Hello again,

I have not yet managed to find a solution for this issue.

However - I did contact the company called Kenton who make the MidiStream referred to earlier in this thread. I described the problem and according to them the MidiStream will not solve my problem and they advised me to contact a company called Black Box Video. I have had a look at their website but have not found anything that I think will help nor have I contacted them yet.

I have, however, ordered a LANC to Midi Time Code Generator and I am waiting for this to arrive.

I am doing (what I think to be) and interesting test at the moment.

I have just used three of my cameras to simultaneously record my 'beeps' for an hour (one tape each). I am interested to see if all the cameras will actually stay in synch with each other (without additional help). The real purpose of this test is to see whether or not I can rely on one of them to be a sort of 'master clock' i.e. using the LANC to Midi Time Code Generator and make the camera the master midi clock during the audio recording process on the mixer / notebook.

One statement that I made has been bugging me as it was misinformation:

I'm embarrased!

It was really late (early) that morning and I was not thinking! The figure that was changing was the data throughput not the frame rate i.e. I ALWAYS get an average frame rate of 25fps - this does not vary. If I was not getting 25fps I would have REAL problems!!!

Sorry for that.

Regards,

Dale.

Hello again,

As promised - here is my update.

I simultaneously recorded one hour of tape on three different cameras and - guess what - three different results i.e. taking the FX1E as the 'standard' - the VX2100E was slightly ahead and the TRV27E was slightly behind.

Sorry Douglas - I just had to prove it to myself!

Anyhow - there goes my idea about using a 'spare' camera to generate a 'master clock' - whether it be a MIDI clock or anything else - right again Douglas!

I must tell you that this is extremely disturbing to me. If anything I thought that the cameras would be 'spot on' as it were.

It means in reality that even with a three camera shoot (let alone seperate audio) not only do you have to worry about cutting to the desired camera shot but even that shot could be out of synch with your 'master' track. How about that!

The worst part about it is that even if I tossed all of the equipment that I have and bought Z1's I would STILL have a problem with the audio synch from the mixer!

Basically the only way to get this right is to ensure that the sound guy gets the mix JUST RIGHT and send this mix to the camera while shooting BUT this is by no means a reliable or failsafe method of doing things. I have just ordered another two Sony UWP-C3's to send the main (stereo) mix out to one of the cameras - more $$$.

Anyway - I think that I have now put this baby to rest (not really) - and sincerely hope that the next time someone tries this they at least have a very good idea as to what they are in for.

Thanks for the input from everyone.

Regards,

Dale.

Basically the only way to get this right is to ensure that the sound guy gets the mix JUST RIGHT and send this mix to the camera while shooting BUT this is by no means a reliable or failsafe method of doing things. I have just ordered another two Sony UWP-C3's to send the main (stereo) mix out to one of the cameras - more $$$.


Dale I've been intently watching for your posts. What you say in the above paragraph is what I was suggesting all along. By the way you wrote it, it appears to me (sorry if I'm wrong) that you don't understand the concept. Please, anyone else chime in.

Dale, if you are having the mixer record six discrete channel to hard drive, you can still output a stereo mix of that to one of the cameras. Because the mix and the six channels are real time and your camera records in real time, send the stereo mix to a camera. That sound HAS to be sync'd with the video. Then match up the three video tracks and then match up the grouped set of 6 tracks to the stereo mix sent to camera one. When those two are sync'd, delete all three camera audio's, even the stereo mix (unless you want to keep it for reference only - then mute it) and you project should play fine. If this won't work for you then I am the one that doesn't understand and I'll go back under my rock.

Jeff

Hello Jeff,

I am glad to see that someone has not dismissed all of my hard work out of hand! :)

Now - I do not mean to argue with you BUT:

I know that you have been correct all along by saying that if I take a stereo main mix out (that is what it is called on the Alesis) from the mixer straight to the camera then the audio will obviously be in perfect synch with the video but if I cannot rely on the quality of that stereo main mix out i.e. if I need to edit those individual tracks - then I have a problem.

Put it this way - I send a stereo main mix out to the camera and the audio is in perfect synch with the video ON THE TAPE - no question. Now I have the audio on the tape as well as on the notebook as recorded via the mixer. Again - no problem so far. But when I then capture the tape from the camera and pull the individual audio tracks from the notebook recorded via the mixer into the same Vegas Project I am back to square one i.e. the mixers audio track is out of synch with the camera's audio / video track. If I want to replace the camera's audio track with the mixers (edited and better quality) tracks then I still have to manually synch the tracks before discarding the camera's audio track.

