Commit f157736e authored by Timothy B. Terriberry's avatar Timothy B. Terriberry

Ogg Opus updates from Ian Nartowicz.

These are the changes proposed in
 <http://www.ietf.org/mail-archive/web/codec/current/msg03058.html>,
 with some minor additions (see follow-up on the list).
parent dacfd28e
......@@ -688,9 +688,9 @@ sample *= pow(10, output_gain/(20.0*256)) ,
<vspace blankLines="1"/>
Virtually all players and media frameworks should apply it by default.
If a player chooses to apply any volume adjustment or gain modification, such
as the R128_TRACK_GAIN, R128_ALBUM_GAIN (see <xref target="comment_header"/>)
or a user-facing volume knob, the adjustment MUST be applied in addition
to this output gain in order to achieve playback at the desired volume.
as the R128_TRACK_GAIN (see <xref target="comment_header"/>), the adjustment
MUST be applied in addition to this output gain in order to achieve playback
at the normalized volume.
<vspace blankLines="1"/>
An encoder SHOULD set this field to zero, and instead apply any gain prior to
encoding, when this is possible and does not conflict with the user's wishes.
......@@ -1215,15 +1215,10 @@ If present, R128_TRACK_GAIN and R128_ALBUM_GAIN MUST correctly represent
If a player chooses to make use of the R128_TRACK_GAIN tag or the
R128_ALBUM_GAIN tag, it MUST apply those gains
<spanx style="emph">in addition</spanx> to the 'output gain' value.
</t>
<t>
If an encoder wishes to use R128 normalization, and the output gain is not
otherwise constrained or specified, the encoder SHOULD write the R128 gain
into the 'output gain' field and store a tag containing "R128_TRACK_GAIN=0".
That is, it should assume that by default tools will respect the 'output gain'
field, and not the comment tag.
If a tool modifies the ID header's 'output gain' field, it MUST also update or
remove the R128_TRACK_GAIN and R128_ALBUM_GAIN comment tags if present.
An encoder should assume that by default tools will respect the 'output gain'
field, and not the comment tag.
</t>
<t>
To avoid confusion with multiple normalization schemes, an Opus comment header
......
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