WEBVTT
Kind: captions
Language: en

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Today, I want to show you a pretty weird device.

00:00:03.734 --> 00:00:07.174
This hi-fi component lookin’ thing from Sony is a

00:00:07.174 --> 00:00:09.422
DIGITAL AUDIO PROCESSOR

00:00:09.422 --> 00:00:12.883
and it’s got a rather strange assortment of connections on the back.

00:00:12.883 --> 00:00:18.543
We have audio in and out, pretty normal, but also… video in and out?

00:00:18.543 --> 00:00:20.866
Annnnd… monitor out?

00:00:20.866 --> 00:00:22.968
Copy out?

00:00:22.968 --> 00:00:28.010
Well, I suppose to figure out what this does
we should hook it up to an audio source and a TV.

00:00:28.010 --> 00:00:30.369
Why, that’s as easy as a jumpcut!

00:00:30.369 --> 00:00:35.478
With my microphone wired to its audio input
and a TV hooked up to its video output,

00:00:35.478 --> 00:00:42.220
we find that this supposed “digital audio processor”
is doing something quite odd.

00:00:42.220 --> 00:00:46.903
Before we get a closer look, be aware that things
are going to get somewhat flickery

00:00:46.903 --> 00:00:49.890
and that will continue throughout much of this video.

00:00:49.890 --> 00:00:54.620
It’s more like rapidly changing patterns than it is a flickering image,

00:00:54.620 --> 00:00:59.399
but if that sounds bothersome to you…
you may want to skip this one.

00:00:59.399 --> 00:01:05.084
At first glance it appears as though we’re
looking at the snow of a TV tuned to a dead channel,

00:01:05.084 --> 00:01:10.880
but there’s definitely some structure to what’s on the screen,
and it’s responding to my voice.

00:01:10.880 --> 00:01:13.000
Let’s take a look at a raw video feed.

00:01:13.000 --> 00:01:15.474
Good luck, YouTube compression.

00:01:15.474 --> 00:01:21.450
As perhaps you can see, similar patterns appear
depending on what exactly my voice is doing.

00:01:21.450 --> 00:01:34.189
If I exteeeend vooowelll sounds weee seeee distreeeeet
blocky shapes come and go.

00:01:34.189 --> 00:01:37.637
And if the spicy snap of sibilance saturates the soundscape,

00:01:37.637 --> 00:01:40.810
we see some spans of snowier snow.

00:01:40.810 --> 00:01:45.281
How ‘bout, instead of my voice, we use a
signal generator for a sine-wave sweep?

00:01:45.777 --> 00:01:53.312
[an ascending sine wave sweep]

00:01:53.964 --> 00:01:55.269
Interesting.

00:01:55.269 --> 00:01:57.789
Let’s do that again but with sawtooth waves.

00:01:57.789 --> 00:02:05.048
[an ascending sawtooth-wave seep]

00:02:05.451 --> 00:02:07.673
Similar, but spiky!

00:02:07.673 --> 00:02:13.605
Now, if a device which turns sound into this
weird imagery seems pretty pointless,

00:02:13.605 --> 00:02:18.324
that’s because these visuals are not the point of it at all.

00:02:18.324 --> 00:02:24.055
Well, ok technically yes they are but you wouldn’t ordinarily be looking at them.

00:02:24.055 --> 00:02:28.897
Devices like this are more generically known as PCM adapters,

00:02:28.897 --> 00:02:33.053
and the mess you’re looking at is actually digital audio data.

00:02:33.053 --> 00:02:37.406
This is what it would look like if you took
the analog sound signal from my microphone,

00:02:37.406 --> 00:02:40.648
digitized it using 16 bit pulse-code modulation,

00:02:40.648 --> 00:02:48.603
then encoded the resulting datasteam as high-low pulses tucked neatly into the scanlines of an NTSC television signal.

00:02:48.603 --> 00:02:53.886
And the reason I can say that with confidence
is because that’s precisely what’s goin’ on here.

00:02:53.886 --> 00:03:00.460
Once again I have friend of the channel James Colvard
to thank for lending this fascinating thing to me.

00:03:00.460 --> 00:03:03.067
This device represents what was for many years

00:03:03.067 --> 00:03:08.985
the easiest solution to the biggest problem facing digital sound reproduction.

00:03:08.985 --> 00:03:15.879
On the surface, digital sound should be easy
as the concepts behind it are actually pretty straightforward.

00:03:15.879 --> 00:03:20.960
At the risk of oversimplifying,
you can make digital sound happen with only two chips:

00:03:20.960 --> 00:03:24.000
the first one, the analog-to-digital converter,

00:03:24.000 --> 00:03:29.218
takes a single input from a microphone or whatever other analog source you like and,

00:03:29.218 --> 00:03:32.502
through a bunch of comparators and logic gates and junk

00:03:32.502 --> 00:03:36.887
it will spit out a binary integer across several outputs.

00:03:36.887 --> 00:03:43.659
To give an example, if we give this theoretical
8-bit ADC an input signal of 700 millivolts,

00:03:43.659 --> 00:03:51.206
that results in these output pins going high
- a result of 01101011.

00:03:51.206 --> 00:03:57.365
And something that I want to stress here is
that while we could convert this result into base-10 numbers,

00:03:57.365 --> 00:04:02.280
there’s no need to do that -
we’re just going to send this sequence of bits to a second chip.

00:04:02.745 --> 00:04:06.446
That chip, the digital-to-analog converter (or DAC),

00:04:06.446 --> 00:04:10.659
has a digital input side and an analog output side.

00:04:10.659 --> 00:04:16.259
To reproduce the original signal intensity,
all we need to do is put the right bits into the right slots.

00:04:16.259 --> 00:04:19.040
So, with our theoretical 8-bit system,

00:04:19.040 --> 00:04:26.325
applying voltage to the pins in the same pattern the ADC just gave us 
(low high high low high low high high)

00:04:26.325 --> 00:04:31.694
will result in thIS chip producing an output signal of 700 millivolts.

