how to sync two video files at DVinfo.net

Marius Boruch · November 9th, 2008, 01:34 PM

I have HDV footage that was shot using two cameras; is there any way to sync it in Vegas? I always have fraction of a second apart. Would using of some sort TBC help???

Jeff Harper · November 9th, 2008, 04:24 PM

I use the audio to sync. Usually come out pretty darn close. Match your peaks on the lines of audio the best you can and then zoom in on the timeline and match it more precisely.

Have you already tried that Marius?

Edward Troxel · November 9th, 2008, 05:19 PM

Same here. Look for a specific audio peak and line them up. Using the 1/3 keys on the numeric keypad helps this process. You can also listen to the audio with both playing and eliminate any "echo" to line them up.

If you have a camera flash, that can often be used as well. Just line up the "flash" on both cameras and you should be in sync.

Ali Jafri · November 9th, 2008, 10:55 PM

You could also buy a clapper and use that at your shoots :) it IS called a clapper right? Sync the audio spikes of the clapper's sound in each footage, this is particularly handy if you usually don't have or can't see any distinctive audio spikes.

Dave Blackhurst · November 10th, 2008, 12:31 AM

A trick I've seen here previously is to pan the two audio tracks far left and far right - use headphones and you should be able to sync the two tracks almost to perfection. I've used that a few times now when I just couldn't quite nail the sync... seems to work pretty well!

Marius Boruch · November 12th, 2008, 03:59 PM

Guys,
Thanks for your input; of course that's what I do I sync audio looking at it (although I heard that Vegas 8 should sync audio automaticly - or is in some extra plugin "Excalibur"???)
what I need, is to sync it VERY precisely almost ideally - it is always like small fraction of second apart. It is like Photoshop and working with leyers; you have to uncheck "snap to" option to freely move layers around to achieve almost "infinite" precision ; if you enlarge the timeline and work in single frames, Vegas behaves like tracks are always a notch shifted so I was hpoping that maybe there is some kind of setting that would free the tracks COMPLETELY.
I need this absolutr precision to produce 3D video (something like TBC).

Mike Kujbida · November 12th, 2008, 04:18 PM

Marius, turn off Quantize to Frames, get everything properly synced up and then turn it back on again.
I've used this technique several times when I need to adjust one track finer than the lenght of a video frame.

Marius Boruch · November 22nd, 2008, 04:40 PM

bingo;
thanks

John Cline · November 22nd, 2008, 09:47 PM

Turning off quantize to frames is fine when you need to sync just audio, but it should never be turned off for video. Video must end up on frame boundaries.

Also, you can't really use audio to sync unless both cameras were fed from the same audio source. Remember that audio travels at about 1 foot per millisecond and that a frame in NTSC is 33ms. If you're using on-board microphones and one camera is 33 feet from the sound source and the other is 33 feet further still, then audio from the first camera will be one frame late with respect to the visuals and the second camera will be off two frames and the two cameras will be off a frame relative to each other. If you're doing 3D then you really must genlock the two cameras so they record in exact "lock step." The problem you are having is that both cameras didn't start at EXACTLY the same time and their frame offset doesn't match up. I've done a fair amount of 3D video for Los Alamos Labs and it simply does not work well unless the cameras are perfectly synced.

Harry Settle · November 23rd, 2008, 09:16 AM

NOTE: I just upgraded to 8.0c and haven't done any editing with it yet. This is what I was doing with 5.0.

Keeping the video locked to the audio tracks
do a close/rough sync
run one audio track to the right channel and the other to the left channel
playback and listen, adjust one track until your echo dissapates.

If you need a finer adjustment
zoom in on the track, you will be able to make micro-adjustments

I shoot with two cameras, so the difference in the video portion won't be noticable at all when making cuts. Only way to see a problem with the video is if you show both video tracks at the same time.

Also, use the flash method, or look for a spot where someone dropped a hymnal creating a spike. (always happens)

Edward Troxel · November 23rd, 2008, 12:26 PM

For fine-tuning the placement of the audio, I prefer to have ONE of the audio tracks selected. Then using the 1 and 3 keys on the numeric keypad I can adjust the position one frame at a time left or right until I get it in sync. No need for zooming or anything else.

Personally, I just leave both in both ears and get rid of any "echo".

November 9th, 2008, 01:34 PM	#1
Marius Boruch Major Player Join Date: Aug 2005 Posts: 421	how to sync two video files I have HDV footage that was shot using two cameras; is there any way to sync it in Vegas? I always have fraction of a second apart. Would using of some sort TBC help???

