WEBVTT Kind: captions Language: en 00:00:00.070 --> 00:00:05.080 It’s 2017, and because I’m such a dedicated techy committed to having the newest technology 00:00:05.080 --> 00:00:10.380 at my fingertips, I just got back from the store with a fascinating piece of technology. 00:00:10.380 --> 00:00:11.870 This video cassette recorder. 00:00:11.870 --> 00:00:16.160 You probably think of the VCR as an uninteresting, outdated piece of tech. 00:00:16.160 --> 00:00:19.540 But there’s some surprisingly interesting stuff inside here. 00:00:19.540 --> 00:00:23.759 The VCR contains a device the solved what seemed to be an unsolvable problem. 00:00:23.759 --> 00:00:25.130 Let’s have a look. 00:00:25.130 --> 00:00:29.390 In the days of analog television, the actual signal that made up the images to be put on 00:00:29.390 --> 00:00:33.989 the screen wasn’t a set of instructions on how to build an image using pixels. 00:00:33.989 --> 00:00:38.700 It was a complicated, high frequency signal of continually varying intensity that contained 00:00:38.700 --> 00:00:42.949 rudimentary triggers to help a television build a coherent image based upon the signal’s 00:00:42.949 --> 00:00:46.710 instantaneous strength which corresponded to image brightness at a particular point 00:00:46.710 --> 00:00:47.710 on the screen. 00:00:47.710 --> 00:00:51.690 Anyway, an analog video signal is an insanely high frequency. 00:00:51.710 --> 00:00:55.450 OK, it’s actually not that high by today’s standards, but bear with me. 00:00:55.450 --> 00:01:00.309 The 5 megahertz signal of analogue television made for a perfectly acceptable picture, and 00:01:00.309 --> 00:01:02.789 there weren’t any problems when it came to everyday use. 00:01:02.789 --> 00:01:07.710 Except, that super high frequency meant that recording the video signal was impossible. 00:01:07.710 --> 00:01:09.570 Let me explain. 00:01:09.570 --> 00:01:13.510 Magnetic tape recording, already in use for recording audio signals from microphones, 00:01:13.510 --> 00:01:17.640 has its frequency response, that is how high of a frequency it could reproduce, limited 00:01:17.640 --> 00:01:19.220 by its speed. 00:01:19.220 --> 00:01:23.190 Due to the structure of the tape itself, to record a high frequency signal it has to be 00:01:23.190 --> 00:01:25.939 moving past the tape heads pretty fast. 00:01:25.939 --> 00:01:29.360 This isn’t a problem for audio signals, as the highest frequency it needs to produce 00:01:29.360 --> 00:01:32.020 is about 20 thousand hertz, or 20 kilohertz. 00:01:32.020 --> 00:01:35.890 A speed of 7.5 inches per second is plenty for this purpose. 00:01:35.890 --> 00:01:40.700 But video signals are about 5 megahertz, that’s 5 million hertz, much too high a signal to 00:01:40.700 --> 00:01:42.590 put on normal tape. 00:01:42.590 --> 00:01:46.130 Because of this limitation, TV shows tended to be live and not pre-recorded. 00:01:46.130 --> 00:01:50.520 If a show was to be recorded before being broadcast, it was usually filmed with a conventional 00:01:50.520 --> 00:01:54.500 motion picture camera, and then a device called a telecine would be used. 00:01:54.500 --> 00:01:58.930 A telecine is a machine that can convert motion picture film into a television signal. 00:01:58.930 --> 00:02:02.840 Aside from the necessary frame-rate conversion that was accomplished by the machine, you 00:02:02.840 --> 00:02:07.040 can think of it as a glorified television camera pointing at a movie screen. 00:02:07.040 --> 00:02:10.490 You could also use a kinescope, which was basically the opposite, like pointing a film 00:02:10.490 --> 00:02:14.970 camera at a TV screen, the upshot of which was that frame-rate conversion wasn’t necessary 00:02:14.970 --> 00:02:18.240 when playing it back due to an already matched framerate. 00:02:18.240 --> 00:02:21.940 But using film wasn’t easy, and most importantly it wasn’t cheap. 