Hi :)

I really haven't found a reliable way to get a timecode without missing frames. I am aware of the problem with mpeg not having all the frames. But I am not the manufacturer :)

So I always record a few seconds colobars when a shot is done. Then when I want to continue I make sure to be in a running timecode. Then Stop. Chance to cameramode and continue recording. But still many times the result is a short stop in the timecode. The same thing when in VCR mode, wanting to record edited Maeterial from Premiere via Firewire.

It seems to work fine with the end-search function. But thats useless, if you wand to recor from a prerecorded spot or when removing tapes and so on.

So is there a secret (or obvious) method to force the z1 to record from the nearest, complete frame to my stop point. Something like: OK, I want to record from 00:20:00:00. Finde me the nearest full frame. This then could be 00:19:59:14.

OK. I guess I made my problem clear to see :)

Thanks!

Peter

You need to black and stripe your tapes before use.

This means recording over the full tape with black silent frames, thereby generating a continuous timecode to record over.

You can do it though the camera (with firewire link to your NLE with no project selected - this should send silent black frames), but you'd be way better off doing it with a deck to save your camera's heads. I don't know whether you can, but if you can stripe a tape on a DV camera/deck and then shoot in HDV on it - that would be useful...

Anyone tried it/know?

You can't stripe a DV tape -- the stripe is always erased by the new shoot. The only thing you can do is cue the camcorder to a the last frame of the previous shot before starting ... which is what happens with a previously used tape -- the camcorder sees the 'previous' shot and continues from there. But it isn't a stripe ...

I expect HDV is the same -- it would be an odd feature to add to any digital format to insert edit during shooting onto a previously used tape. Even legacy analog formats like BetaSP only required that for an edit master -- you couldn't insert to a stripe during a shoot!

As for HDV not having all frames, this isn't really true. All the frames are there, just not all of them have complete image data. I'd be surprized to learn that they don't have all the non-image data though ...

GB

Thanks for your ideas,

Still i am not sure, whats going on with the HDV timecode.

I figured out, that stopping the tape in VCR and the changing to camera mode shifts the timecode a few frames. Recording from there in cameramode makes a seamless timecode most of the times. But still not always.

But it never works when I record in VCR mode from Premiere.

Another strange thing is, that when capturing in Premiere those stopping timecode seems not to be a problem. I don't get a error message and it records just over the spot.

I don't like not beeing sure about that all ...

any ideas ?

Peter

I'd be interested in understanding more about this also. I have read that not 'striping' the tape can cause problems if you want to recreate a series of source clips from the original reels (in situations for example where you have edited in DV and now want to use the same edits to create a HD version).

Andrew

Geoff, sorry mate, but that's not the case.

You certainly CAN stripe a DV tape, and the camera will record over the frames but not the timecode. Done it a million times. Timecode is generated on DV only the first time it is recorded. After that the camera uses the current timecode on the tape, so unless there's a break i the TC you will have continous TC even if you fast forward the tape in between shots.

What you CAN'T do on DV is set an externally generated timecode or start from any point other than 0:00:00:00 (well, actually, you can - but not on the majority of equipment, and certainly not on lower end cameras)...

Not sure what the deal is with HDV as I have yet to buy a camera - but that is *definitely* the case for DV.

You are absolutely wrong. The camcorder will always, without fail, without exception, record a new timecode track. No model built or sold offers insert on a stripe while shooting ... the only models that ever offered insert were decks, and only during editing.

This can be proved quite easily, with a little experimenation. It can also be confirmed with Google searches, or discussion with equipment experts.

The only thing striping does is ensure that you are shooting on used tape, and that there is a timecode value for the camcorders heads to read & start the new recording based on that value ... but once it starts it behaves as it always does and records a new timecode track. This can cause big problems with tapes that have stretched, or been frequently ejected, as the old values will drift out of sync with the new values and cause a discontinuity with the next start.

But that's beside the point -- my claim is quite true -- no stripe preservation in camcorder.

GB

Correct me if I'm wrong, but DV tape isn't like analog tape.

In the analog world there is "burn" via "control track", but in the DV world the TC is put down in real time when recording. Whether it's the 1st or 10th time recording it doesn't matter. Once you pop a fresh tape into the drive and hit record it's laying TC. If you notice when you record something and then rewind to check your work...it's timecode that it's using. But, when you fast forward again to get to the end of the footage you'll see blue video.

I believe that's why you have to start recording "in video" whenever you've jumped the control track in analog video, but you can still record on blue video in DV. It just start laying TC at that point. However, I always rewind to video because of my analog days. I remember projects getting all messed up when you broke the control track. You had to dub your tape and lose a generation so you could keep editing!

Geoff and Christopher are correct.
If you stripe a tape, then record images over it, new TC is laid in. If you make a break in the new timecode, and time passes between the end of one shoot session, and the beginning of the next shoot session, you see the old time code "beneath" the new. But you're always laying new T/C in the DV world in the majority of cams out there.
the Z1 has a few other options, including offset, but....that's turning into another subject. :-)

Douglas, I read your "Studio" article...good job. Also, are you part Native American? I've got a little Joppa in me (east coast tribe).

There's something else which may be coming into play here! In MPEG encoding each group of pictures (GOP) has a header telling the number of frames in that GOP. Normally there are about 15, but my JVC HD10 has a six frame GOP. In normal MPEG encoding a new I-frame (independant frame - a complete frame not relying on data from a previous frame) is inserted at the beginning of each scene EVEN IF THE PREVIOUS GOP IS NOT COMPLETED. The previous scene's header then reflects the shorter-than-normal GOP.

Look what happens in an in-camera edit. Either the camera must synchronize to the GOP "flow" of the tape before an edit OR it will more likely shorten tha last GOP from the previous scene by not paying attention to the GOP structure. This means that the last GOP from the previous scene will NOT have the proper header identifying it as a short GOP.

I KNOW the edits in my HD10 are not proper. The camera drops audio momentarily during playback. The included capture software only captures individual scenes. The Ulead capture program loses audio sync.

All this points to a likely discontinuity at in-camera edits, which could easily cause a disruption of time code. Hopefully the Sonys do better at this. Anybody shed any light on this? Inquiring minds want to know!

Are you sure Quickrec is off [Menu / Others]?

I have an FX1 and not a Z1, but from the little information I can gather from the manual, Quickrec can cause timecode breaks.

I think that the basic idea of Quickrec is to allow you to rapidly start recording when the tape has stopped rolling because of prolonged inactivity. Normal mode will take longer because the camera will patch up the latest GOP, AFAIK.

<<<<<<<<Douglas, I read your "Studio" article...good job. Also, are you part Native American? I've got a little Joppa in me (east coast tribe).>>>>>>>>

http://www.spottedeagle.com/credits.htm

Yes, I'm part indigenous, my website goes into my background.
Glad you liked the article, I'd actually forgotten about it. There's another one on audio this month, I think.
See you at NAB?

Douglas,

I'll be getting into Vegas on the 20th - a little later than I wanted. I'll be at the Stratosphere the 20th and Sahara from the 21st to 24th. (making a little vacation out of it) If you or anyone else is hanging out somewhere and want to get together let me know..

Ok. This may sound stupid, but hey, why not ask. I know what 'blacking out' a tape is. What is striping?

When you black a tape, you are also laying down time code, or striping, if you're working with DV. (and most other formats)

What he said. Unfortunately, you also erase your previous black/stripe when you shoot again on the same tape, so all is for nought.

GB

"It seems to work fine with the end-search function. But thats useless, if you wand to recor from a prerecorded spot or when removing tapes and so on."

This always work for me, if you remove the tape or checking the tape in VTR mode, then play/pause it 16 frames before where you want the camera to record again, then switch to camera mode and record, it always record 16 frames after your pause point when you are in vtr mode, so if you want continous timecode then always make sure you have atleast 1 second of video after your pause point.

Now I understand something about when timecodes are laid down.

But I've not heard a clear voice yet concerning if the practice of striping the tape prior to shooting is really necessary. Specifically this: if I never take the tape out of my FX1 until its done, only record and stop, do I risk any breaks in the timecode? I'd been striping my DV tapes for years, but I've basically gone away from ever rewinding and checking my shots (I'm not a pro, I'm usually just shooting candid shots of my kids at play, so it can't be recreated anyhow).

Should I stripe my tapes in my FX1?

Thanks!

