On Wed, 3 Oct 2007 08:35:06 -0500, Tilghman Lesher wrote: >I invite you to try it. You could make a lot of really smart people look like >fools if you're able to mix compressed audio together without decompressing, >or you might make yourself look like a fool, because you get back garbage for >attempting to mix compressed data.
I wholly understand the problem here. You can't, at present, mix compressed audio stream, in compressed domain. You must decode them to baseband, do the manipulation, then re-encode. OK, we get that. That's today. Such things have parallels in my day job, which is television production & transmission. At least in the US the signal that a TV station delivers to its DTV transmitter (ie the new digital one, not the old analog one that the feds will make us turn off in 2008) that is a compressed stream. Typically MPEG2 @ 19.2 MPBS. There was a time when that was a signal stream that could not be manipulated. It was just the transport mechanism from the last leg before the transmitter. Many companies wanted to be able to perform what seemed simple manipulations on the stream, for example to add a station logo, without taking the very significant quality hit of decompression and recompression. Such hardware systems have become available over time. Manipulation of the transmission streams in the compressed domain is possible, but its very compute intensive...and so expensive. It's done in massively parallel hardware architecture. There are a few vendors in the broadcast business who provide such systems. And that's for high bandwidth broadcast video. It would also be possible for voice streams, but the math is very complex. Hardware acceleration of encoding is already very common, witness Digium's own encode/decode board. Given the right motivation to spur the development this could be possible. In truth I suspect that there's little economic reason to do it. Michael -- Michael Graves [EMAIL PROTECTED] Sr. Product Specialist www.pixelpower.com Pixel Power Inc. [EMAIL PROTECTED] o713-861-4005 c713-201-1262 skype mjgraves fwd 54245 _______________________________________________ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
