Add optional support for .webm movies ( libvpx library )

[ggarra13]

To do so, FFmpeg needs to be compiled with the --enable-libvpx option. This optonal BSD codec/format is very important as it is specifically designed to work at 8K. Most 8K movies use it.
Currently, albeit I added code to turn on the codec (trivial code change), tlRender reads the movies partially and then shows the frames black. Just like what happened with the TopGun clip I showed you once.

[darbyjohnston]

Most 8K movies use it

In what context? For example the latest production test footage from the ASC uses mostly QuickTime ProRes:
https://dpel.aswf.io/asc-stem2/

reads the movies partially and then shows the frames black

Is this for a specific webm movie or all webm movies?

[ggarra13]

Most 8K movies use it

In what context? For example the latest production test footage from the ASC uses mostly QuickTime ProRes: https://dpel.aswf.io/asc-stem2/

Google and youtube seem to use it for their 8K movies.

reads the movies partially and then shows the frames black

Is this for a specific webm movie or all webm movies?

Fot most webm movies. I only have an 8K movie that plays fine.

[ggarra13]

Here's a .webm movie that on my Mac it starts playing fine and then turns black;

https://mega.nz/file/2fhEUSza#6vrzJlNVAhkT8-VC3aRMPCEhr-91Pv4zIiO2rySTENM

[ggarra13]

Note: I added a PR #80 with the changes needed in tlRender to build FFmpeg with libvpx support, albeit only dynamically.