Files & File Systems: Crash Course Computer Science #20
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- Опубліковано 29 вер 2024
- Today we’re going to look at how our computers read and interpret computer files. We’ll talk about how some popular file formats like txt, wave, and bitmap are encoded and decoded giving us pretty pictures and lifelike recordings from just strings of 1’s and 0’s, and we’ll discuss how our computers are able to keep all this data organized and readily accessible to users. You’ll notice in this episode that we’re starting to talk more about computer users, not programmers, foreshadowing where the series will be going in a few episodes.
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We're now up 20 Layers of abstraction.
l a y e r s
That’s not how it works...
Every time I watch one of these videos I always imagine going back in time and showing it to an early computer scientist and seeing their reaction to how far we've come.
Heh, yeah. But I meant going back to a time when the technology was still developing. And seeing their reaction for those times when Carrie Anne casually references the capabilities of modern computers.
evolution of computer is fast...
Yeah, but they would be shocked we still don't have human level ai.
Love that the part about 'deleting a file' is the most replayed
Does the Mongol Warrior file have a bug where it benefits from an "exception"? Or is that a feature?
sudo dd bs=1M if=/dev/zero of=
That will _actually_ wipe clean whichever storage device you write it to. :)
really enjoying this series
this great explanation but i knew it all of them and i watched to learn about togglable file systems which is not part of video and i still have 0 clue about what it might be.
So interesting and engaging, great work. I think this is my favorite crash course series
Wow, you are so amazing. I love the course.
Man, I waited half an episode for you to get around to talking about fragmentation?
And oh, for the days when your save game file was a (maybe) compressed dump of a global struct. I wrote many a safe game editor, back in the early 90s. Also, Basic's READ, anyone?
amazing content. Thanks
ASCII ? haven't we moved on to utf-8?
they used scoodypop lol
9:42 Skoodilypoop_Animations. ;)
This crash course is one of the most delightful things to ever appear on the internet.
Thank you Carrie Anne, Stan and everybody else involved.
Defragmentation was fun to watch... If you had angelic patience and nothing better to do.
Before defragmentation - 25% fragmentation.
12 hours later - 24% fragmentation.
24 hours later: 26% fragmentation.
Only 90's kids remember how fun it was to watch defrag.
Pajaat Or 00's kids with passed-down legacy hardware. I remember watching Windows XP defrag. I think I also remember Windows 7 defragging, but it wasn't nearly as fun. (born '97, so anything before 2002 is lost to childhood amnesia)
You can always get third party defraggers with nice GUIs that show off the data juggling.
I wouldn't say it was fun. I was expecting my Windows to run smoothly after every defrag, but it never happened :(
I'm 00's kid, and I remeber that defrag^^
The Windows 9x defrag utility was the best, all those little blocks.
XP just had the stupid bar which didnt tell you much
Windows vista and newer got rid of the animations with the claim it improves performance.
Just realised it's a bit ironic that these computer science courses are called "crash" course. ;)
Crash Course rocket science... coming soon!
coincidence isn't irony but that doesn't stop the phrase from being ironic
I wonder who first used "crash" to describe a computer getting into a fankle. It's such a common usage I'd never thought about it until you just mentioned it.
no its not ironic because Crash Course was not made just fpr computer science, this is all brand new subject, man after they have every subject on earth done there will be No need for school or teachers and thank god
😂
WHEN WILL THERE BE "ANOTHER LEVEL OF ABSTRACTION" TSHIRTS?!!!!
It's great that the presenter doesn't shy away from "advanced" topics (in any of the videos in this course) - that provides something for every "level" (beginner / intermediate / advanced) of viewer. Great job with these videos !
After so many years, I finally know defragmentation means and what it does. Thank you so much.
I can understand the simplification, but it is important to remember that many programs running under Unix/Linux do not care about extension and furthermore EXT4, a common Linux filesystem, does not experience fragmentation.
Peterolen very few programs (at least that I work with) care about the extension
How I am so late to know about this amazing channel!!! I guess nowadays youtube is getting so much filled by shitty channels that awesome channels are getting missed!
I often speed up informative UA-cam videos by 25%.