Marc,

Striping is irrelevant in your case. The only people I ever came across striping their tapes were my students when I taught in Turkey. Basically we criticised them if they ever had gaps/resets in their timecode. Pretty much what was happening was, as you said, they were reviewing their shots. A few of the more savvy ones figured out that striping their tapes was a way to avoid this, but I do remember it caused as many problems as it solved, as there were timecode breaks where the footage dropped back to the blacked sections. This caused problems with tape pre-rolls either in capturing or when being used in linear tape to tape suites. So I can absolutely guarantee from personal experience that DV DOES erase the old timecode.

However, I've also found breaks in TC in my PD150 footage (and I never stripe my tapes) when stopping and starting, but striping wouldn't have made any difference.

"But I've not heard a clear voice yet concerning if the practice of striping the tape prior to shooting is really necessary"

Hey, I'll be as clear as I can: Striping a DV tape doesn't do what you think it is doing, your stripe will be entirely erased when you record again on that tape, and the practice of 'striping' a DV tape before shooting can cause problems with duplicated/skipped timecode values that are hard to spot ...

You stripe an analog tape you intend to use as an edit master so you can insert video and audio on top during the edit. Period. You never stripe a tape you are using in a camcorder for shooting -- no camcorder will use or preserve the stripe, so you are at best wasting your time.

If the goal is to avoid gaps and resets in your timecode, don't ever shuttle past the end of your last shot into blank tape, or if you do, backwind a frame or two into the last shot before shooting. This is how DV camcorders are designed to work, and this will eliminate completely any timecode gaps/restarts.

I expect the HDV world will be the same ...

HTH

GB

Same thing - it's an expression, I think, based on the fact that the frames are black but it has the timecode "stripe" running along it - hence "Black and Stripe"...

All pre striping a tape does is ensure that there are NO sections on the tape that there is no timecode. At least all consumer and Prosumer camcorders search for the timecode when a tape is inserted and use this timecode to continue from when record is started. The timecode is embeded in a particular area of the tape and is re-writen when recording is started. Correctly adjusted camcorders will not miss, and will maintain continuous timecode. Care must be taken to ensure that pre striping was done at the tape speed of the recording. Its no good striping at LP and then recording at SP for instance or vis versa. Timecode will be writen at the correct speed but the start point will be wrong. That is starting half way through an LP tape ( 45 mins) and record to the end at SP will leave an end time of 01:15:00 in SP!!! Cameras pre roll before starting to record so it is possible to re insert a tape on the last value of timecode on tape and then have a recording with a timecode break since the roll will go to a blank section before recording starts and the camcorder will think it is blank tape and start timecode at zero again. IF you never remove or view the tape untill full the camera will back roll each time to ensure this doesn't happen.
I actually miss the timecode re-write feature on Hi8. Timecode is writen on Hi8 tape in much the same way by the rotating heads but all my Sony Hi8 equipment has the ability to re-write timecode which of course solved all these problems of timecode breaks.
Vertical interval timecode on analogue equipment like SVHS has the same problem as DV, once writen your stuck with it. Control track timecode was not on all VHS/SVHS equipment ( there was always a linear control track but not always any code just pulses for the record/playback head timing) I think some of the JVC SVHS machines had control track time code that could be re-writen.
The bottom line is pre striping tape wil result in a continuous timecode but the recording will be on a tape that has already had a previous recording of black. Since there is no fine cue/review control to back up just a few frames with HDV like most DV cameras, either shoot a long tail on all shots if you are going to remove tape and view, so that you can stop way before the end of the shot to start the next shot and avoid camera going over end of timecode.
For my holiday and family tapes I prestripe since everyone wants to watch all the time!!!! For the event projects I do I use new tape and don't view tape untill editing.

Ron Evans

Ron, I'm happy that your 'prestriping' has never given you grief, but I have been given tapes to edit where the combination of prestriping and advancing before the last shot has created duplicated or skipped timecode values -- this is typical of tapes that were 'striped' in a single long pass, but are later used for mulitple short shots, particularly when temperature changes typical of an Ottawa winter are also affecting the tape ... the result crashes a batch capture attempt, or most Premiere attempts at capture.

If you have a tape with timecode problems, make a Firewire dub of the tape. The new tape will have new, continuous timecode & the video and audio will be an unchanged 'clone' of the original -- every bit the result of your old 'rewrite the timecode' solution. And given that you will only ever have to do this to tapes where your advancing/reviewing resulted in timecode breaks, you'll probably save time and effort as you won't have to waste a pass on every one of your tapes, just dub the problem ones.

