HM-HDS4

For all discussions regarding the JVC HM-HDS4 (80GB hard disk and S-VHS recorder)

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JPRus

HM-HDS4

Post by JPRus » Sun Jan 23, 2005 12:23 am

I bought an HDS4 Friday 21st January 2005 as I wanted
an HDD that had DV 25 MBPS output.

The picture and sound are good but about 50 percent of the
time, the recordings on the HDD have audio which occurs
slightly ahead of the video. Things are not lip-synched and look
awful.

This occurs from both off-air and dubbing from S-VHS/VHS

I'd rather keep the machine if possible. Has any one seen this fault?

I've got untill next Friday before I'll ask for a refund. :cry:

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Andy Cippico
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Post by Andy Cippico » Mon Jan 24, 2005 10:41 am

Hi JPRus,
Thanks for stopping by!

Unfortunately, not knowing the HM-HDS4 I think I'll refer this question to Andrew. All I can say is that I've never seen this on the HDS1 and it sounds like a definite fault with your unit to me. I mean, if it can't do what it says on the tin, then you need to take it back. A machine of that price tag should perform flawlessly for you right out of the box.

Andrew W - any thoughts?

Andy C.
Last edited by Andy Cippico on Tue Jan 25, 2005 11:19 am, edited 1 time in total.

Andrew wilkinson

HMHDS4

Post by Andrew wilkinson » Mon Jan 24, 2005 11:20 am

Hi
I have 2 of these machines in daily operation myself and can't say I've noticed any lipsync errors- save for Freeview lip sync errors-
I would like to establish how severe/otherwise the problem is. As with any digital av stream lipsync errors can occur due to the variable bit rates used for the video encoder- software can/should be able to compensate for this however. I s the delay more than app 0.15s ? If under that then the manufacturer would probably consider that reasonable- if over then I would consider it excessive.
There is no adjustment for this in service mode/software.
If you can do a few short tests for me I can then put more info to JVc to see what they say.
E-E (live mem) mode SP LP EP SEP modes. does the delay remain the same on each of these modes? or does it vary- some modes better than others?
regards Andrew Wilkinson

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andywilks
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Another thought

Post by andywilks » Mon Jan 24, 2005 11:43 am

You haven't just changed Tv as well? 100hz modern Tvs can have the same issues since they need to digitally process the pic- this takes time and thus the sound needs to be delayed- just a thought! AW

JPRus

HM-HDS4 Faulty Audio Delay on Brand new unit

Post by JPRus » Mon Jan 24, 2005 11:30 pm

Thanks guys for getting back so quickly.
This machine can record onto its HDD at:
DV 25 Mbps
SP 6.4 Mbps, LP 4.5,EP 3.2, SEP 2.2
I bought this machine as it was the only "consumer" type
HDD that could record at 25 Mbps. The SONY HX1000 does
max 15 Mbps.
I've done some tests to-day and it seems that its only
in the DV data rate speed that the fault occurs. ( The rate I bought
the machine for! )
Making a test "clapper-board" movie in Premiere, I then input from
my DV camcorder via the analogue F1 ( S-VHS ) input.
It's quite distinctive. In DV mode the audio from the HDD occurs
ahead of the video, in all other modes it's in time. I made three recordings
for both DV speed and SP speed. However I have one off-air sample
that seems to be in-sync in DV mode. I only have analogue channels BBC1, BBC2, ITV1 and C4 ( never had ch 5 ). If I record from the camcorder via the D1 ( IEEE ) port then the recordings are fine.
I called JVC UK Help line this morning and they said that there had
been software problems with some of their HDD "stuff" but he was not
very comital. The shop I bought from was also some what disbelieving.
I'm rather loath to let it go. I'm a broadcast video designer of some twenty years.

What is the service/mode software that you mention? Is there a service
mode available from the remote control. The delay is at least 1 frame
( 40ms ) ahead. I need to do further tests to veryfy the exact delay.
DV is an intra coding scheme, whereas all the others are interframe
coded. Perhapes a compensating delay was forgotten!!??