00:02:21.940 --> 00:02:25.920 It would be super convenient to put video signals right onto magnetic tape which was 00:02:25.920 --> 00:02:31.090 cheaper and easier to use, not requiring film processing and also being reusable.. 00:02:31.090 --> 00:02:33.260 But again, speed was a problem. 00:02:33.260 --> 00:02:36.810 In order to record video signals onto this tape, it would have to be traveling at many 00:02:36.810 --> 00:02:38.470 feet per second. 00:02:38.470 --> 00:02:42.010 With this 1,200 foot spool of tape, you could expect a recording time of about 00:02:42.010 --> 00:02:43.630 72 seconds. 00:02:43.630 --> 00:02:47.400 It would look a lot like this during normal operation: 00:02:47.400 --> 00:02:49.120 But that didn’t stop progress. 00:02:49.120 --> 00:02:53.620 At first, attempts were made to just make a really-fast tape recorder. 00:02:53.620 --> 00:02:59.340 One such system, the Vision Electronic Recording Apparatus, or Vera, was developed in 1952 00:02:59.340 --> 00:03:05.300 by the BBC, the project being led by (now here’s an awesome name) Dr. Peter Axon. 00:03:05.300 --> 00:03:09.830 The VERA used massive 20 inch reels that contained 15 THOUSAND feet of tape. 00:03:09.830 --> 00:03:12.950 That’s nearly 3 miles of continuous tape. 00:03:12.950 --> 00:03:14.040 Yikes. 00:03:14.040 --> 00:03:17.261 Even with that vast amount of tape, though, the recording time was only 15 minutes because 00:03:17.261 --> 00:03:22.010 the tape traveled at 16.7 feet per second, or over 11 miles an hour. 00:03:22.010 --> 00:03:25.970 If it wasn’t obvious that this was impractical, it should’ve been. 00:03:25.970 --> 00:03:30.330 Other oddities exist in the linear-video-tape world, such as Toshiba’s LVR system that 00:03:30.330 --> 00:03:34.460 used a loop of tape that moved very fast and a head that slowly moved along the tape from 00:03:34.460 --> 00:03:38.880 top to bottom essentially making a spiral, but for the most part the idea was abandoned 00:03:38.880 --> 00:03:42.060 because, let’s face it, this is just silly. 00:03:42.060 --> 00:03:45.640 So what could be done to practically record video onto magnetic tape? 00:03:45.640 --> 00:03:49.230 There’s no getting around the fact that the tape has to travel past the heads at at 00:03:49.230 --> 00:03:52.950 least a dozen feet per second or so to get a reasonable picture. 00:03:52.950 --> 00:03:57.400 To solve this problem, the American company Ampex, based in California, asked a brilliant 00:03:57.400 --> 00:04:01.540 question: Why not have the heads move past the tape? 00:04:01.540 --> 00:04:07.520 Ampex’s quadruplex system used a rotating drum containing four tape heads that sat perpendicular 00:04:07.520 --> 00:04:10.900 to the traveling path of 2 inch wide magnetic tape. 00:04:10.900 --> 00:04:14.840 The drum, rather than the tape, is what moved at a high speed. 00:04:14.840 --> 00:04:19.110 Spinning at a rate of 3,600 rpm, the heads traveled past the tape very very fast, but 00:04:19.110 --> 00:04:22.380 the tape only moved at a speed of 15 inches per second. 00:04:22.380 --> 00:04:26.550 By slicing up the width of the tape into small parts of the video signal, the surface of 00:04:26.550 --> 00:04:29.530 the tape could be used much more efficiently. 00:04:29.530 --> 00:04:33.740 Electronics switched the output between the 4 heads allowing for a seamless video signal. 00:04:33.740 --> 00:04:37.460 The Ampex machine was a hit, and it quickly became the standard format for television 00:04:37.460 --> 00:04:39.230 studios nationwide. 00:04:39.230 --> 00:04:44.520 But these machines were insanely expensive, with the 1956 price being 45,000 dollars, 00:04:44.520 --> 00:04:47.130 equivalent to almost four hundred thousand dollars today. 