media matrix: formats and syntaxes in an issue body #196

Media embedding matrix: each embed has a heading saying what it is and how it is written. Uploaded by an experimental atgc build. Safe to close.

1. PNG, static, markdown image ![](x.png) (control) #

2. GIF, animated, 268 KB, markdown image #

3. WebP, animated, 281 KB, markdown image #

4. APNG (animated PNG), 140 KB, markdown image #

5. SVG with SMIL animation, markdown image #

6. GIF, raw HTML <img src width="240"> #

7. MP4, 134 KB, markdown image syntax ![](x.mp4) (expected not to play) #

8. MP4, raw <video src controls loop muted autoplay> #

9. MP4, <video controls><source src type="video/mp4"></video> #

10. MP4 with a poster image, <video src poster controls> (no autoplay) #

12. GIF near the 1 MB image cap: 945 KB, 8.5 s at 480x270 #

13. WebP, 8 s at 480x270: 680 KB (compare with 12) #

14. MP4 near the 5 MB video cap: 4.1 MB, 12 s at 1280x720, <video> #