[HN Gopher] VHS-Decode - Software defined VHS decoder ___________________________________________________________________ VHS-Decode - Software defined VHS decoder Author : muterad_murilax Score : 173 points Date : 2022-12-11 12:07 UTC (10 hours ago) (HTM) web link (github.com) (TXT) w3m dump (github.com) | crispyambulance wrote: | I find this stuff really interesting. It reminds me of another | project where someone developed an optical scanner to capture the | shapes of vinyl record tracks (without making physical contact, | of course). The idea was then to "play-back" the record by | simulating a needle responding to the tracks in an ideal way and | then simulate the needle's transducer and finally the turntable | pre-amplifier. | | I see this project still uses an actual VHS head. I wonder if, in | the future, folks will try to capture magnetic tape signal by | using something like a hard drive head scanning over the top of | the tape but not touching it? This could potentially retrieve | signal badly damaged, unplayable tapes-- lay out a segment of | tape on flat surface, scan it, repeat, until entire tape has been | scanned. | anfractuosity wrote: | I assume this is the project you mean? - | https://ofersp.github.io/digital_needle/ it's a shame there | doesn't seem to be sourcecode. Very cool though. | | You can also get laser turntables - | https://en.wikipedia.org/wiki/Laser_turntable which look | intriguing | | I'm rather curious about these microscopes - | https://matesy.de/en/products/magnetic-field-visualization/m... | which can visualise magnetic fields, they're very expensive | though. | userbinator wrote: | If I remember correctly, laser turntables were not popular | because they also reproduced all the fine dust on the surface | of the disk. | iforgotpassword wrote: | Yep. Every tiny dust particle makes an audible pop, while | an actual stylus would've just pushed it out of the groove. | interestica wrote: | So laser turntable needs a leading 'dust plow' ? | h2odragon wrote: | Tangential but cool: in 1998 there were commercial, 50GB data VHS | tapes. | | https://en.wikipedia.org/wiki/D-VHS | | about a decade after that someone asked me for help reading a | crate of these tapes that had been flooded then stored in a shed | for several years. Couldn't help them at all but it was an | amusing diversion figuring out what the hell they had. | Bluecobra wrote: | There was also a hokey VHS tape backup card for the PC around | the same time that used standard VHS tapes: | | https://youtu.be/TUS0Zv2APjU | greggarious wrote: | There's a store in Pittsburgh that does this for people as a | paid service. | | OP's project is cool but it's my understanding the specialized | hardware is the big barrier to doing this at home, for most | folks, especially if you don't want the tapes routed through a | third party for the same reason people invented the polaroid so | you don't have to send everything to the Ritz as the mall. | jinto36 wrote: | There are other weird VHS-based formats, such as WVHS, which | was used to store HD-ish analog video on VHS- | https://en.wikipedia.org/wiki/W-VHS | | Alesis also developed an 8-track digital audio recorder based | on VHS, ADAT, which used SVHS tapes and could record 20-bit | 48khz. ADAT was pretty popular in smaller studios, and was | great for the time before multi-gigabyte hard drives. | https://en.wikipedia.org/wiki/ADAT | Hackbraten wrote: | Also, ADAT has been immortalized in the first verse of the | lyrics in The Prodigy's _Diesel Power_ [1]. | | [1]: https://genius.com/The-prodigy-diesel-power-lyrics | actionfromafar wrote: | Very cool. This could have been an excellent backup medium in a | different timeline. | esrauch wrote: | Tape is a backup medium in this timeline though, just not | exactly vhs form factor. | nuxi wrote: | VHS was also used for backups, see e.g. | https://en.wikipedia.org/wiki/ArVid. | | And - if I remember correcly - GRAU and/or StorageTek | robotic tape libraries also had support for VHS devices. | matheusmoreira wrote: | Magnetic tape is an excellent backup method even today. LTO | cartridges already have tens of terabytes of capacity. The | problem is there are no consumer tape drives, only expensive | enterprise models. | apaprocki wrote: | Well, there used to be. The early QIC drives that hooked up | to a FDC connector like the 3.5" were pretty ubiquitous in | the prosumer world. They eventually transitioned to better | tapes/standards, but all worked well and even Windows | eventually had native support (via Microsoft Backup). I | restored my files off of these tapes 25 years after | recording them, so I'm grateful they existed at the right | moment in time when drives and floppies would have | otherwise failed me. I naively assumed in modern times LTO | must be dirt cheap due to decades of competition, but it | never came to be. | userbinator wrote: | LTO is expensive because it's enterprise-oriented, and | despite the O in the name meaning "open", seems actually | a proprietary standard since you can't just go to their | site and download the specs. | amelius wrote: | It would be great if someone could blog about the reverse | engineering of such