Added VAAPI encoder support

[blue-kaleidoscope]

Added VAAPI encoder support for ffmpeg which is necessary for Intel architectures like Haswell and older.

Topic was discussed here: #2450

Acceptance Criteria:

• Features and enhancements are fully implemented so that they can be released at any time without additional work
• Automated unit and/or acceptance tests have been added to ensure the changes work as expected and to reduce repetitive manual work
• User interface changes are fully responsive and have been tested on all major browsers and various devices
• Database-related changes are compatible with SQLite and MariaDB
• Translations have been / will be updated (specify if needed)
• Documentation has been / will be updated (specify if needed)
• Contributor License Agreement (CLA) has been signed

[CLAassistant]

All committers have signed the CLA.

[lastzero]

Excellent, thank you very much! I was wondering why it didn't work on Haswell. This explains it.

[blue-kaleidoscope]

@lastzero Unbelievable but I commited a mistake here. Line 88 should be "-vf", format=nv12,hwupload instead.
Not specifying the format throws an error message when trying to encode. Could you correct this small mistake?

[lastzero]

I'm not quite sure I understand? "format" is a variable, so it is not the actual value of the parameter:

format := "format=nv12,hwupload"

Feel free to send us a quick pull request if you want to change any details (after you have tested it...)!

[blue-kaleidoscope]

Ooops, I posted quicker than I read.

I just got error messages on my system when trying to encode with VA-API and first thought it was about a missing specification of the format.
Now I see in line 82 I specified it. Sorry... my bad.

The error messages by the way are related to HEVC which means: The old Haswell architecture is not able to encode HEVC (so basically any new iPhone shot) video: https://wiki.libav.org/Hardware/vaapi

With H.264 however, it works with the snippet above.

Maybe I should accept that my NAS is simply too old for the new fancy bancy stuff. ;-)

Have a nice evening and sorry for the confusion!