This extremely good presenter obviates the need, and speaks just about 25% faster than "normal" with perfect articulation and fluidity that makes it easy to take in what she is saying without any flaws to distract.
A playback speed of 80% would "undo" a 25% increase over "normal". (1/1.25=0.8).
If you slow this video to 75% (the closest to 80% that's available), the presenter sounds like she's speaking a little more slowly than normal, so I'd say, yes, she's naturally speaking about 125% of normal rate.
And, very well done!
9:40 Putin.jpg
The best thing about SSD's? No defragmentation required.
Not only is it not required, but it would actually be detrimental to the "health" of the SSD, since each storage cell can only be written to a limited (albeit reasonably large) number of times.
미셜비 that only half the truth. ssds will preread/precache the next blocks just in case they are needed, defragmentation can have a performance benefit even on ssds
teleturbo Trying to defrag a SSD would do more harm than good as explained by Gert Brink Nielsen.
AndyThePandaNinja it depends how you defrag and what filesystem you use .
usually, SSDs have their own firmware and controller that knows what is the health of each block and where the data is best located. the controller along with the firmware handles defragment and file placement. this is much better than relying on your operating system since the firmware maintain optimal health and speed and reduce data corruption is best left to the manufacturer since each type of SSD uses different NAND types, and different controllers and different configuration.
Wait, so SSD is not write in order?r
I remember the first time a teacher told me to find a _file_ on a computer ..... I spent 5 embarrassing minutes looking for any icon that looked like a clipboard or spiral notebook. Later I found out that was the Calendar icon.
hahahaha
Wow, my first time watching a video from your channel. As I am interested in File Systems I came across this video. You, Carrie, can explain it very clearly and your animations and sounds are pleasing on the eye ;)
I absolutely love this series. Thank you for putting this together. Do you mind sharing that Putin.jpg [9:45] file that was inside the WORLD_HISTORY directory? Oh, and tell Stans that saving passwords inside a .txt file is not a very good idea. ;-) .
I know you have already done 20 of these in Computer Science, but please keep them coming. Thank you.
you were thinking Putin.jpg? i was wondering what Skoodilypoop_Animation.mp4 was...
You can find that in World History.
This is ridiculous, you can't learn anything because she speaks to dam fast, how are we supposed to process this information if you already talking about a new thing before we even get to think about it. CrapCourse
I just read a full textbook chapter on this, but the way you described file systems made it so easy to understand!
Thanks for this excellent, concise video. Great work!!
I feel like I struck gold with this series! Thanks for making these videos!
"Defragmentation [...] once upon a time it was really fun to watch."
Indeed.
RIP old Windows defrag tool 😢
Ext4 is the best!
Correctrix *xfs ;3 lol. I think we can all agree these three are better than HFS+ ;)
But... don't you like case-insensitive filenames, strange extended attribute storage, and a *special* version of Unicode denormalization applied to every filename? :p
archlinuxrussian Umm, actually FAT32 is the best file system
My 5GB files disagree :P
You kids get off my lawn. FAT12 forever!
this episode makes me desperately want a crash course linux series (sincerely, a braindead Ubuntu user)
>Opens audio editor
>renames a jpg as .wav
>opens ".wav" in audio editor
>adds effect
>saves ".wav"
>Renames to .jpg
>Opens in hex editor
>fixes metadeta that was lost/damaged
>Opens image
This video is really informative for knowing nitty gritty about file system specially "Block Storage"... It can also be used to understand about newly evolved Object storage...
Carrie you are my new spirit animal.
crash course has biggest impact on the world in recent decade. it changes the way we see UA-cam, technology and education. thanks to green brothers.
best explanation for file system. I saw around 10 videos till now. thanks and congrats
HALT and CATCH FIRE, I miss the good old days.
Tell me you also watch the show!
This was pretty good! Read a couple chapters today in a Linux book covering storage partitions and file systems and this had some tidbits a fairly technical book left out.
I’ve been developing for 5 years now and finally just now falling in love with computer science
Hey, y'all gonna go more in depth about graphics?
Oreo Cakester Graphics is a complicated subject. Even if they cover it wouldn't go deep enough to be of reall value I think. Maybe they'll explain some basic concepts.
