WEBVTT Kind: captions Language: en 00:00:00.080 --> 00:00:01.080 Lasers! 00:00:01.080 --> 00:00:02.080 Rainbows! 00:00:02.080 --> 00:00:02.960 The eighties! 00:00:02.960 --> 00:00:03.840 Drum Machines! 00:00:03.840 --> 00:00:04.560 Digital! 00:00:04.560 --> 00:00:05.560 Big hair! 00:00:05.760 --> 00:00:07.180 This is some righteous stuff! 00:00:07.360 --> 00:00:11.200 No kidding, the compact disc was a radical departure from how, 00:00:11.200 --> 00:00:13.980 well really how a lot of stuff worked. 00:00:13.980 --> 00:00:18.920 You could argue that the CD, with its vast data capacity, relatively robust nature, and 00:00:18.920 --> 00:00:23.800 with the further developments it spurred along, changed how the world did virtually all media. 00:00:24.360 --> 00:00:28.880 That is at least until physical media became the seemingly undesirable thing it is today, 00:00:28.880 --> 00:00:33.880 a time when streaming services and libraries on hard drives are all the rage. 00:00:33.880 --> 00:00:36.080 Unless of course it’s vinyl, then by all means please 00:00:36.080 --> 00:00:37.140 build your collections. 00:00:37.140 --> 00:00:39.380 Wow the snark’s coming early today. 00:00:39.380 --> 00:00:42.480 Well, this is the third video in a series on digital sound. 00:00:42.480 --> 00:00:45.950 You can find a playlist to the previous two videos, in which we covered how digital sound 00:00:45.950 --> 00:00:50.560 works (as well as the Nyquist-Shannon sampling theorem), but for now, sit back and relax 00:00:50.560 --> 00:00:55.070 as you feast your eyes on the silver platter that is the compact disc. 00:00:55.070 --> 00:01:00.100 No discussion of the Compact Disc is a good discussion unless it pays homage to its predecessor, 00:01:00.100 --> 00:01:01.100 the LaserDisc. 00:01:01.100 --> 00:01:04.510 Now, I’ve done a series on Laserdisc if you’d like to learn more, but in brief, 00:01:04.510 --> 00:01:07.980 this was the very first commercial optical storage format. 00:01:07.980 --> 00:01:13.680 First released in test markets in 1978, Laserdiscs were usually 12 inch or 30 centimeter discs, 00:01:13.680 --> 00:01:18.180 and they were an analog video format, holding up to one hour of video per side. 00:01:18.180 --> 00:01:22.290 Competing in a world where the videocassette recorder which could record from live TV already 00:01:22.290 --> 00:01:27.030 existed, the Laserdisc failed to capture the hearts and minds of many individuals even 00:01:27.030 --> 00:01:29.090 though it had steller video quality. 00:01:29.090 --> 00:01:33.640 Throughout its life, it stayed a videophile-only format in most markets. 00:01:33.640 --> 00:01:37.850 But, the development of the Laserdisc, which was done in large part by Philips, presented 00:01:37.850 --> 00:01:41.800 an obvious solution to the problem of digital sound storage. 00:01:41.800 --> 00:01:45.780 See, although Laserdisc is an analog format, the signals encoded on it are as a series 00:01:45.790 --> 00:01:47.270 of pits and lands. 00:01:47.270 --> 00:01:49.770 OK, optical disc fundamentals time! 00:01:49.770 --> 00:01:53.670 You might already be aware of this, but optical discs are read by shining a laser up at a 00:01:53.670 --> 00:01:56.780 reflective disc that is covered with little pits. 00:01:56.780 --> 00:02:00.850 These pits are roughly one quarter as deep as the wavelength of laser light that will 00:02:00.850 --> 00:02:01.850 hit them. 00:02:01.850 --> 00:02:06.310 I ran into some inconsistencies regarding the exact depth of the pits, because the only 00:02:06.310 --> 00:02:11.120 source I found which specifies it has the wrong wavelength of light listed for the CD, 00:02:11.120 --> 00:02:15.470 but all you need to know is that when the focused laser hits a pit, the increased depth 00:02:15.470 --> 00:02:19.951 causes the reflected light to destructively interfere with the projected light, which 00:02:19.951 --> 00:02:23.130 reduces the overall intensity of the light reflected back. 00:02:23.130 --> 00:02:26.340 That’s actually a pretty neat part that often gets overlooked. 