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ABSOLUTELY- IT'S WORKING!

Last post 10-28-2008, 14:45 by lavinog. 5 replies.
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  •  07-31-2008, 9:39 217459

    ABSOLUTELY- IT'S WORKING!

    This might be interesting for a lot of you that are dealing with terrible PVT problems, just as I did before! The major problem seemed to be, that the signal strength that the device was provided with was never strong enough to keep it alive throughout the length of an entire VHS tape. I had recordings that ended after a few minutes or after 1 or 2 hours. However, I have a lot of old tapes that contain LP material, i.e. 8 hrs long. Luckily I had 3 VCRs at hand that I was able to experiment with. Two "normal" VCRs did not provide for a stable signal, although they were of good quality, and one of them even quite new (Sharp, JVC). And then I had this VCR, that I actually never really used, a Sony RDR VX420, which actually is a combination of VCR and DVD writer. Now, this device provides for a signal strength beyond all expectations. It probably does so in order to supply the internal DVD writer with a constant and unbroken stream of data. The signal is so strong, that there is no flickering on the PVT input even when a record ends and before an new record starts. And as if this is not enough, the signal does not even die when the tape is stopped, obviously the underlaying signal is strong enough to make the PVT think that it still reads data .. which of course opens another problem of how to shut off the transmission once the tape had finished. Anyway, I think if you really need VHS data to be digitized and a normal VHS to PVT transfer does not work or turns out to become too stressy - get yourself a VHS to DVD combination and forget about all the little tricks and hints which might or might not work with you. Also, a device like the above mentioned Sony makes it easy to monitor the recording. I transfer video data through the S-Video link and audio data through a additional pair of cinch connectors. I use a small TV set to monitor the recording and for this I link it to the VCR through SCART. The resulting quality is superb and the handling is comfortable, except for the yet unresolved question on how to end the recording. Now, this all being said, and I think for a lot of you it this is worthful information, I have to end with a question, for which I may or may not open a new thread: For whatever reason, the PVT writes to disk in FAT-32, which means that the maximum file size can only be 2 GB, which is nothing in video. I have so far not found a program that could quickly combine all chunks being written from one tape. What I am looking for is a quick solution, something that just tacks two or more 2 GB chunks within minutes, not hours. Does anyone have a recommendation here?
  •  07-31-2008, 11:37 217489 in reply to 217459

    Re: ABSOLUTELY- IT'S WORKING!

    Interesting advice.

    It seems funny thought that you would need a VHS/DVD combo capable of transfering your tapes to dvd to get this device to work...for those that just want to digitize/archive their tapes it seems that it would be better to just transfer to DVD in the first place.

    But it does make me wonder if a simple video amplifier could accomplish the same thing.

    For your end of tape issue...a simple solution would be to put the vcr on a wall outlet timer, and set it to turn off after 6 hours (or however long the tape is)

    For splicing multiple chunks together, you may want to try avidemux. Load the first chunk into it, then click on file>append and load the next chunk...leave audio and video set to copy and change the format to mp4...then click save and set the filename. The chunks should be combined in minutes.

    The file size limit is 4 GB for fat 32...there used to be a 2GB limit on AVI files. 

    If you are recording in 5+Mbit mode the problem could be that the PVT ran out of buffer space. I am not sure how big the buffers are, but encoding can't be done in realtime. Its like filling up a bucket with a hole in it...if the water going in is at a higher rate than the water comming out...eventually the bucket will overflow. I am pretty sure this buffer is the cause of alot of complaints reguarding the device continuing to write to the media for a while after stopping the recording. The longer your recording, the longer you have to wait for it to finish the encoding process (like the time it takes for the bucket to drain when you turn off the water supply)


  •  07-31-2008, 13:04 217517 in reply to 217489

    Re: ABSOLUTELY- IT'S WORKING!

    Right lavinog - I've thought about involving a timed outlet myself. This is obviously the easy side. And FAT-32 size limit is 4 GB, you're right. 2 GB was FAT-16. Makes me wonder whether it is FAT-16 anyway what they internely write out from the PVT. That would actually be no problem, as long as writing onto another file system would lift that limit. I did not really investigate deeper into this, and I am actually not a file format guy, but funny enough, when I loaded one of the chunks into Magix' DVD recording software, it issued a message that the format does not allow for the file to be extended, and I was already working on a NTFS system. I will check out about the avidemux software that you mentioned, I've never heard about it and I hope that it is free. I did not really understand what you meant with regards to a possible buffer space problem. When I shut the PVT off manually, then it finishes the file correctly and within seconds. It does not throw away any content that would still be kept in the buffers, I can see that the data ends where it should end. If I would not shut the PVT off forcibly, it would continue to "record" for I dont know how long, because it just seems to listen to the line and as long as the VCR provides for a strong basic signal, the PVT seems to get fooled about valid data coming in. All in all, yes, it is a funny approach, but on the other hand it is also very logical. Obviously, in a VHS-to-DVD combination, you will have to ensure that a strong signal is available or otherwise people would complain about dozens of DVDs being burned inappropiately.
  •  08-01-2008, 16:08 217884 in reply to 217517

    Re: ABSOLUTELY- IT'S WORKING!

    Today I have tested the interaction between the PVT and the Sony VHS-to-DVD VCR a litte closer. Unbelievable but true: The PVT keeps "recording" as long as the VCR is still on-line and attached to it, and be it for hours after the tape finished. Now, while this may become a bother on the one side - if you even need maximum assurance that the PVT will record your stuff, the Sony RDR VX420 sure provides for a signal strength so reliable that you can completely forget about all these drop-out problems. When the PVT appears to fail, this is only due to feeble VCR signals.

  •  10-28-2008, 14:40 248355 in reply to 217884

    Re: ABSOLUTELY- IT'S WORKING!

    I have been doing some research, and have heard that bad tracking (common on old home videos) can be mistaken for a macrovision signal, thus preventing the unit from recording the whole tape. 

    The Macrovision signal in copy protected tapes sends bogus gain adjustment signals to the recording device to reduce the gain to where there is no video can be recorded. TV's are immune to this because of the way they draw pictures on the screen.

    In the case where the gain signal is bogus, the PVT may be adjusting the gain to where it thinks there is no signal and may never get another signal from the source to raise the gain back before it times out.

    To get the VCR Combo to record to DVD, it may have some more advance circuitry to handle bogus gain adjustments.

    If this is the case, we may never see a firmware to address this...partly for legal reasons, but also because the signal issues are due to the design of the VCRs...On the other hand, it could be an issue with the the time constant for the automatic gain control circuit (as mentioned in one of the links below) which might be correctable by firmware.

    There are devices that can strip macrovision signals (now they are called copy enhancers or stabilizers)

     Here are some links I found that can relate to the subject:

    http://www.diyaudio.com/forums/showthread.php?postid=52470#post52470

    http://www.velocityreviews.com/forums/showpost.php?s=dbf8848b6587cef386d8706e4d421fde&p=1425551&postcount=4

     

    Here is one device that might work:

    http://www.ziastudios.com/shop/digstab.htm

     

  •  10-28-2008, 14:45 248358 in reply to 248355

    Re: ABSOLUTELY- IT'S WORKING!

    Here is another link about the issue:

    http://www.nepadigital.com/mv/

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