[MacPorts] #55168: ffmpeg 3.4 VDA (VideoDecodeAcceleration) fix

[MacPorts]

#55168: ffmpeg 3.4 VDA (VideoDecodeAcceleration) fix
----------------------+--------------------
 Reporter:  RJVB      |      Owner:
     Type:  defect    |     Status:  new
 Priority:  Normal    |  Milestone:
Component:  ports     |    Version:
 Keywords:  haspatch  |       Port:  ffmpeg
----------------------+--------------------
 port:ffmpeg at 3.4 has a regression in its VDA support, partly signalled in a
 comment in the Portfile.

 I'm attaching a patchfile which fixes this as far as building the feature
 and exporting the associated symbols is concerned (as expected e.g. by
 VLC). I admit I haven't tested beyond that point (hardware video decoding
 support is flaky on my CPU/GPU anyway).

 The patch needs a small modification to the Portfile which I'm copying
 inline here:

 {{{
 --- a/multimedia/ffmpeg/Portfile
 +++ b/multimedia/ffmpeg/Portfile
 @@ -187,7 +187,13 @@ platform darwin {
      # configure now fails on 10.11+ if --enable-vda is forced citing
 missing vda dependencies
      # if we just remove --disable-vda, ffmpeg will auto configure vda if
 the required dependencies are available
      # this allows ffmpeg to configure and build, effect on the bug cited
 above not verified
 -    #   configure.args-append --enable-vda
 +        if {${os.major} < 15} {
 +            # we're on an OS version that has VDA. Enable it explicitly,
 and ensure that the
 +            # appropriate symbols still get exported from libavcodec as
 they were in 3.3 and before.
 +            configure.args-append --enable-vda
 +            patchfiles-append \
 +                              patch-fix-vda.diff
 +        }
      }

      # AudiotoolBox support requires CoreMedia Framework available on
 10.7+
 }}}

 Together the effect is:

 1 enable VDA on 10.6.3 through 10.10
 2 work around an issue in configure where it claims not to find
 `vda_framework` (it's part of the system so we don't need to check for it
 anyway after step 1)
 3 patch the exported symbol generator file so that expected symbols are
 exported as they were in the past (on 10.6.3 through 10.10).

--
Ticket URL: <https://trac.macports.org/ticket/55168>
MacPorts <https://www.macports.org/>
Ports system for macOS