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Old April 17th, 2006, 11:36 AM   #31
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Just another thought (full of them today).

When I capture video with Sony Capture XPress 6.0d I always get a report at the end that says something like 'Average FPS'. I forget what the figure is now but I do know that I have NEVER got a figure of EXACTLY 25fps after the capture i.e. it is always something like 23.976 and the like no matter what workstation I use.

I have never actually worried about this figure before (only the dropped frames part which I have never had).

What is actually being reported on?

Is it possible that THIS could have something to do with this synch issue?

I mean - the last thing that I would ever question would be my cameras - but - maybe they are not ACTUALLY getting EXACTLY 25fps (for these tests I am using my VX2100E but the problem originally occured with the FX1E). Is that possible?

I suppose I could plug a mic into my editing workstation and another mic into the notebook and record just audio using Vegas and see if those two align exactly after an hour. This would certainly eliminate the mixer / notebook combination from the equation.

I hope that this is interesting for members of this group (and OK by the moderators). I mean to say - I hope it is OK for me to be posting my thoughts / queries / test results as they come to me. If not - please be polite and let me know - and I'll stop taking up the space.

Shawn - by the way - no - the Alesis does not have a midi port at all - so I don't think that that will work. But - if there is a way to connect the MidiStream to the notebook (maybe there is a PCMCIA card that will allow this connection) then I don't see why the Alesis control panel will not let you choose the MidiStream as the master clock and your camera will already be synched to the MidiStream - if I understand this all correctly that is!

Regards,

Dale.
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Old April 17th, 2006, 11:42 AM   #32
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Dale Dale Dale,

Please try sending a signal straight to the camera. A mixer should have outputs for each channel you are recording AND an output of mixed stereo. Make the camera record audio from the mixer AND record discrete tracks to be mixed down later. Then you will be using the stereo mix for the reference and adding the 5.1 channels for finished audio.

Jeff
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Old April 17th, 2006, 11:45 AM   #33
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Dale,

Don't EVER think you are wasting space. This forum is to help everyone and God knows I need it to. Hang in there.

Jeff
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Old April 17th, 2006, 12:57 PM   #34
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Hey Jeff, thanks for that.

Sorry - I did not ignore your suggestion about sending the audio to the camera from the mixer AS WELL. The problem is that it is not going to make any difference if one of the clocks is 'slipping' or has a timing difference. Think about it. The video and audio on the camera WILL be in synch whether the audio is coming from the cameras mic or from the mixers output - no doubt about it BUT the individual tracks as recorded on the mixer WILL STILL be out of synch with the video and audio recorded on the camera - all you will have is a different audio source. If you are meaning that you can then use the audio from the camera as a reference point to synch the mixers recorded audio to the cameras audio / video that is a different thing but I have found that my 'beeps' at the beginning and the end of the recordings are far more accurate.

My problem is not so much that the stuff is going out of synch - this we already know (and we also know that it can be fixed by 'stretching' the audio by four frames of video for every hour in my case).

My problem firstly is to know WHY (and the general consensus so far seems to be timing differences between the different device clocks) AND how can I ensure that it does not happen AND exactly WHICH device is to blame.

I have just done another hour test - this time disabling WDM in the Alesis Control Panel and turning off the automatic detection for recording device latency in Vegas - have to wait for the video capture to finish before I know the results.

Assuming that the above makes no difference I think that the best test that I could do next is to set up the notebook to record audio using Vegas via the mixer and set up my editing workstation to also record audio using Vegas. If these two tracks align perfectly that would really eliminate the mixer / notebook and at this point I have a strange feeling that they will in fact be perfectly aligned.

Unfortuanately - I just have that kind of mind - WHY is the question? This could keep me awake for days!!!

Edit:

Sorry Jeff - I just read your message again. At any given event I am recording a MINIMUM of six channels (which have to be edited afterward). Just to check that I am not misunderstanding you - how am I going to send six discrete channels plus a stereo mix to camera in real time? I can tell you that the mixer only sends each discrete channel to the FireWire port - otherwise they are all mixed to the various stereo outs.

Regards,

Dale.
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Old April 17th, 2006, 03:45 PM   #35
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I was thinking that the audio from the mixer into the camera would be identical in stereo to that of the 6 discrete tracks so it would have to sync just fine. I guess I'm out of help. Good luck!

Jeff
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Old April 17th, 2006, 03:54 PM   #36
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OK - well - here endeth the lesson!

