Comment by squeaky-clean | Hacker News Reader

Comment by squeaky-clean | Hacker News Reader

Sort of related tangent, there were some attempts at copy-protection for VHS. Technology Connections has a good video [0] on "MacroVision" [1], which would mess with the vertical-blanking signal in a way that wasn't particularly noticeable on playback, but would mess with VHS recording.

There was also apparently another method which was just a straight up lie, called KTC, that claimed it was coated with a chemical that would destroy any VHS recorder attempting to record it. Here's a screenshot of the pre-video bumper warning, alerting you to "STOP RECORDING NOW" [2]. Also any RedLetterMedia fans may remember this from the "dog sitting" video in Wheel of the Worst #7 (around 35:00 in). It sounds like a phony technology, and it is. It's just a lie intended to scare away anyone attempting to record the tape.

[0] https://www.youtube.com/watch?v=-VqsU1VK3mU

[1] https://en.wikipedia.org/wiki/Analog_Protection_System

[2] https://company-bumpers.fandom.com/wiki/K.T.C._Warning_Scree...

> which would mess with the vertical-blanking signal in a way that wasn't particularly noticeable on playback, but would mess with VHS recording

On a related note, one of the copy protection systems I put on some Sinclair Spectrum cassette games involved changing the baud rate part way through loading.

It was over 35 years ago so the details are hazy, but I had a custom "master maker" to play the audio[1] and at a specific byte count would change the frequency. The mastering and duplication machines coped with it fine and the loader was written to expect it, but it threw out most home tape to tape systems for reasons I can't exactly remember.

[1] These were usually recorded directly from the Spectrum onto 2 inch reel to reel tapes in a studio, that was then used as the master at the duplicators.

Macrovision only worked on VCRs with the Automatic Gain Control (AGC) enabled. It was super easy to defeat by disabling the AGC, or if you had more sophisticated equipment like a time base corrector (TBC) or similar. These dubs will still have the Macrovision as is, but it won't affect the recording's video signal. Using a standards coverter NTSC->PAL for example would completely remove the macrovision from the dub.

You could buy macrovision strippers from high street stores for years, Radio Shack / Tandy was a good candidate, they were usually sold as "video enhancers" or "video stabilizers" or similar language.

Right, those were the consumer names of time base correctors.

Edit: https://en.wikipedia.org/wiki/Time_base_correction

I don't think they were that advanced. The cheap consumer stuff would just use analogue circuitry to blank out the signal during the vertical blanking interval.

It depends on the model. There were some that would allow one to adjust the contrast/chroma/etc. Of course it was all analog circuits, that's what made it all so accessible! Also, it probably wouldn't blank out the entire blanking as you'd lose CC or Teletext data. I forget the exact lines the macrovision appear on, but it was much higher than 17. We also used to embed ID codes in the blanking that would not get interferred with from macrovision defeaters that was also above line 17, so that was probably also on lines below macro. man, this is some blast from the past type stuff.

Today you can get HDMI copy protection strippers in the form of certain exact model numbers of HDMI signal splitters. You have to get the exact correct model and it will pretend to be a DRM-enabled HDMI endpoint and strip it on the split end. You do not have to plug two HDMI monitors in. Just one is fine.

They will enable things like Amazon or Roku HDMI dongles to work with computer monitors that do not support HDMI encryption. The most common use is just that, not to pirate anything.

Man I love that we now live in an era where this kind of thing can be easily purchased. Back in the day when I had SageTV as my DVR ripping off the content protection crap was impossible… all HD content had to be analog.

I was forced to go this route to get a Roku dongle to work through my receiver. I had actually bought an Amazon Fire Stick first and it had the same problem and returned it. Once the Roku failed in the same way I had to resort to the more drastic measures of going on Amazon and buying a $20 splitter.

But now if I wanted to pirate something I could. It would be super easy too, since there's an open port I could plug the recorder right into.

Or, before they disappeared, copy onto a Beta VCR, they were immune to Macrovision because they took their AGC reading from a different portion of the NTSC waveform, and therefore the Macrovision signal did not impact them.

That's a great idea for any content <30 mins

Is this because Betamax recorders and/or tapes had the same sort of 29:59 limit that some cameras have today (e.g. cheaper Canons)?

No. Today's digital/tapeless cameras are probably limited to some FAT 4GB filesize limit, and they have decided to not do the common file rollover. It may or may not have something to do with chip temps as well. It also helps push people to buy video cameras in lieu of video on stills cameras only. Essentially, it's as much corporate political decisions as much as technical ability.

Betamax was limited to tape speed and how much tape could fit in the cassette. It was one of the downfalls of Beta. It only recorded at one speed. VHS could record in 3 speeds SP (normal), EP (half speed doubling record time), or SLP (third speed tripling record time). At the end of VHS, they were able to create an extremely thin tape allowing for 180 minutes of SP time in the cassette. In SLP, that's 9 friggin hours of record time. It looked horrible, but people loved it. People were essentially running their own DVR with a programmable VCR in SLP with a 180 minute load. You had to fast forward/rewind to find your shows, but even commercials we being skipped.

I've always read that it's down to an EU tax, without that limitation the device gets classed as a video camera and has a sizable import fee: https://www.borrowlenses.com/blog/video-recording-limits-in-...

An answer here https://photo.stackexchange.com/a/21181 says it's to do with codec licensing but the businesswire link is dead and I can't find anything else to back it up.

> It only recorded at one speed.

In the beginning, yes. As time went on, Beta also offered three speeds (Beta I, II, and III) exactly as was offered by VHS and their three speeds.

Maximum recording time for Beta ended up at 5 hours on a single cassette (L830 cassette and Beta III speed). The L750 cassette was more commonly available, it recorded 4.5 hours at Beta III speed.

Of course, VHS's physically larger cassette always allowed it to have a somewhere longer recording time at every step of the competition.

Edit: Add link to Wikipedia page for Beta tape lengths and recording times:

https://en.wikipedia.org/wiki/Betamax#Tape_lengths

No, this is because the original Beta cassette size that Sony first offered contained enough tape for 1/2 hour of recording.

As time went on, longer cassettes and slower recording speeds were released and Beta recorders eventually had tape cassettes available that recorded for 4.5 hours (L750) or 5 hours (L830) of time on a single cassette.

That explains why we never had trouble making copies. Our VCRs were ancient top loader models with automatic nothing. My teenage self thought Macrovision was a weak bluff to stop people from even trying to make copies.

Wouldn't a proper TBC eradicate Macrovision? At least one that reconstructs the timing signals, anyway.

Wow, that's the same MacroVision company, now Tivo, that bought Globetrotter for the FlexLM licensing tools. Talk about a vertical market, this one company has been irritating media and software customers alike for decades.

https://en.wikipedia.org/wiki/TiVo_Corporation

Deeply disappointed that Tivo is now associated with Macrovision && FlexLM, the software equivalent of a rusty razorwire chastity belt. I've spent way too much time in my career swearing at lmgrd....

Yeah, back when you'd need to wire lmgrd into whatever product you were building and also administer it on your lan for whatever tools you bought. Static, floating, HA, so many things to confuse or go wrong.

The whole DRM design pattern is a chain of weak links designed to keep a product from working. The customer is only satisfied if and only if nothing in the chain broke today, yet.

I remember Nagravision on Canal+, a paid TV channel in Europe. Most people pirated it on TV cards because:

- Nagravision on a Pentium 2 was trivial to decode

- Soccer

- Porn

- Blockbusters

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