Help! - Pixels on Play Back

Graham Bernard · September 2nd, 2003, 04:38 PM

1 - Playback to TV - from XM2 - Pixels .

2 - Capture to Vegas, via firewire - from XM2 - Pixels

3 - TAPE removed and put in Panasonic VTR - NO PIXELS!

New tape, fresh filming - same results as 1 & 2

WHat gives?

Any thoughts?

Grazie

Ken Tanaka · September 2nd, 2003, 05:11 PM

Sounds like it's time to run a cleaning tape.

Jeff Donald · September 2nd, 2003, 06:14 PM

I agree, dirty playback heads. Cleaning tape should fix you right up.

Graham Bernard · September 2nd, 2003, 06:50 PM

Yup, cleaned heads. One cycle of 10 seconds. I must say I didn't get the - "HEADS DIRTY, USE CLEANING CASSETTE" WARNING. Had this before, and applied the head cleaning tape. It worked then. I've done the head clean procedure only twice since having the XM2. I've run nearly 100 hours of activity - record/playback and the edit capture procedure - yeah?

How often can one run this cleaning procedure? I don't want to over do it? I haven't had this pixeling before, and not having had the head cleaning warning I didn't want to "over" wear the heads with the cleaner. Do you understand my confusion?

The pixelation occurs in the same point in the "recording". Does this mean that the point at which it was recording is/was not correct? Does it mean the recording head and not the playback portion is "dirty"? The point I'm making here is that cleaning "now" will not bring back that which was recorded on "dirty" recording head/s - the playback just shows it?

Me playing the "suspect" tape on another deck - the Panasonic - should show the same pixelation, surely? Why doesn't it?

Do you understand my confusion?

What do I do? Do I keep cleaning and use fresh recording tapes to record to, until I get a good recording? - I only use fresh tapes. I have never recorded over old tape.

Hmmmm...

Help!

Grazie

Ken Tanaka · September 2nd, 2003, 08:41 PM

I don't know that anyone can offer you a firm cleaning frequency rule. I generally clean my camera heads after every 20-25 shooting sessions. I clean my deck after about the same number of captures.

Graham Bernard · September 3rd, 2003, 12:40 AM

Thanks Ken & Jeff,

How much actual cleaning should I do now? 2 passes or 3 passes or carry on until the pixels go? Will I do any damage by cleaning until I get rid of the pixels?

Grazie

Jeff Donald · September 3rd, 2003, 05:48 AM

Does this happen on any other tape? Follow the instructions on the cleaning cassette. It should say how long in seconds and how many cleaning attempts to try. Never exceed the cleaning time or number of cleanings. Major damage can be caused by not following the instructions.

Graham Bernard · September 3rd, 2003, 11:18 AM

"Does this happen on any other tape?" - Haven't tried this . . yet!

"Follow the instructions on the cleaning cassette. " - OH yes ! !!!

. . .thanks Jeff . . .

Okay, update:

1 - Cleaned heads ONCE. Did a shoot . . . not too good

2 - Repeated shoot this time with a "fresh" tape out of a newly opened box. Excellent!

3 - Took "duff" tape to mate who:

a) Uploaded it to his Casablanca AVIO via his Panasonic DV/miniDV deck

b) Downloaded same footage from Avio to NEW fresh tape

c) Checked - no pixels!

d) Playback newly downloaded tape on the XM2 through to TV. Excellent!

So conclusions:

1 - XM2 recorded everything

2 - Tape MUST be suspect

3 - Panasonic less finicky than XM2 playback. This can be the only result.

Thanks for all your support people. I'll get on with the rest of my Life - as tomorrow IS my Birthday Yahhhooooooooo . . ..

Grazie

Jeff Donald · September 3rd, 2003, 05:31 PM

The error correction on the camera was too picky, or the Panasonic has a better error detection and error correction circuit.

Graham Bernard · September 4th, 2003, 12:26 AM

Jeff, thanks for that. Do you have any further info on that - you seem a pretty "clue-up" chap. Your comment was in the same ball-park as me and my chum.