00:04:47.130 --> 00:04:50.240 Aside from costing more than a house, they were also huge, about the size of a large 00:04:50.240 --> 00:04:54.780 chest freezer not including their many electronic components mounted on racks. 00:04:54.780 --> 00:05:00.250 Not to mention, they were obviously very heavy, along with being decidedly not easy to use, 00:05:00.250 --> 00:05:02.420 requiring training to operate them. 00:05:02.420 --> 00:05:07.210 Fast forward to the mid 1970’s, and consumer video tape recorders are starting to appear. 00:05:07.210 --> 00:05:11.950 Betamax and VHS were the two most common formats, with VHS eventually winning the drawn out 00:05:11.950 --> 00:05:12.950 format war. 00:05:12.950 --> 00:05:17.210 Both of these formats use similar technology to the original quadruplex system, so let’s 00:05:17.210 --> 00:05:19.330 have a look at what’s on the inside. 00:05:19.330 --> 00:05:22.910 This is a run-of-the-mill VHS cassette recorder from the early eighties. 00:05:22.910 --> 00:05:26.920 All VCRs contain a video head system similar to the quadruplex system. 00:05:26.920 --> 00:05:28.310 That's it there. 00:05:28.310 --> 00:05:32.170 But before we get too involved in that, let's have a look at the cassette itself. 00:05:32.170 --> 00:05:36.260 Any cassette tape is really nothing more than Magnetic Tape stored inside of a plastic shell 00:05:36.260 --> 00:05:40.740 so it can be handled more easily and so the machine can interact with it automatically. 00:05:40.740 --> 00:05:44.630 The audio cassette used a relatively simple system of three access holes, located on the 00:05:44.630 --> 00:05:48.630 bottom edge of the cassette, that the erase head, play head and pinch roller could fit 00:05:48.630 --> 00:05:49.890 inside of. 00:05:49.890 --> 00:05:54.490 This works fine for the relatively uncomplicated process of moving audio tape past two stationary 00:05:54.490 --> 00:05:55.530 heads. 00:05:55.530 --> 00:05:59.630 But for a video format, the tape has to go in many places and most importantly it has 00:05:59.630 --> 00:06:02.350 to wrap around the video Head drum. 00:06:02.350 --> 00:06:07.530 Earlier machines had to be threaded manually, but that isn’t exactly consumer-friendly. 00:06:07.530 --> 00:06:11.370 To accomplish threading automatically, the machine actually removes some of the tape 00:06:11.370 --> 00:06:14.010 from the cassette and pulls it through the path of the heads. 00:06:14.010 --> 00:06:18.530 Cout-outs in the bottom of the cassette allow for two spindles to stick up behind the tape. 00:06:18.530 --> 00:06:23.030 As the cassette is lowered into machine, the hinged lid which keeps the tape away from 00:06:23.030 --> 00:06:27.330 grubby little hands is opened, and once play is selected the spindles move toward the rear 00:06:27.330 --> 00:06:30.820 of the machine which pulls the tape past all the necessary components. 00:06:30.820 --> 00:06:34.370 Let’s look at some of the components inside without a cassette in place. 00:06:34.370 --> 00:06:39.740 The path the tape makes is in the shape of an M. First it travels past this erase head. 00:06:39.740 --> 00:06:43.400 When recording, the erase head is energized which removes any signals currently on the 00:06:43.400 --> 00:06:44.710 tape. 00:06:44.710 --> 00:06:48.180 It’s next stop is the video head drum. 00:06:48.180 --> 00:06:52.580 After being wrapped around, it exits the drum and goes past two more stationary heads. 00:06:52.580 --> 00:06:55.620 These heads record the audio and a tracking signal. 00:06:55.620 --> 00:06:58.780 These two signals are recorded along the edges of the tape. 00:06:58.780 --> 00:07:02.770 Obviously the audio track contains sound, meanwhile the tracking signal contains reference 00:07:02.770 --> 00:07:05.100 pulses to match each frame of video. 