On Sun, 24 Aug 2003, smoerk wrote:
there are different channel profiles for 5.1: L R C LFE Ls Rs (DVD) L R Ls Rs C LFE L C R Ls Rs LFE (Film)
I don't see why you need more than one of the above formats. It's not like you can't decide to put the LFE channel into "input 3" or "input 5" or whatever set of inputs your sending it to, depending on how that set of inputs is configured.
i agree, but then flac needs a parameter to map the channels when converting from wav to flac or flac to wav.
example:
i'm working on a dvd production and my 5.1 files are L-R-C-LFE-Ls-Rs and FLAC's format is L-C-R-Ls-Rs-LFE. when encoding and decoding FLAC have to change the channel order of the file.
but then we still have the possibility to use not all channels. think of
L-C-R L-C-R-LFE L-R-Ls-Rs L-C-R-Surround L-R-Surround and more
this is only for 5.1.
i still think we need a more flexible approach than only defining 16 different channel mappings.
then we have ambisonics where we have 1st, 2nd and 3rd order (4, 9 and 16 channels), but then you can also have 2 dimensional ambisonics without heigt signal, which gives another 3 options, plus different UHJ encoded variants, etc.
Well, we already have the problem of being able to encode only a very limited number of independent tracks in this field, too. Currently the limit is 8, which does me no good when I want to FLAC-encode a multi-track "master" from my studio, which can easily be 48 tracks or more.
FLAC can only encode 8 tracks? Why?
One option would be to add a code for "get 16 bit number of tracks from end of header." (Don't laugh at 16 bits; I've got friends who have produced pieces with more than 256 tracks.)
Given that, you might well just be able to add another code for "ambisonic, get 8-bit number of tracks from end of header," and then use the number of tracks to figure out the format.
1 W (kinda dumb way of doing monaural) 2 UHJ (stereo-compatable) 3 WXY (first order without height) 4 WXYZ (first order with height) 5 WXYUV (second order without height) 6 WXYUVW' (second order without height, mixed 1st/2nd order data) 9 WXYZRSTUV (second order with height) 10 WXYZRSTUVW' (second order with height, mixed 1st/2nd order data) 16 WXYZRSTUVKLMNOPQ (third order with height)
(There can be no third order without height, since the coefficents of all of the third order equations have a height component. Note that I am just blindly using the equations from http://www.york.ac.uk/inst/mustech/3d_audio/secondor.html; one would want to check this with someone really in the know before standardizing on it.)
only 5.1 encoded ambisonics is missing, i think it's called g-format. but i can ask in the sursound mailing list, if this options are sufficient.
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