00:00
[THEME MUSIC]
00:00
00:13
>> DAVID J. MALAN: Can you hear me, world?
00:32
So in next week's episode we'll
talk about microphone technology.
00:34
But for now, let's begin.
00:38
Hello, world, we are
back, as is my voice.
00:40
And this is CS50 Live.
00:42
>> And boy, do we have a good
show for you this week.
00:44
In particular, we've
got the Heartbleed bug
00:47
that's been all over the news of
late, some stories from students,
00:49
a trip to Vegas, a behind
the scenes tour of Dropbox.
00:52
And I'm hearing, yes, CS50's
own Ramon Galvin is back.
00:56
CS50's Ramon Galvin is in
the studio again today.
01:00
>> But first, some desk lamps.
01:03
Of course desk lamps have been a bit
of a thing this semester in CS50.
01:05
And you may recall Ahmad,
from a previous episode, who
01:08
submitted a video
making his case for why
01:11
he'd like to receive
his own CS50 desk lamp.
01:13
Well, we sent a desk
lamp ultimately to Ahmad.
01:16
And he kindly sent us
this photo of himself
01:18
in Pakistan with a CS50 desk lamp.
01:21
>> Meanwhile, you may recall Lamp
Story, submitted by Eggers in Latvia.
01:24
We sent over a desk
lamp to Latvia as well.
01:27
And pictured here is that desk lamp.
01:29
Finally, you may recall Philip
who didn't just submit a photo,
01:32
but also submitted a video
via which to thank us
01:35
for his desk lamp, which we
sent all the way to Germany.
01:38
Let's take a look.
01:42
>> PHILLIP: Hi.
01:43
Dear David, and dear all of
you amazing people at CS50.
01:44
I'm Phil and I want to thank you
so much for this incredible gift.
01:47
It is unbelievable to
me that you actually
01:52
sent this all the way
over here to Germany.
01:54
But you know what?
01:57
Why don't I thank you personally?
01:58
>> Hey, David, I want to thank you
so much for this CS50 desk lamp.
02:01
You can not imagine
what this means to me.
02:05
>> DAVID J. MALAN: Desk lamp?
02:08
>> PHILLIP: Right.
02:10
OK, I'm going to leave,
but, yeah, thanks.
02:11
DAVID J. MALAN: Now, two of your
classmates actually traveled
02:17
to us to have a chat of late.
02:19
In particular, Amy from Massachusetts
and Jack from Dublin, Ireland,
02:21
came all the way to Sanders Theater
to sit down and talk about CS50
02:25
past and present.
02:28
02:30
>> This is Sanders Theater.
02:33
So this is where CS50's
lectures are held.
02:34
Thanks so much for coming to campus.
02:38
Shall we start with the introductions?
02:40
I'm David.
02:41
>> AMY: I'm Amy.
02:42
I work on the web and I
live here in Cambridge.
02:43
>> JACK: I'm Jack and I'm
from Dublin, Ireland.
02:46
I'm a junior in high school.
02:49
>> DAVID J. MALAN: And what brings you here
today in particular from so far away?
02:50
JACK: For a visit to Boston.
02:53
>> AMY: How has CS50 evolved
as you've been teaching it?
02:55
>> DAVID J. MALAN: It's definitely
gotten more dramatic over the years.
02:58
We've been filming since 2007, so
we can literally go back in time
03:02
and watch past years, first
lectures in particular.
03:05
And I think the first lecture
in 2007 was pretty much
03:08
me, coming out in front of the class.
03:11
Saying, hello, this is CS50.
03:13
And we dove into the day's material.
03:16
>> All right, so welcome
to Computer Science 50,
03:18
Introduction to Computer Science 1.
03:21
My name is David Malin and I
will be your instructor this--
03:23
>> Now there's music.
03:26
The lights go down.
03:28
We drop down a huge screen.
03:29
There may or may not be
Muppets in a given year.
03:30
03:33
And it's funny, because this
has all happened very gradually
03:38
over the years, just a
little bit more each year.
03:42
But the delta, now, between the
first year and the last year
03:44
is actually rather atrocious, just how
different the first five minutes are.
03:47
>> AMY: I'm curious, what do you see
as the differences between the edX
03:51
version and the live course?
03:56
>> DAVID J. MALAN: So curricularly
and technologically CS50
03:59
on campus and CS50x off campus
are fundamentally the same.
04:02
What does differ between the
two is the level of support
04:06
that we're able to provide.
04:09
Even though CS50 has a huge team of
some 100 teaching fellows, course
04:11
assistants, myself, and
our production team--
04:15
we can just barely keep up
with the 700 students on campus
04:18
and the 150 Extension School students
who are local or online themselves.
04:22
So for CS50x, we simply don't have
the support structure of office hours,
04:27
for instance, four nights
a week for several hours.
04:30
JACK: And what do you guys talk about in
office hours that will be different to,
04:33
say, what you have on lectures,
or on sections, or shorts?
04:36
DAVID J. MALAN: On campus
office hours are really
04:39
opportunities for students to
pose questions, one on one,
04:41
with a member of the teaching staff
or even a classmate of theirs nearby.
04:44
And generally wrestle with bugs
that they're having in their codes.
04:48
>> AMY: I think Reddit kind of gives
a reasonable facsimile of an office
04:51
hours.
04:55
>> DAVID J. MALAN: Agreed, agreed.
04:55
I've been really impressed,
though, with the Reddit community
04:56
and the newcomers to
the group, too-- just
04:59
how eager and hopeful people have been.
05:01
And Reddit definitely lends itself
better, I think, to posting of code
05:03
and having threaded discussions.
05:06
>> JACK: And do you think
people should try,
05:08
if they know they're
doing something wrong
05:10
or it's like, they've implemented--
spent too much time on it,
05:12
think they should stop and start again?
05:15
Or look for help?
05:17
Or how should they--
05:18
>> DAVID J. MALAN: Take a break, minimally.
05:20
Sometimes, especially for me at least,
as your stress level starts to rise you
05:22
start hacking away and copying
and pasting, forgetting
05:26
what you've already tried.
05:29
It's just time to go to
sleep, or go take a jog,
05:30
or go shower, and just
kind of get some distance.
05:32
And this has happened
many, many times to me
05:35
where I'll be lying there in bed
even, or even driving to work,
05:39
or walking somewhere, kind
of debugging in my head.
05:42
>> And only once you have that distance
and a lot less stress on your shoulders,
05:44
I think, can you realize,
like, oh, I'm an idiot.
05:47
I forgot to call this function,
or initialize some variable.
05:49
>> So as a little surprise if you'd like
to take a look under your CS50 seat
05:54
cushion, a little something awaits you.
05:58
06:00
Those were good looks.
06:07
Did we get those looks?
06:08
>> Under their seat cushions, of
course, was a bit more Dropbox space.
