Convert FLAC files to Opus using FFmpeg

[hknutsen]

Remove dependency on opus-tools by updating audio/encode_opus.sh to use ffmpeg instead of opusenc:

• In sysadmin/install_software.yml, remove task Install Opus Tools:

  fedora-workstation/sysadmin/install_software.yml

  Lines 237 to 242 in f4c4cd7

  	- name: Install Opus Tools
  	become: true
  	ansible.builtin.dnf:
  	name: opus-tools
  	state: present

• In audio/encode_opus.yml, replace command opusenc with ffmpeg:

  fedora-workstation/audio/encode_opus.sh

  Line 41 in f4c4cd7

  opusenc --bitrate 128 --vbr --quiet "$flac_file" "$opus_file"

  Remember to investigate if the following behaviour is also true when using FFmpeg:

  fedora-workstation/audio/encode_opus.sh

  Lines 43 to 63 in f4c4cd7

  	# The Opus encoder provided by opus-tools will propagate tags from the input
  	# FLAC file to the output Opus file, except "REPLAYGAIN_*" tags.
  	#
  	# Opus follows the EBU R128 specification for loudness normalization.
  	# According to the Opus specification, gain must be stored in the "Output
  	# Gain" field in the ID header. Media players should apply this gain by
  	# default. Additional track and album gain can be stored in the
  	# "R128_TRACK_GAIN" and "R128_ALBUM_GAIN" tags in the comment header.
  	# Ref: https://datatracker.ietf.org/doc/html/rfc7845#section-5.2.1
  	#
  	# If the input FLAC file has a "REPLAYGAIN_ALBUM_GAIN" tag, its value will be
  	# converted to the R128 reference level and stored in the "Output Gain" field
  	# of the output Opus file. If the input FLAC file has a
  	# "REPLAYGAIN_TRACK_GAIN" tag, its value relative to the album gain will be
  	# converted to the R128 reference level and stored in the "R128_TRACK_GAIN"
  	# tag of the output Opus file.
  	# Ref: https://github.com/xiph/opus-tools/blob/v0.2/src/flac.c#L179-L193
  	#
  	# Some media players might require ReplayGain to be turned off in order apply
  	# the default output gain (i.e. the album gain) without applying the
  	# additional track gain.

  Also remember to update prerequisites for script (should be ffmpeg instead of opus-tools):

  fedora-workstation/audio/encode_opus.sh

  Line 8 in f4c4cd7

  # opus-tools

[hknutsen]

Made redundant by 4c71515