Cheers,
GB
Ottawa, Canada

GB
The one time I had a problem was with my Sony PC10 that was continuously causing timecode problems and was a result of a defective chip. This was evident in that while shooting I could see the timecode reset to zero in the viewfinder!!! Not had problem since. I only prestripe when I know its going to be a case of shoot look, shoot look etc. You are correct in that a copy with 1394 will give a nice fresh timecode that can be relied on for batch capture. The timecode faults you see could also be a problem with LP and SP recording on the same tape which could lead to big discontinuities by recording short clips in SP over an LP encoded tape.

Ron Evans

Hi everyone,

Maybe this will put this issue to rest!

I too was advised to “stripe” my tapes, to prevent gaps in the time code and thereby prevent problems with gaps when batch capturing etc. I fact, it was recommended that you should stripe with color bars.

After reading this entire post today, I decided to conduct an experiment.

I put a new tape into my XL1s and recorded a short shot, and then fast forwarded a little and recorded another shot. As all would expect, I had two short shots each with the time code starting from zero.

Next I put in a striped tape. I fast-forwarded to a black striped section with time code but no image. I recorded again, for about 15 seconds. Upon playing back the footage, it looked fine with no apparent problems with time code changes.

To verify this, I put the same tape into my CH-VF1 deck, where I could control the playback better. Playing at normal speed it appeared again to be fine, and it appeared to be fine when using a slow playback.

Then I played the footage using my remote, which allows me to play it at about a half frame per button push, IE it takes two presses of the slow forward button to move forward one frame. When I did it this way, it moved from blank area time-code to the footage time-code without missing a beat—No Problem. But, when exiting the shot and returning to the striped area of the tape, it did have a problem. The time code stepped --:--:15, --:--:16, --:--:20. In other words it dropped 4 frames. This of course would probably cause some capture problems at times.

So what this proves is that you can’t maintain the correct time-code when you stripe a tape. It may work at times, but it obviously will not work all the time. I guess, from now on, I will skip striping and just use care in recording. I hope that this information will help in this post.

Mike

Mike,

This is great, it's a duplication of the faults we used to see with my students who would prestripe. They would get into difficulties when pre-rolling for batch capture or on linear machines. The deck would re-wind over that skip and then fail to find the pre-roll point, in some cases rewinding to the previous section and playting ad infinitum.

In another situation students would capture whole tapes in one long pass for offline, and set up the NLEs to ignore TC breaks, which meant after a few timecode skips, their TC would be right off by the end of the tape, by up to a second or two, so when they re-captured at online quality just their sequence clips the edits were often very wrong.

Ron, our experience with this issue took place with VX1000s, which have no LP mode, only SP.

Some from what I gather a good practice would be to:


1. Fast forward and rewind your fresh tape to loosen dust and tention the tape.

2. Record a few seconds/minute before and after a shot.

3. Start recording the next shot in the duration of time recorded AFTER the last shot (before the time code breaks).


Is that correct?

Yes Marco, I think you describe the best tape handling habits. Pack the tape once, roll tape at the top, maybe to bars and tone, and for all shots afterwards let the tape run a second or two long. If you watch what you've shot, cue for the next shot with the heads parked on the extra material you shot before -- if you don't review your material, you shouldn't have to do anything, though I have found that if you power up and start shooting with no pause or time at all between power on and shooting, you might cause a timecode reset to zero. If a reset causes you grief, make a lossless dub via Firewire and get a new tape with continuous timecode.

GB

Thanks a bunch. My main concern is dropped frames and dropped audio. I never really seem to have issues with time code. I usually capture just the scenes I need, manually. I wouldn't know what to do with batch capture. Once in a while I would get a scene that would lock for a frame or two and then continue, very frustrating. Packing the tape seems to have help a lot.

