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Post by paul carney on Jan 11, 2017 14:39:16 GMT
Sue and Paul I have no idea what you are talking about but if it can save more vintage tv I'm all for it!
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Post by John Green on Jan 11, 2017 15:24:48 GMT
How about (someone suggested) building a really fast sampling analogue to digital converter that could save the 405-line waveform as data without attempting a conversion? Conversion could be sorted out later. Funny you should say that. But there is no 'waveform' to save, but rather the raw analog data, the 377 video lines and the two field sequence. There is a project in the works and it's funded. It would then mean a small cost to transfer a tape, but the R&D costs are high. Paul Sounds good! It's either that or animate it... |
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Post by Sue Butcher on Jan 12, 2017 1:43:22 GMT
How about (someone suggested) building a really fast sampling analogue to digital converter that could save the 405-line waveform as data without attempting a conversion? Conversion could be sorted out later. Funny you should say that. But there is no 'waveform' to save, but rather the raw analog data, the 377 video lines and the two field sequence. There is a project in the works and it's funded. It would then mean a small cost to transfer a tape, but the R&D costs are high. Paul That's what I thought, capture the whole video waveform including the sync pulses, back porches, fields, lines and blanking, whatever the 405 line standard had, and sort out the instabilities later with computer processing. I imagine you could repair "holes" in the signal, or stretch and time-shift it to keep sync, in a similar manner to repairing audio signals by computer. |
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Post by Paul Vanezis on Jan 12, 2017 15:32:31 GMT
...capture the whole video waveform including the sync pulses, back porches, fields, lines and blanking, whatever the 405 line standard had, and sort out the instabilities later with computer processing. I imagine you could repair "holes" in the signal, or stretch and time-shift it to keep sync, in a similar manner to repairing audio signals by computer. What you're talking about is something that 'scans' whatever RF is on the tape. Every time we've looked at this, the technical obstacles appear huge. In theory, whatever signal is on the tape that isn't linear could be played back on a machine that just reads the tape and lays down a digital file. You would need to know what machine made the recording in the first place. Then, an application would be used to 'apply' for example a CV2000 profile, or a Peto Scott profile, or a Philips 1500 profile etc... You would do without having to have a pesky machine dedicated to the format, you could just have a half inch tape machine 'reader' and a one inch 'reader' etc... The problem with this method is that you are now adding a second parameter into the works, the ballistics of the 'reader' machine itself which you would also have to design and build. It would need to work perfectly every time, run at the correct speed regardless of the format and 'read' perfectly something that is analogue in nature, but also was not recorded in perfect circumstances. So no, the issues really are too difficult to resolve. Better to utilise refurbished machines in the original formats, serviced to as new spec, factory settings if you like, and just get as best a playback as is possible. From there, you just need a flexible ADC card and some clever software. But the actual capture would be a 377 line two field sequence. Paul |
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Post by Deleted on Jan 12, 2017 16:22:47 GMT
But the actual capture would be a 377 line two field sequence. Paul I've followed this discussion with a lot of interest and enjoyment, so I'd like to ask a question, which is troubled by absolutely no working knowledge on this subject at all ... I'm assuming the signal on the CVS, N1500 or Petro Scott etc can be transferred from that machine, through a connecting cable, to a PC/Mac. It would then exist as a digital file on that pc/mac, with the characteristics you describe (377 line, two field, whatever that means) contained therein. Therefore, surely some clever programme developer would be able to create a capture programme to enable that file to be converted to a watchable format. I realising I'm probably being naively simplistic over this, but it struck me as an obvious step. The simp[lest way is the best. |
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Post by Paul Vanezis on Jan 12, 2017 18:01:04 GMT