a tape drive here. | SoftTalker wrote: | It was. I remember people doing it. | actionfromafar wrote: | DVHS? | drmpeg wrote: | Linus Tech Tips just did a video on D-VHS. | | https://www.youtube.com/watch?v=papQ8xQxizA | | When I was at LSI Logic, I developed the IEEE1394 interface for | the second generation JVC D-VHS decks (the HM-DH40000U and HM- | DH5U). I worked directly with engineers in Japan and I used to | get them to bring me copies of the Japanese ham radio magazine | "CQ ham radio" when they would come to visit us in Milpitas. I | can't read Japanese, but it's just a wonderful magazine about | 300 pages thick (like the old Byte magazine). | | https://www.w6rz.net/IMG_0103.jpg | PaulHoule wrote: | I think of how most of the established ham radio brands are | Japanese like that ICOM on the cover. | h2odragon wrote: | Very cool! Thank you for sharing that. | | When I was hunting information for that client; I found a | deck and interface card on ebay for some fairly trivial | amount, $200 or so. I was really tempted to grab it just for | the "neat weird gear" pile but couldn't justify it. The tapes | they wanted read had been submerged for some days and were | crusty. The media _might_ have been recoverable but it would | have meant pulling it out and putting the tape into new | cartridges. | | Am I correct in remembering that standard VHS tapes were | usable in these drives? | xattt wrote: | Just want you to know that those particular DVHS decks were | an object of desire for a geeky teenager wanting the latest | and greatest! | | I had no practical use for them as my family didn't have an | HDTV for a few more years, nor lived in an country where 1394 | was enabled by default on cable boxes. However, the very idea | of having a MPEG TS captured on a commodity tape was alluring | in being able to have a perfect copy of whatever was on TV. | rwmj wrote: | Really nice! In case anyone was wondering, this is for capturing | and decoding the raw VHS RF signal from special test points on | your VHS recorder. Some hardware hacking is required: | https://github.com/oyvindln/vhs-decode/wiki/Hardware-Install... | | By the way, great Japanese docudrama about the making of VHS with | Toshiyuki Nishida and Ken Watanabe: | https://rarefilmm.com/2020/05/hi-wa-mata-noboru-2002/ | actionfromafar wrote: | If you are familiar with TBC or Time Base Corrector, you can | think of this program as an offline non linear time base | corrector with a LOT of options. Also because it takes the VHS | data as early after tape capture as possible, a lot of | components in the VHS player are bypassed and implemented by | superior software. | pmarreck wrote: | combine this with some ML-powered artifact correction and | perhaps a bit of upscaling and you might invent the best VHS | digitizer available | jacquesm wrote: | You definitely want to tee the process before you start | doing any ML artifact correction to make sure that it | actually is an improvement. | lathiat wrote: | I wonder if this could be used to better decode tapes with some | degradation and artefacting. | actionfromafar wrote: | Absolutely. While a tape player may drop out and struggle to | recover, this software stands a much better chance of | deciphering. | jacquesm wrote: | This may be a viable path to fixing up really old recordings | as well, those tend to have a lot of noise and pops / | crackles in them. | lightedman wrote: | I wonder if this could be helpful in finally making an emulator | of the Action Maxx console system, which used VCR tapes for | content. | gattilorenz wrote: | I'm not familiar with the Action Max, but the Wikipedia page | links to this emulator: | https://web.archive.org/web/20110405205335/http://www.jaeger... | boboche wrote: | too bad the first and best capture option costs several hundred | of dollars otherwise this would be epic. Now its just awesome ;) | gattilorenz wrote: | The easiest supported option seems to be this: | https://a.aliexpress.com/_mrd5cMK | mod50ack wrote: | Yes, which you still need to add to a VHS player. | aidenn0 wrote: | This uses high speed ADCs to capture the signal. Anyone know the | bandwidth of VHS? If it's narrow enough, using a much cheaper SDR | could be an option. | | The usage of a DC blocking capacitor implies it's not baseband. | rasz wrote: | much cheaper than $30 25MHz 16bit/50MHz 8bit cards they are | using? | aidenn0 wrote: | First item in readme was much more expensive than that | TylerE wrote: | ~5.5mhz split 3.4m luminance 400khz chroma / 1.7mhz stereo fm | audio | aidenn0 wrote: | Yeah that's too wide for say an RTL SDR | tomphoolery wrote: | has anyone told Technology Connections about this?? | Sporktacular wrote: | What is it about OSS project webpages and burying any layman's | explanation or context. | | It's like they've been knee-deep in it so long, surrounded by | fellow geeks they just assume everyone should know what they're | talking about. | capableweb wrote: | They owe you nothing, so if you want to figure something out, | searching the web is your best chance. | | Also, how is it not clear what the project is? First thing I | see from the submission link: | | > Software defined VHS