00:04:31.694 --> 00:04:36.483
All we need to do is ensure that these two
chips speak the same language - as in,

00:04:36.483 --> 00:04:43.380
the same sequences of bits produced by the ADC
are mapped to the same signal outputs in a matching DAC.

00:04:43.380 --> 00:04:46.601
And that’s done at the hardware design level.

00:04:46.601 --> 00:04:53.010
This particular flavor of digital sound is called pulse-code modulation or PCM.

00:04:53.010 --> 00:04:58.780
The analog-to-digital converter takes an instantaneous
snapshot of the analog input’s signal strength

00:04:58.780 --> 00:05:00.490
and spits out a code.

00:05:00.490 --> 00:05:05.734
Then the digital-to-analog converter takes
that code and spits out an analog output

00:05:05.734 --> 00:05:09.940
(which you might call a pulse) 
that matches the original snapshot.

00:05:10.374 --> 00:05:14.808
It’s actually pretty easy,
but the problem is that to reproduce sound,

00:05:14.808 --> 00:05:19.289
you need to take a lot of snapshots of the signal.

00:05:19.289 --> 00:05:21.691
We usually call those snapshots samples,

00:05:21.691 --> 00:05:28.994
and to faithfully reproduce sound
you need to take a few dozen thousand samples every second.

00:05:28.994 --> 00:05:30.384
No big deal.

00:05:30.570 --> 00:05:34.419
Technically, that truly is not that big of a deal.

00:05:34.419 --> 00:05:37.547
We can take samples from the ADC very frequently

00:05:37.547 --> 00:05:42.720
and it’s not a big challenge to make a DAC
which can ingest those samples just as fast.

00:05:42.720 --> 00:05:47.062
We had the tech to do that readily available in the 1960’s.

00:05:47.062 --> 00:05:52.279
Trouble is, while it might be easy to make
data from sound and sound from data,

00:05:52.279 --> 00:05:57.321
doing that in real-time is just building an overly-complicated radio.

00:05:57.321 --> 00:05:59.320
Digital sound wouldn't have much of a point

00:05:59.320 --> 00:06:04.261
unless we can store the pulse-code data somewhere to be read back later.

00:06:04.851 --> 00:06:07.979
And that step ain’t easy.

00:06:08.569 --> 00:06:14.694
An analog-to-digital converter spitting out
pulse code data may not be doing anything all that complex,

00:06:14.694 --> 00:06:19.516
but it produces an utterly unmanageable quantity of data.

00:06:20.416 --> 00:06:27.199
These days, of course, it’s a breeze,
but when digital sound was getting off the ground this was a heckuva problem.

00:06:27.199 --> 00:06:33.551
The very first PCM audio recorder was built by NHK in Japan back in 1967.

00:06:33.551 --> 00:06:39.500
This single-channel recorder had a sampling rate of 30 kilohertz
 and took 12 bit samples.

00:06:39.500 --> 00:06:44.870
That’s a bit shy of modern standards,
but thanks to the Nyquist-Shannon Sampling Theorem,

00:06:44.870 --> 00:06:51.134
we know that it could reproduce sounds up to 15 kHz,
which is about where FM radio tops out.

00:06:51.134 --> 00:06:57.504
While there most definitely were computers
that handled and stored digital data back in 1967,

00:06:57.504 --> 00:07:02.157
nothing remotely suitable for digital audio was available on the market.

00:07:02.157 --> 00:07:04.931
I mean, punch cards? Forget that.

00:07:04.931 --> 00:07:07.030
9-track tape?

00:07:07.030 --> 00:07:14.100
That might work, but NHK’s device would
completely fill up a 2400 foot tape in less than 17 minutes.

00:07:14.100 --> 00:07:16.243
And while hard drives did exist,

00:07:16.243 --> 00:07:23.772
even if you wanted to shell out the however many tens of thousands of dollars it took to buy one of IBM’s room-sized monsters,

00:07:23.772 --> 00:07:31.855
NHK’s singl-channel PCM recorder
would fill up the entire nine-disk array in less than two hours.

00:07:32.444 --> 00:07:34.501
That just ain’t gonna work!

00:07:34.501 --> 00:07:42.779
However, NHK didn’t need the complexity of a file system
or the random-access capabilities of true “data storage” -

00:07:42.779 --> 00:07:50.370
they just needed something that could write down a whole bunch of binary
really really fast, and then read it back just as quickly.

00:07:50.370 --> 00:07:53.669
As it turned out, although it would need a little modification,

00:07:53.669 --> 00:07:56.749
an existing technology would fit the bill just fine.

00:07:56.749 --> 00:08:03.955
And it was one that NHK, being Japan’s national broadcaster, 
had really easy access to:

00:08:03.955 --> 00:08:05.940
a simple videotape recorder.

00:08:06.301 --> 00:08:10.627
See, you need tons of signal bandwidth for storing video signals.

00:08:10.627 --> 00:08:14.970
Analog video is made up of very rapidly-drawn lines.

00:08:14.970 --> 00:08:19.999
With 525 lines per video frame and 30 frames
being displayed every second,

00:08:19.999 --> 00:08:26.319
an ordinary TV draws 15,750 lines every second.

00:08:26.319 --> 00:08:31.746
Videotape recorders, through the use of spinning
heads that fly across long slices of magnetic tape

00:08:31.746 --> 00:08:33.812
(as well as a whole bunch of clever circuitry)

00:08:33.812 --> 00:08:38.952
were able to record those signals and
reproduce television images with decent fidelity.

00:08:39.821 --> 00:08:43.286
But there’s no rule saying what those images have to be!

00:08:43.286 --> 00:08:47.038
If you slap some high-low pulses across the video scanlines,

00:08:47.038 --> 00:08:51.124
that might look like a bunch of white and black spots to your eyes,

00:08:51.124 --> 00:08:54.902
but to the right circuit that looks like bits.

