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Old 27 January 2019, 02:37   #41
Hewitson
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Originally Posted by TroyWilkins View Post
I could be wrong here, but I suspect the data density on the physical medium has something to do with it. I mean, 1.2MB on a high density 5.25" PC disk, or 1.44MB on a high density 3.5" PC disk. The physically smaller disk has more data packed into a smaller physical space. This even counts for the double density disks that most Amigas used, 880KB on a 3.5" Amiga disk requires more dense storage than 1.2MB stored on a 5.25" disk.
This is of course true but you'd still think that with a fully exposed media the 5.25 would be far more unreliable than a 3.5, which obviously has a shutter protecting the media when not in use.


Quote:
Originally Posted by Gorf
At least in Europe and a SCART enabled VRC it would not be a problem to use the chroma signal for data (or redundancy / error correction) as well.
Why wouldn't it? The video information is still stored on the tape as composite video. I just don't think the chroma signal would have the accuracy needed for something like this.
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Old 27 January 2019, 03:14   #42
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Why wouldn't it? The video information is still stored on the tape as composite video. I just don't think the chroma signal would have the accuracy needed for something like this.
because SCART* or s-video have a separated Y/C signal lines.
(*SCART in this case is actually RGB that gets translated into Y/C by the VRC)
While it is still stored on tape as a modulated signal, it has a much better signal to noise ratio and less artifacts.
So I do not really see a big technical problem here to e.g. use two different Y signal-states in addition to the two C values (black and white), which would double the density.

For comparison:
Some SVHS VRCs were able to store 48kHz 16-bit stereo digital audio on the audio-track next to the video information. This means 4 bytes x 48k x 3600 / 1024 equals 675 MB per hour! Only on the audio-track, which only occupies a small fraction of the tape.


DTRS and DA-88 use Hi8-video-tapes to store multiple digital audio tracks (24bit and up to 192 kHz) - typically 4,8 GB per tape

Last edited by Gorf; 27 January 2019 at 03:34.
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Old 27 January 2019, 17:36   #43
idrougge
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Originally Posted by Gorf View Post
because SCART* or s-video have a separated Y/C signal lines.
Not when connected to a VHS it doesn't. Scart can carry all kinds of video, but that doesn't mean that it does in every case. When connected to a VHS recorder, all you get is composite video.
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Old 30 January 2019, 22:06   #44
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Not when connected to a VHS it doesn't. Scart can carry all kinds of video, but that doesn't mean that it does in every case. When connected to a VHS recorder, all you get is composite video.
That depends on your VRC or more general on your setup. When you connect an Amiga via a D-sub to SCART cable, then it is definitively RGB.
(Not all VRCs will be able to record with this setup.)
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