XH-A1 Corrupted Footage on LP but no drop outs- Advice? at DVinfo.net

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Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


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Old January 16th, 2008, 02:35 PM   #1
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XH-A1 Corrupted Footage on LP but no drop outs- Advice?

Hi all. I just sold my two trusty XL2 cameras and upgraded to 2 x Canon XH-A1's.

Most of my filming is multicamera (2-3 cam) event filming.
I filmed many, many events over a year, with the XL2's set to LP Long Play mode & using Cheap Sony 5DVM60R3 miniDV tapes.

Worked perfectly, with NO dropouts, despite being on longplay.

However, the Brand New XH-A1s have almost caused a disaster!
Initally they recorded fine on LP (and Sony MiniDV tapes). After 3-4 hours filming, I noticed very occasional corruption on imported footage - a flash of mosaic pattern on screen, momentary sound corruption.

Then, the last event I filmed in December - massive corruption- completely unusable footage - Video and audio distorted and broken up when digitized - However, playback on camera LCD screen / speaker was mostly ok, with very little indication of problems...

What was unusual, was there were NO dropped frames - Just the footage was corrupted once digitized into the computer.
By a stroke of luck I thought to put the tapes back into one of my old XL2 cameras, and successfully digitized the footage into the computer with only very occasional & minor glitches.

So to summarise:

1) Recorded on XH-A1 on LP using Sony MiniDV tapes.
2) Initially playback / digitization fine, then slowly increasing minor glitches over 4-6 hours use.
3) After next filming, sudden massive audio / video corruption on digitization (but no dropped frames)
4) Footage was able to be recovered by digitizing through a Canon XL2 camera.
5) This pretty much happened to BOTH XH-A1 cameras at the same time, so perhaps suggests a tape issue than anything else???
6) SP footage on these cameras seems to digitize fine.

I contacted Canon New Zealand, and they seemed very perplexed, but did hint that I should switch to Panasonic tapes instead - Even so, they said this was very unusual... They suggested the XL2 tape mechanism may be more tolerant tape errors.

I've just got some Panasonic AY-DVM63AMQ (these are what people are recommending?) tapes today, ran 10 seconds of cleaning tape through the cameras, and will do some Long Play test records over next couple of days.

Just wondering if anyone else has any similar experiences and advice. LP recording has worked perfectly till now and is quick a necessity for the events I film.

So frustrating!

Thanks,

Chris.
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Old January 16th, 2008, 03:41 PM   #2
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Using the XH-A1 for SD video?

LP recording can be hit-or-miss, and thus generally is not considered reliable enough for important event work. Best results are obtained if the tape is played in the same camcorder as it was recorded shortly after it was recorded (i.e., not many operating hour later).

Camcorder playback analog output (e.g., to the monitor) circuits include significant error correction features that are not applied to the firewire output data stream, thus what you see from the composite or component video output may not show the same level of tape read error artifacts that you see in the firewire capture stream.

If necessary you could try capture from the analog output stream to salvage the footage if tape read errors make firewire capture unworkable.

Another option you might consider trying is using 80 minute tapes at SP speed. That at least gets you close to same record time as LP speed record time on a 60 minute tape.
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Old January 16th, 2008, 04:13 PM   #3
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Quote:
Originally Posted by Don Palomaki View Post
Using the XH-A1 for SD video?

Best results are obtained if the tape is played in the same camcorder ...

If necessary you could try capture from the analog output stream to salvage the footage if tape read errors make firewire capture unworkable.

Another option you might consider trying is using 80 minute tapes at SP speed. That at least gets you close to same record time as LP speed record time on a 60 minute tape.
Hi Don - thanks for the reply - Yes, crazy as it seems, the majority of my work is filmed in SD. The Xl2 cameras were great, but the Iris ring, larger view finder, peaking and push-auto focus on the XH-A1 won me over.
I just haven't had time to play in HD yet... soon, soon, soon.

I understand that LP is inherently more risky, yet with a multicam shoot I have footage from an additional 1-2 cameras to cover any glitches... on the XL2s, I virtually never had any dropped frames on LP.

Yes thanks, tried to capture from the same camera, immediately after filming - still corrupted.

