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Discussion Starter · #1 ·
I am embarking on a project to archive all my concert laser disks, about 50, to file based storage. Now many collectors have done this with DVD encoding software. But I'm taking a different approach.


I will be storing the library as UNCOMPRESSED SD. running at 10bit it's roughly 100GB per hour. I have some legacy servers that have the capacity and speeds for uncompressed SD capture. The digital audio will also be straight across uncompressed except that I will have to sample rate convert from 44.1 to 48khz locked to the video.


It may seem a bit overkill but this way I can avoid any compression artifacts and/or keep the door open to using new compression codecs in the future.


I will decode the composite video to SDI with a broadcast grade decoder and apply some color correction as needed. Noise reduction will not be used on the record side. I'll do that on playback. As this is uncompressed video, storing noise isn't a penalty as it is with MPEG and most other compression algorithms. My upconverter is a Black magic Teranex unit.


I'll post some pics as I go.
 

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Do you still use the SDI-modded CLD-95? That sound(ed/s) like an awesome player.


I'm playing with software LD decoding (it's actually less hard than you said it was
) and NTSC decoding, and if you can share it I'd like to see a second or two from the Video Essentials S&W zone plate, especially when I get around to making it a 3D filter (it's just a 3-line 2D right now) My decoding software's modular so I won't have trouble adapting SDI data to it. Thanks!
 

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Discussion Starter · #3 ·

Quote:
Originally Posted by Chad Page  /t/1524689/laser-disk-archive-project#post_24546364


Do you still use the SDI-modded CLD-95? That sound(ed/s) like an awesome player.


I'm playing with software LD decoding (it's actually less hard than you said it was
) and NTSC decoding, and if you can share it I'd like to see a second or two from the Video Essentials S&W zone plate, especially when I get around to making it a 3D filter (it's just a 3-line 2D right now) My decoding software's modular so I won't have trouble adapting SDI data to it. Thanks!

Yes, I'll be using the composite SDI path to the decoder, then the decoder into the capture card. Audio will also be embedded into the component SDI stream as that's all the Black magic card takes. At least this way I can preserve the native digital audio track, just need to bump it up to from 44.1k to 48K.


My impetus for this is some laser rot issues as well as the age of the player. If some better decoding technology comes along, I can always go back and do it over if the discs are still good.


There was a paper in the SMPTE journal a few months ago where some European group was doing a software based RF demodulation for Betacam SP format. This could be adapted to laser disk. Of course with BetacamSP they didn't have to worry about color subcarrier.
 

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Found the article online - thanks! Actually LD is a little less complicated, since it's NTSC composite video without a subcarrier. I've made quite a bit of progress, although the de-emphasis isn't perfect yet - it's not quite as steep as Betacam's at least. That and I'm dealing with audio harmonics, but that might be crosstalk from the low-end player I'm using right now. I've got some pics - mostly of earlier versions - at


Seems to me like you should find a way to keep the 44.1k audio, since sample rate conversion usually has some loss. I guess a good enough re-sampler would minimize that.


I'd definitely be interested in seeing more of your setup, and I hope the capture project goes well!
 

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Discussion Starter · #5 ·
For sample rate conversion I am using a surplus Nvision DA4050 card. This not only does the rate conversion but will lock the 48K stream to video which is required for SDI embedding.


It was true 20 years ago that a good DtoA and AtoD style sample rate conversion was superior to a pure digital conversion due to the complex filtering required for such a small frequency change from 441. to 48. But more modern converters have intermod products down in the -120db range, well past the noise floor of a 16bit 44.1. recording.


The other approach would be to record the audio as a separate WAV file at 44.1 and sync that to the video playback. But that's a bit overkill even for me!



I will follow your project with keen interest as well.
 
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