06:11
Now you may recall we recently
traveled to Saint Louis, Missouri,
06:14
where we had a unique opportunity
to actually blow glass
06:17
at the Third Degree Glass factory.
06:20
Our host for the day made
this beautiful bowl of glass
06:22
by spinning and spinning it until
you got this beautiful wavy effect.
06:26
And this now lives in our
offices here in Cambridge.
06:29
>> I, on the other hand, made
this big ball of orange glass
06:32
that now sits on my desk.
06:35
But we were in Saint Louis, of
course, for the CS50 hackathon
06:37
in Saint Louis with Launchcode,
where we had an opportunity
06:39
to sit down with a number of your
classmates and hear their CS50 stories.
06:42
>> EZRA: Once I saw computer
coding and the kind of-- that's
06:48
the career that I want to be in.
06:55
And I think that I would
be very good at it.
06:56
>> CHARLES: Well, I've been
job hunting for a while.
07:00
Bachelor of Science,
biomedical engineering.
07:02
It hasn't been going too well.
07:04
So I thought maybe I'd look
into a different field.
07:06
>> KIMBERLY: In Green Bay, Wisconsin
I was a school counselor.
07:09
And I really knew I
wanted to change careers.
07:12
>> SAM: I've heard a lot of
people saying, like, everyone
07:16
should learn how to code.
07:19
Everyone should be exposed to it.
07:20
And before I was just kind
of like, eh, whatever.
07:22
>> AUSTIN: I had taken a semester off.
07:25
And I'm now doing the CS50x program.
07:27
>> KELLI: It's very accessible
to anyone at all.
07:30
>> LEANNE: I've been a
developer in the past.
07:34
But I had a situation and I wanted
to kind of increase my confidence,
07:37
and I wanted to learn
C, and I wanted to learn
07:41
PHP, which I saw that CS50 was teaching.
07:44
AUSTIN: People are really helpful.
07:47
There's definitely more
of a community than you
07:49
would think from an online course.
07:50
>> KELLI: I'm working on my problem
set five, that I just started.
07:52
So I get to do a little forensics.
07:55
>> CHARLES: It has been challenging.
07:59
It's definitely meant
to stretch your limits.
08:01
I'm working on problem set five.
08:04
>> KIMBERLY: My classmate and I are
working on our final project.
08:06
>> SAM: I'm working on my final project.
08:09
I've got two other people working
with me, we're the tri-force of power.
08:11
>> LEANNE: I'm attempting to work on
an iOS app that is a calendar agenda
08:15
application that I wanted to create,
just for my own use, to start out with.
08:21
>> AUSTIN: My final project is
going to be a website that
08:26
is an image and visual repository.
08:28
Basically it's going to have
a listing of helpful phrases
08:31
and sign language for medical personnel.
08:35
>> EZRA: Let's say my final project
was a puppet doing a dance,
08:38
and they asked me, can you make this
puppet to do this dance twice as fast?
08:42
I would be able to go to my code, change
it, save it, compile it, upload it,
08:49
and show them right away that
I can-- that not only did I
08:55
make this final project, I understand.
08:58
I can tweak it however
they want me to tweak it.
09:01
>> CHARLES: I figure once I get
my final project completed
09:03
and some potential
employers have a chance
09:06
to look at that they'll have a
better assessment of whether they
09:08
think I'll be a good fit for them.
09:11
SAM: Now I'm very confident and I'm
learning new stuff all the time.
09:12
And it's great.
09:17
It's changed my life.
09:18
>> EZRA: This is really
hard material, especially
09:20
if you're doing this and also
working, and maybe also have a family,
09:24
and maybe also have children,
and maybe also have a mortgage.
09:31
But it's so worth it if
you just put the effort in.
09:35
What you get out is so much more
valuable than the time that you put in.
09:41
DAVID J. MALAN: And
now, this week in tech.
09:47
Odds are you've heard of
the so-called Heartbleed
09:49
bug, which has affected web
servers throughout the world.
09:51
But what is this bug, exactly?
09:53
Well, turns out that many web
servers run software called open
09:55
SSL, where SSL of course
is Secure Sockets Layer.
09:59
And this is the technology that
encrypts traffic between a web browser,
10:02
or client, and a web server.
10:05
Now unfortunately, in
December of 2011, a programmer
10:07
introduced an accidental bug into
the source code for open SSL.
10:10
>> And open SSL unfortunately is
used in so many other products,
10:14
among them the Apache
web server, and others,
10:17
that are hugely popular on the
internet for hosting websites.
10:20
The result of this was that the
following attack is possible.
10:23
As part of open SSL there's a
so-called heartbeat feature,
10:29
whereby a client like a browser
can send a message or a payload,
10:32
which is really just a string,
like hello, to a server.
10:36
And in addition to that
payload it sends a number
10:38
which should be the
length of that payload.
10:40
In the case of hello, it should be five.
10:43
>> Unfortunately, the bug in
open SSL operated as follows.
10:45
It ignored that number.
10:49
And so if you-- rather,
it trusted that number.
10:50
So if you, the client, sent a message
like hello, and not the number 5
10:55
but the number 100, what would happen
is that the server would blindly
10:59
respond to that payload by
echoing back not only hello,
11:03
those 5 bytes, but 95 additional
bytes thereby trusting
11:06
that you were telling the truth when you
said that the payload was in fact 100
11:10
bytes.
11:14
Now why is that problematic?
11:14
>> Well, you may recall
from CS50, of course,
11:16
from memory management that
on the stack and the heap
11:18
are remnants of data paths, when you've
called a function, used a variable,
11:20
those values stay in memory even
if you're no longer actively using
11:24
those chunks of memory.
11:28
So when the server responds not with 5
bites but with 100 bytes, 95 of which
11:29
are not technically supposed
to go back to the client,
11:34
those 95 bytes could contain
passwords, or the server's
11:37
security certificates, or the servers
secret keys, so to speak, all of which
11:40
are used for encryption.
11:45
>> And so ultimately your
information could be handed back
11:46
to some random adversary
on the internet simply
11:49
because your password, or
credit card information,
11:52
or something else that's
sensitive happened
11:54
to be in the web server's memory
at that particular location.
11:56
Now this was a big
deal, because this bug
11:59
affected web servers
throughout the world.
12:01
Among them Amazon Web Services, Box,
Dropbox, Etsy, Flickr, GitHub, Gmail,
12:03
Go Daddy, Google, Instagram,
Minecraft, Netflix, OKCupid, Pinterest,
12:08
SoundCloud, Tumblr, Twitter,
Venmo, Wikipedia, WordPress, Yahoo,
12:11
YouTube-- and those are just
the companies, just some
12:15
of the companies that actually disclosed
that their servers had been running
12:19
the afflicted software and had
only recently, as this past week,
12:22
been updated.