00:07:05.100 --> 00:07:09.030 The recorder uses the pulses to maintain the correct tape speed when playing a tape back. 00:07:09.030 --> 00:07:13.170 It also allows for the machine to compensate for slight differences between tapes recorded 00:07:13.170 --> 00:07:16.510 on different machines, enabling video tracking. 00:07:16.510 --> 00:07:20.510 Later machines used the tracking pulses as a sort of timecode, counting each pulse to 00:07:20.510 --> 00:07:22.700 determine how much time had elapsed. 00:07:22.700 --> 00:07:25.810 The last main component is the capstan and pinch roller. 00:07:25.810 --> 00:07:29.230 These components work together to squeeze the tape between themselves. 00:07:29.230 --> 00:07:33.020 The capstan spins at a very precise speed, and that’s how the tape is actually pulled 00:07:33.020 --> 00:07:34.380 through the mechanism. 00:07:34.380 --> 00:07:38.740 Cogged spindles engage with the spools that hold the tape, but they only actually pull 00:07:38.740 --> 00:07:41.740 the tape with force when fast forwarding or rewinding. 00:07:41.740 --> 00:07:45.440 Otherwise they simply serve to spool the tape and keep it taut, with the capstan doing the 00:07:45.440 --> 00:07:46.440 real work. 00:07:46.440 --> 00:07:50.160 So let’s go back to the most exciting part, the video head drum. 00:07:50.160 --> 00:07:52.290 Here lies the heart of the machine. 00:07:52.290 --> 00:07:55.720 If you remember the days of VCR’s, you probably remember this sound. 00:07:55.720 --> 00:07:58.919 That’s the sound of the head drum starting to spin. 00:07:58.919 --> 00:08:02.930 For machines in the US, it spins at about 1,800 rpm. 00:08:02.930 --> 00:08:07.169 One complete revolution makes one frame of video, and since the framerate of US television 00:08:07.169 --> 00:08:13.930 is 29.97 frames per second, it spins nearly 30 times in a second. 00:08:13.930 --> 00:08:15.730 But where are the heads themselves? 00:08:15.730 --> 00:08:17.900 The heads are really tiny and hard to see. 00:08:17.900 --> 00:08:22.020 They are tucked away in the slit that separates the two halves of the drum. 00:08:22.020 --> 00:08:24.660 All VHS recorders have at least 2 heads. 00:08:24.660 --> 00:08:29.919 Because NTSC video is interlaced, each head records half of the video frame at one time. 00:08:29.919 --> 00:08:34.330 Upmarket VCRs would have 4 or even six heads, with the extra heads helping to improve image 00:08:34.330 --> 00:08:38.479 quality by recording a more precise signal tailored to the specific tape speed. 00:08:38.479 --> 00:08:41.599 You might have noticed that the head drum doesn’t sit level with the rest of the machine. 00:08:41.599 --> 00:08:45.620 In fact it looks sorta like it was just tossed in there and let to stay where it landed. 00:08:45.620 --> 00:08:47.980 But in fact the wonky angle is deliberate. 00:08:47.980 --> 00:08:51.680 If you look closely, you’ll see that the head travels diagonally down the surface of 00:08:51.680 --> 00:08:52.779 the tape. 00:08:52.779 --> 00:08:57.490 One pass of the head, and thus one half frame or field of the video signal, is recorded 00:08:57.490 --> 00:08:59.560 on this long distance of tape. 00:08:59.560 --> 00:09:01.520 This is called helical scanning. 00:09:01.520 --> 00:09:05.090 By running the heads along the tape in this fashion, the tape didn’t have to be nearly 00:09:05.090 --> 00:09:09.120 as wide as the 2 inch tape tape found in the quadruplex system, and it also meant that 00:09:09.120 --> 00:09:12.279 one pass of the head contained an entire field of video. 00:09:12.279 --> 00:09:16.460 See, because the quadruplex system broke up the fields into multiple sweeps, requiring 00:09:16.460 --> 00:09:20.860 16 head passes per full frame of video, it wouldn’t produce any sort of intelligible 00:09:20.860 --> 00:09:23.470 picture unless playing at the appropriate speed. 00:09:23.470 --> 00:09:26.820 This meant fast forwarding or rewinding was done blind, and freeze-framing 00:09:26.820 --> 00:09:28.090 wasn’t possible. 