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Webcam // Audio — Sync Issue
I’m using a webcam to capture video and another device to record audio. I’m doing a cover of a song with an instrument. Here’s what I’m doing. I play to the song while recording my audio and video, which works fine. They are sync fairly well even though I had to adjust the audio timing a bit. I then extract the audio, and overlay the song onto it. But when I do this I realize that my version is actually shorter/longer than the song itself! So the timing of the video/audio capture seems wrong.
Any ideas on correcting this?
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1 Reply
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Rather than correct it, the first thing you should do is avoid it. I would record your audio with the real song playing in you ear with headphones. This way you stay in sync. Just a small ear bud with a hidden wire will do.
The way to fix what you have is by time stretching. I have to do this all the time when I record a live performance and then need to sync the “studio” version of the song with it. Here’s what you do:
- Open the master song in the trimmer and drop a marker at each start of each measure. This will add embedded markers to the media.
- Open your recording in the trimmer and drop a marker at each start of each measure
- Lay your recording and the song on two tracks and sync the first markers to match
- Sync your recorded audio to the video and group them together (this is very important to keep them in sync)
- Move down the timeline of the master song and each time it strays from the marker on the song you recording, split the event and Ctrl+Drag it to match the marker.
- Repeat step 5 for each marker
This will stretch the music so that it stays in sync with your recording. It will be hardly noticeable because you are stretching each measure individually and the changes will be small. As I said, I’ve used this technique to take a live performance that was only done with an accompanying piano, and add back the entire band.
~jr
http://www.johnrofrano.com
http://www.vasst.com
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