I haven't taken this course, but this may be something that interests you? www.coursera.org/learn/image-processing
I'm surprised the music directory didn't include a file named "NVRGVUUP.WAV".
Love this whole series, you make it easy to understand the flow of technological advancement
This is by far the Crash Course series from which I have learned more. Thanks, Excellent work!!!
ZFS is my favorite file system! (Go check out the video with Michael W Lucas)
file systems are why i hate iTunes. If you have 10 song files in a folder, they're in the folder, they'll always be in the folder. but they may not be in iTunes, or some may be missing, until you refresh. why can't programs like iTunes be like a folder explorer?
I remember when I first got a smartphone. Took me a bit of hunting around the Google Play store to find a music playing program that actually used directories rather than some stupid database.
I hate that database approach. It's just a mess. Just treat audio files like any other file and let me use the file system to organise them how I want!
Where are my "new level of abstraction" shirts and tote bags?
If directory files are the mapping tables, are they what get deleted when you format a drive?
Yes.
SkoodilyPoop_Animation.mp4...
Saucy
but how does the addressing work, it needs some form of numbers for wach byte/bit of data, like in RAM. but unlike RAM the Addresses would need to be gigantic to properly address every piece of data, like in a 930GB SSD...
Super Suchti Well a 64 bit Number would be enough, but most storage media store data in adressable blocks between 100 & 1000000 Bytes in size, which are then read out sequentially
A bit of extra info about the making of custom file formats: since the data just needs to be in an order that the program using it can process, and that program is usually made by humans to at least some extent (though rarely entirely nowadays), it's also not uncommon to design new formats on top of text formats so that they'll be "human-readable". This is especially useful if you want users to be able to adjust data themselves, such as in the case of configuration files and simpler level editors for video games. That method also helps the data be easier to transfer across different computer architectures, which is why it's used in html and xml (formats used for websites and similar applications).
The downside, of course, is that text-based formats are rather space-inefficient and writing routines to read them isn't the simplest of tasks. Mainly because when it's human-readable, humans will edit it, and the mistakes they make are many and varied, requiring a lot of work on your part to figure out where they've gone wrong and come up with a suitable error message. Much like writing a compiler, actually. Most of the work there is making sure the file it's been fed is valid Foogol code (I hope nobody has made an actual language with that name because it's a good placeholder name).
YAY two of my favorite series uploaded on the same day.
Looking forward to Crash Course: Interpretive Dance :)
You have a "John_scream.wav" on your computer?
ahaha, wasting time watching defragging blocks blink
this grammatical structure is hard to comprehend
Thank you, I finally figured out what is metadata, and why it has this f...antastic name.
I learned a lot from Carrie Anne than my professors xD Thank you Crash Course! :D
1:11 says "Hi, I'm Carrie Anne" in UTF8/ASCII 8-bit
well i'm an idot
i didn't realize they would show the results 15 seconds later
2 minutes of my life wasted
I so wish you would go into the details of defragmentation. Whenever I defragmented a drive I was CONVINCED I could come up with a better method. My theory is that someone came up with a very slow approach that worked well enough in the 1950s and then everyone kept using it. Prove me wrong!
I remember loading programs through DOS on start up. Changing command prompts etc. Now, all I ever deal with is testman errors using FORD scan tool software. No clue with all this new stuff.
Small correction. All microphones are analog. There is no something like digital microphone.
More correctly it is analog acoustic to electrical transducer.
Ew Calculus
Is there gonna be one about encryption or cyber security?
Yep!
OMG!! the explanation of Metadata looks a lot like a nucleic acid secquence... a gene... uuuuuuhhh
"It's usually best to use an existing standard, like jpeg or mp3"
Both of which had long standing patent issues (trolls) surrounding them - mp3's last patent expired a month after this video was published...
I have a doubt @ 8:00 it has been said that we actually don't remove the data we just remove the record from the directory file.And since we are only
storing the block number , How do we know that where a new file which over writes the deleted(actually not) file ends.
for example let's say that a block contains only 8 bits of data. and suppose block 2 had the data 10001110 . Now we deleted it. And than some
other file was being written to the block but it has only 5 bits of data so the first five bits are overwritten and the new block contains 10110110
so isn't this data corrupted.?