00:02:26.340 --> 00:02:29.870 Endless articles talk about the fact that the pits change how the light is reflected, 00:02:29.870 --> 00:02:33.160 but very few mention the destructive interference aspect of it. 00:02:33.160 --> 00:02:37.400 I’ve shown this diagram before, and it perfectly demonstrates what happens. 00:02:37.400 --> 00:02:41.631 When the laser hits a not-pit, the light gets reflected right back down to the laser, and 00:02:41.631 --> 00:02:44.500 a prism reflects some of this into the photocell. 00:02:44.500 --> 00:02:49.030 But when it hits a pit, the destructive interference greatly reduces the intensity of the reflected 00:02:49.030 --> 00:02:52.150 light, so very little light hits the photocell. 00:02:52.150 --> 00:02:56.220 This is how a laser pickup system can tell the difference between a pit and a land. 00:02:56.220 --> 00:03:00.730 In the LaserDisc system, these pits and lands were used to encode analog video and audio 00:03:00.730 --> 00:03:05.880 signals via a weird hybrid of pulse-width modulation and frequency modulation-- 00:03:05.880 --> 00:03:07.860 Don't ask, it’s complicated 00:03:07.860 --> 00:03:12.470 --and the result is a usable analog video signal from a shiny plastic disc. 00:03:12.470 --> 00:03:17.350 So, having already invented a thing that used lasers to read information on a disc, when 00:03:17.350 --> 00:03:21.660 it came time for a digital music format to hit the scene, Philips was poised to knock 00:03:21.660 --> 00:03:27.540 it out of the park with a new disc, this one no less lasery, but quite a bit more compact. 00:03:27.540 --> 00:03:32.810 They named the format along the lines of their previous compact invention, the compact cassette, 00:03:32.810 --> 00:03:37.540 and in a non-coincidence, the diameter of the CD is roughly the same as the diagonal 00:03:37.540 --> 00:03:39.260 length of the Compact Cassette. 00:03:39.260 --> 00:03:41.940 Ah, but let’s not forget Sony’s role. 00:03:41.940 --> 00:03:46.900 Sony, the people who seem to only make either runaway successes or disastrous failures, 00:03:46.900 --> 00:03:50.020 had been working on digital audio for some time. 00:03:50.020 --> 00:03:54.180 They were the ones that developed a PCM adapter for use with U-Matic videocassette recorders 00:03:54.180 --> 00:03:58.170 as discussed in the previous video, and in fact they were working on an digital optical 00:03:58.170 --> 00:04:01.400 audio disc before Philips released the Laserdisc. 00:04:01.400 --> 00:04:06.019 One of their early prototypes from 1977 was the same size as one of these honkers and 00:04:06.019 --> 00:04:11.349 held only an hour of digital audio, though at the same exact quality of the soon-to-be 00:04:11.349 --> 00:04:14.050 Compact Disc-Digital Audio standard. 00:04:14.050 --> 00:04:18.259 Philips and Sony were sort of working on the same thing at the same time, though Philips 00:04:18.259 --> 00:04:22.339 had the notable advantage of having already developed and manufactured the Laserdisc by 00:04:22.339 --> 00:04:24.370 the time things really heated up. 00:04:24.370 --> 00:04:26.880 Still, Sony contributed a lot. 00:04:26.880 --> 00:04:31.639 I don’t want to get too into the weeds of who did what, so let’s just jump to 1979, 00:04:31.639 --> 00:04:36.180 the year that Sony and Philips first decided to for realsies collaborate on the project. 00:04:36.180 --> 00:04:39.610 By this time, optical disc fundamentals had been established. 