00:08:54.902 --> 00:09:03.666
So, NHK rigged up their PCM encoder to spit out the sample data produced by its ADC as a sequence of high-low pulses,

00:09:03.666 --> 00:09:09.419
then carefully timed them to match the video characteristics
of a black and white television signal.

00:09:09.419 --> 00:09:18.430
They hooked that contraption up to an ordinary
videotape recorder, and suddenly they had a practical way to store digital audio data.

00:09:18.430 --> 00:09:24.640
To retrieve it, the videotape was rewound to the start of the program
and the recorder was set to play mode.

00:09:24.640 --> 00:09:31.420
Now, the PCM recorder became a PCM decoder,
recovering the bitstream coming from the videotape,

00:09:31.420 --> 00:09:36.500
sending it to a DAC, and then finally the
digital sound was heard again.

00:09:36.500 --> 00:09:40.800
And that’s precisely what this thing from Sony... is.

00:09:40.800 --> 00:09:45.568
This is the exact same idea as NHK’s original PCM recorder concept,

00:09:45.568 --> 00:09:51.134
though updated with better capabilities on account of being from 1983.

00:09:51.134 --> 00:09:53.832
This takes a stereo analog audio input,

00:09:53.832 --> 00:10:01.087
digitizes it using 14 or 16 bit pulse-code modulation
at a sampling rate of 44.056 kilohertz

00:10:01.087 --> 00:10:04.841
(which might sound kinda weird but hold your horses we’ll get to that bit),

00:10:04.841 --> 00:10:10.000
and then spits out the resulting data across the scan lines of a video signal.

00:10:10.000 --> 00:10:16.250
Every one of those lines you see contains the data for six audio samples,
three for each channel,

00:10:16.250 --> 00:10:18.643
as well as a bit of formatting.

00:10:18.643 --> 00:10:24.415
Hook this thing’s video output up to a VCR and,
as far as the VCR knows,

00:10:24.415 --> 00:10:28.487
you’re just trying to record a weird TV program.

00:10:28.487 --> 00:10:32.073
Though it may question your taste, it’ll record it just fine.

00:10:32.073 --> 00:10:37.704
And you now have a videocassette which contains digital audio data.

00:10:37.704 --> 00:10:42.568
That on its own isn’t super useful, of course,
but this thing works in reverse, too!

00:10:42.568 --> 00:10:46.512
Rewind the tape you just created, hit play on the VCR,

00:10:46.512 --> 00:10:52.176
and now it’s looking at its video input
hoping to see some high-low pulses it can understand.

00:10:52.176 --> 00:10:56.488
If it finds them it starts decoding them and
sends the raw data through a buffer,

00:10:56.488 --> 00:11:03.081
and then to its digital-to-analog converter which reproduces
the stored sound through the stereo audio output.

00:11:05.749 --> 00:11:10.297
[a brief bit of garbled sound, then music of startingly good fidelity]

00:11:13.369 --> 00:11:21.346
And you have just experienced an effective method of creating and reproducing digital audio recordings using an ordinary videocassette recorder!

00:11:22.835 --> 00:11:27.153
This may seem convoluted,
in no small part because it absolutely is,

00:11:27.153 --> 00:11:32.230
but this is how digital audio worked for a very long time.

00:11:32.230 --> 00:11:37.724
Remember, we had the capability to record digital sound back in 1967,

00:11:37.724 --> 00:11:41.929
but the compact disc - the first truly digital audio format

00:11:41.929 --> 00:11:44.003
(well, other than piano music) -

00:11:44.003 --> 00:11:47.405
wouldn’t hit the market until 1982.

00:11:47.405 --> 00:11:55.029
And CDs had to resort to friggin lasers and
precision optics reading microscopic bumps on a shiny silver disc!

00:11:55.029 --> 00:12:04.056
Until that tech was mature, with very few exceptions high-fidelity 
digital sound reproduction relied on videotape recorders to be possible.

00:12:04.056 --> 00:12:08.681
It was the only reasonable way to handle so much data so quickly.

00:12:08.681 --> 00:12:11.453
But this wasn’t as easy as it might seem.

00:12:11.453 --> 00:12:18.893
Digital audio and videotape are not a perfect match
because the video signal isn’t actually continuous.

00:12:18.893 --> 00:12:24.610
Every field of video starts with a blanking interval which we can’t store any data in.

00:12:24.610 --> 00:12:29.150
And in fact, every video line also starts with a short blanking interval.

00:12:29.150 --> 00:12:34.589
But we can’t have gaps in the data -
audio sample data needs to be perfectly continuous.

00:12:34.589 --> 00:12:38.220
So, to deal with this, the adapter uses a buffer.

00:12:38.220 --> 00:12:44.790
When recording onto a tape, the continuous samples
coming from the ADC are briefly held in memory.

00:12:44.790 --> 00:12:50.030
The samples will pile up during the blanking intervals,
but once we’re past them and able to write data again,

00:12:50.030 --> 00:12:53.873
they’re quickly spat out in the six-sample chunks on each line.

00:12:53.873 --> 00:12:57.003
By the end of the video field, we’re caught up.

00:12:57.003 --> 00:13:02.810
During playback, of course, the opposite happens -
- as the samples come in, the samples get stored in a buffer

00:13:02.810 --> 00:13:07.220
so that the DAC can decode them sequentially without any gaps.

00:13:07.220 --> 00:13:09.790
Then there’s the issue of errors.

00:13:09.790 --> 00:13:16.167
No videotape recording is flawless - bad spots
on the tape will cause signal dropouts,

00:13:16.167 --> 00:13:23.769
and while they’re usually not much of a big deal when watching a movie,
the bits we’re dealing with here are teeny tiny.