I would be interested to know if other units exhibit this delay in DV mode.

Thanks for your help.

J Russell

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andywilks
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re Delay in DV stream

Post by andywilks » Tue Jan 25, 2005 5:36 pm

Ok, so I need to check my machines now to test if they're the same... I must admit I have never used the DV mode- upto press- I use my 2 machines as time shift vcr's. I'll report back asap.

I assume it was JVC customer services you spoke to... They are usually very good and on the ball- I can send an email to the head tech guy and see if he has any thoughts, but I would doubt there is much more they can do directly. If however a definite issue is there to be addressed, JVC Japan as the machines designers would need to be made aware of the problem and its from there a solution would come- in what form who knows?

There is a (sort of) service mode.. it is accessed using a special programmer remote- which can then send data in FF:FF hex format to the appropriate memory location. I had a look at the manual yesterday before replying and there is nothing relevant to the mpeg/digital section. The adjustments are for the EVR settings re the VHS deck.

How/ where the software resides/controls the encoding etc is frankly beyond myself- hence why only the designers can really address this.
A delay imposed on the audio stream however is not that difficult to achieve in a firmware upgrade- just how JVC could get that upgrade in to the machine is yet to be established.

I doubt this can be realistically all resolved in the few days you have mentioned, but I will try to get back asap with whether all machines do it or whether its just yours..
regards
AW

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andywilks
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re Delay in DV stream

Post by andywilks » Wed Jan 26, 2005 7:28 pm

Ok so I have tested the lip sync on both my machines. There is a just discernable seperation between the a & v streams on both of them. I can't quantify it to an exact time advance but it is slight. I recorded clapping, and whilst transferring it sounded correct, upon playback you could just sense the lead in the sound. As for 40ms well that seems to sound about right and I would conclude all 3 machines exhibit the same symptom. Thus all HMHDS4's will be the same.

The response I got from JVC is that it is not likely to be a resolvable issue. In view of the (lack of) severity it wouldn't warrant the time/effort necessary. Sorry.

I leave it to you whether this is acceptable for the purpose you need it for.

regards
Andrew W

JPRus
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Joined: Mon Jan 24, 2005 11:54 pm
Location: England

Sound Delay in DV Mode

Post by JPRus » Sun Jan 30, 2005 10:36 am

Andy,
Thanks very much for confirming my suspicions.
I grabed various scenes into my iMac and then
transfered the raw DV stream to Premiere on the PC.
I realise that this in itself could introduce delays but the upshot
is that I have to delay the audio between 2 or three picture
frames for the lip-sync to look ok. I've not done any audio/video
stream measurements.
However all the other speeds/modes seem ok so I have decided
to keep the unit. The material that I wish to save to DV tape will
have to be audio delayed before saving.
I've had not much success in grabbing DV into the PC. The image
is ok but the audio is either silent or reported back as 32KHz when
I know it's 48KHz.
Are there circuit diagrams or service manuals for this machine available?
Can the FF codes be accessed with the user remote?
Do you know the model and make of the hard drive?

Thanks for your responses.

JR

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andywilks
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re FF codes and manuals

Post by andywilks » Sun Jan 30, 2005 5:37 pm

You can't get to the service menu from the user remote I'm afraid. The only adjustments are the EVR's for the VHS deck settings.

As for the HDD its a Maxtor diamond max- known models are listed elsewhere on this forum.. if yours is different then please let us know, we are trying to compile a complete list of variants. Unlike the HMHDS1 it doesn't seem to be that important what the drive is- as long as the correct cloned image is put on it. As for bigger drives... we are still working on how to do that. If anyone reading this resolves how to do it then pllease let us know.

As for manuals I can email you the schematics etc with pleasure...
*** However I will not be held responsible for whatever damage you do as a result of the info I send you !!! ***

Ok so send me your email address to
wilkinsons dot hifi at talk21 dot com

regards
AW

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