00:04:39.610 --> 00:04:43.780 An optical disc seemed the perfect format for digital data, because you could just easily 00:04:43.780 --> 00:04:45.620 call a pit a one and a land a zero. 00:04:45.620 --> 00:04:47.279 But that’s not how it works! 00:04:47.279 --> 00:04:51.599 No, the pits and lands are important, but it is the change between a pit and a land 00:04:51.599 --> 00:04:55.389 that encodes a 1, and no change encodes a zero. 00:04:55.389 --> 00:05:00.120 This is time-based, so a four-bit span of time which is comprised of either all pits 00:05:00.120 --> 00:05:03.710 or all lands will produce 4 zero bits. 00:05:03.710 --> 00:05:08.770 Start the sequence with a change and then continue as is, and you get 1000. 00:05:08.770 --> 00:05:13.979 No change, change, no change, no change, and you get 0100. 00:05:13.979 --> 00:05:14.990 And you get the idea. 00:05:14.990 --> 00:05:18.319 This is called Non-Return-To-Zero inverted encoding. 00:05:18.319 --> 00:05:23.430 Now, this has limitations because a long span of zeros requires an outside clock to keep 00:05:23.430 --> 00:05:26.699 track of how many “dead” spaces have passed. 00:05:26.699 --> 00:05:32.009 The longer you have between ones, or changes, the more ambiguous the number of zeroes becomes. 00:05:32.009 --> 00:05:33.869 I know what you’re thinking. 00:05:33.869 --> 00:05:35.699 Was that six zeros or only five? 00:05:35.699 --> 00:05:39.919 Well, to tell you the truth in all this excitement I kinda lost track myself. 00:05:39.919 --> 00:05:44.629 Which is why you need an outside timing source keeping track of how many shots, I mean bits, 00:05:44.629 --> 00:05:45.819 have passed. 00:05:45.819 --> 00:05:47.750 This isn’t somewhere you should just feel lucky. 00:05:47.750 --> 00:05:48.960 But that’s not a problem. 00:05:48.960 --> 00:05:51.879 What is a problem is the nature of everything. 00:05:51.879 --> 00:05:57.210 How likely do you think it is that a pressed CD is absolutely perfect, has no scratches 00:05:57.210 --> 00:06:02.270 at all, and that the CD player reading the disc will perfectly, without any errors, reproduce 00:06:02.270 --> 00:06:05.229 the correct sequence of ones and zeros? 00:06:05.229 --> 00:06:08.069 If you answered “not likely at all” you’re a winner! 00:06:08.069 --> 00:06:12.309 To help make the data less susceptible to stupid little things, two robust error-fighting 00:06:12.309 --> 00:06:14.719 mechanisms are built into the data stream. 00:06:14.719 --> 00:06:18.960 The Red-Book standard, the first of the Rainbow Books that defines the physical, digital, 00:06:18.960 --> 00:06:23.949 and other various standards surrounding each type of Compact Disc, not only specifies the 00:06:23.949 --> 00:06:28.639 sample rate and bit depth of the Compact Disc Digital Audio format, which as previously 00:06:28.640 --> 00:06:35.760 discussed is 44.1 kilohertz, 16 bit, but it also defines how the data is encoded on the disc. 00:06:35.760 --> 00:06:39.559 Now this is rather technical but I think interesting, so bear with me. 00:06:39.559 --> 00:06:44.160 So, each audio sample is a signed, which means it can be positive or negative, 00:06:44.160 --> 00:06:46.240 16 bit two’s complement, 00:06:46.240 --> 00:06:50.580 which is a mathematical operation on binary numbers that we’re just gonna not worry about right now because it hurts my brain, 00:06:50.580 --> 00:06:51.700 integer. 00:06:51.700 --> 00:06:55.639 I mean, we knew we’re dealing with 16 bit audio so each sample is gonna be 16 bits. 00:06:55.639 --> 00:07:00.439 Now, on the disc, 12 samples, 6 each for the left and right channels, are stored together 00:07:00.439 --> 00:07:06.259 in a frame of 192 bits (that’s 24 bytes, for those playing along at home). 00:07:06.259 --> 00:07:10.589 These frames are then encoded using an error correction scheme called CIRC, which stands 00:07:10.589 --> 00:07:13.509 for Cross-interleaved Reed-Solomon coding. 