If I did not have to edit or tweak the individual audio tracks there would be no problem i.e. I would not even have to record the audio track on the noteboook - I could just use the audio on the camera's tape but this will never be the case so even although I have audio perfectly in synch with the video ON THE TAPE when I capture this tape to an editing workstation it will be out of synch with the, let us call it, the 'master audio' recorded on the notebook from the mixer.

Make sense?

Actually - on second thought - I think that we are talking at cross purposes here. I think that you are saying that by doing it your way I will have the camera's audio track as a reference to synch the audio tracks on the notebook recorded via the mixer - quite correct. That is true except for the fact that it is not so easy to synch the audio to the audio without my 'beeps' - I am trying to eliminate this 'manual synch' step altogether.

Regards,

Dale.

Are you positive you are recording 24/48 and not 24/44.1?
Jeff

Hi Jeff,

Definitely 48/16 but have also tried 48/24.

It is definitely this clock issue.

Anyway - I'm sure that somewhere down the line there is a solution which I WILL find!

Regards,

Dale.

Jeff,

Dale is experiencing two different synchronization errors that are under discussion here:

1) Offset error, produced by the time it takes sound to travel through the air to Dale's camera mic. vs. on-stage mics through wires to mixer and pc. This would be perfectly addressed by the wireless link you're suggesting.

2) Timebase error, produced by the clocks of the digital mixer and the camcorder running at slightly different speeds. This is not addressed by taking mixer audio to camera. This can be fixed in two ways:
a) Shrink or expand the duration of the mixer audio track in post until it matches the duration of the camera audio track. Made easier by beeps or other references that are visible in the waveform display. Inexpensive, and not very difficult once you've done it a couple times.
b) Upgrade camcorder and mixer (or digital recorder) to equipment that accepts timecode input and generates timecode output. Then, slave the audio recorder to the camcorder. Costs well over $10,000 but less than $20,000 for camcorder and audio recorder, depending on audio recorder selected.

To repeat, timebase error is not fixed by taking mixer audio to the camera, wireless link to the camera fixes only one of the two problems Dale is experiencing.

Why? Imagine two film cameras. Film a scene (with motion!) with one camera at 12 frames per second, and the other at 24fps. Take the processed film reels, and put them up on two projectors side-by-side and show them both at 24fps. The original 12fps-reel will show in half the duration at twice the (apparent) speed. This is timebase error, the two clocks were far from synched, it affects speed of action and duration when the content gets synch locked in projection, or on the timeline.

In this example, we had a 50% speed/duration difference. Dale's errors are much smaller, on the order of less than .1%, but that's enough to throw lipsync visibly off over an hour of content when the two audio tracks are locked to the soundcard's clock.

I've done a lot of synching in my time, with no beeps. Not so hard to fix offset error or timebase error in post. At least that's my experience, your mileage may vary.

Good Morning.

Thanks Seth for that explanation - explained as only a master could.

There is one other thing that is bugging me and would just like clarification (just for interest sake):

Correct me if I am wrong but even with cameras that have 'free run' timecode like the Sony Z1 you will still experience the same problem. Would I be correct in making this statement?

The reason I ask is that during my search for a solution to my problem I saw a thread somewhere (it was referring to the Canon GL2 but I think that you can follow the same procedure with the Sony Z1) that detailed how to start the 'free run' timecode with the remote on multiple cameras and then when it came to post things were just a lot easier as each tape (scene) had the correct corresponding timecode tape for tape / scene for scene.

After demonstrating that not one of three of my cameras run in perfect synch to each other I make the assumption that even with three or four Sony Z1's there would STILL be a difference between each cameras timecode i.e. timebase errors (learning all the time) over a long period. Correct? The 'free run' timecode would just make it easier to synch multiple camera shots IF AND ONLY IF the multiple shots were not of a lengthy duration.

Also - just for the record - I think I understand what a 'free run' timecode is but what is a 'record run' timecode?

Something else that has just come to mind: Does the difference between my cameras (for example) mean that they are not shooting at EXACTLY 25fps (PAL)? During capture when Vegas reports that my average fps for the capture of an entire tape is 24.98fps or maybe 25.03fps is it this timebase error that is being reported and should resampling each cameras video / audio track not solve the problem (although I did try this with no change in synch between the video /audio tracks from each camera)?

I know that none of the above has anything to do with the problem that I am trying to resolve - just want to know for interest sake.

Regards,

Dale.

Dale,

Free-run is handy, but, as you suspected, doesn't help with the offset and timebase errors you're experiencing.

The default for most prosumer camcorders is record-run, which runs more like a tape counter. Typically it starts at 00:00:00;00, what's recorded at the end of a one-hour tape will be about 01:00:00;00 or a couple minutes more, as tapes usually are 1-3 minutes longer than their stated capacity. So, the timecode generator lays down nearly continuous timecode on tape. (***edit - regardless of whether you've started and stopped the camera***)

So, the timecode generator only rolls when the tape is recording.