decoder | | > A fork of LD-Decode, the decoding software powering the | Domesday86 Project | | Which links to https://github.com/happycube/ld-decode and | https://www.domesday86.com/ | | > Software defined LaserDisc decoder | | and | | > Domesday86 is a project that aims to recreate the experience | of the original BBC Domesday project using modern hardware and | software | | Which leads me to searching what BBC Domesday is, as I didn't | know: | | > The BBC Domesday Project was a partnership between Acorn | Computers, Philips, Logica, and the BBC to mark the 900th | anniversary of the original Domesday Book, an 11th-century | census of England. It has been cited as an example of digital | obsolescence on account of the physical medium used for data | storage. | | Not sure why everything has to be made for/explained as it's | made for literally everyone. Some software is for a niche | section of programmers/developers/$niche-group, that's | perfectly fine. If you're curious, use a search engine like the | rest of us. | funstuff007 wrote: | > They owe you nothing, so if you want to figure something | out, searching the web is your best chance. | | Of course that's true, but most OSS devs would prefer broader | usage to narrower usage. | Sporktacular wrote: | Commercial software owes me nothing either. | | So, to understand it, I should know what CVBS is and click on | links to other projects. Which I did: | | Apparently LD-Decode is a Software defined LaserDisc decoder. | Great. It also buries its basic purpose in further links. | | As for Domesday86 Project, its About page is about project | members, privacy policy and general disclaimers. And it's | just weird that you think "The BBC Domesday Project was a | partnership between Acorn Computers, Philips, Logica, and the | BBC to mark the 900th anniversary of the original Domesday | Book, an 11th-century census of England. It has been cited as | an example of digital obsolescence on account of the physical | medium used for data storage." is a good description of | whatever it is. | | I have an electronics degree and I struggled to get this | basic info, so imagine how bewildering this would be to a | less technical audience. It doesn't need to be this way. OSS | can do so much for people, if only the slightest effort can | be made to let them in and indulge their curiosity. | | Also, before you respond with an explanation of why jargon is | good, consider the reason you didn't boot up your computer | with a careful sequence of toggle switch positions, is | because someone before you was kind enough to make the | technology accessible, even to snarky YC commenters. | joemi wrote: | Things don't need to be explained from base principles or | anything like that and as you mentioned they're not beholden | to anyone, but explaining to a bit broader of an audience | than one's particular niche is still generally a good idea. | It makes it easier for people not-in-the-niche-but-somewhat- | close to be able to understand/evaluate things. It could be a | project that's relevant to this near-to-the-niche person, but | without somewhat broader explanation, they'd miss it. | | Another good idea (that no one is obligated to do) for | project descriptions/overviews is to give a brief mention of | why. For instance, it would have been nice if the readme for | this project mentioned the purpose being "To bypass all non- | essential hardware, and process it all in software directly | for an affordable and simple way to create a true 1:1 | archival copy of analogue tape mediums." It wasn't too hard | for me to dig a bit into the project wiki to find that out | and piece it together, but I'm used to doing so, specifically | because so many readmes tend to not do it themselves. | | Finally, you've said "they owe you nothing" and I've also | noted the lack of obligation, but while technically/legally | true, there are still some expectations and unofficial | obligations to varying degrees when releasing open source | software. Generally, the more useful/interesting the software | is, the more expectations and unofficial obligations there | are. Take for instance any software that has a benevolent | dictator for life (BDFL) scenario. That term on its own has | expectations of benevolence built-in. There are expectations | that they'll guide the project in good directions, that | they'll ensure bugs get fixed, and to some degree that the | community will have some input on things even though the BDFL | makes the final call. More generally on most projects, there | are expectations that bugs will get fixed, pull requests | considered/merged when appropriate, documentation will be | provided, and so on. It's hard (perhaps impossible) to have a | successful open source project that does not do these kinds | of things, so in a real-world practical sense, there _are_ | obligations in open source projects, if you want any kind of | success for the project. | ThinkBeat wrote: | Can I use this to defeat Macrovision copy protection on old VHS | movies? | jccalhoun wrote: | This would be super overkill. There are tons of ways to get | around macrovision. | jeffbee wrote: | Yes. Macrovision works by interfering