00:07:13.509 --> 00:07:18.129 In addition to adding one data parity byte to every three raw data bytes, the effect 00:07:18.129 --> 00:07:21.990 of CIRC is basically to spread the data out over a longer distance. 00:07:21.990 --> 00:07:24.979 That’s where the interleaving part of the name comes from. 00:07:24.979 --> 00:07:30.520 By jumbling up multiple frames and adding parity bytes, CIRC can correct up to 3,500 00:07:30.520 --> 00:07:35.890 bits of error-filled or even missing data, and can compensate for up to 12,000 bits by 00:07:35.890 --> 00:07:38.800 masking errors via interpolation. 00:07:38.800 --> 00:07:44.199 This translates to up to 2.4mm gaps in data being completely corrected for, and up to 00:07:44.199 --> 00:07:49.330 an 8.5mm scrambling of data, either through a scratch or some other damage, being reasonably 00:07:49.330 --> 00:07:51.409 interpolated and masked. 00:07:51.409 --> 00:07:54.347 The end result is that the error is either completely corrected, 00:07:54.347 --> 00:07:57.330 or it’s fudged well enough that you won’t hear it. 00:07:57.330 --> 00:07:59.280 Now we’re gonna go on a minor tangent here. 00:07:59.280 --> 00:08:00.280 I apologize. 00:08:00.320 --> 00:08:05.020 I’ve linked in the description the source material from the Wikipedia article on CIRC. 00:08:05.039 --> 00:08:09.339 This source material is from a book written by Kees Schouhamer Immink, one of the central 00:08:09.339 --> 00:08:12.520 engineers involved in the development of the Compact Disc. 00:08:12.520 --> 00:08:17.090 He even won an Emmy for his work on coding technology for optical recording formats. 00:08:17.090 --> 00:08:21.379 I’m bringing this up because for every person that tells you Wikipedia is a worthless starting 00:08:21.379 --> 00:08:26.839 point for research, I want you to show them the references section at the bottom of articles. 00:08:26.839 --> 00:08:32.610 Yes, you would be very unwise to cite “Wikipedia” in any research, but let me tell you, 00:08:32.610 --> 00:08:37.130 you may be amazed at the quality of the source material, and you’d be a fool to not at 00:08:37.130 --> 00:08:41.780 least look at these references when doing any preliminary research of your own. 00:08:41.780 --> 00:08:42.700 Rant over. 00:08:42.700 --> 00:08:47.400 In addition to CIRC, the use of eight-to-fourteen modulation limits the total number of possible 00:08:47.400 --> 00:08:50.150 combinations of ones and zeros. 00:08:50.150 --> 00:08:54.510 EFM translates each 8 bit word into a 14 bit word. 00:08:54.510 --> 00:08:59.750 These 14 bit words are translated back into their original 8 bit words using a lookup table. 00:08:59.750 --> 00:09:03.030 The point of doing this is to reduce the possibility of errors. 00:09:03.030 --> 00:09:08.610 The use of EFM makes it such that binary ones are always separated by at least two zeros, 00:09:08.610 --> 00:09:10.840 and a maximum of 10 zeros. 00:09:10.840 --> 00:09:14.780 This means that every pit and land is at least 3 clock cycles long. 00:09:14.780 --> 00:09:19.070 It also means that if the CD player reads one, zero, one, it knows it must have made 00:09:19.070 --> 00:09:21.560 an error because that’s not a possible sequence. 00:09:21.560 --> 00:09:26.260 Plus, with a maximum of 10 zeroes, it reduces the accuracy required in the clock of the 00:09:26.260 --> 00:09:32.110 CD player for worst-case clock recovery, as there must be a one after every eleventh bit, 00:09:32.110 --> 00:09:35.850 and this will in effect synchronize and restart the zero-counting clock. 