I've followed this discussion with a lot of interest and enjoyment, so I'd like to ask a question, which is troubled by absolutely no working knowledge on this subject at all ... I'm assuming the signal on the CVS, N1500 or Petro Scott etc can be transferred from that machine, through a connecting cable, to a PC/Mac. It would then exist as a digital file on that pc/mac, with the characteristics you describe (377 line, two field, whatever that means) contained therein. Therefore, surely some clever programme developer would be able to create a capture programme to enable that file to be converted to a watchable format. I realising I'm probably being naively simplistic over this, but it struck me as an obvious step. The simplest way is the best. Sadly not. Modern capture cards do not have great tolerances. They require a stable playback within the specification of video, for SD to CCIR levels. The only way to achieve this is to play back the material through a time base corrector. We have lots of choices for time base correctors for 625 material. I have a preferred one which is also a switchable Pal/NTSC device and is a broadcast standard TBC with analogue inputs and SDI outputs. But there is no point in using a time base corrector if you haven't got a stable replay to begin with. There is something to be said for bypassing a TBC and capturing direct if the replay is stable enough. If you have the right software, once captured the digital file can play back as if it has been through a time base corrector. With 405 line material, the problem is made more difficult by the fact that 405 line recorders were only manufactured in the 1960's and never got to an advanced enough stage for reliable record and replay either reel to reel or in cassette form. This is because of the advent of 625 and colour. You could buy a colour Shibaden recorder in 1971 and of course early U-Matic recorders were available in September 1971. So, can you capture 405 line video using a standard capture card on a PC? No. There are no cards and software that support 405 line 'out of the box'. 405 lines are longer than 625. The output voltage is higher than composite video resulting in over modulated video. What you need is a card that can cope with this and the software to capture and display the incoming and non standard video. Currently there is nothing like that. Paul |
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Post by richardwoods on Jan 12, 2017 18:50:13 GMT
I've followed this discussion with a lot of interest and enjoyment, so I'd like to ask a question, which is troubled by absolutely no working knowledge on this subject at all ... I'm assuming the signal on the CVS, N1500 or Petro Scott etc can be transferred from that machine, through a connecting cable, to a PC/Mac. It would then exist as a digital file on that pc/mac, with the characteristics you describe (377 line, two field, whatever that means) contained therein. Therefore, surely some clever programme developer would be able to create a capture programme to enable that file to be converted to a watchable format. I realising I'm probably being naively simplistic over this, but it struck me as an obvious step. The simplest way is the best. Sadly not. Modern capture cards do not have great tolerances. They require a stable playback within the specification of video, for SD to CCIR levels. The only way to achieve this is to play back the material through a time base corrector. We have lots of choices for time base correctors for 625 material. I have a preferred one which is also a switchable Pal/NTSC device and is a broadcast standard TBC with analogue inputs and SDI outputs. But there is no point in using a time base corrector if you haven't got a stable replay to begin with. There is something to be said for bypassing a TBC and capturing direct if the replay is stable enough. If you have the right software, once captured the digital file can play back as if it has been through a time base corrector. With 405 line material, the problem is made more difficult by the fact that 405 line recorders were only manufactured in the 1960's and never got to an advanced enough stage for reliable record and replay either reel to reel or in cassette form. This is because of the advent of 625 and colour. You could buy a colour Shibaden recorder in 1971 and of course early U-Matic recorders were available in September 1971. So, can you capture 405 line video using a standard capture card on a PC? No. There are no cards and software that support 405 line 'out of the box'. 405 lines are longer than 625. The output voltage is higher than composite video resulting in over modulated video. What you need is a card that can cope with this and the software to capture and display the incoming and non standard video. Currently there is nothing like that. Paul Thanks Paul, for someone like me, with a life long interest in 405 line TV sets, this is really interesting stuff. |
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Post by jbuoys on Jan 12, 2017 23:31:30 GMT