12:26
>> Now it turns out the fix, in source code
for, this Heartbleed bug is actually
12:27
remarkably simple.
12:31
It pretty much boils down
to these two lines of code.
12:32
If payload is greater than
the actual length, return 0.
12:35
Do not return some
potentially disclosing bits.
12:39
Now in reality the lines of
code were a little more complex.
12:42
It looked a bit more like this.
12:45
But this is just some
additional arithmetic
12:47
and there were a few
other lines of code,
12:48
but the fix really was that simple.
12:50
>> And so if you've never
believed in lectures
12:52
when we say that you should always
check the boundaries of your array
12:54
and make sure to check the
lengths of any chunk of memory
12:57
before blindly traversing
through your computer's memory,
13:00
this is what can happen.
13:03
And truly it's been a
globally impactful bug.
13:05
Now what can you yourself do to
learn more and protect yourself?
13:08
Well, head to heartbleed.com,
which is a terrific website that
13:11
explains in a bit more detail exactly
what the threat is, how folks have
13:14
responded, what
software's been affected,
13:18
and how you can defend yourself.
13:20
But it pretty much boils down
to this-- change your passwords,
13:21
arguably on most any
website you know if unsure
13:25
whether that particular
website was affected.
13:27
>> Because one of the scariest
things about this bug
13:29
is that it's not so much auditable.
13:31
It's not clear if, even
over the past two years,
13:33
a server was vulnerable, if your
information was indeed compromised.
13:36
So as is the case
generally with security,
13:39
the best approach is paranoia
and change any passwords
13:42
on websites that are
particularly sensitive to you.
13:45
But head to that URL there
for even more detail.
13:48
>> Now in other news, Mark
Zuckerberg recently posted this.
13:50
I'm excited to announce
that we've agreed
13:53
to acquire Oculus VR, the leader
in virtual reality technology.
13:55
Now virtual reality is
an interesting thing
13:59
that's beginning to gain
a bit more traction.
14:01
It generally involves
putting on a pair of goggles
14:03
that might look like these inside
of which are a pair of lenses that
14:05
allow you to see a computer screen
right up close to your face.
14:08
And on that computer screen could
be anything, the inside of a house,
14:12
the outside of the house, a
virtual world inside of a game.
14:15
And the result is an incredibly
immersive opportunity
14:18
to feel as though you're actually
someplace that you're actually not.
14:22
I, for instance, might
be in a conference room
14:25
when really I think I'm in
a Tron-like virtual world.
14:27
And indeed, I had an opportunity.
14:31
I haven't personally played with
Oculus, but I did visit our friends
14:32
in Seattle, Washington,
recently at Valve software, who
14:35
were working on a very
similar VR technology.
14:38
And I was very fortunate
to have the opportunity
14:40
to put on their pair of
goggles for 60 seconds of this.
14:43
>> [MUSIC PLAYING]
14:47
>> Now, CS50's own Dan Coffey
also had an opportunity
15:48
to take a trip recently to
Mountain View, California,
15:51
where he sat down with our
friends at Dropbox, among them
15:53
CS50's own former head teaching
fellow Thomas Carriero,
15:56
who's been responsible for
all of that Dropbox space
15:59
underneath your seat cushions.
16:02
Thomas very kindly opened the doors
of Dropbox and gave us an exclusive
16:03
behind the scenes of what
it's like to work at Dropbox
16:07
and daresay live at Dropbox.
16:10
>> THOMAS CARRIERO: Hi, I'm Thomas
Carriero, former CS50 head TF.
16:14
We're here at the Dropbox headquarters
in San Francisco, California.
16:19
Welcome.
16:21
I'm going to show you on a tour.
16:22
Come with me.
16:23
16:24
Cool.
16:26
So this balloon right here,
this green check mark,
16:27
is the balloon that we put on your
desk when you first join the company.
16:30
And the idea is that the balloon
will stay kind of up there as long
16:34
as you're a new hire.
16:37
So the balloon of course loses
helium over time and by the time
16:38
the balloon is dead
you're no longer a noob.
16:42
This takes a couple of months to
happen because these are really, really
16:47
expensive balloons.
16:51
We think we might keep the green check
mark balloon business in business.
16:52
>> Cool, so this right here is AT&T Park.
16:57
This is where the San
Francisco Giants play.
17:00
We actually have a Dropbox box suite,
one of our other awesome amenities,
17:02
just across the way.
17:08
So I'm standing by this
really cool light display.
17:09
So what's going on here is
we're getting real time data
17:11
about what's happening
in our Mailbox app.
17:13
Each of the colors corresponds
to a different action.
17:16
>> And so as users are doing
these actions, these lights
17:19
are lighting up with those colors to
kind of let us know what's going on.
17:23
Sometimes if stuff is going wrong, the
colors will all start to be one color
17:26
and we know that something
bad is happening.
17:30
So this is kind of one
of the ways that we
17:33
keep track of what's
going on in Mailbox.
17:34
17:36
>> Cool, so let's see what's
for dinner tonight.
17:39
Looks like we have eight hour
smoked beef brisket right here.
17:42
And right here is my favorite
station, the Indian station.
17:46
It's an open face samosa chop today.
17:49
Well, I guess that was
my favorite station
17:53
but this is my other favorite station.
17:55
>> This is the pizza station.
17:57
So they always make different kinds of
pizza with our pizza oven right there.
17:58
Looks like they're making a Sicilian
pizza, which is one of my favorites.
18:02
All right, so the chef told me
that they are freshly made Ho Hos.
18:06
I told him I was going to wait
until after I'd eaten my dinner
18:10
but I'm definitely going to
have one of those tonight.
18:13
OK, I'm going to have mine now.
18:15
Real good.
18:19
18:19
>> So this is kind of the bonus station
that's outside of the tech shop.
18:23
For lunch we have Mexican
food here and sushi here.
18:26
And for dinner we have
some kind meat delicious.
18:29
Looks like roasted pork loin tonight.
18:34
Get a close up on that.
18:37
Cool, so this is our design area.
18:40
This is where we design
a bunch of the products.
18:42
We have lots of fun
poster boards and stuff,
18:44
with kind of all the mocks
that we're working on.
18:47
We also have along the
ground a bunch of the mocks
18:50
that we've been working
on over the years.
18:53
So you can get a close
up of that in a second.
18:56
>> But this sign is one of my
favorite things about Dropbox.
18:58
So this sign actually
came from the old office.
19:01
And our slogan is, it just works.
19:03
But if you look closely, there's
a subliminal message in the sign.
19:05
>> So one of my favorite parts about
Dropbox are these vending machines.
19:10
Instead of having chips or
soda or anything like that,
19:14
we actually have electronics.
19:17
So if you need a new trackpad, or
a new keyboard, or some headphones,
19:19
all you need to do is swipe
your badge right here.
19:24
Type in the number and then
the out comes your electronics.