00:13:23.769 --> 00:13:29.040
Even just the littlest blip could flip a bit,
so we’ll need some way to deal with that.

00:13:29.505 --> 00:13:32.180
And it turns out we have one!

00:13:32.180 --> 00:13:34.510
Look closely at the structure on-screen:

00:13:34.510 --> 00:13:43.649
we know there are six samples across every line, and we can see six clear sections spanning about the first 3/4s of the screen.

00:13:43.649 --> 00:13:45.480
But what’s all this then?

00:13:45.480 --> 00:13:48.420
Could it be some sort of checksum for error correction?

00:13:49.165 --> 00:13:51.530
Well, basically yes.

00:13:51.530 --> 00:13:57.703
I was finding frustratingly little information
on the technical specs of the data recording scheme here, but

00:13:57.703 --> 00:14:04.750
I did find this 1977 patent which talks about cyclic redundancy check words
getting added to the data.

00:14:04.750 --> 00:14:06.769
So that’s probably what that is.

00:14:06.769 --> 00:14:08.490
Some sorta math.

00:14:08.490 --> 00:14:10.270
And it works quite well!

00:14:10.270 --> 00:14:14.110
This modern VCR has various on-screen display elements,

00:14:14.110 --> 00:14:20.387
and despite plopping a big ol’ PLAY symbol in the top-right corner
and obscuring quite a bit of the bits,

00:14:20.387 --> 00:14:22.534
nothing sounds amiss when it’s up there.

00:14:25.666 --> 00:14:29.942
[music where nothing sounds amiss]

00:14:30.634 --> 00:14:37.339
Stray video dropouts can eat up entire lines
but I don’t even notice a blip in the sound when that happens.

00:14:37.339 --> 00:14:41.580
Actually, several lines can get corrupted before you hear an issue.

00:14:42.759 --> 00:14:49.188
[music which is mostly fine but stutters
or drops out briefly with big blips on the screen]

00:15:17.919 --> 00:15:19.880
Hi, I have an editor’s note!

00:15:19.880 --> 00:15:23.738
Though I don’t have concrete specifics,
I did find some promotional copy

00:15:23.738 --> 00:15:32.397
for an earlier PCM adapter of Sony’s and was able to confirm
that the data is interleaved between television scan lines.

00:15:32.397 --> 00:15:37.880
I don’t know exactly how, but shuffling
the data around and not recording it sequentially,

00:15:37.880 --> 00:15:42.829
along with the help of those cyclic redundancy
check codes getting tossed in with the data,

00:15:42.829 --> 00:15:46.370
allows it to recover from pretty gnarly video issues.

00:15:46.370 --> 00:15:50.942
And, like the compact disc, it has a system
to interpolate missing data

00:15:50.942 --> 00:15:54.220
to mask when large sections of it are not recoverable.

00:15:54.220 --> 00:15:56.550
It’s honestly quite impressive.

00:15:56.550 --> 00:15:59.053
As it happens, PCM adapters like this,

00:15:59.053 --> 00:16:02.897
along with the professional-grade U-matic videotape format,

00:16:02.897 --> 00:16:06.859
had a big part in the development of the compact disc.

00:16:06.859 --> 00:16:19.019
The objectively pretty weird 44.1 kilohertz sampling rate of compact disc digital audio happened because different parts of the world used different video standards.

00:16:19.019 --> 00:16:21.870
When developing their professional PCM adapters,

00:16:21.870 --> 00:16:28.647
Sony wanted to use a sample rate that would work
regardless of where you were, and 44.1 kHz 

00:16:28.647 --> 00:16:34.792
(that was three samples per video line across 14,700 visible lines per second)

00:16:34.792 --> 00:16:40.430
represented the best possible fit between NTSC and PAL equipment.

00:16:40.430 --> 00:16:46.470
Trying to squeeze any more samples in would risk
part of the data ending up in the vertical blanking interval.

00:16:46.470 --> 00:16:52.772
So, 44.1 kilohertz became the de-facto standard for PCM adapters,

00:16:52.772 --> 00:16:57.734
and was then incorporated as an official standard with the compact disc.

00:16:57.734 --> 00:16:59.141
But wait a second.

00:16:59.141 --> 00:17:04.181
Earlier me said that this thing runs at 44.056 kilohertz.

00:17:04.181 --> 00:17:07.339
That’s 0.1% less than 44.1.

00:17:07.339 --> 00:17:09.501
Explain the discrepancy!

00:17:09.501 --> 00:17:10.929
Well, see,

00:17:10.929 --> 00:17:19.010
Sony’s professional PCM equipment of the NTSC flavor
used videotape recorders that operated in black and white mode.

00:17:19.010 --> 00:17:23.688
But this is a consumer PCM adapter meant to
work with consumer VCRs,

00:17:23.688 --> 00:17:27.213
and those VCRs record color TV.

00:17:27.213 --> 00:17:30.130
And, for reasons we don’t need to get into here,

00:17:30.130 --> 00:17:36.600
color TV runs at 29.97 frames per second rather than 30.

00:17:36.600 --> 00:17:40.187
This thing still records six samples on every line of video,

00:17:40.187 --> 00:17:48.267
but those lines come in ever so slightly less often
and thus the sampling rate is a teeny bit slower.

00:17:48.267 --> 00:17:50.477
And now, here’s where I go

00:17:50.477 --> 00:17:52.151
“huh?”

00:17:52.151 --> 00:17:56.876
See, I have a pretty fundamental question regarding this unit.

00:17:57.776 --> 00:17:59.398
Why does it exist‽

00:18:00.236 --> 00:18:04.350
I knew encoding digital sound onto videotape was a thing we did,

00:18:04.350 --> 00:18:08.411
and I knew the story of U-matic tapes being important to CDs.

00:18:08.411 --> 00:18:14.484
But I always imagined PCM adapters as a decidedly
professional piece of equipment.

00:18:14.484 --> 00:18:16.903
Which this is clearly not.

