Lost Tv Programmes

In the 60's and 70's, the BBC recorded over many old TV shows as well as burning or throwing in a skip the 35mm films of TV shows. The films are of course gone forever but is it possible with modern technology to regain old shows on video tapes which were "wiped" or recorded over?

I don't understand...did you record BBC programs on a tape that you've lost? I'm sure the BBC still has almost everything they've made on tape.

To the best of my knowledge, it is not possible to reverse 'tape' data and recover it. If it were digital though, a good chance would exist.

A lot of old BBC stuff has been lost/destroyed. Early Dr Who episodes are a notable example.

the BBC is required by law to have three copies stored in seperate locations of all of their broadcasts.
they lost all their 911 coverage.

entropy says no to recovering of images recorded over. if the tape was just erased, maybe it could still have a semblance of the original information, but i personally doubt it.

ah...that must have been a major incident in the history of BBC. We owe them so much...the best documentaries in the world.

I know it is possible to detect different levels of magnetic fields in one area, so maybe?


In the new series of Mission Impossible in 1988, there was an episode where they recovered a film of one of their operatives being murdered on a video tape where it had been recorded over. It was a scratchy image. I wondered if such a thing was possible then and if it had been improved upon?

highly unlikely.
it's like if you had a recently emptied pepper shaker that had a thin layer held by surface tension to the inside of the glass, and then you filled it with pepper again, and shook it a bit. it would be nearly impossible to distingiush between the 'old pepper', and the 'new pepper', because they are identical particles.

such it would be with magnetized particles on a tape. the old weaker trace would be indistinguishable from the newer traces.

maybe, in a special case, where the original recording was done with a stronger magnetic field(better head) than the newer recording, and the erase head was doing a half arsed job, you could see both images. i've experienced this with cassettes, back in the day.
a crappy erase head leaves a muffled version of the old recording mixing in and out with the new one, but seperating them would mean, once again, seperating pepper from pepper. it is hard to unmix things like.

in the case of audio tape, you would have to have a phase reversed copy of the newer recording, and then dub the (now three) recordings together to get the two newer ones to cancel each other out, leaving some semblance of the original.

unless there's a way to physical scrape off micron thin layers, and a property of the tape is to retain the original on the deepest layers, that is. i can't say 'impossible', but it seems highly unlikely that the deepest layers would behave any different the second time around, than they did the first.

This post has been edited by newton on Jun 1 2007, 05:49 PM

Lets see, if you would want to erase your hard drive, then the recommended number of times you need 'bleach the surface' (Re-record it juxtapositioning the 1's and 0's) according to industry standards, is minimum eight times....

Anything that is magnetically recorded can be somewhat retrievable, but the aging process is probably more damaging then most of the rest, and that one depends critically upon how it got stored.

Apparently the BBC did a really big production piece, did it on a computer in Code that they can no longer run as they no longer have the original coding to run it....

Some way of losing stuff, sad sorta....

Once maybe, but not anymore.

Maybe when there were writing at densities of 10,000 bpi, but now that we are at 100,000 tracks per inch and 250,000 bits per inch the bit densities are close to the theoretical Signal to Noise ratio limits. Since decent wipe programs use random patterns of 0/1s they can ensure that a one pass wipe is sufficient.
If the data is overwritten just once with random data then the difference between what it was before and what it is now is several magnitudes below the S/N threshold making it unrecoverable, even if you are the NSA.

But hard drives are formatted digitial devices.

An ANALOG recording that is erased and written over would be intrinsically much harder to recover than a drive which has specific tracks/bits and I suspect the BBC recordings were analog.

Arthur