19:27
Pretty awesome.
19:30
Thanks so much for joining
me on this tour of Dropbox.
19:30
It's been really fun showing you around.
19:33
>> I'm going to close this out
with the way we close out
19:35
all of our all hands meetings.
19:37
This is a special chant we do.
19:40
Can I get some help here?
19:41
One, two, three-- Dropbox!
19:44
It's usually much cooler than that.
19:47
19:49
DAVID J. MALAN: Now if
you'd like to visit Dropbox,
19:57
head to Mountain View, California, hop
on Route 101 north to San Francisco,
20:00
where they actually are.
20:04
Now we've also had an
opportunity recently
20:06
to travel to Las Vegas,
Nevada for the NAB show,
20:07
the National Association
for Broadcasters show,
20:11
which brings together some
100,000 people interested
20:13
in audio and video and
technology more generally
20:16
to talk about the very
latest and greatest.
20:18
>> CS50's own Ramon Galvin took
this trip and brought with him
20:21
a camera crew in order to this
footage from the show's floor.
20:24
RAMON GALVIN: Hello, world.
20:28
OK, I got it.
20:29
Hello, world.
20:31
Do I have to say my name?
20:32
>> CAMERAMAN: Correspondent in the field .
20:34
RAMON GALVIN: Can I get
a lower third of that?
20:37
Correspondent in field.
20:39
>> CAMERAMAN: Senior.
20:43
RAMON GALVIN: There you go.
20:44
20:45
I know, but I have to
do it. [INAUDIBLE].
20:53
20:55
I'm clueless.
21:08
21:09
>> Now's my prima donna pose.
21:14
21:16
DAVID J. MALAN: And
they keep mentioning 4K.
21:35
What is 4K exactly?
21:37
>> RAMON GALVIN: That's a
really good question.
21:40
Very basically--
21:42
>> DAVID J. MALAN: Cut to
a clip explaining 4K.
21:43
21:46
Hello, world.
21:53
My name is David Malan.
21:54
RAMON GALVIN: I'm Ramon Galvin.
21:55
DAVID J. MALAN: And we're here
at NAP, the National Association
21:57
of Broadcasters conference
in Las Vegas, Nevada.
21:59
But why are we here?
22:01
RAMON GALVIN: I don't know.
22:02
I don't know, David.
22:03
>> DAVID J. MALAN: That was pretty good.
22:05
Is this usable?
22:07
>> RAMON GALVIN: Probably not.
22:08
DAVID J. MALAN: We're back,
as is CS50's own Ramon
22:10
Galvin, who you may recall
from last week's episode.
22:12
Ramon, so glad you are indeed back.
22:16
>> RAMON GALVIN: I'm glad I
still have a job, David.
22:17
>> DAVID J. MALAN: So let's
address the elephant
22:19
that was in the room in
Las Vegas, namely 4K.
22:21
I've heard about this in the context
of TVs and computer monitors,
22:22
but what is 4K?
22:25
>> RAMON GALVIN: So it's a resolution.
22:27
Whenever you're watching a
walk through video or a lecture
22:28
you get what we call 1080p video.
22:31
What that means that the
video is 1,000 pixels tall.
22:33
>> DAVID J. MALAN: Or 1080.
22:37
>> RAMON GALVIN: Or 1080.
22:38
Or roughly 2,000 pixels wide.
22:39
Now 4K is 4,000 pixels wide, roughly,
and roughly 2,000 pixels tall.
22:42
DAVID J. MALAN: OK.
22:49
So that's kind of like having
a grid of four 1080p monitors
22:50
right in front of you.
22:53
>> RAMON GALVIN: Exactly.
22:55
DAVID J. MALAN: OK, so that's all
fine and good but why is this useful?
22:55
>> RAMON GALVIN: I'm glad I asked you
to ask me that question, David.
22:59
>> DAVID J. MALAN: It's
on the teleprompter.
23:01
>> RAMON GALVIN: So there's
a documentarian named
23:03
Errol Morris that actually
makes use of 4K technology.
23:04
Ordinarily to shoot an
interview, which he usually does,
23:08
he would have to either use multiple
cameras to get a zoomed in shot
23:10
or a zoomed out shot, or
shoot the interview twice
23:14
to get the same zoomed
in, zoomed out shot.
23:17
However, now he's using a 4K
camera to shoot one huge 4K shot.
23:19
And then when he's editing,
artificially cropping that shot.
23:25
DAVID J. MALAN: And
zooming in, essentially,
23:30
to give you still 1080p but only
some of the pixels from the 4K image.
23:31
>> RAMON GALVIN: Exactly, giving
him multiple camera shots
23:35
out of that one original camera shot.
23:38
DAVID J. MALAN: Interesting.
23:40
So how could we make
use of this for CS50?
23:41
>> RAMON GALVIN: I'm glad you asked
me that question, too, David.
23:43
Because I shot the walk through
videos with Zamyla last semester.
23:46
And for those videos we would
have to run through the walk
23:50
through once with a zoomed out shot.
23:53
And then I'd have to adjust the
camera to get a zoomed in shot.
23:55
And then we'd run through it again,
running through it two times.
23:59
With a 4K camera we can cut
our production time in half.
24:03
DAVID J. MALAN: I see.
24:05
So that should be quite exciting
for us, then, this fall.
24:06
RAMON GALVIN: Exactly.
24:09
DAVID J. MALAN: Well, from
the looks of the video
24:10
it sounds like it was a
pretty exhausting trip.
24:11
It sounds like you didn't
really have much time to relax.
24:13
RAMON GALVIN: Not one bit.
24:16
24:17
DAVID J. MALAN: Well,
that's it for CS50 Live.
24:20
Thanks so much to this
week's contributors.
24:22
Thanks so much to the
team behind the camera.
24:23
Thanks so much to our correspondent--
24:25
RAMON GALVIN: Senior.
24:27
DAVID J. MALAN: Senior
correspondent in the field.
24:28
This was CS50.
24:30
>> RAMON GALVIN: And this is
something, I don't know what.
24:32
>> DAVID J. MALAN: It was
our dress rehearsal.
24:35
So that all sounds great.
24:38
Bigger TVs, more
pixels, more resolution.
24:39
But why is this actually useful?
24:42
>> RAMON GALVIN: I'm glad you
asked that question, David.
24:43
>> DAVID J. MALAN: I'm glad you asked--
I'm glad I asked you to ask me that.
24:45
>> RAMON GALVIN: No, I say I'm
glad you asked me the question.
24:48
And then you say, well
it's in the prompter.
24:50
I'm glad I asked you to
ask me that question.
24:52
DAVID J. MALAN: Well, it's
in the prompter there.
24:54
RAMON GALVIN: I'm glad you--
24:56
DAVID J. MALAN: I think it's
funnier if you just say,
24:56
I'm glad I asked you to
ask me that question.
