, and the audio portion can be heard. Similarly, the video beginning at :49 also appears to not be damaged, despite having "flat line" audio on Sound Mixer bar. Is what I'm asking a possibility? Can the damaged portion be cut out, while saving the remaining video?

[aljimenez]

I have used scissors to cut out portions of videos just fine, so I think the answer to your question is yes.

[virg]

Please forgive me for not stating my question more precisely. I'll try again to state my problem and ask two questions as follows:

Question 1. Is it recommended to use the Sound Mixer Bar if one is not adding any additional sounds like voice over or music?
I was only using it to try to view & use it to determine what portions of my video that have corrupted video or audio frames that must be eliminated or removed during my Edit workflow before I move on to my Share workflow. But as previously stated, after playing past the corrupted frames, the sounds from the original video are audible again, but the Sound Mixer Bar still shows a flat line instead of sound waves. But while still playing in the Preview window in the Edit phase, the sounds of my home movie continue with the video and then after several minutes the sound bar starts showing sound waves again on the Sound Mixer Bar.
However, after multiple attempts to remove the corrupted frames during my Edit Workflow and then produce a DVD of my Project in my Share Workflow, I find that there are now large sections of video, after where the previously mentioned pixelated frames were removed, that have lost audio on my finished video.
Question 2. If the Sound Mixer Bar is not one of the recommended tools to determine what corrupted frames need to be removed, what tool or technique is recommended?
Thanks in advance for your time and expertise. I really appreciate your help. Virg

[lata]

Hi Virg

How we edit our projects just personal preference, but yes I would advise you use the Sound Mixer

The Sound Mixer will display the wave form which is useful in syncing clips as the wave form can be compared between clips.
For your problem having a corrupt video section, you could be identified simply by watching the video to view the pixilated sections, seems a bit of a mess there.
Using the Sound Mixer as you have done will also help as the problem sections also corrupted the audio which can be seen when viewing the wave form.

That’s the problem in deciding how much to remove, and whether its possible to replace the audio, especially for background sounds, not good for lip sync.

Some audio wave forms may show as a straight line yet play ok, that’s just the magnitude of the sound, zooming into the timelines may / should show more detail.

But yes I think you are approaching the problem correctly, not easy to do, annoying to have a corrupt recording.

You mentioned the video was from a DVD disc, is that correct?
I would assume when burnt would have been ok, so has the disc surface been damaged.
If it was from disc try cleaning the disc surface, then reimport to VS. Maybe another import will be better quality.

[virg]

Thanks for the help, and I'll address your four questions.
1. Tried zooming in to the Timeline but that didn't show more detail.
2. Yes, my original source was a small dvd from a 2000 era movie camera; which I discarded after purchasing my Sony handycam.
3. Tried recapturing the video from the original dvd, but encountered the same three short corrupted video spots.
4. Examined the original dvd surface and it appears to still be clean as new and there are no visible marks or scratches.

My solution was to continue removing a greater number of frames immediately in front of and after the pixilated area. Ended up losing more than I wanted, (about a fourth of the dvd) but at least I now have more home movie memories than I would have had if I had scrapped the entire original dvd.
Thanks to the forum for your patience and suggestions. Virg Mueller