livepeer: add a -hevcDecoding flag

[j0sh]

Adds a new boolean flag -hevcDecoding to better configure the existing HEVC support.

If the flag is omitted, the default behavior on GPUs is unchanged, which is to auto-detect HEVC decoding support at transcoder start-up.

GPU transcoders can disable HEVC decoding if there is an issue with HEVC jobs via -hevcDecoding=false.

CPU transcoders now have HEVC decoding disabled by default since processing HEVC jobs is CPU-heavy, so operators are not caught off-guard once we start putting HEVC jobs into the network. This is technically a breaking change, and some un-upgraded transcoders may still be surprised anyway.

Note that LPMS already has CPU HEVC decoding compiled into the ffmpeg build, however this is implicitly derived from other compile-time flags. For the sake of explicitness we should add the native HEVC decoder to install_ffmpeg.sh but that can be added later .

What does this pull request do? Explain your changes. (required)

Specific updates (required)

• Adds a -hevcDecoding flag
• Disables HEVC decoding (and non-H264 encoding) by default on CPUs
• Depends on core: Rename 'InArray' to 'HasCapabilities' #3118

How did you test each of these updates (required)

• Manual testing with the following flags
  • -transcoder -nvidia all -hevcDecoding=false (correctly removes HEVC decoding from capabilities)
  • -transcoder -nvidia all (HEVC is enabled; no change from today)
  • -transcoder (HEVC is disabled)
  • -transcoder -hevcDecoding (HEVC is enabled)
• Light unit testing for a new RemoveCapability function

Does this pull request close any open issues?

Checklist:

• Read the contribution guide
• make runs successfully
• All tests in ./test.sh pass
• README and other documentation updated
• Pending changelog updated

[codecov]

Codecov Report

Attention: Patch coverage is 22.22222% with 21 lines in your changes missing coverage. Please review.

Project coverage is 57.34000%. Comparing base (825b3e2) to head (bcde0e5).

Files	Patch %	Lines
cmd/livepeer/starter/starter.go	0.00000%	17 Missing ⚠️
cmd/livepeer/livepeer.go	33.33333%	2 Missing ⚠️
core/capabilities.go	71.42857%	2 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##              master       #3119         +/-   ##
===================================================
- Coverage   57.40917%   57.34000%   -0.06917%     
===================================================
  Files             92          92                 
  Lines          15771       15797         +26     
===================================================
+ Hits            9054        9058          +4     
- Misses          6113        6134         +21     
- Partials         604         605          +1     

Files	Coverage Δ
cmd/livepeer/livepeer.go	50.64103% <33.33333%> (-0.33936%)	⬇️
core/capabilities.go	83.39223% <71.42857%> (-0.30342%)	⬇️
cmd/livepeer/starter/starter.go	7.78210% <0.00000%> (-0.12304%)	⬇️

... and 1 file with indirect coverage changes

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Files	Coverage Δ
cmd/livepeer/livepeer.go	50.64103% <33.33333%> (-0.33936%)	⬇️
core/capabilities.go	83.39223% <71.42857%> (-0.30342%)	⬇️
cmd/livepeer/starter/starter.go	7.78210% <0.00000%> (-0.12304%)	⬇️

... and 1 file with indirect coverage changes