From: Bill F. <bil...@ca...> - 2001-05-11 07:04:03
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On 05/09/2001, Guenter Bartsch wrote: > BTW: do you have any ideas about proper ways to do downmixing? simply > adding the channels and dividing isn't always the best solution as it > often results in a very low-volume center playback > (left_channel = l_surr + left + 0.5 center / 2.5 or something like that) - > I guess we'll need some logarithmic scaling here or something of that kind > ... I hope this won't harm if we do downmixing first and then do the > imdct... I've been wondering about this. Is it actually correct to treat all 5 inputs equally, which is what: left_channel = (l_surr + left + center/2) / 2.5 effectively does. Or would it be more correct to treat total left, center, and total right equally for 3 basic inputs, with total left and total right each having 2 subcomponents. This would make the equation something like: left_channel = ((l_surr + left)/2 + center/2) / 1.5 which simplifies to: left_channel = (l_surr + left + center) / 3 I may be all wet since I admit not knowing anything much about the AC3 specs, but it would give the center channel more weight, which is the problem I've noticed with voices being too low in action scenes with a loud score, and someone else mentioned that voices are generally in the center channel. -Bill |