with primitive auto-gain | circuits. This would easily defeat it. | | You can also ignore macrovision if you have an older deck with | manual gain. | EGreg wrote: | Can we have AI remove the artifacts from VHS after it is | digitized? | | Anything exists like this available ONLINE? | rasz wrote: | no, but we can have AI hallucinate alternative "pretty looking" | version | Lindalee51 wrote: | userbinator wrote: | In terms of physical construction, I believe early 90s VCRs were | the best. Late enough to have most of the reliability issues | worked out, and before cost-saving became a priority. That said, | perhaps the last designs (late 2000s?) are also alright because | they were simplified to reduce assembly cost, but may be more | fragile too. | capableweb wrote: | Slightly off-topic, but bit related: | | I'm about to start a project for digitalizing a bunch of | recordings from a 1990s Sony Handycam for a film project run by a | friend of mine. The quality doesn't have to be perfect, but I | want to ensure I don't risk degrading the "tapes" themselves. | Anyone know of any hardware that is up for the task? Doesn't have | to be professional quality, but of course I want good results. | | Just about to start the project so haven't had time yet to look | into what hardware I need yet, maybe people here have good ideas, | you usually do :) | jacquesm wrote: | The big problem with old tape is that it tends to stick. Try | winding it manually for a short stretch to see if the tape is | still loose and if it isn't then you probably should contact | someone with more expertise to get the tape to be unstuck | before putting it in a machine. Stuck tape also tends to break | very easily. | jccalhoun wrote: | assuming the camera has rca out jacks, you can get a rca to | hdmi adapter box for less than $20. If you computer doesn't | have hdmi capture they also make rca to usb boxes as well (I | don't think the cables from rca to usb without a chip in it | will work but I might be wrong). Then OBS can record it | actionfromafar wrote: | If the tapes are really degraded, state of the art is to | digitize them _once_ and do that run as good as possible. | | Stuck tapes sometimes are stuck because of moisture. In that | case, the tapes are "baked" at a certain temperature to get the | moisture out. If the tapes are in really bad condition, you get | only one chance to capture what's on them, but the flip side is | that one run can be of pretty high quality. | | Edit: if your tapes are DV or Digital-8, get a camera with | firewire out. | | If your tapes are Hi8 analog, get a digital-8 camera which can | play analog tapes with firewire out. You won't get a better | quality without going the VHS-Decode way. | | If none of that is an option, get a decent composite to HDMI | converter, than capture the HDMI from that into a PC with a | HDMI ripper. | | Or one of those "HDMI to SD card" rippers floating around. | Gordonjcp wrote: | Sony Handycam implies possibly Video 8 or Hi8 tapes. | | If you can get hold of a Digital8 deck that works (and well) | then you can hook that to your PC with a FireWire card, and do | a direct digital capture of analogue tapes. The DSP in the D8 | deck will do an excellent job of decoding, far better than an | analogue deck, and you'll get a really clean output without all | the "convert down/convert up/convert back down" thing you get | using composite jacks. | | You'll need to convert the raw DV files into something suitable | for editing and distributing, but I guess - since you're on | here - you already know about ffmpeg. | | Here's an example of a very old - 2000/2001 or so! - tape that | I had lying around in a box in the shed for the past 20 years. | I shot it with a hand-held Sony Video 8 camcorder when some | power station chimneys were being demolished near where I | worked. This would (of course) be the day I forgot to throw a | tripod in the car, "Oh I don't need to pack that, I've got one | in the workshop, I'll leave mine at home..." | | https://www.youtube.com/watch?v=ZPmCygZIjio | | It was a pretty grey and drizzly day, as I recall. I could have | got the colours up a bit in editing but I didn't feel like it, | and this is pretty much how it came off the quite-badly-damaged | tape. | haunter wrote: | I went with a lazy way to digitalize old VHS/VHS-C tapes. | Bought a Panasonic DMR-EX99V [0] which is a DVD/HDD/VHS/TV | tuner combo in one. That was the last model Panasonic made and | it also has an HDMI output. So basically I recorded all the VHS | to the internal HDD > then just moved them to the PC through | the DVD recorder. It has a USB port but unfortunately you can't | access the raw recorded files on the HDD that's why the DVD > | PC step is needed. I'm not an expert probably someone could | hack it to gain access... Anyways it was one of the better | purchases I've made. Works perfectly and so far no problems at | all. And it just works hence why I said lazy at the beginning, | simple system with good quality. | | 0, https://m.media- | amazon.com/images/I/71mbsPXPhzL._AC_SL1500_.... ___________________________________________________________________ (page generated 2022-12-11 23:00 UTC)