Also tried capturing via the analog output into an Analag-Digital converter and had problems with that -even though the camera LCD screen/speaker seemed to play back ok, the analog output also had issues... The ADVC just wouldn't work with it. - thats when I thought of the XL2 , and successfully imported the footage (what a relief that was!)

Thanks for the tape suggestion -At this very moment i've got one of the cameras filming on LP on to a Panasonic AMQ tape - I'll record 3-4 tapes today and see what the playback digitization is like.

ALSO! I just now had a call back from Canon, who said it could be a 'tape tracking' issue within the camera. They asked me to send up the camera with the 'corrupt tape', and the service technicians could use their 'service software' to adjust the camera tracking to the Sony tape tracking.
Possibly after the tracking correction, all future Sony tapes should record and playback correctly on LP.

I'll wait for the outcome of the Panasonic tape tests first, as i'm probably going to use Panasonics from now on - they do seem to have the best reputation / most recommendations. If there are any issues, I may try having the tracking adjusted to the Panasonic tapes.

Has anyone else out there had their tracking adjusted to match a tape brand?

Thanks Don!

Chris.
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Old January 16th, 2008, 04:34 PM   #4
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Hi Chris..........

First off, just to set the record straight, the signal on the tape is DIGITAL, no matter whether you record HD, SD or LP.

When transfering the data to the computer via Firewire, you are doing a straight digital copy, not digitizing anything (unless, says angel on shoulder, you are DA converting from the tape to either component/ composite, then re - digitizing the analogue stream, for reasons I can't begin to fathom).

Ok, from there we go to the tape/ A1 issue. From the numerous (hundreds?) of posts on DVinfo on the subject of HDV cameras and tapes, I think I can safely say that the A1/ G1/ HV20 seem to be particularly picky when it comes to tape stock as compared to a SD only camera (tho' whether they are more picky than any other make of HDV camera is a moot point).

That you have come unstuck with "cheap Sony" tapes is thus not much of a suprise.

Now, that a LP tape played back on the A1 seemed fine on the camera screen and speaker but was corrupt on the computer (assuming it was a Firewire transfer) is a phenomina that I am struggling to explain. Likewise the fact that the same tape could be read into the computer OK from an XL2 (thought you'd sold those?).

Whatever, going on the warnings printed in the A1 manual concerning LP use (page 71) I would say it's use as a matter of course (on the A1) sounds dodgy in the extreme.

Without preempting the results of better quality tapes and the liberal application of a head cleaning tape, I am driven to ask what would appear to be a very obvious question:

Why on earth buy, not one, but two, "Rolls Royce" Canon A1 HDV cameras and use them to haul coal by using LP mode? At the very least you could get Panny 80 minute tapes and record SD in standard play. Better still, record in HD and downconvert to SD somewhere along the food chain. What sort of event has a 90 minute duration with not one minute of down time somewhere?

Come to think of it, what do you do with event SD footage recorded in LP mode - it would have to make average look pretty flash?

All of which are only slightly rhetorical and of no use in solving your problem.

I shall await the new tape/ cleaning results with interest.


CS
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Old January 16th, 2008, 05:04 PM   #5
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sfsdfsdfsdf

Quote:
Originally Posted by Chris Soucy View Post
1) First off, just to set the record straight, the signal on the tape is DIGITAL, no matter whether you record HD, SD or LP.

2) I think I can safely say that the A1/ G1/ HV20 seem to be particularly picky when it comes to tape stock as compared to a SD only camera

3) Likewise the fact that the same tape could be read into the computer OK from an XL2 (thought you'd sold those?).

4) Whatever, going on the warnings printed in the A1 manual concerning LP use (page 71) I would say it's use as a matter of course (on the A1) sounds dodgy in the extreme.

5) Why on earth buy, not one, but two, "Rolls Royce" Canon A1 HDV cameras and use them to haul coal by using LP mode? At the very least you could get Panny 80 minute tapes and record SD in standard play. Better still, record in HD and downconvert to SD somewhere along the food chain. What sort of event has a 90 minute duration with not one minute of down time somewhere?

Come to think of it, what do you do with event SD footage recorded in LP mode - it would have to make average look pretty flash?


