Recording Audio on MD while shooting on a DV camera

[tingkumajique]

Hi all...

was hoping that some one could help me out here...

I had a gig which required me to record audio from various mic sources via a mixer which was located 100m from my camera. Of course instead of running a 100m XLR cable which sorta hinders the camera movement, I opted for HiMD recording.

Since the live presentation was over 7 hours long, and i couldn't be next to my MD player (Sony MZ-M10), I left it to record on LP mode which gives me about 32 hours recording time.

Now the problem i have is that when i bring them all into my editing suite... the audio recorded on the HiMD player doesn't sync up with the audio from the camera's onboard microphone. To make matters worse, i have a total of 800 different tracks which i have to go through and pick out the ones which has the audio i want to use.

I have resorted to "rerecording" the recorded audio back into my computer... this way, i realize... it minimizes the sync issue.

could some one explain how this can be? is it something to do with the 44.1KHz and 48KHz difference?

Also would appreciate it if some one could provide some tips on reducing the number of recorded tracks on the HiMD... many of which are just silent passages...

any help will be much appreciated... i'm totally swamped with 2 HiMDs with a total of 14 hours of audio recordings...

thanks!

gabe

[tingkumajique]

*bump*

[A440]

Can't help you on the sync issue. Maybe a video expert can.

Line-in recording creates a new track mark after 2 seconds of silence. There's no way around it.

Are you using SonicStage or Mac Transfer? I don't know the Mac software, but SonicStage has a Combine function under Edit. Highlight (in the order you want--don't do it from bottom to top or you'll regret it, since there is no Undo), hit Combine and go out and do some errands while it slowly puts the files back together.

[King Ghidora]

There can be a difference between 44.1khz and 48khz but I've not seen it happen. I record with MD and sync with video all the time. The only time I ever had a real problem it turned out to be bad discs apparently. It happened when I first bought my HIMD (used) and it happened with more than one disc. The discs were cheap though so I assume it had to have been the problem because it hasn't happened since. I really can't say for sure though.

You can use programs like Goldwave to time warp your audio file and make it fit the same time as the video. It isn't as hard as it sounds to do. I worked out the ratio by looking at how many seconds each device recorded and dividing to get the ratio to use to adjust the time in time warp. It may not be perfect but you can make slight adjustments after you get it close and you should be able to get it in sync.

If you have a problem with the 800 tracks causing slight delays when you use the combine feature then you may be in for a whole lot of problems getting things back in sync.

I hate to say it but it's always best to test your equipment before you use it for something important. You should have checked whether there would be a sync problem before you recorded a one time event that can't be reproduced. There very well could be a problem with either your MD or your camera.

Usually I don't see tracks out of sync more than a frame or two over the course of a full 1 hour DV tape. That usually comes from a bad spot in a tape and it's easy to fix. I'm sorry you had this problem but there are things you can do to fix it. I'd definitely start with time warp. Goldwave has a free trial that is fully functional. That's what I used to fix the problems I had when I first got the HIMD. I thought I was going to have to use it all the time but luckily it was just the bad discs. Once I got the hang of making the adjustments it wasn't hard at all though.

Good luck.

[frankz00]

Wow. This kind of concerns me because this exactly what I plan on doing for future productions I'll be working on. Do you mean that it goes out of sync beyond something that's simply an offset. In other words, if I'm synced up at the beginning, will I be out of sync by the end? The only thing I can thing of is finding the beginning and end points of the audio and stretching it to fit the segment of the video. But I have to do that, that really stinks!!

[A440]

What King Ghidora is saying is that he has generally had little or no problem synching up his MD and video recordings and that he believes something is malfunctioning.

"Usually I don't see tracks out of sync more than a frame or two over the course of a full 1 hour DV tape. That usually comes from a bad spot in a tape and it's easy to fix. "

"There very well could be a problem with either your MD or your camera."

[silence]

The biggest problem that you seem to face is the sheer size of having 14 hours of audio and 7 hours of video.

You have a movie-size problem BUT all is not lost

All it takes is patience, not necessarily technology.