24:57
Because it's kind of a play
on what you would expect.
24:59
>> RAMON GALVIN: OK.
25:02
I'm glad you asked me to
ask that question, David.
25:02
There's a documentarian.
25:05
>> DAVID J. MALAN: I'm glad
I asked you to ask me.
25:06
RAMON GALVIN: I'm glad I asked
you to ask me that question.
25:08
>> [MUSIC- CAKE, "THE DISTANCE"]
25:11
歌词与翻译
[中文]
...
[主题音乐]
...
>> DAVID J. MALAN：世界，你能听到我吗？
所以在下周的剧集中我们将
谈论麦克风技术。
但现在我们开始吧。
你好，世界，我们是
回来了，就像我的声音一样。
这是 CS50 Live。
>> 孩子，我们有好的吗
本周为您呈现。
特别是，我们
got the Heartbleed bug
that's been all over the news of
迟到了，一些学生的故事，
拉斯维加斯之旅，背后
Dropbox 的场景之旅。
我听说，是的，CS50
自己的拉蒙·加尔文回来了。
CS50 的 Ramon Galvin 加入
今天又来工作室了。
>> 但首先，一些台灯。
当然台灯有点
这学期CS50的一件事。
您可能还记得艾哈迈德，
来自上一集，
提交了视频
阐述为什么他希望收到
他自己的 CS50 台灯。
好吧，我们送了一张桌子
灯最终给了艾哈迈德。
他好心地派我们去
this photo of himself
in Pakistan with a CS50 desk lamp.
>> 同时，你可能还记得灯
故事，由拉脱维亚的艾格斯提交。
我们通过桌子发送
灯也运往拉脱维亚。
图中是台灯。
最后，你可能还记得菲利普
他不仅提交了照片，
，还提交了视频
via which to thank us
for his desk lamp, which we
一路送到德国。
我们来看看。
>> 菲利普：嗨。
亲爱的大卫，亲爱的所有人
CS50 的你们都是了不起的人。
我是菲尔，我想感谢你
对于这份令人难以置信的礼物就这么多了。
令人难以置信
我知道你实际上
一路发送了这个
到德国这里来。
但是你知道吗？
为什么我不亲自感谢你呢？
>> 嘿，大卫，我想谢谢你
关于这款 CS50 台灯就说这么多了。
你无法想象
这对我意味着什么。
>> 大卫·J·马兰：台灯？
>> 菲利普：好的。
好的，我要走了，
但是，是的，谢谢。
DAVID J. MALAN: Now, two of your
最近同学们实际上
来找我们聊天。
特别是来自马萨诸塞州的艾米
和来自爱尔兰都柏林的 Jack，
千里迢迢来到桑德斯剧院
坐下来谈谈 CS50
的过去和现在。
...
>> 这是桑德斯剧院。
这就是 CS50 的所在
举办讲座。
非常感谢您来到校园。
我们从介绍开始吧？
我是大卫。
>> 艾米：我是艾米。
我从事网络工作，并且我
住在剑桥。
>> 杰克：我是杰克，我是
来自爱尔兰都柏林。
我是一名高中三年级学生。
>> DAVID J. MALAN：是什么让你来到这里
今天特别是从那么远的地方？
杰克：去波士顿参观。
>> AMY：CS50 是如何演变的
正如你一直在教的那样？
>> DAVID J. MALAN：这绝对是
这些年来变得更加戏剧化。
我们从 2007 年就开始拍摄，所以
we can literally go back in time
and watch past years, first
特别是讲座。
我认为第一堂课
2007 年，我几乎就是
，在全班同学中脱颖而出。
说，你好，这是 CS50。
然后我们深入研究当天的内容。
>> 好的，欢迎光临
to Computer Science 50,
Introduction to Computer Science 1.
My name is David Malin and I
will be your instructor this--
>> Now there's music.
灯灭了。
We drop down a huge screen.
可能有也可能没有
某一年的布偶。
...
这很有趣，因为这
has all happened very gradually
over the years, just a
little bit more each year.
但是现在，
first year and the last year
is actually rather atrocious, just how
different the first five minutes are.
>> AMY：我很好奇，你看到了什么
as the differences between the edX
version and the live course?
>> DAVID J. MALAN：所以课程上
技术上CS50
校内和 CS50x 校外
基本上是相同的。
两者有何不同
二是我们能够提供的支持级别
。
尽管 CS50 拥有庞大的团队
大约 100 名助教、课程
助理、我本人和
我们的制作团队--
我们勉强跟上
与校园
的 700 名学生和 150 名扩展学校学生一起
他们自己在本地或在线。
所以对于 CS50x，我们根本没有
办公时间的支持结构，
例如，四个晚上
每周几个小时。
JACK：你们都聊些什么
办公时间将与
比如说，您的讲座时间有所不同，
还是在部分或短裤上？
大卫·J·马兰：在校园里
办公时间确实为学生提供了
个机会
与一名教学人员一对一提问
甚至是他们附近的同学。
并且通常会解决错误
他们在代码中拥有这些内容。
>> AMY：我认为 Reddit 有点给予
合理的办公时间传真
。
>> DAVID J. MALAN： 同意，同意。
我印象非常深刻，
不过，随着 Reddit 社区
和新人的加入
这个团体也是如此——
人们是多么渴望和充满希望。
Reddit 绝对适合您
我认为，最好发布代码
并进行线程讨论。
>> 杰克：你认为
人们应该尝试，
如果他们知道自己是
做错了什么
或者就像他们已经实施了--
花了太多时间，
认为他们应该停下来重新开始？
或者寻求帮助？
或者他们应该如何--
>> DAVID J. MALAN： 至少休息一下。
有时，尤其是对我来说，
当你的压力水平开始上升时，你
开始破解和复制
然后粘贴，忘记
您已经尝试过的内容。
是时候去
睡觉或者慢跑，
或者去洗澡，然后就可以了
有点距离。
这已经发生了
很多很多次对我来说
，我会躺在床上
甚至，甚至开车去上班，
或步行去某个地方，善良
在我的脑海中进行调试。
>> 只有当你达到这个距离时
你肩膀上的压力也减轻了很多，
我想，你能意识到吗，
就像，哦，我是个白痴。
我忘了调用这个函数，
或初始化一些变量。
>> 如果您愿意，可以给您一个小惊喜
看看您的 CS50 座椅
坐垫下面，有一些东西在等着您。
...