The whole byte would probably be written in as 00010110. Even memory is addressed on the byte level so to put a new 5 bits in front of the 3 would require load, manipulate and store. Assembly language allows the easy manipulation of a byte. This provides more freedom for bit manipulation but it is the programmer to do it write. I would zero fill (or 1's for signed negative ints) from the top or bottom depending on if its for logic or arithmetic functions. If you just want to write the upper five bits in, you could AND it with 11111000 to zero fill the rest of the byte address. Byte splitting may be extreme but if it is the memory system of an embedded system in a muscle implant or mars sensor, that might be what you limitations are. Just my 10 cents
Way awesome then Galvin Book!
Okay, so I have a burning question;
How does the computer use binary? I know that binary is basically a long list of off and on instructions for transistors but I don't understand how turning on and off can perform an action?
You translate them into ever more complicated systems.
The basic "on/off" states are what is usually referred to as "binary numbers" and are written as 0s and 1s:
10011100 11110010. As such, binary is just a number format, like decimal (base-10) or hexadecimal (base-16); binary being base-2. You can translate any number between those formats, it's just a way of writing numbers down, and computers use the binary format because that's easy to store in two states (on/off). For storing a decimal number that way, you'd need a technical way to store 10 different states of a thing.
They talked about the subsequent steps afterwards: When the computer is expecting some form of command, such a string of numbers can be interpreted as Opcodes, i.e. things like "read" and "add", etc.
Depending on the program that is running, data can be interpreted in different ways after that: If it's an image viewer, the 10011100 11110010 can be translated into colour information for a pixel. If it's a text file, it may be letters. If it's a MS Word file, maybe it's text, and a formatting code for "bold". And if it's another program, the data may be interpreted as another command that is executed by that program.
IOW: _Everything_ is broken down into a number for computers, and that number is stored in an "on/off" format.
Liam Rice You should go back and watch all the earlier videos in this series. It's explained very well.
All this time I thought disk defragmentation was a physical process that was necessary due to wear and tear on hard disk drives. Is this a consequence of me being too young?
i always somehow end up coming back to this computer science crash course XD
Nice programme
In WHAT way was watching a 250 GB HDD defrag all the porn one's saved 'fun"?
I BEG TO DIFFER.
You're out by three orders of magnitude from when it was fun. It was back when you had a 250MB disk and would run SDEFRAG on it overnight, dropping by on the way back to bed after a trip to the loo to watch the screen showing it reading and writing the blocks of the disk and standing there mesmerised for a few minutes before you remembered you really needed to get some sleep.
i remember my father doing defragmentation on windows xp. it was about 7-8 years ago. i remember it was so colourful
Thanks for the very informative video, but you could speak a bit slower :)
So guys am having a bit of trouble understanding the difference between quire data and storage data. Please help if you can
Someone's been watching world building! Link in the dooblido
.wav, .bmp, defrag... very retro episode this week!
This new level of abstraction clip starts to become annoying. Could you please not?
mind sharing TFIOS_PART2.doc at 9:45 with us?
Not sure if I should watch this without getting John Siracua's review first...
I like how these videos make use of the font Terminal. It's a really good pixel font, which it honestly has to be since it's used on the Command Prompt.
Nice videos! It would be great if you could talk about other file systems, for example ext or fat and show how they work and their limitations. And also, in the part of file format could have been mentioned linux administration for them (inods)
Thank you very much!
can't believe you described all that and never mentioned the term F.A.T
If you think Crash Course Videos will help you pass a class you are sadly mistaken.
That's not how audio is stored, but I guess there wasn't time to explain FFT.
Number of abstraction level > storage space in my head👍
A show about computer files, by computer philes, for computer philes.
what a satisfying video, I love my file system
i just came and i see a creeper in the background.
you gain a subscriber.
A thumbs down? On THIS video? Why would that be?
so what we seen in the finder or file explorer is the directory file? People of youtube correct me if im wrong.
yeah I miss watching defrag operations that were visually represented.
I want too"" learn all I can about science & technology good to learn what we don't know thanks
Disappointed that there was no "ding" when file systems were first mentioned...
Skilled narration from Austin Powers daughter.
superb ...
you have worked hard to make these videos.These videos are the best about computer science.