On Mon, 2014-09-08 at 13:11 -0700, Timothy B. Terriberry wrote: > As an individual... > > Mark Harris wrote: > > output gain field of the Ogg Opus header. Is it expected that > > these > > units would be adopted by other codecs? > > I can't speak for anyone else, but if _I_ were making a new codec, I > wouldn't see a need to innovate here. This design has the lessons of > doing this for 15+ years baked into it. > > > concerned that if Ogg Opus uses 1/256 LU units, and another > > format or > > codec uses the much more obvious LU (dB) units, then someone may > > be in > > Then they should pick a different tag name. >
Just to comment on this: The format of the "vorbiscomment" fields is very similar between at least Ogg Vorbis, FLAC, and Ogg Opus. As a result, the tags are often copied verbatim between the three formats during transcoding, and the interpretation of tag meaning based on name is usually shared between all three codecs in parsing code. As a result, without explicit code in the parser to e.g. reject or interpret differently this tag between different formats, a player that implements the R128_*_GAIN fields will as a side-effect add support for the same tag in FLAC and Ogg Vorbis. (This is the same reason that some players - at least gstreamer-based players, rockbox, and foobar2000 - currently accept and use REPLAY_GAIN tags in Ogg Opus files) Since this tag format is defined/specified in the Ogg Opus specification, it might make sense to use a prefix on the tag name - e.g. OPUS_R128_TRACK_GAIN - if the intent is that this tag is to be used only in the Ogg Opus format. This would reduce the likelihood of conflicts in the mostly-unregulated vorbiscomment namespace. If the intent is that the R128 tags are intended to be used also in FLAC and Ogg Vorbis then I think it would be best for it to be defined outside of the Opus specification, somewhere that developers can reference independently. In particular, care would be needed to describe interactions with the REPLAY_GAIN tags that are still used in these other formats. -- Calvin Walton <[email protected]> _______________________________________________ codec mailing list [email protected] https://www.ietf.org/mailman/listinfo/codec