CS
Hi Chris, thanks for the reply.

Point 1): Ok, "digitized" was incorrect terminology on my part, think 'imported' instead... Yes, its all digital...

2) & 3) Yes this would seem to be the crux of the matter.
XH-A1 is vastly more picky, compared to the XL2 which could in fact read the footage, despite it being recorded on a different camera in LP.
(Had sold the Xl2s but fortunately was yet to deliver one to new owner...)

It's all very unusual, even Canon are uncertain...

4) I'm sure the same LP warnings are in the XL2 manual - I've recorded hundreds of hours on LP on the XL2 & many hours on a XL-H1 without dropped frames.
For various reasons LP has worked brilliantly for me (up till now), obviously SP is the safer option, and most likely better option from now on.

5) I hadn't heard of Panasonic 80min SD miniDV tapes - I'll look into this...
Despite 'hauling coal' through these cameras, the results are great, even on LP - which is SD, just with less error protection.

Thanks Chris.
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Old January 16th, 2008, 05:08 PM   #6
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Curiously, I just shot SD on a Panasonic HDV tape with the XH-A1.

This was the first time to try SD with the camera. I didn't have the time to crop and down convert, as I was changing a part of a finished project.

There were a couple of bad spots in the recording, like you would get from an old Betacam tape. There was no dropped frame, but corruption for about 5 frames in a couple of spots.

I patched up the tape as I might with an old Betacam tape, but deleting frames and replacing them with adjcacement frames... also patching in a piece of audio.

Does the XH-A1 have trouble working in SD in general, regardless of tape speed?
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Old January 16th, 2008, 05:26 PM   #7
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CS[/QUOTE]

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Originally Posted by Jack Walker View Post
Curiously, I just shot SD on a Panasonic HDV tape with the XH-A1.

Does the XH-A1 have trouble working in SD in general, regardless of tape speed?
Hi Jack.

I've only had the cameras for a very short time, have only recorded a couple hours of SD and had no trouble so far...

The corruption you described sounds very much like what I experienced - no dropped frames, but distorted video / audio on import... I really don't know what this means, other than Canon's offer to individually adjust the cameras to a particular tape brand.

Maybe the tape was a 'dud' tape to begin with?

Perhaps talk to Canon in your location, and see what they think about it - and the if they will offer to adjust your camera tracking as well? (if required?)

Good Luck!

Thanks,

Chris.
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Old January 17th, 2008, 08:19 AM   #8
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Keep in mind that all MiniDV tape is very nearly the same, whether labeled for SD or HDV. There are some differences in quality control, and perhaps formulation of the base, magnetic layers, and lubricants among the different brands and models within a brand, but subject to the results of quality control issues, all can be used for SD or HDV recording. (Lesser quality control can result in more tape-based anomalies such as drop outs.)

AY-DVM80XJ and EJ are the nominal designation for Panasonic's 80 minute tape in their consumer-oriented product line.

AY-DVM83PQ and MQ are the nominal designation for Panasonic's 80 minute tape (probably ~83 minutes) in their Professional-oriented line.

Sony offers a DVM-85HD HighH Definition MiniDV tape in the 80 minute class (~85 minutes actually)

The 80 -minute tapes tend to to cost on the order of 2x the 60 minute tapes (still cheap if you need the extra 20 minutes) , and may be a bit harder to find in stock. The base is usually thinner, so they are a bit less robust for reuse and abuse.

Quote:
Now, that a LP tape played back on the A1 seemed fine on the camera screen and speaker but was corrupt on the computer (assuming it was a Firewire transfer) is a phenomina that I am struggling to explain.
Goes back to correction of tape read errors. Analog playback and display systems often include error correction schemes, such as replaying the previous good frame/field/block, to mask uncorrected tape read errors. If the scene was relatively static the viewer may never notice the error correction. That is why capture from an analog stream may at times provide a more usable end result. However, the firewire data stream is usually just a read off the media with only limited data-read error correction and no masking of uncorrected read errors.