By the way it's my Burfday today - Yeah!!!

Grazie

Jeff Donald · September 5th, 2003, 04:23 AM

Happy birthday!

If your interested in error correction do a Google search for Reed-Solomon. It is the basis for modern error correction.

Graham Bernard · September 5th, 2003, 05:44 AM

Is this by way of a birthday present?

I particualrly like and approve of the following .. . mmmm . .. nice . ..

" Mathematically, Reed-Solomon codes are based on the arithmetic of finite fields. Indeed, the 1960 paper begins by defining a code as "a mapping from a vector space of dimension m over a finite field K into a vector space of higher dimension over the same field." Starting from a "message" $(a_0, a_1, . . ., a_{m-1})$, where each $a_k$ is an element of the field K, a Reed-Solomon code produces $(P(0), P(g), P(g^2), . . ., P(g^{N-1}))$, where N is the number of elements in K, g is a generator of the (cyclic) group of nonzero elements in K, and P(x) is the polynomial $a_0 + a_1x + . . . + a_{m-1} x^{m-1}$. If N is greater than m, then the values of P overdetermine the polynomial, and the properties of finite fields guarantee that the coefficients of P--i.e., the original message--can be recovered from any m of the values. "

Hell! . . . this'll keep me amused to next year . . . .

But thank you all the same - You are the business!

Grazie

Jeff Donald · September 5th, 2003, 06:03 AM

See if you can find a link at a Panasonic site. Maybe search their site. They used to have a great explanation of error correction for DV. It may be gone now. Manufactures post and publish that kind of info when a format is new. After a few years they probably take down the links and all, they figure those that want to know have already read it.

September 2nd, 2003, 04:38 PM	#1
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	Help! - Pixels on Play Back - HELP! 1 - Playback to TV - from XM2 - Pixels . 2 - Capture to Vegas, via firewire - from XM2 - Pixels 3 - TAPE removed and put in Panasonic VTR - NO PIXELS! New tape, fresh filming - same results as 1 & 2 WHat gives? Any thoughts? Grazie

September 2nd, 2003, 05:11 PM	#2
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	Sounds like it's time to run a cleaning tape. __________________ Lady X Films: A lady with a boring wardrobe...and a global mission. Hey, you don't have enough stuff! Buy with confidence from our sponsors. Hand-picked as the best in the business...Really! See some of my work one frame at a time: www.KenTanaka.com

September 2nd, 2003, 06:14 PM	#3
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	I agree, dirty playback heads. Cleaning tape should fix you right up. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

September 2nd, 2003, 06:50 PM	#4
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	Sorry . . did this too . . . Yup, cleaned heads. One cycle of 10 seconds. I must say I didn't get the - "HEADS DIRTY, USE CLEANING CASSETTE" WARNING. Had this before, and applied the head cleaning tape. It worked then. I've done the head clean procedure only twice since having the XM2. I've run nearly 100 hours of activity - record/playback and the edit capture procedure - yeah? How often can one run this cleaning procedure? I don't want to over do it? I haven't had this pixeling before, and not having had the head cleaning warning I didn't want to "over" wear the heads with the cleaner. Do you understand my confusion? The pixelation occurs in the same point in the "recording". Does this mean that the point at which it was recording is/was not correct? Does it mean the recording head and not the playback portion is "dirty"? The point I'm making here is that cleaning "now" will not bring back that which was recorded on "dirty" recording head/s - the playback just shows it? Me playing the "suspect" tape on another deck - the Panasonic - should show the same pixelation, surely? Why doesn't it? Do you understand my confusion? What do I do? Do I keep cleaning and use fresh recording tapes to record to, until I get a good recording? - I only use fresh tapes. I have never recorded over old tape. Hmmmm... Help! Grazie