这些看起来很漂亮。
我们看到这些表情了吗？
>> 在他们的座垫下，
当然，Dropbox 空间要多一些。
现在您可能还记得我们最近
前往密苏里州圣路易斯，
，在那里我们有一个独特的机会
在第三度玻璃工厂实际吹制玻璃
。
我们今天的主持人做了
这个漂亮的玻璃碗
通过不断旋转直到
你就得到了美丽的波浪效果。
这现在存在于我们的
位于剑桥的办事处。
>> 另一方面，我做了
这个橙色玻璃大球
现在放在我的桌子上。
但我们在圣路易斯
当然，对于在圣路易斯举行的 CS50 黑客马拉松
，使用 Launchcode，
我们有机会
与你们的一些人坐下来
同学们，听听他们的 CS50 故事。
>> EZRA：有一次我看到电脑
编码和那种——这就是
我想要从事的职业。
而且我认为我会
非常擅长。
>> 查尔斯：嗯，我一直在
找了一段时间的工作。
理学学士，
生物医学工程。
进展不太顺利。
所以我想也许我应该看看
进入不同的领域。
>> KIMBERLY：位于威斯康星州绿湾
我是一名学校辅导员。
我真的知道我
想转行。
>> SAM：我听过很多
人们说，每个人
都应该学习如何编码。
每个人都应该接触到它。
在我只是友善之前
就像，呃，无论如何。
>> 奥斯汀：我休了一个学期的假。
我现在正在执行 CS50x 程序。
>> KELLI：非常方便
对任何人来说。
>> LEANNE：我一直是
过去的开发商。
但我遇到了一个情况，我想要
为了增加我的信心，
，我想学习
C，我想学
PHP，我看到CS50正在教这个。
奥斯汀：人们真的很有帮助。
肯定还有更多
一个比您
从在线课程中想象到的社区。
>> KELLI：我正在解决我的问题
第五集，我刚刚开始。
所以我要做一些取证。
>> 查尔斯：这很有挑战性。
这绝对是这个意思
突破你的极限。
我正在解决第五组问题。
>> KIMBERLY：我和我的同学
致力于我们的最终项目。
>> SAM：我正在做我的期末项目。
我还有另外两个人在工作
和我一起，我们就是三股力量。
>> LEANNE：我正在尝试
一个 iOS 应用程序，它是我想要创建的日历议程
应用程序，
仅供我自己使用，首先。
>> 奥斯汀：我的最终项目是
将成为一个
是图像和视觉存储库的网站。
基本上会有
为医务人员提供有用短语
和手语的列表。
>> EZRA：让我们来说说我的最终项目
是一个木偶在跳舞，
他们问我，你能做这个吗
木偶以两倍的速度跳这支舞？
我可以转到我的代码，进行更改
它，保存它，编译它，上传它，
并立即向他们展示
我可以——我不仅
完成了这个最终项目，我明白。
不过我可以调整它
他们希望我调整它。
>> 查尔斯：我想一旦我得到
我的最终项目已完成
和一些潜力
雇主有机会
看看他们会有一个
更好地评估他们
是否认为我适合他们。
SAM：现在我非常有信心并且我
一直在学习新东西。
太棒了。
它改变了我的生活。
>> EZRA：这真的是
硬质材料，尤其是
，如果您正在这样做并且还
工作，也许还有家庭，
，也许还有孩子，
也许还有抵押贷款。
但如果
你只要付出努力。
你得到的会更多
比您投入的时间更有价值。
DAVID J. MALAN：并且
现在，本周在科技领域。
您可能听说过
所谓的 Heartbleed
错误，影响了网络
服务器遍布世界各地。
但这个错误到底是什么？
好吧，事实证明许多网络
服务器运行名为 open
SSL 的软件，当然是 SSL
是安全套接字层。
这就是技术
加密网络浏览器、
或客户端与网络服务器之间的流量。
现在不幸的是，在
2011 年 12 月，一位程序员
引入了一个意外错误
开放式 SSL 的源代码。
>> 不幸的是，打开 SSL 是
用于许多其他产品，其中
Apache
网络服务器和其他
在网上非常流行
用于托管网站的互联网。
这样做的结果是
以下攻击是可能的。
作为开放式 SSL 的一部分，有一个
所谓的心跳功能，
客户端就像浏览器一样
可以发送消息或有效负载，
实际上只是一个字符串，
就像向服务器打招呼一样。
除此之外
它发送一个数字
，它应该是
该有效负载的长度。
在 hello 的情况下，应该是 5。
>> 不幸的是，这个错误
打开SSL操作如下。
它忽略了该数字。
所以如果你——更确切地说，
它信任这个数字。
因此，如果您（客户端）发送了一条消息
比如你好，而不是数字 5
但是数字 100 会发生什么
是服务器会盲目地
响应该有效负载
不仅回显 hello，
这 5 个字节，还回显额外的 95 个字节
字节，从而相信
您说的是实话，当您
说有效负载实际上是 100
字节。
现在为什么会出现问题？
>> 嗯，你可能还记得
当然，来自 CS50，
来自内存管理
堆栈和堆上的
是数据路径的残余物，当您
调用函数，使用变量，
这些值甚至保留在内存中
如果您不再主动使用
这些内存块。
所以当服务器响应不是 5 时
咬，但有 100 个字节，其中 95 个
技术上不应该
返回到客户端，
这 95 个字节可以包含
密码，或服务器的
安全证书，或服务器
可以说，所有密钥
都用于加密。
>> 所以最终你的
信息可以返回
给一些随机的对手
在互联网上只需
因为您的密码，或者
信用卡信息、
或其他信息
敏感信息碰巧
在网络服务器的内存中
在那个特定的位置。
现在这是一个大事件
交易，因为这个错误
影响了网络服务器
全世界。
其中 Amazon Web Services、Box、
Dropbox、Etsy、Flickr、GitHub、Gmail、
Go Daddy、Google、Instagram、
Minecraft、Netflix、OKCupid、Pinterest、
SoundCloud、Tumblr、Twitter、
Venmo、维基百科、WordPress、雅虎、
YouTube——而这些只是
这些公司，只是实际披露的一些
公司
他们的服务器一直在运行
受影响的软件并且
直到最近，即上周，
才进行了更新。
>> 现在结果是在源代码中修复了
因为，这个 Heartbleed 错误实际上
非常简单。
基本上可以归结为
到这两行代码。
如果有效负载大于
实际长度，返回0。
不返回一些
潜在的泄露位。
现在实际上是
代码稍微复杂一些。
它看起来更像这样。
但这只是一些
额外的算术
，还有一些
其他代码行，
但修复确实就是这么简单。
>> 所以如果你从来没有
相信讲座
，当我们说你应该始终
检查数组
的边界并确保检查
盲目遍历之前任意内存块
的长度
通过计算机的内存，
这就是可能发生的情况。
这确实是
具有全球影响力的错误。
现在您自己可以做什么
了解更多并保护自己？
那么，前往 heartbleed.com，
这是一个非常棒的网站，
对此进行了更详细的解释
威胁是什么，人们
如何应对，什么
软件已受到影响，
以及您如何保护自己。
但这基本上可以归结为
为此--更改您的密码，
可以说在大多数情况下
如果不确定
是否是该特定网站，您就知道
网站受到影响。
>> 因为最可怕的之一
关于这个错误
的问题是它不太可审计。
目前尚不清楚，即使
在过去两年中，
一台服务器容易受到攻击，如果您的
信息确实遭到泄露。
情况也是如此
一般来说，对于安全性来说，
最好的方法是偏执
并更改以下网站上的所有密码
对你特别敏感。
但请前往该网址
了解更多详细信息。
>> 现在在其他新闻中，马克
扎克伯格最近发布了这一消息。
我很高兴地宣布
我们已同意
收购领先者 Oculus VR
在虚拟现实技术中。
现在虚拟现实是
一件有趣的事情
正在开始收获
多一点牵引力。
它通常涉及
戴上一副护目镜
里面可能看起来像这些
其中一对镜片
可以让您看到电脑屏幕
就在靠近你的脸的地方。
在计算机屏幕上可以
可以是任何东西，房子的内部，
房子的外部，
游戏内的虚拟世界。
结果令人难以置信
身临其境的机会
，让您感觉自己实际上
某个你实际上不在的地方。
例如，我可能会
当我真的以为我在会议室
时
一个类似 Tron 的虚拟世界。
事实上，我有一个机会。
我个人没玩过
Oculus，但我确实拜访了我们在华盛顿州西雅图的朋友
，
最近在 Valve 软件公司，
正在开发一个非常
similar VR technology.