00:09:28.090 --> 00:09:31.790 Using one sweep for one complete field eliminated those problems. 00:09:31.790 --> 00:09:35.330 If you could see the information on the tape, it would look like this. 00:09:35.330 --> 00:09:39.890 Two linear tracks are present at the edges, and a bunch of long, diagonal lines fill the 00:09:39.890 --> 00:09:40.890 middle. 00:09:40.890 --> 00:09:45.020 Each of these lines is one half of one frame of video, called a field. 00:09:45.020 --> 00:09:49.310 Each field fills in the whole screen, but only every other line of the image. 00:09:49.310 --> 00:09:52.710 Every sweep of the heads along the helical path of the tape made half of the image, with 00:09:52.710 --> 00:09:55.290 the other head sweeping by to create the other half. 00:09:55.290 --> 00:09:58.950 The VCR would automatically switch what it showed on the television back and forth between 00:09:58.950 --> 00:10:02.220 the heads, creating an apparently seamless image. 00:10:02.220 --> 00:10:04.790 Now here’s an interesting question. 00:10:04.790 --> 00:10:07.450 How is the machine able to actually read the tape? 00:10:07.450 --> 00:10:11.580 If the heads are spinning around, they can’t have wires attached to them like these stationary 00:10:11.580 --> 00:10:13.770 heads do or they’d tangle. 00:10:13.770 --> 00:10:17.920 Early video tape recorders used what’s called a slip ring pickup, essentially a set of thin 00:10:17.920 --> 00:10:21.520 wires that brushed against a spinning ring which was electrically connected to the heads 00:10:21.520 --> 00:10:22.520 with wires. 00:10:22.520 --> 00:10:26.610 These proved problematic, however, as corrosion and wear would introduce noise to the signal. 00:10:26.610 --> 00:10:32.350 By the time VHS was invented, rotary transformers were used to provide a wireless coupling between 00:10:32.350 --> 00:10:34.470 the top and bottom halves of the head drum. 00:10:34.470 --> 00:10:38.150 The actual slices of tape that made up the signal are very thin. 00:10:38.150 --> 00:10:43.779 The tape traveled at only 1.313 inches per second, and with 60 slices of video fields 00:10:43.779 --> 00:10:48.580 squeezed in the space, you’re looking at a slice width of about .022 inches or just 00:10:48.580 --> 00:10:50.910 slightly more than half a millimeter. 00:10:50.910 --> 00:10:54.710 To help avoid interference between the tiny tracks on the tape, the heads were assembled 00:10:54.710 --> 00:10:59.100 with different azimuths, that is different angles between the tape and the head. 00:10:59.100 --> 00:11:02.381 Rather than hitting it straight on, one head would hit the tape at plus seven degrees, 00:11:02.381 --> 00:11:04.800 and the other at minus seven. 00:11:04.800 --> 00:11:09.000 This created destructive interference between the tracks, thus ensuring each head picked 00:11:09.000 --> 00:11:11.029 up only what it was supposed to. 00:11:11.029 --> 00:11:16.640 This became even more important as the Long Play, LP, and then Super Long Play, or SLP 00:11:16.640 --> 00:11:18.120 recording speeds were introduced. 00:11:18.120 --> 00:11:22.840 LP halved the normal tape speed and thus halved with width of the track, with SLP only being 00:11:22.840 --> 00:11:24.990 a third the standard speed. 00:11:24.990 --> 00:11:28.350 This doubled and tripled the amount of time you could record on the tape, but it reduced 00:11:28.350 --> 00:11:33.390 the quality of the image noticeably, particularly when recording at the SLP speed as now the 00:11:33.390 --> 00:11:37.500 width of the tracks created by the heads was less than 2 10ths of a millimeter. 00:11:37.500 --> 00:11:41.680 The tape-to-head speed of consumer formats wasn’t quite fast enough to reproduce broadcast 00:11:41.680 --> 00:11:42.700 quality images. 00:11:42.700 --> 00:11:48.470 VHS had a bandwidth of only 3 megahertz, compared to broadcast bandwidth of 5. 