Well all you guys got me wondering how I haven't seen any of these problems so I just did a DV test ( I will try and render some HDV and try HDV also over the weekend) I have 4 DV pieces of equipment, all Sony. A DHR1000 deck, a PC10 camcorder, TRV50 camcorder and a FX1. I prestriped a Sony Premium ( cheap )tape at LP on the TRV50 on the assumption that this would be the worst of all worlds for an insert test. I then used Premiere 6.5 with my Canopus DVRaptor RT2 to insert a colour matte ( red ) for 4 seconds onto this pre striped tape, and moved the tape between each of the pieces of equipment in turn. NONE of them missed on timecode continuity going from an LP pre strip to an SP record of the red matte. The deck was two frames late on insert point( which I could adjust for and then hit the insert point) but all the camcorders were exactly on the insert point with the export default device control setup. So I prestriped the tape at SP and repeated the test. Exactly the same result. There was no timecode corruption on entry or exit though this was only a 4 second insert and could get much worse over a long period of time resulting in a timecode difference at exit. I quess this explains my input and my assuption that this was the way it was according to spec and practice. Obviously not for everyone!! Apologies if I have misslead anyone.

Ron Evans

Well having posted and then read some of the posts I had missed I though that I should test for a longer insert to see if my camcorders would create an error over a longer insert. So used just the TRV50 this time and striped with red matte for 30 mins. Then went back and inserted a blue matte first 2 mins, then 4 mins, then 6 mins and then 8 mins. all cases were the same as before. No timecode errors on entry or exit. Two of the inserts , the 4 and the 8 min had a frame of mixed blue and red blockies on exit but the timecode was solid on this frame repeatedly single steps forwards and backwards through these changes both on the TRV50 and repeated on the DHR1000.
Clearly there is no real need to stripe but for some continuity in time ( how much time do I have left on this tape?- when on holiday) it may be worth it even if a copy is made afterwards to get clean code for editing. I will still do it for my holiday and family tapes for just this reason.

Regards
Ron Evans

I believe you are most likely to have problems if you have created the 'stripe' in a single long recording pass (as you typically would), and subsequently shoot again on that tape with many short shots, over some days of variable temperature ... and you review your material in camera, which was the tape handling habit that suggested this 'solution' in the first place.

The combination of dissimilar tape passes, temperature changes & tape shuttling lead to the problem, in my opinion. The math reveals that it doesn't take very much of tape stretch to generate a single field (or just more than half a single field) change which would cause a timecode skip or repeat .... remember that the key point is that the tape 'stripe' is not preserved, the way it is on a analog edit deck -- it is destructively erased when the tape is reshot. The only purpose of the stripe is to give the camcorder a value to start recording timcode, even if you've cycled past the last shot.

Cheers,
GB

GB,

You've got the right idea there. I think the initial idea of "striping" DV was to insure that the TC generator doesn't start at zero again in the middle of a tape. Years ago the term "jam-sync" was used to indicate that a TC generator could read existing time code, and then continue from that count as it went into record. No existing code - start at zero. That is what happens with less than professional DV and HDV. The "pros" give you options. As GB says though, the out point of your last shot will only be close.

When I started with DV, my primitive software did not preserve the original TC. It simply started each capture at zero. If you captured that way, there would be no pre-roll problems. The TC would not match the tape, however. This would only be important for "off-line" editing, or maintaining TC if something must be re-captured. I still capture with new TC. There will not be a pre-roll problem that way. This saves the copying step that was mentioned earlier as a solution to this problem.

I striped 20 Sony Premium miniDV tapes before my last assignment in Africa. On several (maybe 4-5) of these tapes there is more than one set of timecodes. It's killing me in the log/capture process with FCP, getting timecode errors. How did this happen? I thought if I striped a tape I would have a continuous timecode.

Shooting on a Sony PD170, never removed a tape until it was no longer going to be used. Did turn the camera on and off several times if that matters.

Is there a way to lay a timecode down that will be continuous? My main concerns are in the batch capture process while in FCP. I was lead to believe that striping tapes would solve my batch capture problems. Guess I was wrong.

Tyge,
FX1 or Z1U? You can set the Z1 to either free-run or record-run.

The simple answer is do nothing and your timecode will be continuous. Striping causes problems, as the stripe is erased on your shoot and doesn't accomplish what you are expecting. The ordinary process of shooting, stopping & shooting again will generate timecode that starts at zero and continues upwards without a break from there -- in the case of the PD170, you can elect to start at something other than zero if shooting DVCam, or shoot 'free run' (which will likely cause your NLE no end of fits) if you want to have timecode that follows the clock and not the 'record run' standard.

Stop striping, it doesn't help.

GB