If you can find the percentage different that the zoom recorder is, you can correct by that number every time you use audio from it. There is a good description of how to do that http://www.mfbb.net/myvideoproblems/viewtopic.php?t=25&mforum=myvideoproblemshere[/link]

Maybe somebody has already done this and can just give you the number though.

No two devices will ever maintain perfect sync unless their clocks are locked or they can both record a common signal such as timecode. You can get the error down to the point where it almost becomes irrelevant but to be 100% certain of sample accurate sync you really need quite expensive gear, even to just generate an audio clock.

That aside Vegas does a perfect job of resyncing!
You don't need Sound Forge, you have the tools in Vegas!
I regularly record audio separately to vision and it's a pretty trivial task to get it back in sync even when the vision and audio run at a slightly different rate. It's easier if you slate the heads and tails of the shots if you can.

Simple explaination:

1) Find a marker of some kind at the start. A clapper is ideal but not always practical. A drum hit will do. OR if you record audio into the camera and the other device and turn AGC off in the camera it's pretty easy to just align the waveforms. OR, get the track from the camera and the track from the audio recorder roughly the same level. Slide the audio track until you hear no echo, as you approach exact sync you'll hear flanging, once you reach the point where the flanging disappears, you're in sync, at the start.

2) Go to the end. Now you need to ctl-drag the end of the audio track to get the end in sync. Use any of the same methods as you used to judge sync at the start and you're done.

Note the above method is unlikely to get 'sample accurate' sync and be careful mixing audio from recordings that are not sample accurate. If the mics are a long way apart (like you have a feed from a desk and the other source is the camera mic at the back of the venue) you're pretty safe.

Bob.

Edit / PS: It generally helps if you run everything at the same sample rate. Seeing as how the camera is recording audio at 48KHz, set your audio recorder the same. In theory it shouldn't matter in a perfect world but in practice it seems there's less error between the clocks relative to absolute if they are both at the same rate.

Thanks to all of you!
I have used the control drag method many times with pictures and
- yes I would have guessed that Vegas could do that even with sound.
Anyhow I´ve bought the Zoom H2 this afternoon and shall test it with a long take simultaneasly with a cam.
I work alone and do mostly music performances for a music highschool.
I use one fixed HV20 and operate a DVX with Rode N2 and
separate sound with a Rode NT4 / Tascam HD-P2 (Flash) which I start long before the concert begins (4 hours take with 4GB).
Zoom H2 is very small, battericharged, easy to place
and can also go for hours with a 4GB card.
The only stressfactor now (with no assistance) is the one hour DV tape limit in the fixed cam (often hard to reach) because many performances goes over one hour
Why isn´t there a cheap (like Zoom H2) flash recorder with FW connection for video yet - I would buy it directly.
Thanks again for all responses!
/Aje

A couple of things,
The H2 has a max recorded file size of 2GB, which will limit your record time, but probably won't affect your use as described, since 2GB of audio at 48,000kHz, 24 bits is stated to be 115 minutes. Although the H2 will roll over to a new file when it hits the 2GB limit, it is reported that there is an 18 second or so gap between the two files.

Note also that most people are reporting that the H2 doesn't work well with external mics - you would want to add a mixer/preamp if using an externa mic, though YMMV.

You can find lots of user-generated information about the H2 here:
http://www.2090.org/zoom/bbs/viewforum.php?f=15&sid=df9f41abc3ec55548d9aae215bb44093

Does your camera have an LP record setting? That extends record time to 90 min and does not change video quality, though my understanding is that you are more likely to get dropouts at that setting. I believe that the LP setting records audio at a reduced bit depth, but if you're recording audio separately, that's obviously not a factor.

OK
I read the comments on your threadrecommendation.
I think that 16/44 is enough to lift the mix with what I want ( its mere a question of location) and then the record time is over 3 hours in spite of the 2 GB border.
I´ve tried LP and that is OK with DV but with the fixed cam HV20
I´m shooting HDV in order to pan/crop more and HDV has no LP possibilities.
By the way there is a DV tape lasting for 80 minutes
(Panasonic 83 ME) - anyone tried ?
Regards
/Aje