Then there is preset, which interacts both with record-run and free-run. Back in ancient times (as few as 10 years ago!), we were doing lots of linear editing with tape machines and editing controllers - they did NOT like seeing the same timecode twice in a project! Usual strategy was to "preset" starting timecode at hour 1 for tape 1, hour 2 for tape 2, etc, and use record-run.

Free-run means that the timecode generator rolls continuously, regardless of whether the camcorder is recording or not.

Free-run has all sorts of applications, but the one we're mostly interested in is so-called time-of-day timecode. Let's say it's 8:30am on the shoot day, and we've had our coffee and doughnuts. We'll preset all devices to 8:35am, switch them to free-run, then, whoever has the good wristwatch or the loudest voice will count down the last 10 seconds to 8:35, at which point everyone starts their timecode generator rolling.

Voila, all the timecode recorded now shows the time-of-day. With prosumer gear, that provides only rough sync - if done carefully, we're better than 10 frames, but that will still require a tweak in post, and, code will drift through the day. We might sync a few times if we care, but usually if this approach gets us within a couple seconds the editor can find the syncing points.

With pro-gear and a master timecode generator that is continuously wired to all devices, this is always frame-accurate. Usually in a multi-camera studio it's cameras, not camcorders, and all the tape decks are in a control room where they are frame-locked always (with master TC or house black, but that's another subject...)

I do this all the time with music recording, very similar to what you have done with your alesis digital mixer/laptop. Yes, I'll roll continuously over an hour tape, or even a 3-hour tape in a studio deck. I always have to correct for offset error, and sometimes have to correct for timebase error, depending on the accuracy of the individual clocks.

My attitude about this is that we now have $3-10,000 USD cameras doing most of what we used to spend $40-60,000 on, only with better pictures. I'm so amazed by the fact that I can personally own equipment and an NLE with these capabilities (instead of being tied to a multi-million dollar facility) that I don't worry too much about having to do these sorts of corrections.

You're concerned with how elegant the solution is - I'm very impressed that the beast is walking at all.

A frame is a frame, that is, it has its own begin and end information. So when you put it up on the timeline it's duration becomes (PAL) 1/25th of a second. If you lay it back to the Z1 after editing maybe it will be plus or minus some fraction of a percent different.

When does this matter? When it goes into large distribution systems like broadcast, cable or satellite. When there is a video switcher in use, and you want it to cut between sources glitch-free, which means cutting during the vertical interval between frames. And so, there are timebase correctors and/or frame synchronizers that retime frames during playback.

But it doesn't matter much for DV in general, because we usually either distribute direct to the consumer on DVD or VHS, or, we hand it off to a broadcaster who routinely fixes timebase errors during playback, because all tape machines have these errors - they are mechanical devices. I suppose things will be somewhat different when there are no tape players in use.

Seth - Thanks for your great explanation of various time-codes. So is there anything on the prosumer level that has time-of-day time code?

The manufacturer doesn't call it time-of-day, they'll call it free-run and preset.

Most of the higher end prosumer cameras, such as PD150/170, XL1, XL2, Z1, DVX100 have this capability. I think PDX10 does. If I remember right, GL1/2 does.

Not sure about the lower cost cousins of the Sony cams such as VX2000/2100, FX1. I'm not that familiar with Panasonic's DV line other than the DVX100.

Good Morning,

FYI - I can confirm that neither the VX2100E nor the FX1E have either free run or record run timecode settings / options / presets.

I found this link on my travels that refers to the PD150 timecode settings:

http://www.urbanfox.tv/workbooks/son...0timecode.html

Regards,

Dale.

An update:

I received my Control-L (LANC) to MIDI Time Code Cable (Generator) by Avit Research.

The cable / generator works perfectly - the cameras time code (FX1E / VX2100E / TRV27E) is sent to Vegas / Acid via the LANC port - no problem there (clearly visible when opting to view MIDI time code 'in').

Problem:

Although you can trigger Vegas / Acid recording and playback using the camera the time code from the camera is not recorded or should I say that when recording, Vegas / Acid do not 'chase' the camera's time code. So even this device makes no difference when trying to record, and keep in synch, audio recorded externally - the same consistent drift is evident.

If anybody knows how to 'instruct' Vegas / Acid to 'chase' the external MIDI time code 'in' then please let me know although I do not think that it is possible as, after reading the Vegas manual, Vegas can generate a MIDI clock and MIDI time code so this would work if the prosumer cameras had time code 'in' but they don't i.e. if they did the camera's would 'chase' the Vegas / Acid clock or time code but not the other way around.

Regards,

Dale.