November 9th, 2008, 05:19 PM	#3
Edward Troxel Sponsor: JET DV Join Date: Dec 2001 Location: Southern Illinois Posts: 7,953	Same here. Look for a specific audio peak and line them up. Using the 1/3 keys on the numeric keypad helps this process. You can also listen to the audio with both playing and eliminate any "echo" to line them up. If you have a camera flash, that can often be used as well. Just line up the "flash" on both cameras and you should be in sync. __________________ Edward Troxel [SCVU] JETDV Scripts/Scripting Tutorials/Excalibur/Montage Magic/Newsletters

November 9th, 2008, 10:55 PM	#4
Ali Jafri Major Player Join Date: May 2008 Location: Karachi, Pakistan Posts: 210	Clap clap clap! You could also buy a clapper and use that at your shoots :) it IS called a clapper right? Sync the audio spikes of the clapper's sound in each footage, this is particularly handy if you usually don't have or can't see any distinctive audio spikes. __________________ Windows 7 Ultimate 64-bit // i7 2600K // 16GB RAM // ASUS P8P67 Board // NVIDIA GTX 470 Sony Vegas Pro 13 // Adobe Premiere Pro CC 2014 // http://vimeo.com/alijafri

November 23rd, 2008, 09:16 AM	#10
Harry Settle Major Player Join Date: Mar 2003 Location: Bemidji, MN Posts: 276	NOTE: I just upgraded to 8.0c and haven't done any editing with it yet. This is what I was doing with 5.0. Keeping the video locked to the audio tracks do a close/rough sync run one audio track to the right channel and the other to the left channel playback and listen, adjust one track until your echo dissapates. If you need a finer adjustment zoom in on the track, you will be able to make micro-adjustments I shoot with two cameras, so the difference in the video portion won't be noticable at all when making cuts. Only way to see a problem with the video is if you show both video tracks at the same time. Also, use the flash method, or look for a spot where someone dropped a hymnal creating a spike. (always happens) __________________ "DOH"!!!

November 23rd, 2008, 12:26 PM	#11
Edward Troxel Sponsor: JET DV Join Date: Dec 2001 Location: Southern Illinois Posts: 7,953	For fine-tuning the placement of the audio, I prefer to have ONE of the audio tracks selected. Then using the 1 and 3 keys on the numeric keypad I can adjust the position one frame at a time left or right until I get it in sync. No need for zooming or anything else. Personally, I just leave both in both ears and get rid of any "echo". __________________ Edward Troxel [SCVU] JETDV Scripts/Scripting Tutorials/Excalibur/Montage Magic/Newsletters

November 9th, 2008, 04:24 PM	#2
Jeff Harper Inner Circle Join Date: Jun 2005 Location: Cincinnati, OH Posts: 8,425	I use the audio to sync. Usually come out pretty darn close. Match your peaks on the lines of audio the best you can and then zoom in on the timeline and match it more precisely. Have you already tried that Marius?

November 10th, 2008, 12:31 AM	#5
Dave Blackhurst Inner Circle Join Date: Feb 2007 Location: Apple Valley CA Posts: 4,874	A trick I've seen here previously is to pan the two audio tracks far left and far right - use headphones and you should be able to sync the two tracks almost to perfection. I've used that a few times now when I just couldn't quite nail the sync... seems to work pretty well!

November 12th, 2008, 03:59 PM	#6
Marius Boruch Major Player Join Date: Aug 2005 Posts: 421	Guys, Thanks for your input; of course that's what I do I sync audio looking at it (although I heard that Vegas 8 should sync audio automaticly - or is in some extra plugin "Excalibur"???) what I need, is to sync it VERY precisely almost ideally - it is always like small fraction of second apart. It is like Photoshop and working with leyers; you have to uncheck "snap to" option to freely move layers around to achieve almost "infinite" precision ; if you enlarge the timeline and work in single frames, Vegas behaves like tracks are always a notch shifted so I was hpoping that maybe there is some kind of setting that would free the tracks COMPLETELY. I need this absolutr precision to produce 3D video (something like TBC).

November 12th, 2008, 04:18 PM	#7
Mike Kujbida Inner Circle Join Date: May 2005 Location: Windsor, ON Canada Posts: 2,770	Marius, turn off Quantize to Frames, get everything properly synced up and then turn it back on again. I've used this technique several times when I need to adjust one track finer than the lenght of a video frame.

November 22nd, 2008, 04:40 PM	#8
Marius Boruch Major Player Join Date: Aug 2005 Posts: 421	bingo; thanks

November 22nd, 2008, 09:47 PM	#9
John Cline Major Player Join Date: Oct 2002 Location: Albuquerque, New Mexico USA Posts: 333	Turning off quantize to frames is fine when you need to sync just audio, but it should never be turned off for video. Video must end up on frame boundaries. Also, you can't really use audio to sync unless both cameras were fed from the same audio source. Remember that audio travels at about 1 foot per millisecond and that a frame in NTSC is 33ms. If you're using on-board microphones and one camera is 33 feet from the sound source and the other is 33 feet further still, then audio from the first camera will be one frame late with respect to the visuals and the second camera will be off two frames and the two cameras will be off a frame relative to each other. If you're doing 3D then you really must genlock the two cameras so they record in exact "lock step." The problem you are having is that both cameras didn't start at EXACTLY the same time and their frame offset doesn't match up. I've done a fair amount of 3D video for Los Alamos Labs and it simply does not work well unless the cameras are perfectly synced.