If the error is at the exact same point on the tape with each read attempt, it is a problem with the material recorded on tape. If it moves around randomly, it may be an issue with the camcorder playback, or the firewire capture system where in the PC occasionally drops a frame thanks in large part to all the other stuff doing on in the PC at the same time.
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Old January 17th, 2008, 08:57 AM   #9
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Well, I had a similar issue with my cams this summer. I have been shooting LP for about 3 years with NO issues on VX2100s This summer I had a tape get trashed and sent it to Sony Media Services. Now, they repaired the tape for me and told me that what LP does is essentially stretch the limits of the tape to get more info on the same tape. So you can see why strecthing that info for DV may be different than the stretch for HDV because you need more bandwidth for HDV. I switched to shooting only SP mode and haven't had any more issues since then. Maybe the QC on tapes has changed, but I am a SP man forever. I use 3 cameras, and even during a 1.5 hr catholic ceremony I will be SP and swtich the tapes. Good luck.
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Old January 17th, 2008, 12:01 PM   #10
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HDV and SD use the same bandwidth on tape, something like 25 Mbps. HDV provides high resolution through higher compression (MPG) to offset the larger number of pixels in the image. Drop outs can be much worse on HDV because a drop out or tape read error may effect the full Group of Pictures (GOP - about 1/2 second of video) rather than single frame.

LP uses slower tape speed, which in turn means the recorded "tracks" on the tape are spaced much closer together and narrower (about 6.7 micrometers vs 10 micrometers for SP). This in turn means there is much less tolerance for even slight tracking variations.
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Old January 17th, 2008, 04:44 PM   #11
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Quote:
If the error is at the exact same point on the tape with each read attempt, it is a problem with the material recorded on tape. If it moves around randomly, it may be an issue with the camcorder playback, or the firewire capture system where in the PC occasionally drops a frame thanks in large part to all the other stuff doing on in the PC at the same time.
Thanks for the info on the tapes - i'll look into them.

I'll recapture a few times to see if error is exact same point on tape. Pretty certain it is. Doesn't appear to be firewire system as computer is not reporting dropped frames.

Thanks!
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Old January 17th, 2008, 06:22 PM   #12
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Hi Bill - thanks for the info and the footage examples. Very similar problems, although your footage was more severely corrupted, still unusable in both cases.

I cleaned the camera heads, then tested filming on LP on Panasonic AMQ tapes. Unfortunately still the same corruption problem. So I suspect it is a camera issue rather than tape / tape brand. It would seem the cameras are recording fine, as footage could be captured off XL2 camera, but playback on the XH-A1 is not (tracking?) working properly.

I've also got test tapes filmed using SD and HDV, which I'll check today, just to be sure this is a LP problem.

I will probably take up Canon NZs offer to inspect and adjust the tracking on the cameras... Unfortunately 2-3 week turnaround time for servicing...

Thanks.

In any case, i'm probably going to start filming HDV from now on - If the Panasonic AMQ tapes work well in HDV as suggested in these forums...


I'll try to upload my corrupt footage example later, for others who are interested.

Thanks,

Chris.
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Old January 17th, 2008, 08:36 PM   #13
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Well I'll be shooting for the first time next week with my new xha1. When I bought the cam, I also bought two five packs of the sony hd dvm63, thinking I didn't want to risk cheaper taps on a 3 grand camera. Now I'm seeing almost everyone is using regular pan dv tapes for sd and HD. I want to settle on one tape, and if there are no issues with the cheaper tapes, then maybe that's the route I should go. What do you all think. and what specific pana dv tape are you using successfully.

And one more clarification. If I shoot sd to be handed off to a consumer cam that was shot on the sony hd tapes, the consumer cam can still use them right? Thanks.

Last edited by Doug Rose; January 17th, 2008 at 08:38 PM. Reason: more info
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Old January 18th, 2008, 03:31 AM   #14
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Then, the last event I filmed in December - massive corruption - completely unusable footage - Video and audio distorted and broken up when digitized. However, playback on camera LCD screen / speaker was mostly ok, with very little indication of problems.

That my friend is a hard drive issue.. more than likely you've captured your footage on a corrupted sector of the drive, considering your footage plays back perfectly within the camera
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Old January 18th, 2008, 08:03 AM   #15
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Sony MiniDV tape labeled for HD will work fine for SD recordings, and any within-spec SD MiniDV camcorder should be able to play them.
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