00:09:35.850 --> 00:09:41.110 Keep in mind that with simple 8 bit encoding, in theory you could have 14 zeros in a row. 00:09:41.110 --> 00:09:44.830 When you realize all of the processing that has to be done by the CD player before it 00:09:44.830 --> 00:09:49.140 can even extract the data it needs to send to the DAC and play the dang music, you gain 00:09:49.140 --> 00:09:52.070 a newfound respect for its achievements of the time. 00:09:52.070 --> 00:09:56.780 Granted, using a look-up table and performing some basic arithmetic is easy for a computer, 00:09:56.780 --> 00:10:01.320 but the fact that this was being done at a consumer hardware level in 1982, with a data 00:10:01.320 --> 00:10:05.450 throughput faster than what any contemporary microcomputer would reasonably be expected 00:10:05.450 --> 00:10:07.700 to process, impresses me. 00:10:07.700 --> 00:10:12.290 To help provide logical access to the contents of the disc, the disc’s data stream is divided 00:10:12.290 --> 00:10:13.560 into three parts. 00:10:13.560 --> 00:10:16.760 The lead-in, the program area, and lead-out. 00:10:16.760 --> 00:10:20.160 The lead-in contains the disc’s Table of Contents, which is basically an announcement 00:10:20.160 --> 00:10:24.090 to the player of how long it is, how many tracks it contains, and what the timecode 00:10:24.090 --> 00:10:25.980 is for each of the tracks. 00:10:25.980 --> 00:10:30.280 The CD player can, through reading the table of contents, determine where each track is 00:10:30.280 --> 00:10:32.700 for accessing it nearly instantly. 00:10:32.700 --> 00:10:38.851 A CD can have up to 99 tracks, which themselves can be divided further into 100 indexes, though 00:10:38.851 --> 00:10:43.920 this feature was rarely ever used and few CD players could access the index information. 00:10:43.920 --> 00:10:48.030 One thing that computers have made a little confusing about the Compact Disc-Digital Audio 00:10:48.030 --> 00:10:52.790 standard is that audio CDs do not contain files. 00:10:52.790 --> 00:10:56.720 If you pop one into a PC, it’s gonna show you each track as its own object. 00:10:56.720 --> 00:10:59.810 But the computer is interpreting that for you. 00:10:59.810 --> 00:11:04.690 In raw form, the data on a CD is just one continuous stream, and the table-of-contents 00:11:04.690 --> 00:11:09.770 in the lead-in simply defines where along the stream each track is. 00:11:09.770 --> 00:11:13.180 The concept of using a CD for computer data storage 00:11:13.180 --> 00:11:15.180 just wasn’t really in the cards yet. 00:11:15.180 --> 00:11:20.100 I mean, a single audio track would easily fill up entire hard drives of the time, so 00:11:20.100 --> 00:11:25.110 the idea of creating files to contain the audio data was just absurd. 00:11:25.110 --> 00:11:29.400 The later CD-ROM, following the Yellow-book standard, would allow for file structures 00:11:29.400 --> 00:11:31.990 on discs like a computer is used to accessing. 00:11:31.990 --> 00:11:33.170 But we’ll get to that later. 00:11:33.170 --> 00:11:36.160 OK, so let’s look a little bit closer at the disc itself. 00:11:36.160 --> 00:11:40.960 First, I want you to see if you can spot a big difference between a Laserdisc and a CD. 00:11:40.970 --> 00:11:44.890 Looking at the edge of a Laserdisc, can you see that seam in the middle? 00:11:44.890 --> 00:11:48.700 Laserdiscs are obviously double sided, so that seam is the join between the two halves 00:11:48.700 --> 00:11:52.490 of the disc, and the data is sandwiched between two sides. 00:11:52.490 --> 00:11:55.320 But if you look at the CD, there is no seam. 00:11:55.320 --> 00:11:59.500 One of the weirder things about the CD is that the data layer is actually at the top 00:11:59.500 --> 00:12:01.770 of the disc, just beneath the label. 00:12:01.770 --> 00:12:05.240 I’ve linked to a How It’s Made episode on the Compact Disc that does a pretty good 00:12:05.240 --> 00:12:08.810 job of demonstrating how mass-produced discs are made. 00:12:08.810 --> 00:12:12.780 Their manufacture is surprisingly similar to that of conventional vinyl records, as 00:12:12.780 --> 00:12:16.280 they are stamped (or rather molded) from a master disc. 00:12:16.280 --> 00:12:20.080 The video does a great job of showing this process, but it skips over the actual etching 00:12:20.080 --> 00:12:22.480 of the data onto the glass master. 