我很幸运
有机会
穿上他们的一双
护目镜持续 60 秒。
>> [音乐播放]
>> 现在，CS50 的 Dan Coffey
最近也有机会
去一趟
加利福尼亚州山景城，
他与我们的同事坐下来
Dropbox 的朋友，其中包括
CS50 自己的前任教学主管
Thomas Carriero 同事，
，他负责
您座垫下方的所有 Dropbox 空间
。
托马斯非常友善地打开了门
Dropbox 的独家内容
幕后花絮
这就像在 Dropbox
工作并敢于在 Dropbox 现场直播。
>> 托马斯·卡里罗：嗨，我是托马斯
Carriero，前CS50队长TF。
我们在 Dropbox 总部
在加利福尼亚州旧金山。
Welcome.
我将带您参观。
Come with me.
...
Cool.
所以这个气球就在这里，
这个绿色复选标记
是我们放在您身上的气球
刚加入公司时的办公桌。
这个想法是气球
只要您是新员工，
就会一直保持在该职位。
所以气球当然输了
氦气随着时间的推移和时间的推移
气球死了
你不再是菜鸟了。
这需要几个月的时间
发生这种情况是因为这些气球真的非常非常昂贵。{2}
...
我们认为我们可以保留绿色支票
在业务中标记气球业务。
>> 酷，这里就是 AT&T 公园。
这是桑人的所在地
弗朗西斯科巨人队比赛。
我们实际上有一个 Dropbox box 套件，
我们其他很棒的便利设施之一，
就在马路对面。
所以我坚持这一点
非常酷的灯光显示。
所以这里发生的是
我们正在获取有关正在发生的情况的实时数据
在我们的邮箱应用程序中。
每种颜色对应
到不同的动作。
>> 正如用户所做的那样
这些动作，这些灯
会以这些颜色亮起
让我们知道发生了什么事。
有时，如果出现问题，
颜色将开始都是一种颜色
，我们知道有些东西
坏事正在发生。
这就是其中之一
我们
跟踪内容的方式
邮箱中正在进行。
...
>> 太棒了，让我们看看是什么
今晚吃晚饭。
看起来我们有八个小时
熏牛胸肉就在这里。
这是我最喜欢的
车站，印度车站。
今天是开面三角饺。
嗯，我想那是
我最喜欢的电台
，但这是我最喜欢的另一个电台。
>> 这是披萨站。
所以他们总是制作不同种类的
我们的披萨烤箱就在那里。
看起来他们正在制作西西里岛菜
披萨，这是我的最爱之一。
好吧，厨师告诉我的
它们是新鲜制作的 Ho Hos。
我告诉他我要等
直到我吃完晚餐
，但我肯定会
今晚吃一份。
好的，我现在就去吃我的。
真的很好。
...
>> 所以这是奖励站
那是在科技商店外面。
午餐我们吃墨西哥菜
这里的食物和这里的寿司。
晚餐我们有
有些肉很好吃。
今晚看起来像烤猪腰肉。
近距离观察这一点。
酷，这就是我们的设计区域。
这就是我们设计的地方
一堆产品。
我们有很多乐趣
海报板和东西，
以及所有模拟
我们正在努力。
我们还有
地面我们一直在工作的一堆模拟
多年来。
这样你就可以结束了
一秒钟就可以了。
>> 但这标志是我的标志之一
关于 Dropbox 最喜欢的事情。
所以这个标志实际上
来自旧办公室。
我们的口号是，它就是有效。
但如果你仔细观察，就会发现
标志中的潜意识信息。
>> 这是我最喜欢的部分之一
Dropbox 就是这些自动售货机。
而不是有芯片或
苏打水或类似的东西，
我们实际上有电子产品。
因此，如果您需要新的触控板，或者
一个新键盘或一些耳机，
您只需滑动即可
你的徽章就在这里。
输入号码，然后
你的电子产品就出来了。
太棒了。
非常感谢您的加入
我参加了这次 Dropbox 之旅。
带您参观真的很有趣。
>> 我要结束这个了
以我们结束
所有全体会议的方式。
这是我们唱的特别颂歌。
我可以在这里寻求帮助吗？
一、二、三 - Dropbox！
通常比这酷得多。
...
大卫·J·马兰：现在如果
您想要访问 Dropbox，
前往加利福尼亚州山景城，跳
位于旧金山以北的 101 号公路上，
，他们实际所在的位置。
现在我们还有一个
最近有机会
去拉斯维加斯旅行，
内华达州参加 NAB 节目，
全国协会
对于广播节目，
汇集了一些
100,000 人对音频和视频感兴趣
更普遍的技术
来谈论最
最新和最好的。
>> CS50 自己的 Ramon Galvin 拍摄
这次旅行并带了
一个摄制组来拍摄
演出现场的镜头。
拉蒙·加尔文：大家好。
好的，我明白了。
你好，世界。
我必须说出我的名字吗？
>> 摄像师：现场通讯员。
拉蒙·加尔文：我可以吗
下三分之一？
现场通讯员。
>> 摄影师：前辈。
拉蒙·加尔文：就是这样。
...
我知道，但我必须这么做
做吧。 [听不清]。
...
我一无所知。
...
>> 现在是我的首要姿势。
...
大卫·J·马兰：还有
他们一直提到4K。
4K 到底是什么？
>> 拉蒙·加尔文：那是
真是个好问题。
非常基本上--
>> DAVID J. MALAN：切到
解释 4K 的剪辑。
...
