New AV warnings on Homebrew

[chapulina]

Environment

• OS Version: macOS Mojave
• Source or binary build? Source, version 3

Description

• Expected behavior: No warnings
• Actual behavior: 4 warnings, turning the build yellow

There are 4 new deprecation warnings on macOS. This is most likely caused by an update of an upstream dependency. Due to Homebrew's rolling nature, we unfortunately need to be addressing these as they come. It would be great to have some stability on the macOS side like we have on Linux.

Steps to reproduce

Run Homebrew CI for this repository.

Output

/Users/jenkins/workspace/ignition_common-ci-pr_any-homebrew-amd64/ign-common/av/src/AudioDecoder.cc:113:3: warning: 'av_init_packet' is deprecated [-Wdeprecated-declarations]
  av_init_packet(&packet);
  ^
/usr/local/Cellar/ffmpeg/4.4/include/libavcodec/packet.h:487:1: note: 'av_init_packet' has been explicitly marked deprecated here
attribute_deprecated
^
/usr/local/Cellar/ffmpeg/4.4/include/libavutil/attributes.h:100:49: note: expanded from macro 'attribute_deprecated'
#    define attribute_deprecated __attribute__((deprecated))
                                                ^

/Users/jenkins/workspace/ignition_common-ci-pr_any-homebrew-amd64/ign-common/av/src/VideoEncoder.cc:801:5: warning: 'av_init_packet' is deprecated [-Wdeprecated-declarations]
    av_init_packet(avPacket);
    ^
/usr/local/Cellar/ffmpeg/4.4/include/libavcodec/packet.h:487:1: note: 'av_init_packet' has been explicitly marked deprecated here
attribute_deprecated
^
/usr/local/Cellar/ffmpeg/4.4/include/libavutil/attributes.h:100:49: note: expanded from macro 'attribute_deprecated'
#    define attribute_deprecated __attribute__((deprecated))
                                                ^
/Users/jenkins/workspace/ignition_common-ci-pr_any-homebrew-amd64/ign-common/av/src/VideoEncoder.cc:895:7: warning: 'av_init_packet' is deprecated [-Wdeprecated-declarations]
      av_init_packet(avPacket);
      ^
/usr/local/Cellar/ffmpeg/4.4/include/libavcodec/packet.h:487:1: note: 'av_init_packet' has been explicitly marked deprecated here
attribute_deprecated
^
/usr/local/Cellar/ffmpeg/4.4/include/libavutil/attributes.h:100:49: note: expanded from macro 'attribute_deprecated'
#    define attribute_deprecated __attribute__((deprecated))
                                                ^

CC @scpeters

[scpeters]

this was deprecated in the following patch:

• https://www.mail-archive.com/[email protected]/msg115189.html

the patch has some clues for migration

[scpeters]

started work in d6b7844

[chapulina]

Do we need ifdefs to support different ffmpeg versions?

[scpeters]

Do we need ifdefs to support different ffmpeg versions?

I used existing ifdefs for my first approach in d6b7844; I think the rest of the cases will need new ifdefs

[chapulina]

Got it, let me know if I can help as buildfarmer 👩‍🌾

[mjcarroll]

Fixed by #220