00:12:22.480 --> 00:12:26.540 In short, the master is covered in a solution that will either evaporate or harden when 00:12:26.540 --> 00:12:30.420 exposed to laser light, depending on the mastering process used. 00:12:30.420 --> 00:12:35.060 By using the laser to etch pits into the coating, which is then hardened with a development 00:12:35.060 --> 00:12:39.280 process, the glass master is now covered in bumps that will represent the lands in the 00:12:39.280 --> 00:12:40.720 molded discs. 00:12:40.720 --> 00:12:45.500 The master disc is metallized to harden these bumps, and now polycarbonate discs are molded 00:12:45.500 --> 00:12:46.500 from it. 00:12:46.500 --> 00:12:49.880 And that’s something that I find really neat about the Compact Disc. 00:12:49.880 --> 00:12:54.290 The data in stamped discs is actually in the plastic itself. 00:12:54.290 --> 00:12:58.120 When the disc comes out of the mold, it’s completely transparent. 00:12:58.120 --> 00:13:00.730 But it has all of the data on its surface. 00:13:00.730 --> 00:13:05.850 To make the disc readable, it’s then covered in a thin film of aluminum via a vapor metallization 00:13:05.850 --> 00:13:09.600 process, and now the disc could theoretically be read by a CD player. 00:13:09.600 --> 00:13:14.240 But remember, those pits and lands are on the top of the disc, exposed. 00:13:14.240 --> 00:13:17.220 If they could be touched, the data would be destroyed. 00:13:17.220 --> 00:13:21.360 So before the disc can be handled, it needs a thin coat of varnish to be spread along 00:13:21.360 --> 00:13:24.330 the top, and now the data is protected from damage. 00:13:24.330 --> 00:13:28.360 Putting the data layer on the top of the disc meant that the disc was even more tolerant 00:13:28.360 --> 00:13:33.740 of scratches, as these scratches are out of focus to the laser reading the disc from below. 00:13:33.740 --> 00:13:35.560 This was a pretty smart move. 00:13:35.560 --> 00:13:40.460 The laser would read through almost the entire 1.2mm thickness of the CD. 00:13:40.460 --> 00:13:44.580 As a consequence, double-sided CDs were never a legitimate thing. 00:13:44.580 --> 00:13:49.390 But there were some weird shenanigans tried with making double sided hybrid discs. 00:13:49.390 --> 00:13:53.340 One of these I have somewhere in my collection but I couldn’t find it because I’m disorganized, 00:13:53.340 --> 00:13:54.990 (sorry) is the DualDisc. 00:13:54.990 --> 00:13:59.340 “Weird Al” Yankovic’s twelfth studio album, Straight Outta Lynwood, was released 00:13:59.340 --> 00:14:05.130 in 2006 as a DualDisc, with one side being a fully compliant DVD containing music videos 00:14:05.130 --> 00:14:07.960 and other goodies, and the other side being a… 00:14:07.960 --> 00:14:09.520 almost CD. 00:14:09.520 --> 00:14:14.860 DualDiscs were .3mm thicker than a standard CD or DVD, comprising a total thickness of 00:14:14.860 --> 00:14:18.590 1.5mm rather than the standard 1.2. 00:14:18.590 --> 00:14:23.910 The CD layer was placed .9 mm into the disc, with the DVD layer .6 into the disc from the 00:14:23.910 --> 00:14:26.690 other side, which is correct for a DVD. 00:14:26.690 --> 00:14:30.950 But it’s off by at least .2mm according to the Red Book standard. 