VideoStudio X9: audio loss and sync

[rjensen]

I have some recorded MKV files. When I cut and delete a section of the video in VS, the audio loses sync.

I convert the MKV to M4V using HandBrake. In VLC and Irfanview, the video plays fine, with audio. In VS, the video plays fine, but no audio.

Any idea how to address this issue?

[tletter]

I have some recorded MKV files ... When I cut and delete a section of the video in VS, the audio loses sync.

What are the properties of these files?

Any idea how to address this issue?

Try splitting the audio from these files in X9. What happens?

tletter
https://www.youtube.com/user/tletter

[Davidk]

I suspect that description is of X9 working properly. Consider:
- a video clip with audio, and an unwanted section is to be cut out
- having done that (cut the video clip at the start of the unwanted section: giving 2 clips. select the clip with the unwanted section, and trim it to remove the unwanted component you wind up with 2 clips each with surviving audio) the 2 surviving clip components have audio which is in sync with it's video, but in the case of the 2nd clip it's discontinuous - ie does not follow from the audio of the 1st clip, which can seem to be 'out of sync').

To fix this there several options for 'technique':
1. be more choosy about where the video clip is cut - not only at the bad video but also at a time when audio is suited such as a pause in a speaking voice. And the amount of trim in the 2nd cut clip to remove bad video also chosen to allow for the audio - again in a suitable pause.. Done right, the audio should seem to be flowing from one scene to the next. You may want to add a transition between the 2 clips in the resulting edited clip sequence.
2. If there is nothing in the audio track that you want to discard, split the audio from the original clip, and save that as an audio file, eg a .wav file. Then do the cut and trim sequence to remove the unwanted video, and afterwards add the original audio wav file back to the project. Note that here, the audio will be out of sequence with the trimmed 2nd clip (for example, it may relate to a removed video component), and the audio file will be longer in duration than the composite video, so at some point you may have to trim it down.

[rjensen]

I have some recorded MKV files ... When I cut and delete a section of the video in VS, the audio loses sync.

What are the properties of these files?

H.264 video
1920x1080
30 fps

AAC Audio
48 kHz, 16 bit,stereo

Any idea how to address this issue?

Try splitting the audio from these files in X9. What happens?

X9 does not detect any audio in the M4V file. Splitting audio is grayed out. Yet the same file plays with audio elsewhere.

[Ken Berry]

If Handbrake produced an m4v file and not an mp4 file, that could be your problem. That's because m4v files often don't have audio. I realize your video *does* have audio which plays in other programs and that Handbrake regularly uses m4v in its conversions. But it could be that VS X9 sees the format and equates it with no audio, and plays it accordingly...

One thing you could try would be to simply change the extension of the clip from .m4v to .mp4.

[rjensen]

I suspect that description is of X9 working properly. Consider:
- a video clip with audio, and an unwanted section is to be cut out
- having done that (cut the video clip at the start of the unwanted section: giving 2 clips. select the clip with the unwanted section, and trim it to remove the unwanted component you wind up with 2 clips each with surviving audio) the 2 surviving clip components have audio which is in sync with it's video, but in the case of the 2nd clip it's discontinuous - ie does not follow from the audio of the 1st clip, which can seem to be 'out of sync').

Respectfully, I'm not that stupid. I cut a video that has good audio, delete one portion, and the remaining video is now 5+ secionds out of sync.
If you have a way for me to upload a 30 MB video file, I will send it to you.

[rjensen]

I discovered the issue with lost audio.
Handbrake encodes with AAC (160 bps) and AC3 (640 bps) audio codecs. Removing the AC3 codec fixes the audio problem.

And after converting to MP4, I can split the MP4 video in VS and the audio stays in sync.

Thank you

[rjensen]

If Handbrake produced an m4v file and not an mp4 file, that could be your problem. That's because m4v files often don't have audio. I realize your video *does* have audio which plays in other programs and that Handbrake regularly uses m4v in its conversions. But it could be that VS X9 sees the format and equates it with no audio, and plays it accordingly...

One thing you could try would be to simply change the extension of the clip from .m4v to .mp4.

I discovered the issue with lost audio.
Handbrake encodes with AAC (160 bps) and AC3 (640 bps) audio codecs. Removing the AC3 codec fixes the audio problem.