- [Instructor] When a picture or sound information
is in its raw state, it's big.
It's really, really very big.
Just regular HD video is 1,920 pixels by 1,080,
and that's 2,073,600 pixels.
In digital stills camera terms, it's about 2 Megapixels.
But remember, there are three color channels for each pixel.
Whether the color information is RGB or YUV,
it's still three 8-bit numbers,
even for the most basic, standard 8-bit video.
So we're actually talking about
6,220,800 monochrome pixels,
and each one of those monochrome pixels is 8-bits.
So now, we're at 49,766,400 bits.
That's individual ones and zeros,
and this is for a single frame.
Multiply that by 24 frames per second,
which is just about the minimum anyone uses,
and we have an enormous 1,194,393,600 bits
for every second of video.
In case your curious,
that's 4,777,574,400 binary bits for UHD.
It's a lot of ones and zeros
to store, transmit, playback and display.
Codecs compress this amount of information
into something more manageable.
It's a little like using shorthand to write something
that somebody's saying.
Shorthand misses out certain letters
that are easy to add back in later
or uses symbols to represent words.
If you knew that anytime you saw the letter T
on its own on a page,
it actually represented the word The
or TY represented Thank You,
you could write those words more quickly
and use less paper doing it.
This is the way codecs work.
And just as there are lots of human languages,
there are lots of different codecs,
each with strengths and weaknesses,
and varying levels of popularity.
Compression often involves discarding image detail.
The question is whether enough of it is retained
to satisfy the viewer,
which is a pretty subjective test.
The challenge when writing in shorthand
is that uses a bit more mental effort to write it,
plus you have to learn it in the first place.
And it takes again, a bit more mental effort to read it,
and of course, the reader has to know it too.
This is exactly the challenge that you face
when working with codecs.