00:18:16.903 --> 00:18:18.736
I mean, it’s not beige,

00:18:18.736 --> 00:18:20.633
it has normal RCA jacks,

00:18:20.633 --> 00:18:23.790
and it’s designed to work with consumer VCRs.

00:18:23.790 --> 00:18:29.881
Of course Sony would prefer that you hook this up to a Betamax deck,
but it works just fine with VHS machines, too,

00:18:29.881 --> 00:18:31.467
as you’ve seen.

00:18:31.467 --> 00:18:33.963
And it’s not like this was a one-off product —

00:18:33.963 --> 00:18:40.171
Sony had an entire line of consumer PCM adapters,
and this was by no means their first model.

00:18:40.171 --> 00:18:43.175
In fact, I think it might be the last.

00:18:43.175 --> 00:18:46.787
But you know what’s perhaps the strangest part of all this?

00:18:46.787 --> 00:18:53.281
The very first PCM adapter Sony ever made was a consumer product!

00:18:53.281 --> 00:18:56.083
Sony’s famous PCM-1600,

00:18:56.083 --> 00:19:03.290
the one that worked with U-matic VCRs, introduced 16 bit recording,
and cemented the standards for the upcoming compact disc,

00:19:03.290 --> 00:19:06.583
was released in 1978.

00:19:06.583 --> 00:19:15.366
But Sony’s PCM-1 was sold in 1977 as an accessory to Betamax home VCRs.

00:19:15.366 --> 00:19:19.884
It cost a cool $2000, and it did pretty much exactly what this thing does -

00:19:19.884 --> 00:19:22.044
just six years earlier.

00:19:22.044 --> 00:19:26.024
And when I learned this, a memory was unlocked.

00:19:26.024 --> 00:19:29.952
You’ve seen this ancient Betamax machine in several prior videos.

00:19:29.952 --> 00:19:35.679
It’s from 1979, so the PCM-1 had been available for purchase for a while.

00:19:35.679 --> 00:19:40.038
And under this little cover in the back is a switch marked

00:19:40.038 --> 00:19:41.806
“PCM”

00:19:41.806 --> 00:19:48.088
That’s there to disable some of this machine’s image-enhancing features
like dropout compensation.

00:19:48.088 --> 00:19:53.233
Those are great for video but can apparently
mess up the data encoded in video lines,

00:19:53.233 --> 00:20:00.169
so if you happen to have bought one of Sony’s PCM adapters,
you’ll want to flip this switch when using it.

00:20:00.169 --> 00:20:02.400
Of course, I had to try this out.

00:20:02.400 --> 00:20:05.337
I hooked the adapter up to this old tank of a thing,

00:20:05.337 --> 00:20:06.675
made a test recording,

00:20:06.675 --> 00:20:07.913
played it back

00:20:07.913 --> 00:20:13.067
and was frankly blown away at what I was witnessing.
[click of buttons, head drum spins up]

00:20:13.293 --> 00:20:19.451
[sudden guitar music]

00:20:19.451 --> 00:20:23.476
This is a very early home videocassette recorder.

00:20:23.476 --> 00:20:28.318
When this thing was new,
almost nobody had heard a real digital sound recording,

00:20:28.318 --> 00:20:31.684
and the compact disc was still three years away.

00:20:31.684 --> 00:20:38.498
Yet this machine was designed from the beginning
to support digital sound recording!

00:20:38.498 --> 00:20:44.647
It’s wild, and honestly this is officially what impresses me most about Betamax.

00:20:46.229 --> 00:20:50.000
[a nice jazz piano composition]

00:21:11.979 --> 00:21:15.293
Oh, by the way, wanna see what happens when you hit pause?

00:21:15.634 --> 00:21:17.717
Fair warning, it’s unpleasant.

00:21:17.717 --> 00:21:22.355
[Music]

00:21:22.355 --> 00:21:26.790
[brrrp - brbrbrbrbrbrbbrbrbrbrbbrbrbrbrbr]

00:21:26.790 --> 00:21:35.020
This shows that although the data does have a lot of formatting and error-correction,
it’s not as if every video frame needs to be perfect.

00:21:35.020 --> 00:21:38.724
The adapter will try its best to decode whatever it sees,

00:21:38.724 --> 00:21:43.265
and in this case it’s decoding the same frame of video over and over again.

00:21:43.265 --> 00:21:47.463
So you hear the same snippet of audio over and over again.

00:21:47.463 --> 00:21:51.083
[rapid clicking and popping]

00:21:51.083 --> 00:21:53.684
And when you try and fast-forward through the tape,

00:21:53.684 --> 00:21:59.604
it decodes snippets here and there
which sort-of help you figure out where you are in the recording.

00:21:59.604 --> 00:22:04.103
But, how well that works will undoubtedly depend on the VCR.

00:22:04.724 --> 00:22:09.749
[a lot of clicking with the occasional bout of intelligible music]

00:22:36.196 --> 00:22:38.561
Another fun thing is what happened here:

00:22:38.561 --> 00:22:44.243
I didn’t realize that I was recording in Beta-III speed
when I first started this test recording,

00:22:44.243 --> 00:22:46.893
and although I quickly switched back to Beta-II,

00:22:46.893 --> 00:22:51.736
because of where the tracking pulses are on
the tape compared to the video signal,

00:22:51.736 --> 00:22:55.005
for a brief while the machine’s running too slowly.

00:22:55.005 --> 00:23:03.632
But the adapter still valiantly tries to do its job - you can clearly hear an old
Warner Brothers home video intro happening here,

00:23:03.632 --> 00:23:06.229
only it’s very not-right.

00:23:06.229 --> 00:23:10.437
That is, until the VCR finally switches to the correct playback speed.