你好，世界。
我的名字是大卫·马兰。
拉蒙·加尔文：我是拉蒙·加尔文。
DAVID J. MALAN：我们就在这里
在 NAP（全国广播协会
会议）上
在内华达州拉斯维加斯。
但是我们为什么在这里？
拉蒙·加尔文：我不知道。
我不知道，大卫。
>> DAVID J. MALAN： 非常好。
这个可以用吗？
>> RAMON GALVIN： 可能不会。
DAVID J. MALAN：我们回来了，
正如 CS50 自己的 Ramon
Galvin，您可能还记得
从上周的剧集来看。
拉蒙，很高兴你确实回来了。
>> RAMON GALVIN：我很高兴我
还有工作，大卫。
>> 大卫·J·马兰：所以让我们
向房间里的大象
讲话
拉斯维加斯，即4K。
我在上下文中听说过这个
电视和电脑显示器，
但什么是 4K？
>> RAMON GALVIN：所以这是一个决议。
每当您观看节目时
浏览视频或讲座
，您将获得我们所说的 1080p 视频。
这意味着什么
视频高 1,000 像素。
>> DAVID J. MALAN：或 1080。
>> RAMON GALVIN：或 1080。
或大约 2,000 像素宽。
现在 4K 的宽度大致为 4,000 像素，
大约 2,000 像素高。
大卫·J·马兰：好的。
所以这有点像
由四个 1080p 显示器组成的网格
就在您的面前。
>> 拉蒙·加尔文：没错。
DAVID J. MALAN：好的，就这些了
很好，但是为什么这有用呢？
>> RAMON GALVIN：很高兴我问了你
问我这个问题，大卫。
>> 大卫·J·马兰：这是
在提词器上。
>> RAMON GALVIN：所以有
一位名叫
Errol Morris 的纪录片导演实际上
利用4K技术。
通常是为了拍摄
采访，他通常这样做，
他必须使用多个
相机获取放大镜头
或缩小镜头，或者
拍摄采访两次
以获得相同的变焦
拉近，缩小镜头。
不过，现在他使用的是 4K
相机拍摄一张巨大的 4K 镜头。
然后当他编辑时，
人为地裁剪那个镜头。
大卫·J·马兰：还有
本质上，放大
仍然可以提供 1080p，但只是
4K 图像中的一些像素。
>> RAMON GALVIN：没错，给予
他从一张原始相机拍摄的照片中拍摄了多张照片
。
大卫·J·马兰：有趣。
那么我们怎样才能使
CS50用这个吗？
>> RAMON GALVIN：我很高兴你问
我也有这个问题，大卫。
因为我拍摄了整个步行过程
上学期与 Zamyla 的视频。
对于这些视频，我们会
必须用缩小的镜头跑完一次
步道。
然后我必须调整
相机以获得放大镜头。
然后我们会再次运行它，
运行两次。
使用 4K 相机我们可以剪辑
我们的生产时间减半。
大卫·J·马兰：我明白了。
所以这应该非常令人兴奋
那么，对于我们来说，今年秋天。
拉蒙·加尔文：没错。
DAVID J. MALAN：嗯，从
视频的外观
听起来像是
相当疲惫的旅行。
听起来你没有
真的有很多时间放松。
RAMON GALVIN：一点也没有。
...
大卫·J·马兰：嗯，
CS50 Live 就到此为止。
非常感谢
周的贡献者。
非常感谢
相机后面的团队。
非常感谢我们的通讯员 --
RAMON GALVIN：前辈。
大卫·J·马兰：高级
记者在现场。
这是 CS50。
>> RAMON GALVIN：这是
有什么东西，我不知道是什么。
>> DAVID J. MALAN： 是的
我们的彩排。
所以一切听起来都很棒。
电视更大，更多
像素，更高的分辨率。
但是为什么这实际上很有用呢？
>> RAMON GALVIN：我很高兴你
问了这个问题，大卫。
>> DAVID J. MALAN：我很高兴你问——
我很高兴让你问我这个问题。
>> RAMON GALVIN：不，我说我是
很高兴你问我这个问题。
然后你说，好吧
它在提示器中。
我很高兴邀请您这样做
问我这个问题。
大卫·J·马兰：嗯，是的
在提示器中。
RAMON GALVIN：我很高兴你 -
DAVID J. MALAN：我认为这是
如果你只是说，
我很高兴我邀请你，那就更有趣了
问我这个问题。
因为这就像一场戏剧
关于你所期望的。
>> 拉蒙·加尔文：好的。
我很高兴你邀请我这么做
问这个问题，大卫。
有一位纪录片导演。
>> 大卫·J·马兰：我很高兴
我让你问我。
RAMON GALVIN：我很高兴我问了
你来问我这个问题。
>> [音乐-蛋糕，“距离”]
[英语]
Show
重点词汇
开始练习
| 词汇 | 含义 |
|---|---|
|
bug /bʌɡ/ A2 |
|
|
encryption /ɪnˈkrɪpʃən/ C1 |
|
|
payload /ˈpeɪloʊd/ C2 |
|
|
vulnerable /ˈvʌlnərəbl/ C1 |
|
|
certificate /sərˈtɪfɪkət/ C1 |
|
|
algorithm /ˈælɡərɪðəm/ C1 |
|
|
memory /ˈmeməri/ B2 |
|
|
heap /hip/ C1 |
|
|
stack /stæk/ C1 |
|
|
server /ˈsɜːrvər/ B1 |
|
|
client /ˈklaɪənt/ B1 |
|
|
compile /kəmˈpaɪl/ B2 |
|
|
debug /diːˈbʌɡ/ B2 |
|
|
virtual /ˈvɜːrtʃuəl/ B2 |
|
|
reality /riˈælɪti/ B2 |
|
|
resolution /ˌrezəˈluːʃən/ B2 |
|
|
pixel /ˈpɪksəl/ B1 |
|
|
conference /ˈkɒnfrəns/ B2 |
|
重点语法结构
-
So in next week's episode we'll talk about microphone technology.
➔ 将来时态 ('will' + 动词原形)
➔ 这句话表达了一个计划好的未来行动。使用“we'll”（we will）表明承诺讨论这个话题。“in next week's episode”这个短语指定了时间范围。
-
And what brings you here today in particular from so far away?
➔ 间接疑问句 ('what' + 'brings' + 主语 + here)
➔ 这是一种礼貌地询问某人来访原因的方式，强调他们所走的距离。“in particular”强调了当前场合。
-
It's definitely gotten more dramatic over the years.
➔ 现在完成时 ('has gotten') 描述随着时间的变化
➔ 这句话表明 CS50 随着时间的推移变得越来越复杂或视觉效果越来越好。“Definitely”强调了这种变化的确定性。
相关歌曲