time drift recording to laptop at DVinfo.net

Renton Maclachlan · November 19th, 2007, 04:24 AM

I filmed on Sunday, a packed house music event in the Wellington Catheral, with three 'Stars'. It was a last minute decision to film and a practise run for me to film such an event. All round a great learning experience, and everything went well given the constraints I was under.

I had three cameras and the event ran for an hour and a half. One camera was in the pulpit filming the audience and recording direct to my laptop as it was impossible to get to the camera once the show was running. It was the first time I have ever recorded to my laptop. (May put two cameras on laptops next time!!!)

I have downloaded everything and discovered an issue I haven't faced before.

The two cameras with tapes are bang on time wise after 58 minutes running,
However the laptop is around 30 seconds slower over the same time.

I was made aware a couple of weeks back that by pressing 'Ctrl' as the cursor is over the end of an audio track, and then dragging, you can stretch or shrink the track and thus affect its speed.

I've just tried it with both video and audio and it works also.

My question is; Are there any adverse effects produced doing this?

John Gordon · November 19th, 2007, 08:08 PM

the only adverse affect of this procedure is the amount of stretch. a little stretch to fit works good, but if you have to do a great deal of stretch, you will start noticing artifacts in the media.

John

Renton Maclachlan · November 19th, 2007, 09:30 PM

Thanks John.

Is 25-30 secs over 60 minutes a lot? I was quite surprised it was that much. In what I have looked at so far, I haven't seen any artifacts.

Both the irivers that I used were about 1 sec slow - or fast - can't remember which.

I also used a Zoom H2 but because I had only got it the day before and didn't really know how to use it, the recording from it was no good - too soft. I was not able to set recording level. Have to learn how to guess!!!

Don Bloom · November 20th, 2007, 07:03 AM

to me 25 seconds seems like a lot but then in my life 25 seconds is meaningless so I guess it's all relative.
As for stretching audio, well some not so good things can happen. Like changing tempo and pitch-so the persons voice can sound like Mickey Mouse or Mickey Moose depending on which way you go.;-)
IF you can't get it to sync up and sound the way it's supposed to then ditch the track and use the others which frankly makes more sense to me but then again you migh need that track and not have that audio elsewhere.
I did audio for a seminar on Saturday and ran a small mixer with 4 mics and a computer playing music out to my other computer and recorded the seminar for the client and it was fine but then I wasn't video taping to compare it.
Don

Bill Ravens · November 20th, 2007, 08:25 AM

25 seconds out of 3600 secs is less than 1% pitch change. Those are the only artifacts you'll induce. I don't think you'll ever notice.

November 19th, 2007, 04:24 AM	#1
Renton Maclachlan Trustee Join Date: Jul 2007 Location: New Zealand Posts: 1,180	time drift recording to laptop I filmed on Sunday, a packed house music event in the Wellington Catheral, with three 'Stars'. It was a last minute decision to film and a practise run for me to film such an event. All round a great learning experience, and everything went well given the constraints I was under. I had three cameras and the event ran for an hour and a half. One camera was in the pulpit filming the audience and recording direct to my laptop as it was impossible to get to the camera once the show was running. It was the first time I have ever recorded to my laptop. (May put two cameras on laptops next time!!!) I have downloaded everything and discovered an issue I haven't faced before. The two cameras with tapes are bang on time wise after 58 minutes running, However the laptop is around 30 seconds slower over the same time. I was made aware a couple of weeks back that by pressing 'Ctrl' as the cursor is over the end of an audio track, and then dragging, you can stretch or shrink the track and thus affect its speed. I've just tried it with both video and audio and it works also. My question is; Are there any adverse effects produced doing this?

November 19th, 2007, 08:08 PM	#2
John Gordon New Boot Join Date: Oct 2007 Location: Virginia Beach, Virginia Posts: 15	the only adverse affect of this procedure is the amount of stretch. a little stretch to fit works good, but if you have to do a great deal of stretch, you will start noticing artifacts in the media. John

November 19th, 2007, 09:30 PM	#3
Renton Maclachlan Trustee Join Date: Jul 2007 Location: New Zealand Posts: 1,180	Thanks John. Is 25-30 secs over 60 minutes a lot? I was quite surprised it was that much. In what I have looked at so far, I haven't seen any artifacts. Both the irivers that I used were about 1 sec slow - or fast - can't remember which. I also used a Zoom H2 but because I had only got it the day before and didn't really know how to use it, the recording from it was no good - too soft. I was not able to set recording level. Have to learn how to guess!!!

November 20th, 2007, 07:03 AM	#4
Don Bloom Inner Circle Join Date: Jan 2003 Location: Chicago, IL Posts: 6,609	to me 25 seconds seems like a lot but then in my life 25 seconds is meaningless so I guess it's all relative. As for stretching audio, well some not so good things can happen. Like changing tempo and pitch-so the persons voice can sound like Mickey Mouse or Mickey Moose depending on which way you go.;-) IF you can't get it to sync up and sound the way it's supposed to then ditch the track and use the others which frankly makes more sense to me but then again you migh need that track and not have that audio elsewhere. I did audio for a seminar on Saturday and ran a small mixer with 4 mics and a computer playing music out to my other computer and recorded the seminar for the client and it was fine but then I wasn't video taping to compare it. Don

November 20th, 2007, 08:25 AM	#5
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	25 seconds out of 3600 secs is less than 1% pitch change. Those are the only artifacts you'll induce. I don't think you'll ever notice.