JVC DR-M100 luma offset/red color flicker

[Kalos Geros]

Hi,

I have recently purchased a JVC DR-M100 recorder (european model, 2 SCARTS)...contrary to what the manual says at couple of places, this recorder doesn't seem to be able to record in RGB directly but rather converts incoming RGB to S-video (separate luma and chroma) prior to recording...compared to the pristine RGB passthrough, the luma/chroma offset when recording is hideously obvious...additionally, there is a noticable flicker on color red which also seems to get recorded...

I have observed the above by viewing my digital set-top box's menus which are the best indication of what the received picture qulity is like...I have also observed the same problem one night when watching a station's test signal...here is the link to the example pictures:

RGB



S-video



I would like anyone who owns this recorder or maybe the earlier DR-M10 model to check with a good source, with it's menus on-screen whether they get the same problem as I do...for the US-based owners it is preferable to have the recorder connected to their TV via component connections because you can eliminate the possibility of a bad connection to the TV ...

Thanx for any input or ideas...

[lordsmurf]

Unless I'm mistaken (and it's possible, beacuse it's early morning and I've not even had breakfast yet), but isn't component and RGB fake anyway, generated by the player or recorder? The actual video data is recorded as Y and UV (s-video!) on the discs, in MPEG format.

USA DR-M10S only has component out, not in. There is no RGB in the USA, that's a PAL type connection.

The DR-M100S does not have either, if I remember correctly, no component in or out. (This said, I don't want to rip my 100S out of it's location to look and verify, but still pretty sure there is no component out.)

PAL video also should not be subjected to chroma shifting (red phase) like NTSC video is.

None of this sounds right. Good luck figuring out the problem.

[Kalos Geros]

Unless I'm mistaken (and it's possible, beacuse it's early morning and I've not even had breakfast yet), but isn't component and RGB fake anyway, generated by the player or recorder? The actual video data is recorded as Y and UV (s-video!) on the discs, in MPEG format.

USA DR-M10S only has component out, not in. There is no RGB in the USA, that's a PAL type connection.

The DR-M100S does not have either, if I remember correctly, no component in or out. (This said, I don't want to rip my 100S out of it's location to look and verify, but still pretty sure there is no component out.)

PAL video also should not be subjected to chroma shifting (red phase) like NTSC video is.

None of this sounds right. Good luck figuring out the problem.

Thanks for your post...

component IS the same as YUV, and it is just a different colorspace representation of RGB...it is absolutely better to encode to YUV MPEG from YUV or RGB source because with S-video, U and V are already combined and cannot be precisely reconstructed back into U and V for MPEG encoding...that's why we in Europe are so stubborn about RGB input instead of just S-video...most gear except VCRs output RGB in Europe....

anyway, the picture looks absolutely identicaly bad when I use the front panel S-video connector...

No please don't rip your 100, it's only if you had a composite link to your TV the problem may remian hidden to your eyes...the european 100 does have component out and if DR-M10 has it then your 100 must have it too...

so you are saying that you didn't observe such a great luma shift...

[lordsmurf]

Yeah, but I said "Y" and "UV" which is not the same sort of carrier as a separate "Y" and "U" and "V". That was my point.

[Kalos Geros]

Right, but to my knowledge MPEG2 DVD-video encodes data to separate Y, U and V channel values...

cheers

[trhouse]

I have a European service manual for the DR-M10S courtesy of Mig-45 in Russia and can look into this for you. Before we do, are you sure that what you are seeing is not the result of of color subsampling?

Analog RGB is often digitized as three bytes ( 24 bit color ) as can YUV. What is recorded to dvd is YUV but color subsampled with a ratio of 4:2:0 which reduces the color information on the U and V channels significantly so this YUV recorded signal cannot be as good as 24 bit RGB. 4:2:0 subsampling is part of the dvd standard.

[Kalos Geros]

trhouse, thanks, but unfortunately this is not the croma subsampling problem although it may look like one...what I photographed are digital box's menus that are not part of MPEG stream and look exactly like having the same problem when passed on to the display and when recorded...only RGB passthrough doesn't exhibit this problem, as soon as the u9nit is turned on, the picure quakity drops with the mentioned effect...

BTW where have my pics from upstairs gone...they are a link to another forum, can this be it?

[trhouse]

I was never able to view your pictures so maybe I misunderstand your setup. By "digital box's menus" are you using a satellite receiver or cable box and feeding the Scart signal into the recorder and then out the recorder's second Scart connector to the TV ( this would be passthrough )? Are you also connecting another output from the recorder ( like composite or component ) to the same TV and switching back and forth between the two?

[Kalos Geros]

I was never able to view your pictures so maybe I misunderstand your setup. By "digital box's menus" are you using a satellite receiver or cable box and feeding the Scart signal into the recorder and then out the recorder's second Scart connector to the TV ( this would be passthrough )? Are you also connecting another output from the recorder ( like composite or component ) to the same TV and switching back and forth between the two?