Step back, look at the problem and see opportunity; for example after 3 weeks of daily synch ing this stuff, you will be a whole lot faster editor and wiser about future projects like that. The truth is that this kind of insight is hard to come by otherwise. I know

What some people faced with that do is:

1) break the problem into small bites,

2) load one hour at the time of audio and video a

3) break that into 12 five minute sections

4) use the on camera strictly for cues

5) once you find a scene that you want, synch the beginning and cut in 15 sec segments

That last step will make your video less boring and teach you a lot of editing tricks.

Put on one of your films and take a stop watch and try to find one cut that last more than 15 seconds...though huh?

6) repeat 800 times

I just hope it is for a worthy cause or for tons of cash or something altruistic you believe in - otherwise it will be painful, but with "patience" you see it through. Good luck

[Strungup]

Hi all...

was hoping that some one could help me out here...

Since the live presentation was over 7 hours long, and i couldn't be next to my MD player (Sony MZ-M10), I left it to record on LP mode which gives me about 32 hours recording time.

Now the problem i have is that when i bring them all into my editing suite... the audio recorded on the HiMD player doesn't sync up with the audio from the camera's onboard microphone. To make matters worse, i have a total of 800 different tracks which i have to go through and pick out the ones which has the audio i want to use.

I have resorted to "rerecording" the recorded audio back into my computer... this way, i realize... it minimizes the sync issue.

thanks!

gabe

This has to do with the conversion of the HiMDLp to wav , Everybody hold on and do a little math with me here.

1.05946

What does this number have to do with anything?

This is the Standard reference for the division of twelve tones in an Octave, ............and its wrong!

At current standard 440hz = A .. easy to divide and multiply 110 , 220 , 440, 880, etc

But if you take 1.05946 start at 110 and mutiply up (answ*1.05946= answ*1.05946=answ* you get the idea)

It will not be 880 ... you will come to a difference of just over a cycle.

This is ok in music/sound, the ear doesn't differentiate that much , but with sound linked to images it is a whole different story.

When the conversion in the Software takes place , there IS , a very subtle difference in the Cycles that add up over time ie. the longer the recording the more noticable it will be.

If the video and the Audio are not coded at exactly the same frame rate , you will have to stretch/compress one or the other

That is tricky because now your dealing with percentages, what Percentage do you stretch /compress to exactly equal the other part .

In this particular venture instead of recording in HiMDLP you would HAVE to record in PCM and change discs very quickly ( Not a good option , The way the video industry does this is use a Hardrive chain, with a Transfer device from your Audio Connection Direct conversion to digital at a specified bit Rate that will match the Cameras frame rate And a Time Code Sync to KEEP them together .

There has recently been a Consumer version of something like that made.

http://www.ikey-audio.com/ikeyplus.htm

Link to the Video http://www.ikey-audio.com/videos.htm

Use that with a preamp for the Mic , when you import the Audio It wont be import Just connect the Hardrive to your Computer. All the Audio will be there and in Sync

You attach and power a USB drive to this thing , set its sample rate ,Recording level , and let it go .Then when your done , Attach the same drive to the computer ,Import the video to the computer .Adjust the position of the audio in relation to the video Make your movie

Edited April 26, 2007 by Guitarfxr

[rayzray]

Can't help you on the sync issue. Maybe a video expert can.

Line-in recording creates a new track mark after 2 seconds of silence. There's no way around it.

Are you using SonicStage or Mac Transfer? I don't know the Mac software, but SonicStage has a Combine function under Edit. Highlight (in the order you want--don't do it from bottom to top or you'll regret it, since there is no Undo), hit Combine and go out and do some errands while it slowly puts the files back together.

i thought you had to "combine" two tracks at a time;; i didn't know you could combine ALL the tracks at one shot..

i have done this combining for about 80+ tracks a few times and it's not fun..

you could NEVER get the real time-line by doing this IMO..

as an added note;; i think i wanna sell ALL my A/V stuff i have been buying;; i don't want to go through all this

or;;

i will continue to do everything un-ortrodoxidly..

i like this thread..

Edited April 26, 2007 by rayzray

[King Ghidora]

IMO the best thing to do to skip the problem with large number of files is to play back your audio through the computer's sound card and create a single file on your computer. You will lose a small amount of quality but likely as not few will notice the difference.

