On Sat, 23 Aug 2003, smoerk wrote: > ... The left and right > channels are converted to center and side channels through the following > transformation: mid = (left + right) / 2, side = left - right. ... > For normal CD audio this can result in significant extra compression.
> is this only relevant for stereo files or also for multi-channel (more > than 2 channels)? I would guess that it's relevant only to stereo files, since knowing which tracks are likely to have less or more information in a recording with more than two channels would depend entirely on the contents and arrangement of the channels. > i wonder how well a 16 channel 3rd order ambisonics file could be > compressed. The mid-side encoding of a stereo signal increases compression because typical signals have a lot of common information between the left and right and speakers. For example, a kick drum or a bass guitar is often panned dead centre in the stereo field, and thus the exact same signal for it will be set to both channels. In an M-S encoding, the mid channel will carry that signal, and the side channel will carry nothing, since there's no difference between the two channels. Whether you can use tricks such as this on an ambisonics recording will depend on the material and what speaker positions the channels are encoding. If you're going to experiment with this sort of stuff, you'd probably want to add the ability to specify various encoding transformations to the encoder (e.g., "(1, 2) <-> ((1+2)/2, 2-1)"), so that you could hand it a set of transformations that are likely to be helpful for the given format and source material. cjs -- Curt Sampson <[EMAIL PROTECTED]> +81 90 7737 2974 http://www.NetBSD.org Don't you know, in this new Dark Age, we're all light. --XTC ------------------------------------------------------- This SF.net email is sponsored by: VM Ware With VMware you can run multiple operating systems on a single machine. WITHOUT REBOOTING! Mix Linux / Windows / Novell virtual machines at the same time. Free trial click here:http://www.vmware.com/wl/offer/358/0 _______________________________________________ Flac-dev mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/flac-dev