I've followed this discussion with a lot of interest and enjoyment, so I'd like to ask a question, which is troubled by absolutely no working knowledge on this subject at all ... I'm assuming the signal on the CVS, N1500 or Petro Scott etc can be transferred from that machine, through a connecting cable, to a PC/Mac. It would then exist as a digital file on that pc/mac, with the characteristics you describe (377 line, two field, whatever that means) contained therein. Therefore, surely some clever programme developer would be able to create a capture programme to enable that file to be converted to a watchable format. I realising I'm probably being naively simplistic over this, but it struck me as an obvious step. The simplest way is the best. Sadly not. Modern capture cards do not have great tolerances. They require a stable playback within the specification of video, for SD to CCIR levels. The only way to achieve this is to play back the material through a time base corrector. We have lots of choices for time base correctors for 625 material. I have a preferred one which is also a switchable Pal/NTSC device and is a broadcast standard TBC with analogue inputs and SDI outputs. But there is no point in using a time base corrector if you haven't got a stable replay to begin with. There is something to be said for bypassing a TBC and capturing direct if the replay is stable enough. If you have the right software, once captured the digital file can play back as if it has been through a time base corrector. With 405 line material, the problem is made more difficult by the fact that 405 line recorders were only manufactured in the 1960's and never got to an advanced enough stage for reliable record and replay either reel to reel or in cassette form. This is because of the advent of 625 and colour. You could buy a colour Shibaden recorder in 1971 and of course early U-Matic recorders were available in September 1971. So, can you capture 405 line video using a standard capture card on a PC? No. There are no cards and software that support 405 line 'out of the box'. 405 lines are longer than 625. The output voltage is higher than composite video resulting in over modulated video. What you need is a card that can cope with this and the software to capture and display the incoming and non standard video. Currently there is nothing like that. Paul |
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Post by jbuoys on Jan 12, 2017 23:32:15 GMT
So what is the system that Video Ark are using to transfer to digital?
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Post by Sue Butcher on Jan 13, 2017 0:46:03 GMT
...capture the whole video waveform including the sync pulses, back porches, fields, lines and blanking, whatever the 405 line standard had, and sort out the instabilities later with computer processing. I imagine you could repair "holes" in the signal, or stretch and time-shift it to keep sync, in a similar manner to repairing audio signals by computer. What you're talking about is something that 'scans' whatever RF is on the tape. Every time we've looked at this, the technical obstacles appear huge. In theory, whatever signal is on the tape that isn't linear could be played back on a machine that just reads the tape and lays down a digital file. You would need to know what machine made the recording in the first place. Then, an application would be used to 'apply' for example a CV2000 profile, or a Peto Scott profile, or a Philips 1500 profile etc... You would do without having to have a pesky machine dedicated to the format, you could just have a half inch tape machine 'reader' and a one inch 'reader' etc... The problem with this method is that you are now adding a second parameter into the works, the ballistics of the 'reader' machine itself which you would also have to design and build. It would need to work perfectly every time, run at the correct speed regardless of the format and 'read' perfectly something that is analogue in nature, but also was not recorded in perfect circumstances. So no, the issues really are too difficult to resolve. Better to utilise refurbished machines in the original formats, serviced to as new spec, factory settings if you like, and just get as best a playback as is possible. From there, you just need a flexible ADC card and some clever software. But the actual capture would be a 377 line two field sequence. Paul I didn't mean anything that complex. What I meant was digitally capturing the warts and all video signal as decoded by the Sony from the output of the Sony's head. It wouldn't be the theoretically best possible transfer to digital, but it would be much better than an optical transfer, and a step forward. I think this is what you're suggesting, isn't it? It's hard to explain technical things this like this in words, I prefer diagrams! I also need to understand the exact workings of the CV2000; I'm really only familiar with VHS. So available video ADC cards only work with recently-current video standards, they're not free-running the way an audio ADC is. Digital oscilloscopes must have a free-running ADC, although I'd guess they can only capture short chunks of a video signal. The one I'm looking at here can only record 6MB of data, which would be less than a second of digitised 405 video signal. Maybe there are better scopes out there. |
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Post by John Wall on Jan 13, 2017 0:50:34 GMT
The cost of computer memory has reduced tremendously thanks to Moore's Law - terabytes now cost (almost) peanuts.
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Post by John Smith on Jan 13, 2017 13:17:19 GMT
So what is the system that Video Ark are using to transfer to digital? If i was to hazard a guess I'd say some sort of hardware mod to the player itself, e.g like the Philips VCR a/v outputs added to RF only machines. |
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Post by Dave Woods on Jan 13, 2017 20:27:16 GMT
The problem with this method is that you are now adding a second parameter into the works, the ballistics of the 'reader' machine itself which you would also have to design and build. It would need to work perfectly every time, run at the correct speed regardless of the format and 'read' perfectly something that is analogue in nature, but also was not recorded in perfect circumstances. There is a question of how to feed tape from a variety of systems through the scanner, but the scanner can read the tape at whatever speed it needs to to produce a scan. It isn't following the analogue signals on the tape and it doesn't need to track or interpret those, it just has to produce an "image" of the magnetic fields on the tape. Getting software to make sense of those signals is difficult, but pretty much anything is possible in software. Getting an ageing analogue machine to read a stretched or otherwise damaged tape, lock onto its signal, and reproduce video from it - all of which it can only do in real time - is sometimes asking the impossible. |
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Post by Sue Butcher on Jan 14, 2017 1:32:46 GMT
The problem with this method is that you are now adding a second parameter into the works, the ballistics of the 'reader' machine itself which you would also have to design and build. It would need to work perfectly every time, run at the correct speed regardless of the format and 'read' perfectly something that is analogue in nature, but also was not recorded in perfect circumstances. There is a question of how to feed tape from a variety of systems through the scanner, but the scanner can read the tape at whatever speed it needs to to produce a scan. It isn't following the analogue signals on the tape and it doesn't need to track or interpret those, it just has to produce an "image" of the magnetic fields on the tape. Getting software to make sense of those signals is difficult, but pretty much anything is possible in software. Getting an ageing analogue machine to read a stretched or otherwise damaged tape, lock onto its signal, and reproduce video from it - all of which it can only do in real time - is sometimes asking the impossible. But when an old machine, like Ronnie's, is producing a reasonable signal, we still don't have a way to save that signal digitally, simply because existing video capture circuitry is "dedicated" for modern formats only. Designing gear that can record a 405 signal digitally isn't cutting edge electronics, it's just re-engineering existing technology, and logically it's the first problem to tackle because domestic off-air tapes have a limited lifetime. |
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Post by Paul Vanezis on Jan 14, 2017 10:59:56 GMT
There is a question of how to feed tape from a variety of systems through the scanner, but the scanner can read the tape at whatever speed it needs to to produce a scan. It isn't following the analogue signals on the tape and it doesn't need to track or interpret those, it just has to produce an "image" of the magnetic fields on the tape. Getting software to make sense of those signals is difficult, but pretty much anything is possible in software. Getting an ageing analogue machine to read a stretched or otherwise damaged tape, lock onto its signal, and reproduce video from it - all of which it can only do in real time - is sometimes asking the impossible. But when an old machine, like Ronnie's, is producing a reasonable signal, we still don't have a way to save that signal digitally, simply because existing video capture circuitry is "dedicated" for modern formats only. Designing gear that can record a 405 signal digitally isn't cutting edge electronics, it's just re-engineering existing technology, and logically it's the first problem to tackle because domestic off-air tapes have a limited lifetime. I certainly think that is the answer for old tapes such as these. If the tapes were falling apart, but played back still, the obvious thing to do in the absence of any other way is to do an optical conversion to at least preserve a record of what was on the tape. However, whilst domestic recordings are getting older and as you say have a limited lifetime, if they are stored properly they will be fine for a few more years. Ronnie's tapes are 40 years old and play back 'fine' apparently. Regardless, he isn't doing anything to make them safe is he and they may as well be missing altogether, so it's a moot point. My focus is to establish a viable system to transfer this type of material and there are literally hundreds of tapes waiting to be looked at. Paul |
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