"Why isn´t there a cheap (like Zoom H2) flash recorder with FW connection for video yet - I would buy it directly."
Well, they aren't cheap, but they do exist. However, consider the following: I recently got an under $400 Toshiba laptop [80 GB HD in it] on sale at Office Depot. Added a $20 FW PC card adaptor to it and installed Adobe OnLocation on it [OnLocation came bundled with Premiere in my CS3 Production Suite]. I now have a most able alternative to the 41.5 minute DVCam tape capacity of my Sony PD150 for those long interviews [movies101.org]. And a cheap USB external mini hard drive is my preferred media for acquisition, no need to transfer files, just plug it into my editing PC, fire up Vegas, and it's off to the races. Additionally, OnLocation provides me with quality control over the shoots that I previously only dreamt of. If OnLocation isn't available, you can use Vegas's capture utility to achieve the same result, albeit without the bells and whistles of OL.

"(Panasonic 83 ME) - anyone tried ?"
Personally used, no.
Experience yes, VCR ate it, not a good experience.
The thought of recording HDV onto that makes me shudder but you might get lucky. Why not just buy a HDV deck like the M15, that way you can record 4.5 hours onto one tape. Doesn't work with Canon's progressive tapes though.

Bob.

I've used many, many 83 minute tapes in both my cameras and decks. They've worked great for me. However, I'm shooting SD and not HDV.

I would suggest setting the H2 for 48KHz.

Jesse

Either a Firestore FS4HD or a nNovia QCDeck will record m2t files to a hard drive without any tape in your camera. The reliability of the FS4 is questionable, as is the 1394 connection. neverttheless, I routinely capture, sans tape, to one of these devices. It saves me head wear, is very easy to setup and use, and I don't have to spend any time capturing as the files are recorded native to m2t.

The buzz on the H2 hasn't been great, sync-wise. That's why I'm still using my discontinued iRivers for audio situations where I don't want to use wireless.

For me, they've maintained perfect sync, regardless of the length that I've recorded. I have 3 units and use them all the time.

I use an Edirol R-4 and a Zoom H-4 - the Edirol keeps perfect synch on hour-long projects, whereas every Zoom I've tried [we have 3] looses synch pretty quickly.
It's a shame, as it's a pretty capable recorder - albeit with a few niggles [like trying to extract the SD card without tweezers or swearing ;-]

Andy Mac

Try pushing down on the SD card and then pull your finger away quickly, letting it spring out a little further. Then grab it.

If it helps for syncing...

Sounds like a pain, but I've done it often & it doesn't take long at all when syncing errors are not linear [where correcting the audio length by cntrl+drag at the end doesn't work accurately]: With video & audio in Vegas, working left to right, find the 1st incidence of the 2 being out of sync by roughly 6 or more frames... Find a relatively quiet spot close to that point, split the audio, ctrl+drag the end of the audio on the left 1/2 of the split to give you room to work. Move the audio clip on the right to sync at the split, ctrl+drag the end of the left-side clip to butt the right side. Moving to the right, repeat as necessary.

I think anything less than 6 frames out is irrelevant, and you can wait for a much higher number (of frames out of sync) at the potential risk of less accuracy. And of course it's always better not to have to fool with it at all.

I've been using the Zoom H4 for double-system sound over the past year, and have the same problem when syncing the sound with the video.

My solution has been to use the TimeWarp feature of the GoldWave audio editor, which I find much more accurate than SoundForge, even SoundForge 9 still isn't good enough. ( I recently had to synch a 90 minute video with sound recorded on the H4, using the Sound Forge 9 TimeStretch function it was still off by 3 frames, while the much cheaper GoldWave TimeWarp function was exactly bang on. )

I've been asking Sony to fix this for a couple of years now, but so far I am still stuck using GoldWave to handle sound synch issues.

Why use Sound Forge when Vegas handles the task perfectly?

Current job I have is a good example of how impossible it is to keep sample accurate sync.

Same show recorded on two different nights. Only difference different cast. All music played back off CD from the same CD player and recorded into the same camera.
Over the length of one song between the two nights there's an error of 4 frames in the length of the exact same song.

Another example from a few years ago. Shoot dance performance. Borrow CDs used for the music, the ones played on the night. Try to drop the music from the CDs into the recorded video. Over a 5 minute dance there's at least a one second error in the length of the music. Simple enough to fix in Vegas but it just shows how difficult this problem is when even a fairly expensive CD player doesn't playout at the precisely correct speed. For those theatres that really need everything perfect you can buy CD players that lock to a master clock.

Bob.