OK, I used right-click to select "show picture" and tje pics loaded so that may work for you...


Yes I'm using the RGB SCART-SCART passthrough from digital DVB-T terrestrial box just like you explained and picture is wonderfully sharp up to the moment when recorder's internal electronics are engaged...I'm not connecting the recorder in any other way to my display, it's just one SCART that's connecting the recorder and the TV, so I'm not mistaking the inputs that I'm watching (I guess that's what you were aiming at, right?)

[trhouse]

Yes, I wanted to be sure I understood how you were connecting all the units together. I will have a look at the service manual to see what the M10S does when it does not passthrough. I cannot view your pictures. Did you say they were links to another site or are you trying to upload to this site?

This is what I see,

[Kalos Geros]

Try this link:

http://www.avforums.com/forums/showthread.php?t=329413

Please note that DR-M10 doesn't boast RGB recording but DR-M100's does, that's why i'm pi**ed off...

[trhouse]

I guess you need to join AVSForums to view those images. I just get a message that I am a "guest" with limited privileges when I clicked on the links. Could you upload them here?

I do not have a M100S service manual unfortunately.

[Kalos Geros]

OK, here they are:

RGB passthrough:

[Kalos Geros]

And

Recorder on (S-video-like picture):

[trhouse]

Yes, I see your point. That is not color subsampling. I will see what the the M10S does with the RGB signal even if it cannot record it.

[Kalos Geros]

Yes, I see your point. That is not color subsampling. I will see what the the M10S does with the RGB signal even if it cannot record it.

That's great, thanx....

[trhouse]

The service manual for the M10 did not help much. It just shows what you said, that the M10 cannot record the RGB signal from the L2 Scart input. It just routes it through some switches over to the L1 input/output Scart connector for viewing on the TV. It is going to require an M100 service manual to understand for certain how the RGB signal makes its way to the encoder.

[Kalos Geros]

The service manual for the M10 did not help much. It just shows what you said, that the M10 cannot record the RGB signal from the L2 Scart input. It just routes it through some switches over to the L1 input/output Scart connector for viewing on the TV. It is going to require an M100 service manual to understand for certain how the RGB signal makes its way to the encoder.

Any idea where the service manual for the DR-M100 can be found (on the net)??? As I figure it would be a major trouble trying to make it record RGB which would probably require soldering etc, but improvement on luma/chroma separation by maybe tweaking something on the mainboard would be sufficient since this recorder was an emergency replacement for my VCR that had died and would eventually be replaced by possibly a HD-DVD or blueray recorder in a couple of year's time...

Thx

[trhouse]

The service manual and schematics all seem to be available here,

https://www.manualsparadise.com/Welcome.do;jsessionid=7AD6C46E097514A9D2559FC7C8125D84...source=AdWords

I am not sure if they have the best price but they have them in pdf format so you can download them. I do not mean to discourage you but I have looked inside numerous brands and types of recorders. There is really nothing to tweak.

Do you have access to another unit at a local store? You might want to test another one to see if there is some problem with the one you have before spending more of your own time doing troubleshooting.

[lordsmurf]

Are you sure the issues does not lie with your wires and other devices on the other end of the connection?

[trhouse]

A good thought but seems unlikely in this case. The same Scart cables carry the RGB signal to and from the recorder. In passthough it looks fine which should be a good test of the cables and TV.

[lordsmurf]

I don't know. I've seen a lot of weird stuff in the past, I don't let anything get these days. I've found something as small as a loose footing on a connector made a big difference in quality, for whatever reason, until I opened the tv set and fixed it.

[trhouse]

Yes, there are conditions that no one could anticipate that can occur and alter performance. I have never seen an Scart cable. It occurs to me that RGB must need bandwidth similar to component and good component cables are normally pretty robust coaxial. The Scart connector is pretty small. I wonder if the Scart cable uses small coax inside. If not, it is possible for the cumulative effect of limited bandwidth cables and recorder to cause a degradation. Shortening the cables should help if that is so.

[Kalos Geros]

My SCART cables are Bandridge brand thick-coated cables and, as trhouse had said, if RGB passthorugh is crisp then nothing should be wrong with the surrounding equipment...SCART cables can be cheaply made, having no coating at all and receive RF interference from an aerial but this looks nothing like the problem that I have...fully wired SCART cables have 21-lines in them but this is no problem if they are of quality make...the problem is somewhat less visible on my projector via component but color red shimmering is still there and i think it's just the prog scan/PJ's resolution that make it less noticable but it's there...maybe all DR-M100 units have this problem but ppl don't see it since they don't have pure-color red menus, it's less noticable on moving picture but it show on areas of red color...

but I'd agree with lordsmurf, solutions can be weird and can come quite unexpectedly from an unsuspectable source..it's only I have exhausted all the possibilites and can only blame the recorder...