## Linking to images and video

Images

If an image exists somewhere on the internet, you can link to it rather than uploading it to Scripta. Here is the model:

image ::URL[]

where URL is something like `http://whatever`. Thre is no space between 'image' and '::'

Figure 1. is this a kind of robin?

You can also format the images in various ways, as in the image on the right. Here we used `float`. Another useful word is `align`. Notice also that we put a caption on this image. i you are using the X option (see upper left), you see how this is done.

The same method works for YouTube video;

You can also set the width and height;

You will want to preserve the width-to-height ratio — the so-called aspect ratios. For the bird video, I did this as follows. First, I measured the YouTube video on my screen: 30.5 cm wide and 17 cm high. The aspect ratio is $30.5/17 = 1.794$. If I want to make the vide 500 pixels wide, I should make it $500/1.794 = 279$ pixels tall. As a check, we compute the ratio $500/279 = 1.792$ — close enough!

This reference has some good historical information.

Vimeo

The same principles apply:

Source; vimeo

*So the aspect ratio is $26/11 = 2.363$. For a 500 pixel wide video the height is $500/2.363 = 212$.

The aspect ratio for old-style television is 4:3, and for HD it is 16:9. The "standard" ratio closest to the bird video above is 5:3. This fact can be deduced from the method of continued fractions or from the following simpler methid. Multiply the ratio 1.794 by the integers 2, 3, etc until you get a number close to an integer, as in the table below.

Multiplier Product Value Rounded Error

5

$5\times1.749$

8.97

9

$-0.03$

2

$2\times1.749$

3.588

4

0.588

3

$3\times1.749$

5.382

5

0.382

4

$4\times1.749$

7.176

7

0.176

Finding the aspect ratio

We conclude that aspect ratio is 9:5