On Oct 4, 2009, at 16:48, James Cloos wrote: > I always thought that the best way to put ambisonic media in flac > was to > use an ogg container, with the 0-order w channel in one flac > stream, the > three first-order channels in a second flac stream, the five second- > order > channels in a third flac stream and the seven third-order channels > in a > forth flac stream.
Excellent idea! > An alternative would be to group the 0-order and first order into the > first stream and continue as above for the second and third order > channels. This was my first thought, but I did not know how well received the idea would be. > Keeping the same-level channels together should help the compression, > but different-order channels are likely to have less inter-dependence. Very true. I'm not sure how the three (?) first order channels would allow FLAC to take advantage of inter-dependence, because I cannot remember the limits of the current algorithm. Certainly, stereo is analyzed, as are mid-side and a few other variations. I'm just not sure whether any advantage is gained beyond two channels. Archives of this list should have comments from Josh about the current algorithm's capabilities. > Limiting each flac stream to just same-order channels requires four > flac streams for a sixteen-channel third-order ambisonic, rather > than just two streams, but makes it easier to drop the higher-order > channels when desired. Agreed. > Allocation of forth and higher order ambison channels into the flac > streams is left open, but higher orders are increasingly difficult > to record and therfore are increasingly rare. Forth and higher level > may be a purely theoretical concern. This also makes sense. Perhaps you should write up an official recommendation! Brian Willoughby Sound Consulting _______________________________________________ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev