Audio Sync Prob because of Sampling Rate (I think) at DVinfo.net

Scott Silverman · January 13th, 2003, 04:08 AM

Hi,
I am currently editing a video where the sound was recorded separately from the video. So now I am editing the video and trying to sync up the sound with the video. Here is my problem: the sound will be synced up it the beginning, but then at the end of the video (45 minutes later) the audio is way off. I figured this was a sampling rate problem. I think my audio (which is off a burnt CD) is 44kHz and my video is 48kHz. I don't know how to fix this problem. I thought about setting the speed of the audio to like 97% to fix it but I don't know if that will really work. Does anyone know my problem and any software/ways to fix it? Thanks so much!

Jeff Donald · January 13th, 2003, 05:38 AM

What was the audio originally recorded to? Was it recorded to audio tape, DAT, MD etc.? It's going to make a difference in getting this to work.

Jeff

Scott Silverman · January 13th, 2003, 02:50 PM

I actually don't know. I did the video recording and another guy handled the audio. I believe it was recorded to a PC or mac. But I am not 100% sure. Thanks.

Jeff Donald · January 13th, 2003, 03:21 PM

If it was done to an audio tape forget it. It will never sync perfectly. If it is an audio CD it will be 44.1KHz and your editing at 48KHz. Import the audio into a program like QuickTime (PC version will work or PC equivlent), then export to what ever audio format your NLE uses and change the rate to 48KHz before you export. Export function will allow you to adjust bit rate, freq. file format etc.

Jeff

Rob Lohman · January 13th, 2003, 04:15 PM

I don't think the 48 kHz vs. 44.1 kHz is the problem. I think the
problem originated in different timing chips whilst recording, isn't
this why the big productions use synced timecode for everything?

Now I know there are applications out there that will make your
audio track exactly as long as your video and it should match
then. Unfortunately I forgot which one. You might try and see
whether Virtualdub at www.virtualdub.com might pull
it off.

Good luck!

David Hurdon · January 13th, 2003, 04:21 PM

I believe Cool Edit 2000 will allow you to set a duration without changing pitch. I've played with the function but never with this purpose in mind.

Jeff Donald · January 13th, 2003, 05:16 PM

If the source was digital (HD, DAT, MD etc.) you should be within a second or less at the end. Typically when I do this for a client from a digital source I'm zero to may be six frames off. I hide the errors at the end with lots of cut aways so it harder to notice.

Locking the timecode assures accuracy to at least 1 field.

Jeff

Scott Silverman · January 13th, 2003, 08:35 PM

I would like to do what Jeff originally mentioned. Importing it into Quicktime and changing the sampling rate and then exporting. Now how would I go about doing this? I have Quicktime on my PC but I don't know how to save and export files. (I didn't even know it was possible.)

PS - I am editing on Premiere 6

Thanks!

January 13th, 2003, 04:08 AM	#1
Scott Silverman Major Player Join Date: Sep 2002 Location: Cupertino, California, USA Posts: 301	Audio Sync Prob because of Sampling Rate (I think) Hi, I am currently editing a video where the sound was recorded separately from the video. So now I am editing the video and trying to sync up the sound with the video. Here is my problem: the sound will be synced up it the beginning, but then at the end of the video (45 minutes later) the audio is way off. I figured this was a sampling rate problem. I think my audio (which is off a burnt CD) is 44kHz and my video is 48kHz. I don't know how to fix this problem. I thought about setting the speed of the audio to like 97% to fix it but I don't know if that will really work. Does anyone know my problem and any software/ways to fix it? Thanks so much! __________________ Scott Silverman Shining Star Digital Video Productions Bay Area, CA

January 13th, 2003, 02:50 PM	#3
Scott Silverman Major Player Join Date: Sep 2002 Location: Cupertino, California, USA Posts: 301	I actually don't know. I did the video recording and another guy handled the audio. I believe it was recorded to a PC or mac. But I am not 100% sure. Thanks. __________________ Scott Silverman Shining Star Digital Video Productions Bay Area, CA

January 13th, 2003, 04:15 PM	#5
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	I don't think the 48 kHz vs. 44.1 kHz is the problem. I think the problem originated in different timing chips whilst recording, isn't this why the big productions use synced timecode for everything? Now I know there are applications out there that will make your audio track exactly as long as your video and it should match then. Unfortunately I forgot which one. You might try and see whether Virtualdub at www.virtualdub.com might pull it off. Good luck! __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

January 13th, 2003, 04:21 PM	#6
David Hurdon Major Player Join Date: Nov 2002 Location: Toronto, Canada Posts: 484	Audio Sync Prob because of Sampling Rate (I think) I believe Cool Edit 2000 will allow you to set a duration without changing pitch. I've played with the function but never with this purpose in mind. __________________ Site:http://www.faceliftmarketing.ca Blog:http://www.websitevideo.blogspot.com

January 13th, 2003, 08:35 PM	#8
Scott Silverman Major Player Join Date: Sep 2002 Location: Cupertino, California, USA Posts: 301	I would like to do what Jeff originally mentioned. Importing it into Quicktime and changing the sampling rate and then exporting. Now how would I go about doing this? I have Quicktime on my PC but I don't know how to save and export files. (I didn't even know it was possible.) PS - I am editing on Premiere 6 Thanks! __________________ Scott Silverman Shining Star Digital Video Productions Bay Area, CA

January 13th, 2003, 05:38 AM	#2
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	What was the audio originally recorded to? Was it recorded to audio tape, DAT, MD etc.? It's going to make a difference in getting this to work. Jeff

January 13th, 2003, 03:21 PM	#4
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	If it was done to an audio tape forget it. It will never sync perfectly. If it is an audio CD it will be 44.1KHz and your editing at 48KHz. Import the audio into a program like QuickTime (PC version will work or PC equivlent), then export to what ever audio format your NLE uses and change the rate to 48KHz before you export. Export function will allow you to adjust bit rate, freq. file format etc. Jeff

January 13th, 2003, 05:16 PM	#7
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	If the source was digital (HD, DAT, MD etc.) you should be within a second or less at the end. Typically when I do this for a client from a digital source I'm zero to may be six frames off. I hide the errors at the end with lots of cut aways so it harder to notice. Locking the timecode assures accuracy to at least 1 field. Jeff