For my last test - I plugged a wireless receiver straight into the sound card of my editing workstation and another into the mixer connected to the notebook (easiest test as both receivers were set to the same receive channel and the same mic transmitted to both of them). Opened Vegas on both with identical record settings and let rip for an hour (with my 'beeps' at the beginning, middle and end i.e. after one hour).

The result - exactly the same difference over an hour i.e. between three and four frames difference per one hour.

What this tells me is that it is NOT the mixer that has the problem or is causing the issue but the notebook. The audio streams are different by the same amount, using the same software, using the identical settings, and it does not matter if the sound is recorded via the mixer or straight into the notebooks sound card - the difference is always the same.

As I hoped - this also means that the cameras do not have and are not causing these issues.

Bascially - after all of this - I can't help but get the feeling that I have not really accomplished anything. All I have proved is that with my combination of hardware I know that my audio is going to be three or four frames behind the video after one hour. Maybe tomorrow I will do the same test with my editing workstation and a spare editing workstation to see if the difference between these two workstations is the same.

The real problem is that when doing these tests it was a simple matter to 'stretch' the mixers audio at the end using the 'beeps' but in practice I can just see this becoming a nightmare. What if you forget to put the 'beeps' at the beginning of the tape / recordings AND at the end of tape / recordings and worse still - what if you are stop / start recording (video)?

Anyway - any input overnight will be greatly appreciated.

Regards,

Dale.
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Old April 18th, 2006, 03:07 AM   #37
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Good Morning!

This is driving me nuts!

This morning I had a look around for some solutions and I came across a thing called 'Horita Wireless Time Code System' - Model No. WTS100M.

Anybody had a look at this?

From what I gather these units (or at least these units in combination with some or the other unit of theirs) can send the timecode from one camera to other multiple cameras so I got to thinking - maybe they could send a timecode from the camera to the notebook and this would somehow synch the notebook / mixers clock to the camera?

I cannot find any documentation on these things other than the usual sales pitches.

Anybody tried these things (or something similar)?

Am I way off here?

The only obvious thing to me is that the audio captured via the mixer does not have a timecode but maybe there is some way .....

Regards,

Dale.
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Old April 18th, 2006, 07:25 AM   #38
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HEY - I JUST HAD A BRAINWAVE!!!

I am making this assumption:

That all (Sony) DV Camcorders are created equal (at least as far as their clocks go).

SO:

What if I connected a 'spare' Sony camera to the notebook via a LANC to MIDI Cable and then set up this camera as the master clock and the notebook (or mixer) as the slave. Would this not ensure synch of the mixers recorded tracks?

Please - this idea I REALLY need input on.

Regards,

Dale.
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Old April 18th, 2006, 08:41 AM   #39
 
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Likely not, Dale. No two anythings are exactly identical in their clocks without a synching device. Working with DV without genlock or other master clock and only being 2-3 frames different after an hour is pretty good, actually. But, if you're dedicated to your quest...sounds like it's keeping you out of trouble.
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Old April 18th, 2006, 09:07 AM   #40
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At any given event I am recording a MINIMUM of six channels (which have to be edited afterward). Just to check that I am not misunderstanding you - how am I going to send six discrete channels plus a stereo mix to camera in real time? I can tell you that the mixer only sends each discrete channel to the FireWire port - otherwise they are all mixed to the various stereo outs.

Regards,

Dale.[/QUOTE]

What I meant was that the stereo out of the mixer should be on the same time as the six discrete channels. Record the six channels and send the stereo mix to the camera. You record via firewire AND use a 1/4 to XLR to the camera. The audio should be timed the same so the audio on tape will be the reference track for when you load the other six wav files. Make sure you have your camera set to receive the mixed signal and not just plug the xlr in and think that's your source signal.

Jeff
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Old April 19th, 2006, 04:14 PM   #41
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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:

Quote:
When I capture video with Sony Capture XPress 6.0d I always get a report at the end that says something like 'Average FPS'. I forget what the figure is now but I do know that I have NEVER got a figure of EXACTLY 25fps after the capture i.e. it is always something like 23.976 and the like no matter what workstation I use.

I have never actually worried about this figure before (only the dropped frames part which I have never had).

What is actually being reported on?

Is it possible that THIS could have something to do with this synch issue?
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.
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Old April 20th, 2006, 01:39 PM   #42
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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.
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Old April 20th, 2006, 03:41 PM   #43
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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
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Old April 20th, 2006, 04:22 PM   #44
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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.
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Old April 20th, 2006, 04:44 PM   #45
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Are you positive you are recording 24/48 and not 24/44.1?
Jeff
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