[Feature Request] Support AV1

[kqyang]

AV1 is the next generation video codec developed by the Alliance for Open Media (AOMedia): https://github.com/AOMediaCodec.

It is supported in Firefox Nightly (since Nov 2017), Chrome 69, FFmpeg 4.0.

Relevant specifications:

AV1 Codec ISO Media File Format Binding
AOM AV1 codec mapping in Matroska/WebM
AV1 Bitstream & Decoding Process Specification

[rainliu]

hi kqyang,

could you take a look at issue #485 ?

For packager/media/test/data/bear-av1.webm, there is no issue for me, but it doesn't work for my av1.webm file.

Thanks.