00:23:10.437 --> 00:23:17.281
[clicks, then very stuttery and slow music]

00:23:27.210 --> 00:23:36.851
But as much as I’m genuinely impressed at the feat of home PCM recording in 1977,
I can’t stop myself from asking -

00:23:36.851 --> 00:23:41.404
why on Earth would anyone buy one of these?

00:23:41.404 --> 00:23:45.178
I mean, in my heart of hearts I know why:

00:23:45.178 --> 00:23:47.940
to impress your audiophile friends, of course.

00:23:47.940 --> 00:23:56.816
But without your own full-on recording studio for capturing real live music,
there are exactly two things you might do with this:

00:23:56.816 --> 00:24:02.473
record programs from the radio or make copies of a record album of some kind.

00:24:02.473 --> 00:24:07.488
For making radio recordings, this thing is overkill to the extreme.

00:24:07.488 --> 00:24:13.960
Even if you had the best FM tuner in the business
with an antenna that can pick up tunes from the moon,

00:24:13.960 --> 00:24:20.389
FM radio just ain’t that high-fidelity
and a decent cassette deck would capture it just fine.

00:24:20.389 --> 00:24:23.712
And if all you want is a copy of somebody else’s record,

00:24:23.712 --> 00:24:26.867
there are much easier ways to go about that.

00:24:26.867 --> 00:24:29.997
Like, for instance, the aforementioned cassette deck.

00:24:29.997 --> 00:24:34.940
Or if that’s not enough fidelity for you,
get an open-reel machine.

00:24:34.940 --> 00:24:41.309
Yes, a PCM adapter would let you make an essentially
identical copy of whatever it is you record with it -

00:24:41.309 --> 00:24:44.027
and that is mighty impressive.

00:24:44.027 --> 00:24:47.999
But using one is extremely clunky and tedious.

00:24:47.999 --> 00:24:51.099
It requires having a very-expensive VCR,

00:24:51.099 --> 00:24:54.644
hooking that into your HiFi
(so I hope you put your TV over there, too),

00:24:54.644 --> 00:24:58.116
and wrangling two machines at the same time.

00:24:58.116 --> 00:25:01.943
That’s a lot of effort to go through for a simple sound recording,

00:25:01.943 --> 00:25:06.776
though in fairness you don’t really interact with the adapter
all that much.

00:25:06.776 --> 00:25:12.108
Now, if you could perhaps bring your exotic PCM videocassette recordings to a friend

00:25:12.108 --> 00:25:17.801
who had also spent as much as a small car on a
videocassette recorder and PCM adapter,

00:25:17.801 --> 00:25:20.762
then maybe there’s some more value here.

00:25:20.762 --> 00:25:23.733
But that leads us to a minor mystery:

00:25:23.733 --> 00:25:28.485
was this ever, like, a real format?

00:25:28.485 --> 00:25:35.742
Could I expect a tape holding data the way this fella writes it
to be readable by a different PCM adapter?

00:25:35.742 --> 00:25:38.387
Signs point to maybe.

00:25:38.387 --> 00:25:42.570
I found a forum post where jamesp, a serious tapehead,

00:25:42.570 --> 00:25:51.511
claims that 16 bit tapes are compatible between a bunch of different adapter models,
so at least Sony had some sort of standard format.

00:25:51.511 --> 00:25:53.895
But what about 14 bit tapes?

00:25:53.895 --> 00:25:56.683
If you know a thing or none about digital sound,

00:25:56.683 --> 00:26:04.172
it might seem a little strange that this device allows you to choose
whether you want to record with 14 or 16 bit sample depth.

00:26:04.172 --> 00:26:09.952
An option for “slightly worse recordings”
seems pretty silly in isolation.

00:26:09.952 --> 00:26:15.896
But it’s less silly when you consider that
Sony’s first PCM-1 was a 14-bit model.

00:26:15.896 --> 00:26:23.759
And, supposedly, that model followed an encoding standard
that the Electronic Industries Association of Japan had come up with.

00:26:23.759 --> 00:26:30.534
There’s definitely evidence that that was a thing,
and here’s a JVC product that utilized that standard.

00:26:30.534 --> 00:26:36.474
For some more evidence, not that long ago
Techmoan covered the Technics SV-P100,

00:26:36.474 --> 00:26:39.970
a digital recording device from 1981.

00:26:39.970 --> 00:26:46.150
That thing was essentially just a 14-bit PCM adapter
with a nicely-integrated VHS VCR,

00:26:46.150 --> 00:26:53.419
and the video it pumps out through its "digital" output
sure looks an awful lot like the video this thing is generating.

00:26:53.419 --> 00:27:00.209
I think there’s a pretty good chance that a 14-bit recording
made with this Sony PCM adapter and a VHS VCR

00:27:00.209 --> 00:27:03.894
would work in that machine, and vice-versa.

00:27:03.894 --> 00:27:08.247
I’m hoping to arrange a test… so stay tuned.

00:27:08.247 --> 00:27:18.385
Merely offering the option to make 14 bit recordings implies to me anyway that they must be backward-compatible with some array of older equipment.

00:27:18.385 --> 00:27:22.191
There’s no way to get the raw data out of this model -

00:27:22.191 --> 00:27:27.291
the copy output just produces another video signal to feed a second VCR.

00:27:27.291 --> 00:27:34.194
So I can’t think of any other reason it would offer a slightly worse recording mode.

00:27:34.194 --> 00:27:35.544
But curiously,

00:27:35.544 --> 00:27:42.059
the pattern on the screen doesn’t really change much
when you move between 14 and 16 bit encoding.

00:27:42.059 --> 00:27:48.496
I figured it would - less bits per sample would mean
less bits per line so they should appear to get bigger.

00:27:48.496 --> 00:27:54.057
But they don’t, it’s just the portion at the end of each line gets rearranged a bit.

00:27:54.057 --> 00:27:59.396
My guess is that Sony altered the error correction portion to fit in the extra bits,

00:27:59.396 --> 00:28:01.210
but that’s just a guess.

