To find out what is needed for present-day browsers to display sources using the html-4 object element.
A nice article about using the object element to both create standards-compliant web pages and have media playing as well, can be found at A List Apart.
1. Just an image object of type jpg.
2. Just an image object of type png.
3. Just an audio object of type m4a.
Now we extend above examples with fall-back elements in case the browser isn't equipped to display the object elements. (This can happen due to multiple reasons. For example, a plug-in might not be installed or disabled, or the browser doesn't support the object element at all.)
4. An image object of type jpg with a fall-back img element.
5. An image object of type png with a fall-back img element.
6. An audio object of type m4a with a fall-back embed element.
Instead of the ugly fall-back we can also try adding an extra parameter to the object elements. First method: to add the src attribute to the object element.
7. An image object of type jpg with an added src attribute.
8. An image object of type png with an added src attribute.
9. An audio object of type m4a with an added src attribute.
Second method: to add a src parameter to the object element.
10. An image object of type jpg with an added src parameter.
11. An image object of type png with an added src parameter.
12. An audio object of type m4a with an added src parameter.
And if everything else fails, we can try adding an iframe... but adding a link to the source is friendlier.
13. An image object of type jpg with a fall-back hyperlink.
14. An image object of type png with a fall-back hyperlink.
15. An audio object of type m4a with a fall-back hyperlink.