--- In logic-users@yahoogroups.com, wonko@n... wrote: > > I'm a bit curious about how digital surround works, esp in regards to > Logic. > > specifically: > 1) does encoding into an AC-3 file do any signal processing to the > channels aside from multiplexing the audio? > a) if any signal processing is needed, does Logic do it for you? > b) does the decoder do any processing other than de-muxing? > 2) is the .1 sub channel just a regular discrete audio channel, or do I > need to do some filtering on it before I encode? > a) what kind of filtering? > b) if not, is that low-freq processing handled by the speaker or > the decoder? > Hi, In response to your queries,here some of what I know: 1. AC3 encoding does not do any processing,as far as any changes in gain,tone,etc... Logic can do processing,but it can't do it for you,you would have to do it yourself, just like any stereo mix. I am not aware that the decoder does any sonic processing,other than de-muxing. 2. It is,but it is only to be used for the LFE (Low-Frequency Enhancer) channel,and as such should only contain frequencies appropriate to the particular encoding you are to use There are some speaker matrices,(Miller & Kreisel for example) which come with a low frequency crossover for their surround speakers.But they also have inputs for the LFE channel as well.Their manual contains the references on why and how they do that. You might find the website below useful,they invented some of the surround encoding processes,and describe in detail what exactly they do: http://www.dolby.com/tech/whtppr.html Cheres, Nick