00:14:30.950 --> 00:14:35.360 Because of this, DualDiscs did not contain the Compact Disc Digital Audio logo on them 00:14:35.360 --> 00:14:37.820 because they technically weren’t CDs. 00:14:37.820 --> 00:14:41.940 They featured language saying that they were intended to work in standard CD players, and 00:14:41.940 --> 00:14:46.650 almost certainly they would given the tolerances a standard CD player is designed to deal with, 00:14:46.650 --> 00:14:51.210 but they could not actually be officially referred to as a Compact Disc. 00:14:51.210 --> 00:14:52.920 So there’s some fun trivia for you. 00:14:52.920 --> 00:14:55.090 AAAND, that’s where we’ll hit pause. 00:14:55.090 --> 00:14:59.220 There’s a lot of neat stuff to uncover about the CD, even though it’s teetering on the 00:14:59.220 --> 00:15:01.300 edge of obsolete and insignificant. 00:15:02.220 --> 00:15:03.800 OK, it is pretty much obsolete. 00:15:03.800 --> 00:15:08.490 This dime-sized SD card holds more data than this entire column of CDs. 00:15:08.490 --> 00:15:11.550 That’s kinda sad, but also amazing. 00:15:11.550 --> 00:15:15.070 In my next video on this subject, we’ll explore more of the innards of the compact 00:15:15.070 --> 00:15:18.500 disc, such as the optical pickups mechanisms and the rather major difference between how 00:15:18.500 --> 00:15:22.230 Philips designed its laser pickup compared to most others. 00:15:22.230 --> 00:15:26.050 If you take a look at the disc tray on this Magnavox unit, you might get a hint. 00:15:26.050 --> 00:15:31.090 Of course we’ll also touch on the other various uses of the CD, such as CD-ROM, CD-R 00:15:31.090 --> 00:15:34.000 and CD-RW, and other stuff. 00:15:34.000 --> 00:15:37.100 And then, we’ll relish in the fact that everything is on the Internet now. 00:15:37.100 --> 00:15:38.900 Thanks for watching, I hope you enjoyed the video! 00:15:38.900 --> 00:15:42.320 If this is your first time coming across the channel and you liked what you saw, please 00:15:42.320 --> 00:15:43.990 consider subscribing! 00:15:43.990 --> 00:15:47.770 As always, thank you to everyone who supports this channel on Patreon, especially the fine 00:15:47.770 --> 00:15:49.710 folks that have been scrolling up your screen. 00:15:49.710 --> 00:15:53.630 If you’re interested in making a contribution to the channel to help it grow, please check 00:15:53.630 --> 00:15:54.840 out my Patreon page. 00:15:54.840 --> 00:15:56.600 Thanks for your consideration! 00:15:56.600 --> 00:16:00.240 Don’t forget there’s a Technology Connections subreddit now, so if you’re a redditer you 00:16:00.240 --> 00:16:03.940 can go over there and watch me not know how to use it, and I’m getting better a Twitter 00:16:03.940 --> 00:16:07.300 so if that’s something you do, you can follow me @TechConnectify. 00:16:07.300 --> 00:16:08.840 Anyway, that’s it for now. 00:16:08.850 --> 00:16:10.180 I’ll see you next time! 00:16:10.180 --> 00:16:11.840 Cue obnoxious music! 00:16:12.300 --> 00:16:16.900 ♫ uncomfortably smooth jazz ♫ 00:16:17.160 --> 00:16:19.760 This line read better before… 00:16:19.760 --> 00:16:22.760 With its vast data capacity, relatively lobrust… 00:16:24.360 --> 00:16:25.360 this line. 00:16:25.370 --> 00:16:27.610 This line is going to kill me! 00:16:27.610 --> 00:16:31.529 When it came time for digital music formats to hit the scene, Philips was poised to knock 00:16:31.529 --> 00:16:33.120 it out of the par--poised? 00:16:33.120 --> 00:16:34.300 (stares into camera doubting himself) 00:16:34.300 --> 00:16:35.940 No, that’s what I wrote. 00:16:37.540 --> 00:16:38.620 That’s what I wrote! 00:16:38.620 --> 00:16:40.480 I’m regretting it now… 00:16:40.480 --> 00:16:44.990 The Red Book Standard, the first of the rainbow books that define the physical, dizhidal, 00:16:44.990 --> 00:16:47.200 and other… dizhidal dizidal diblelr…. 00:16:47.820 --> 00:16:48.320 (clears throat) 00:16:48.720 --> 00:16:52.800 ...reduces the accuracy required in the clock of the CD player for weush… 00:16:55.240 --> 00:16:57.140 [exasperated sigh] 00:16:57.140 --> 00:16:59.900 The master disc is metAL…. 00:17:00.300 --> 00:17:01.800 Metalized.