00:11:48.470 --> 00:11:52.220 This meant that the quality of the signal coming from the tape wasn’t quite as good 00:11:52.220 --> 00:11:53.250 as live tv. 00:11:53.250 --> 00:11:54.270 Are you ready? 00:11:54.270 --> 00:11:57.570 This is VHS quality. 00:11:57.570 --> 00:12:01.680 No joke, this has been recorded onto a VHS tape, fed through a capture device, and then 00:12:01.680 --> 00:12:03.040 back into this video. 00:12:03.040 --> 00:12:05.380 If you’re not watching full-screen, you should be. 00:12:05.380 --> 00:12:06.380 It’s awful. 00:12:06.380 --> 00:12:11.210 But keep in mind that back in the day we weren’t using massive TVs with 4k displays, let alone 00:12:11.210 --> 00:12:12.600 even 720 p. 00:12:12.600 --> 00:12:15.680 On an old tube-set, this quality was perfectly adequate. 00:12:15.680 --> 00:12:19.120 Let’s talk about those different recording speeds, shall we? 00:12:19.120 --> 00:12:22.480 This is what you could expect from a recording made at the standard play speed. 00:12:22.480 --> 00:12:26.730 This is the best picture you’re going to get, and it goes downhill from here. 00:12:26.730 --> 00:12:31.420 Now I’ll switch to LP. LP’s not terrible, but sound quality 00:12:31.420 --> 00:12:32.990 got noticeably worse. 00:12:32.990 --> 00:12:35.690 Now here’s SLP. 00:13:20.490 --> 00:13:26.220 However, the later development of VHS-HiFi, which stored FM stereo audio within the video 00:13:26.220 --> 00:13:30.180 signal of the tape using a second set of heads on the video drum, meant that sound quality 00:13:30.180 --> 00:13:33.839 was constant even with an EP tape, and it’s really good, too. 00:13:33.839 --> 00:13:39.200 VHS HiFi has a full 20 to 20 kilohertz frequency response, excellent signal-to-noise ratio 00:13:39.200 --> 00:13:43.560 in addition to dynamic range, and excellent stereo channel separation as well. 00:13:43.560 --> 00:13:47.660 It was very close to CD quality, with many people (myself included) not being able to 00:13:47.660 --> 00:13:48.890 tell the difference. 00:13:48.890 --> 00:13:53.920 Thus the best way to play 8 hours of music nonstop in 1985 was to record your favorites 00:13:53.920 --> 00:13:59.140 on a T-160 tape running at SLP speed on a hi-fi equipped VCR. 00:13:59.140 --> 00:14:03.790 The only caveat to VHS-HiFi was that because the audio was recorded along the helical scanned 00:14:03.790 --> 00:14:08.670 portions of the tape, the source of the sound had to switch back and forth with the heads. 00:14:08.670 --> 00:14:12.790 Our ears are actually far more sensitive to gaps in information than our eyes, so if the 00:14:12.790 --> 00:14:16.980 tape was damaged or the heads didn’t line up quite right, you would hear a low 60hz 00:14:16.980 --> 00:14:17.980 buzz. 00:14:17.980 --> 00:14:21.020 Ordinarily, though, this was a fairly rare occurrence. 00:14:21.020 --> 00:14:25.400 As a side note, for reasons I don’t really understand, the LP speed disappeared from 00:14:25.400 --> 00:14:26.930 many VCRs. 00:14:26.930 --> 00:14:31.790 Though all but the very earliest VHS recorders can play back a tape made at the LP speed, 00:14:31.790 --> 00:14:35.339 few made after the 1980’s could record at LP. 00:14:35.339 --> 00:14:39.519 I remember as a kid in the nineties being bummed when our new VCR couldn’t record 00:14:39.519 --> 00:14:43.410 LP, as I found it a nice compromise between recording time and picture quality. 00:14:43.410 --> 00:14:46.730 Oh well, I guess only nineties kids remember... 00:14:46.730 --> 00:14:50.840 The longer recording time available on VHS was the main reason that Beta didn’t win 00:14:50.840 --> 00:14:51.970 the format war. 00:14:51.970 --> 00:14:56.640 Sony’s decision to use a smaller cassette with less actual tape inside meant that the 00:14:56.640 --> 00:15:01.520 longest tapes typically held was four and a half hours, compared to the eight + possible 00:15:01.520 --> 00:15:02.640 with VHS. 00:15:02.640 --> 00:15:07.190 VHS was continually improved during its life, with the most noticeable improvement being 00:15:07.190 --> 00:15:09.940 the S-VHS standard released in 1987. 