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mrgriscom | 3 years ago

In my dabblings with SDR, playing around with analog video was one of the highlights. Something about this technology that was such a prominent yet opaque feature of my youth and now being able to control it from the inside out felt extremely empowering.

I wrote my own decoder in python (nowhere near realtime) because at the time I couldn't find one that handled color. The deep dive on the design tradeoffs and signal processing hacks for NTSC was fascinating.

A few of my exploits below:

Full-frame decode of VHS w/ closed captioning: https://mrgris.com/a/ntsc-cc.mp4

Faithful reproduction of analog artifacts: https://mrgris.com/a/colorbars_slow.gif

Analog scrambling: https://www.youtube.com/watch?v=qceZgxSBHwo

Inject custom captions (it supports color!): https://mrgris.com/a/thanks.mp4

Sad that these signals are gone now... would have loved to play around with SAP/MTS, teletext, C-band...

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anyfoo|3 years ago

I can see just by the artifacts gif that you've definitely been down the same rabbit hole. Kudos for actually pulling through on also adding some scrambling, I only read about that (and since I don't have any descrambling hardware, I would have had to do that part, too).

I share the sadness about those signals being effectively gone. How fun it would have been to work with real live broadcast ones at their heyday. There still are a few ones, but they're mostly pretty basic now.