[mythtv] Resync to ffmpeg 4.0

[Stuart Auchterlonie]

On 31/05/18 06:07, OpenMedia Support wrote:
> Will we be able to enable some new features like NVDEC via this sync?
> 
> It would be great to see some better deinterlace support for VAAPI as well
> 

We really need to move over to the ffmpeg hwdecode api to properly be
able to leverage any new support they add.

All our hardware acceleration support is hand crafted against the
relevant libraries, which makes adding newer methods non trivial.

In the long term the best solution is to leverage the hwdecode api,
but that does require rewriting and re-architecting quite some code.


Regards
Stuart