Once you do that you can use a program with a time warp feature to get the tracks back in sync. You will only have to do it once. Yes it's a question of percentages but they are easy to come by. If for example you had one 30 second video file and one 60 second audio file the percentage would be 50%. It's simple math. You just have to do it with seconds because it's hard to figure percentages of minutes unless you're gifted at math.

Once you get the general percentage right you can make slight adjustments to get things perfect. For example instead of 50% you might want to try using 50.1%. A few attempts at adjusting and you should be able to make it a perfect match. It isn't nearly as hard as it sounds.

Again I've never had problems like this but I've never tried to record anything that long and get it in sync. I can see where what GuitarFX says can cause a problem (converting LP files to wav's is going to cause a slight problem in time length) but I can't see it causing a large problem even over the hours you recorded. Maybe I'm wrong but it seems more like you have an equipment problem to me. Have you tried doing samples that are much shorter to see if the problem occurs? If you're off 5 minutes in a 30 minute sample then you have an equipment problem.

I wouldn't give up if I were you. There are things you can do to make things go much smoother. For one thing you could record both audio and video to a separate recorder in real time. A stand alone DVD recorder might work or better still a laptop with a video in jack or a USB video capture device or a capture card. You would record both audio and video to a file without having to worry about sync issues because it should never get out of sync.

If this was a one time event you should just check your equipment to see if you can eliminate the problem somehow. Maybe recording to PCM would solve the problem. I really think you can fix the problem you have now easier than you think. Time warp really does work magic.

You can also learn a few tricks about syncing. Keep the audio track on your video camera. You can sync another audio track with it fairly easy. Use a loud noise at the beginning of your recording and at the end to create points that are easily synced. Be sure to keep all recorders going all the time to avoid having to sync more than once. And learn to use visual cues to show you where the audio should go. If someone claps their hands together you might be able to sync audio by looking at the hand claps for example.

This stuff comes with experience. I think you'll be able to work it out with some effort.

[tingkumajique]

hi all...

sorry for the late reply...

thanks for all the inputs... it's kinda frustrating to know that you've got a piece of equipment that can record audio for 32 hours but get the problem of sync issues. yea... i kinda guessed that the conversion from Sony's format to .wav would screw up the sampling...

recording with PCM and swapping every 1 hour wouldn't do for me coz i would wanna eliminate as many distractions as possible when going live...

will definitely look into the ikey solution... looks really promising

thanks again for all the inputs... this site's really helpful coz of guys like you!

gabe

[fishstyc]

I don't know if I am repeating someone, because there was a lot to read, but it is completely normal that it's not in sync. MD and your video camera each have their own internal clock, right? And there is always a small deviation.

The soundcard in your PC will also deviate from the other 2 devices, so playing back the recorded audio on your PC will play the same audio slightly faster or slower than your MD will. So there is nothing wrong with any of the equipment. Professional equipment would be linked and set as a slave to the same Master Clock, so that every device stays in sync.

For synching, I suggest changing the frame rate, because that is discrete and the software only has to double or drop a frame once in a while to get everything in sync. Apart from that it's some math and some trial and error as someone suggested.

[Avrin]

Never had this problem myself, since I do not use MD for recording while shooting drama on a digital (or analog) camera, but a friend of mine told me a while ago, that this happens. Seems perfectly natural to me. fishstyc described the cause absolutely correctly. I first encountered this effect some 15 years ago, while experimenting with different CD players. Put 2 absolutely same CDs (same pressing, etc.) into 2 different CD players, and start playing synchronously (from pause). Chances are that you'll get a noticeable discrepancy in just a few minutes. And we're talking about hours here.

The solution to this would be to mark the time passing between two noticeable events (like drum peaks) on both records (video and audio) separated by a lot of time (hours or more), then calculate the difference ratio, and apply it to speed up (or slow down) the audio record. Then you will be able to synchronize audio with video without any problem. I would advice working in the 32 bit domain here (Adobe Audition or a similar program comes in handy for this), to minimize possible sound distortions from resampling.

A serious problem may arise if the operating conditions of one of the devices are not stable. Like the video camera heating up during operations (causing its clock to change speed). In this case the discrepancy ratio will not be constant. Though I don't expect this effect to be too noticeable.

Edited May 3, 2007 by Avrin