00:28:01.210 --> 00:28:05.517
If they did, perhaps the 14-bit mode is less prone to errors

00:28:05.517 --> 00:28:10.935
but I gotta say from the tests I’ve done
the 16-bit mode is mighty resilient.

00:28:10.935 --> 00:28:14.475
Anyway, even assuming there was a standard recording method

00:28:14.475 --> 00:28:21.528
and you could expect PCM recordings made on one rich audiophile’s VCR
to work at another rich audiophile’s house,

00:28:21.528 --> 00:28:25.786
there still seems to be very little reason to own one of these

00:28:25.786 --> 00:28:27.789
beyond bragging rights.

00:28:27.789 --> 00:28:30.764
At its core, this is just a really expensive,

00:28:30.764 --> 00:28:31.974
really tedious,

00:28:31.974 --> 00:28:33.412
and really exotic...

00:28:33.412 --> 00:28:37.301
tape deck designed to work with your average hi-fi system.

00:28:37.301 --> 00:28:43.389
If you actually had your own recording studio
and could truly take advantage of this thing’s capabilities,

00:28:43.389 --> 00:28:48.137
you’d probably be quite annoyed that it doesn’t have XLR inputs.

00:28:48.137 --> 00:28:53.412
This is just far too basic to work as a professional piece of recording equipment,

00:28:53.412 --> 00:29:00.951
and without music getting released on PCM videotape,
you’re only ever gonna be listening to your own recordings.

00:29:00.951 --> 00:29:04.443
So… why go to this extreme?

00:29:04.443 --> 00:29:08.274
There is, however, one concrete advantage to this thing:

00:29:08.274 --> 00:29:09.947
recording time.

00:29:09.947 --> 00:29:17.239
So long as your VCR is halfway decent,
you could use its slower recording speeds with the PCM adapter.

00:29:17.239 --> 00:29:23.922
That meant you could get a 4 and a half hour recording out of 
*this thing* and an L-750 Beta cassette,

00:29:23.922 --> 00:29:28.118
and potentially an 8 hour recording with a VHS machine.

00:29:28.118 --> 00:29:33.836
That bests pretty much every sound recording format that used physical media,

00:29:33.836 --> 00:29:38.989
especially when you consider that the audio quality
would be essentially perfect.

00:29:38.989 --> 00:29:42.556
So you could fit a whole lot of…

00:29:42.556 --> 00:29:47.219
borrowed music on there and make quite the mixtape.

00:29:47.219 --> 00:29:51.168
But unless you had that specific use in mind,

00:29:51.168 --> 00:29:56.089
this still reads to me as an item of very questionable usefulness.

00:29:56.089 --> 00:30:03.707
Despite the peculiarity of a home PCM-adapters,
professional PCM-adapters would stick around for a while.

00:30:03.707 --> 00:30:09.456
There still wasn’t a great way to store
several hundred megabytes of data in 1982.

00:30:09.456 --> 00:30:15.779
While we had the compact disc,
recordable compact discs wouldn’t appear until the end of the 1980s.

00:30:15.779 --> 00:30:24.454
Commercially-produced CDs were pressed,
and after all something had to store data to bring to the CD-making machines.

00:30:24.454 --> 00:30:29.066
That something was largely U-matic tapes and the PCM adapters

00:30:29.066 --> 00:30:34.907
until Sony finally released an actually-digital tape format in 1987 called, fittingly,

00:30:34.907 --> 00:30:36.714
digital audio tape.

00:30:36.714 --> 00:30:44.278
As a curious side-note, Sony intended for that format to supplant the venerable compact cassette in the consumer space,

00:30:44.278 --> 00:30:47.305
but it was too expensive to really get off the ground.

00:30:47.305 --> 00:30:53.884
Plus, it freaked out the recording industry because suddenly people could have perfect copies of their buddy’s CDs

00:30:53.884 --> 00:30:56.742
and there was a whole kerfuffle about that.

00:30:56.742 --> 00:31:01.664
It’s not surprising that they never bothered
getting hot and bothered by PCM adapters because

00:31:01.664 --> 00:31:05.676
these were just too clunky to use and would never see mass-market appeal.

00:31:05.676 --> 00:31:12.261
Finally, since you could get 8 hours of CD-quality
audio running on a VHS tape with this thing,

00:31:12.261 --> 00:31:15.886
you might be wondering how much actual data that is.

00:31:15.886 --> 00:31:20.836
Well, the simple way to calculate that is
to take the 480 minutes in 8 hours,

00:31:20.836 --> 00:31:24.617
divide that by the 80 minutes a standard CD-R can hold,

00:31:24.617 --> 00:31:29.311
and multiply that by the 700 megabytes each of those CD-Rs can hold.

00:31:29.311 --> 00:31:31.739
That would be 4.2 gigabytes.

00:31:31.739 --> 00:31:37.582
However, CD-digital audio actually conveys more data than a CD-ROM does.

00:31:37.582 --> 00:31:39.304
To be absolutely precise,

00:31:39.304 --> 00:31:44.913
this thing records two 16 bit samples 44,056 times per second.

00:31:44.913 --> 00:31:49.207
That’s 1,409,792 bits per second.

00:31:49.207 --> 00:31:50.742
Multiply by seconds per minute,

00:31:50.742 --> 00:31:51.559
minutes per hour,

00:31:51.559 --> 00:31:52.579
hours per tape,

00:31:52.579 --> 00:31:55.761
then divide by 8 to find the total number of bytes.

00:31:55.761 --> 00:31:59.956
After the amusement of realizing you just multiplied by 8 and then divided by 8,

00:31:59.956 --> 00:32:09.305
you’ll discover that a T-160 VHS tape holds a bit over
5 gigabytes of data when storing PCM audio at the SLP speed.