00:15:09.940 --> 00:15:16.640 S-VHS, short for super VHS could record a 5.4 megahertz signal with improved tape formulation 00:15:16.640 --> 00:15:21.680 and recording techniques, actually providing a better picture than broadcast television. 00:15:21.680 --> 00:15:26.380 This was only half-true, though, because while the luminance bandwidth was very good, S-VHS 00:15:26.380 --> 00:15:30.090 did not improve the color rendering of standard VHS. 00:15:30.090 --> 00:15:34.850 See on VHS and beta as well, the bandwidth required to make the image was dedicated mostly 00:15:34.850 --> 00:15:36.930 to luminance, or a black-and-white signal. 00:15:36.930 --> 00:15:42.649 VHS used a “color-under” encoding method whereby color data, recorded after the luminance 00:15:42.649 --> 00:15:46.460 signal, was essentially drawn on top of a black and white image. 00:15:46.460 --> 00:15:50.490 This was done to prioritize image sharpness with the limited bandwidth available. 00:15:50.490 --> 00:15:55.100 The resolution of this coloring was by contrast quite poor, on the order of just 12% that 00:15:55.100 --> 00:15:56.860 of the black and white detail. 00:15:56.860 --> 00:16:01.380 So while the picture of S-VHS was sharper than broadcast tv, the color rendering left 00:16:01.380 --> 00:16:02.870 a lot to be desired. 00:16:02.870 --> 00:16:06.899 Partly because of this, and along with the significantly higher price tag of S-VHS machines 00:16:06.899 --> 00:16:10.330 and media, S-VHS never really went anywhere. 00:16:10.330 --> 00:16:12.040 Standard VHS was good enough. 00:16:12.040 --> 00:16:17.000 You might be surprised to learn that toward the end of VHS’s life, D-VHS was introduced, 00:16:17.000 --> 00:16:18.610 with the D standing for Digital. 00:16:18.610 --> 00:16:24.130 It is certainly possible to record digital data onto magnetic tape, and the D-VHS equivalent 00:16:24.130 --> 00:16:29.550 of a standard T-120 tape could hold 25 gigabytes, the same as a single layer bluray disc. 00:16:29.550 --> 00:16:33.930 In fact, the D-VHS standard included support for 1080i video. 00:16:33.930 --> 00:16:37.920 You should definitely check out these video clips from one of my favorite YouTubers Techmoan, 00:16:37.920 --> 00:16:41.670 where he shows a demo tape with HD scenes of New York from 1994. 00:16:41.670 --> 00:16:46.570 It actually kind of jarring to see street footage of that age in that clarity. 00:16:46.570 --> 00:16:51.390 As I close this video out, I hope that you can admire the ingenuity in these old machines. 00:16:51.390 --> 00:16:56.030 These intricate mechanisms and the out-of-the-box thinking that led to their creation are just 00:16:56.030 --> 00:16:57.030 more fun. 00:16:57.030 --> 00:17:02.029 The video head drum solved an unsolvable problem in an ingenious fashion, and the intricacies 00:17:02.029 --> 00:17:06.179 involved in the machine just to get the tape to wrap around it are far more interesting 00:17:06.179 --> 00:17:09.809 to me than a laser diode and optical pickup reading data off a spinning disc. 00:17:09.809 --> 00:17:14.639 We’ll be exploring VHS and Beta as well in more detail, and I’ll also be discussing 00:17:14.639 --> 00:17:17.339 the format war between them in later episodes. 00:17:17.339 --> 00:17:20.679 Thanks so much for watching, I hope you enjoyed the video! 00:17:20.679 --> 00:17:25.329 If you did, be sure to give it a thumbs-up and subscribe to technology connections! 00:17:25.329 --> 00:17:32.200 I’m doing my best to keep video like this coming your way. 00:17:32.200 --> 00:17:51.509 I’ll see you next time!