September 2nd, 2003, 08:41 PM	#5
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	I don't know that anyone can offer you a firm cleaning frequency rule. I generally clean my camera heads after every 20-25 shooting sessions. I clean my deck after about the same number of captures. __________________ Lady X Films: A lady with a boring wardrobe...and a global mission. Hey, you don't have enough stuff! Buy with confidence from our sponsors. Hand-picked as the best in the business...Really! See some of my work one frame at a time: www.KenTanaka.com

September 3rd, 2003, 12:40 AM	#6
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	Thanks Ken & Jeff, How much actual cleaning should I do now? 2 passes or 3 passes or carry on until the pixels go? Will I do any damage by cleaning until I get rid of the pixels? Grazie

September 3rd, 2003, 05:48 AM	#7
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	Does this happen on any other tape? Follow the instructions on the cleaning cassette. It should say how long in seconds and how many cleaning attempts to try. Never exceed the cleaning time or number of cleanings. Major damage can be caused by not following the instructions. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

September 3rd, 2003, 11:18 AM	#8
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	I see where you're going . . . "Does this happen on any other tape?" - Haven't tried this . . yet! "Follow the instructions on the cleaning cassette. " - OH yes ! !!! . . .thanks Jeff . . . Okay, update: 1 - Cleaned heads ONCE. Did a shoot . . . not too good 2 - Repeated shoot this time with a "fresh" tape out of a newly opened box. Excellent! 3 - Took "duff" tape to mate who: a) Uploaded it to his Casablanca AVIO via his Panasonic DV/miniDV deck b) Downloaded same footage from Avio to NEW fresh tape c) Checked - no pixels! d) Playback newly downloaded tape on the XM2 through to TV. Excellent! So conclusions: 1 - XM2 recorded everything 2 - Tape MUST be suspect 3 - Panasonic less finicky than XM2 playback. This can be the only result. Thanks for all your support people. I'll get on with the rest of my Life - as tomorrow IS my Birthday Yahhhooooooooo . . .. Grazie

September 3rd, 2003, 05:31 PM	#9
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	The error correction on the camera was too picky, or the Panasonic has a better error detection and error correction circuit. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

September 4th, 2003, 12:26 AM	#10
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	Anything further Jeff? Jeff, thanks for that. Do you have any further info on that - you seem a pretty "clue-up" chap. Your comment was in the same ball-park as me and my chum. By the way it's my Burfday today - Yeah!!! Grazie

September 5th, 2003, 04:23 AM	#11
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	Happy birthday! If your interested in error correction do a Google search for Reed-Solomon. It is the basis for modern error correction. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

September 5th, 2003, 05:44 AM	#12
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	Jeff . . Y'know how to cheer a bloke up !!! Is this by way of a birthday present? I particualrly like and approve of the following .. . mmmm . .. nice . .. " Mathematically, Reed-Solomon codes are based on the arithmetic of finite fields. Indeed, the 1960 paper begins by defining a code as "a mapping from a vector space of dimension m over a finite field K into a vector space of higher dimension over the same field." Starting from a "message" $(a_0, a_1, . . ., a_{m-1})$, where each $a_k$ is an element of the field K, a Reed-Solomon code produces $(P(0), P(g), P(g^2), . . ., P(g^{N-1}))$, where N is the number of elements in K, g is a generator of the (cyclic) group of nonzero elements in K, and P(x) is the polynomial $a_0 + a_1x + . . . + a_{m-1} x^{m-1}$. If N is greater than m, then the values of P overdetermine the polynomial, and the properties of finite fields guarantee that the coefficients of P--i.e., the original message--can be recovered from any m of the values. " Hell! . . . this'll keep me amused to next year . . . . But thank you all the same - You are the business! Grazie

September 5th, 2003, 06:03 AM	#13
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	See if you can find a link at a Panasonic site. Maybe search their site. They used to have a great explanation of error correction for DV. It may be gone now. Manufactures post and publish that kind of info when a format is new. After a few years they probably take down the links and all, they figure those that want to know have already read it. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors