VideoBackup - restore in Winuae ?

[TCD]

Originally Posted by jimbob

I was curious why TCD thought this worthy of a Darwin award.

VHS as a medium is quite low quality The ratio between 'possible' raw store capacity and reliable usable capacity is quite low. It still offers about a CD size (figure in modrobert's last post) of storage medium at a time when everything else in that region was indeed a lot more expensive. Before I read about the error correction used I really thought that it was a not really clever idea to use the VHS tapes as a backup medium. Now I'm really curious if the data is still readable And I hopefully made clear that I take my Darwin award remark back

[jimbob]

Agreed, VHS is terrible for fidelity of analogue video. I thought last night when I first read your posts that you must have had some personal experience about how well this worked in reality to be calling for the inventors to be removed from the gene pool

I'd still like to know how you get the data back from the video signal?

[TCD]

Let's say that with video data I had my experience as to why I don't want those days back

[Jope]

Originally Posted by jimbob

I'm trying to imagine how it worked though. Did the software actually generate a video signal recorded to VHS via composite or even RF? If so I'm having more trouble imagining how you recovered the data. I can't imagine you did it with a frame grabber

When backing up, it used the Amiga's video out. When restoring, it used a relatively simple bit of hardware that was connected to the VCR's composite out and the Amiga's serial port.

It was not a frame grabber, more like a luminance to RS232 translator.

[pandy71]

Similar system was available also for PC - http://linbacker.sourceforge.net/screenshots.html also video tape was used in 80's for audio PCM tape recording - Sony produce some PCM Processors - same idea recreated http://www.myprius.co.za/pcmx1_processor.htm

IMHO this should be not a problem to capture and recover VBS on PC (natively without UAE).

[modrobert]

Thinking about possibilities, interesting way to upload binary data to youtube.com, and use them as a download service. Lots of alternatives out there to do that I guess, but perhaps not with google bandwidth.

[wlcina]

Originally Posted by pandy71

Similar system was available also for PC - http://linbacker.sourceforge.net/screenshots.html also video tape was used in 80's for audio PCM tape recording - Sony produce some PCM Processors - same idea recreated http://www.myprius.co.za/pcmx1_processor.htm

IMHO this should be not a problem to capture and recover VBS on PC (natively without UAE).

Yep thats a way just to recover data or disk images, :-) But who in the world can develop such a software

[pandy71]

Originally Posted by wlcina

Yep thats a way just to recover data or disk images, :-) But who in the world can develop such a software

im not a programmer but... there is Avisynth on PC, with reasonable time i think even plain avs script should be capable to decode data from captured video and some lossy compression can be used (MJPEG) as AFAIR VBS is low density system (horizontal decimation can be used).

Perhaps someone can capture VBS video from WinUAE? For some sample of video signal. Or someone can sample real VBS from Amiga/tape and upload on YT.
Short clip should be OK - as YT use compression and convert video to U.S. standard it will be OK to use something different than YT - AFAIR Vimeo provide possibility to download original file then some H.264 mp4 should be OK.

WinUAE capture should be performed on 800x600p50 (or similar - not sure what is maximum WinUAE capabilities for OCS/ECS) - as video is bitonal (b/w) then some lossless compression like huffyuv should be more than enough.

[Toni Wilen]

There is nothing special in video format. It is plain "raw" serial data, trivial to convert back to binary. Single scanline has 4x11 bits (8 lores pixels/bit, if I remember correctly). 11 bits = 1 start bit, 9 data bits, 1 stop bits. (start and stop bits are always active)

I examined how VBS worked in 1990s just for fun, video and serial stuff, not the format itself.

Converting captured data back to data that makes sense requires VBS format specs or really boring reverse engineering project and is far from trivial.

[pandy71]

I see no point to do this in WinUAE when specialized (video processing) software on PC can perform dirty work.

With Avisynth and this plugin http://forum.doom9.org/showthread.ph...74#post1582574 should be possible to recover VBS data.

btw - ffdshow can run Avistynh scripts thus in theory if WinUAE support video capture this can be made inside WinUAE but once again - i see no point to do this in that way.

For my curiosity - i assume that Amiga even now don't have standardized method (in OS) to support video capture?

[Toni Wilen]

I never said WinUAE should be used (it would be stupid in my opinion too), I only said converting the video (whatever the format) back to binary data is not a problem, very simple pattern matching will work.

[prowler]

Here's an earlier thread on this subject from some two years ago which has some interesting information in it:
VCR backup: did anyone of you really used it?

[clenched]

I have one of those Backer units pandy71 linked to. Longevity of average grade VHS tape is at least three years. Reliability is exceedingly good with the low bit rate recording. Higher bit rate will have errors but can be compensated in a number of ways:

- better tape
- better VCR
- more error correcting bytes in stream
- record data more than once. (this uses more tape but can even recover wrinkled sections)

Sometimes a gem of a VCR came along that would even work reliably at LP speed. Since Backer and Amiga unit are dissimilar, I just told about experience with tape.

[pandy71]

Frequently stories can be read about people moving home VHS collection to DVD and after few years DVD's can't be read but VHS tape still works.

[clenched]

Check the Zone for a little demonstration AVI. Recording two files at high bit rate. 1 is an 880KB ADF. 2 is etext of On the Origin of Species 948KB.

EDIT: For the time being a high quality MPEG of the same video is on the EAB file server /~Public_User_Uploads/clenched folder.

[prowler]

Hey, clenched, thanks for uploading that video file. The Backer application looks very slick.

BTW, what do "CODBYTE:26" and "ERRBYTE:06" mean?

...and did it really take just 44 seconds to dump?

[clenched]

CODBYTE:26 = variable number sort of like a sector on floppy - the actual data
ERRBYTE:06 = same thing but bytes used by RS error recovery - more gives greater chance to recover bad data at a modest cost in speed and tape.

Yes, that is unedited elapsed time start to finish. Keep in mind to crunch this video to an acceptable Zone size, The FPS is only 12 or so. Viewing the original 18 MB MPEG the lines are much finer and "dance" a lot faster. So really you're only seeing a fifth of the recording but the runtime is right.

[wlcina]

So anyone found a way to restore data from video? No matter if on PC (creating adf file)

Came here to ask the same. I am looking for the cable to connect to my A1200. Hopefully my BBS backups are still working ...