00:32:09.305 --> 00:32:10.878
And to finish up the video,

00:32:10.878 --> 00:32:15.430
one thing that’s always been pretty amusing to me is that, in hindsight,

00:32:15.430 --> 00:32:22.248
it seems it took a long time for people to realize that digital audio data was, in fact,

00:32:22.248 --> 00:32:23.418
data.

00:32:23.418 --> 00:32:28.623
Like, it took us years to turn the compact disc into the CD-ROM -

00:32:28.995 --> 00:32:35.998
some of that was down to 8-bit home computers having 
absolutely no idea what to do with 650 megabytes,

00:32:35.998 --> 00:32:46.792
but when you consider that Sony sold a device back in 1977 that could reliably store literal gigabytes of data on Beta tapes of all things…

00:32:46.792 --> 00:32:51.762
well you’d think people would have made
use of that for more than just audio.

00:32:51.850 --> 00:32:54.419
Of course, eventually we did.

00:32:54.419 --> 00:33:02.410
LGR covered a device from 1996 that was designed
to make actual data backups onto VHS tapes.

00:33:02.410 --> 00:33:05.046
That thing was effectively a PCM adapter,

00:33:05.046 --> 00:33:09.919
but one that interfaced with data backup software running on your PC.

00:33:09.919 --> 00:33:12.762
To attain the reliability needed for data backups,

00:33:12.762 --> 00:33:20.834
it recorded less densely than this PCM adapter did, and could only backup about
3 gigabytes of data in the best of conditions.

00:33:20.834 --> 00:33:28.061
But honestly, it’s pretty wild to me that it took until the mid-nineties
for anyone to commercialize that concept.

00:33:28.061 --> 00:33:33.059
I mean, did everyone just forget about PCM adapters?

00:33:33.059 --> 00:33:39.190
Or did people never realize that the digital audio data they barf out
is still data?

00:33:39.748 --> 00:33:45.043
Yeah, using a VHS-based computer backup system
was incredibly clunky -

00:33:45.043 --> 00:33:50.674
even worse than a PCM adapter as now you have to deal with a
computer and software interface.

00:33:50.674 --> 00:33:57.360
But we had been recording gigabytes of data onto videotape from the 70’s.

00:33:57.360 --> 00:34:00.929
How did that not bleed into home computing sooner?

00:34:00.929 --> 00:34:03.075
I think the likely answer is, of course,

00:34:03.075 --> 00:34:10.785
that it took many years for us to need such vast quantities of data
for anything other than audio reproduction.

00:34:10.785 --> 00:34:15.552
Until the multimedia PC was a thing, 
you were mainly dealing with floppy disks,

00:34:15.552 --> 00:34:21.418
and one hundred-megabyte hard drives still felt pretty cutting-edge in 1990.

00:34:21.418 --> 00:34:28.275
Needing to burn through 1.4 megabits of data every second 
remained an audio-only task

00:34:28.275 --> 00:34:33.705
pretty much right up until home computers started incorporating CD-ROM drives.

00:34:33.705 --> 00:34:42.530
And at that point we were still struggling to figure out how
on Earth to make use of their vast 650 million bytes!

00:34:42.530 --> 00:34:46.220
But now, I think I’ve finally run out of things to talk about.

00:34:46.220 --> 00:34:53.056
Though I still think having a PCM adapter in your home
was a pretty silly proposition for the vast majority of people,

00:34:53.056 --> 00:34:56.083
they were without question very cool -

00:34:56.083 --> 00:35:02.314
and I’m happy they did make it to the consumer market because without audiophiles with too much money to throw around,

00:35:02.314 --> 00:35:05.039
I doubt I’d have been able to show you one.

00:35:05.039 --> 00:35:13.802
Although, as it turns out, apparently digital sound was quite the contentious topic among audiophiles back in the early eighties.

00:35:13.802 --> 00:35:15.700
Because of course it was.

00:35:15.700 --> 00:35:20.434
Oh, audiophiles, never stop being you…

00:35:21.240 --> 00:35:23.917
♫ 16-bit smooth jazz ♫

00:35:25.134 --> 00:35:26.779
Keep recording, okay?

00:35:26.779 --> 00:35:28.760
I want you to keep recording.

00:35:29.101 --> 00:35:31.060
♫ DON’T STOP ♫

00:35:31.060 --> 00:35:32.220
♫ RECORDING. ♫

00:35:32.220 --> 00:35:38.084
Discreeeeeet bloooooocky shaaaapes come and goooo.

00:35:38.084 --> 00:35:39.667
And if the spicy snap of s…

00:35:39.667 --> 00:35:43.731
yeah, heh, I forgot how slowly I’m gonna read that!

00:35:44.475 --> 00:35:46.209
It will spit out a binary

00:35:46.209 --> 00:35:47.895
[burps]
[laughs]

00:35:48.609 --> 00:35:54.875
So, 44.1 kilohertz became the defacto standard for PCM adapters and wwww that…

00:35:54.875 --> 00:35:56.381
ah, fark!

00:35:56.908 --> 00:36:00.994
And it did pretty much exactly what this thing does,
just five years earlier.

00:36:00.994 --> 00:36:02.670
... sanity check processing ...

00:36:02.670 --> 00:36:05.259
Six - it’s six years earlier! I did…

00:36:06.283 --> 00:36:08.018
Of course, I had [bonk] to…

00:36:08.018 --> 00:36:09.059
well, that didn’t work.

00:36:11.356 --> 00:36:13.153
OK, two things:

00:36:13.153 --> 00:36:16.084
First. I forgot to fade the music back up here.

00:36:16.084 --> 00:36:17.344
A tragic oversight.

00:36:17.344 --> 00:36:19.976
Everybody loves this song and to dooty doots here.

00:36:19.976 --> 00:36:22.719
Second,

00:36:22.719 --> 00:36:24.140
actually I don't have a second thing.

00:36:24.140 --> 00:36:25.973
Just wanted to say something about that editing mistake.

00:36:25.973 --> 00:36:26.473
'kay bye