Re: Some Basic Questions about MultiChannel Audio
Re: Some Basic Questions about MultiChannel Audio
- Subject: Re: Some Basic Questions about MultiChannel Audio
- From: Chandrasekhar Ramakrishnan <email@hidden>
- Date: Tue, 14 Mar 2006 08:12:13 -0800
Mark Coniglio schrieb:
> This makes me assume that I need to set the input format of the
> output unit to, let's say, four channels, and then give an four
> channel stream to the output unit so I can route the channels.
Yes, this is how I do it. To play a quad sound file, I set the stream
format on input bus 0 to be 4 channels. My software also internally
numbers the speaker in clockwise order from the back left to back
right. I then use the channel map to re-patch my numbering scheme to
whatever the setup actually is.
> But how do I take two stereo audio streams, and combine them into a
> four channel stream so I can route all of the stuff individually? Is
> the AUMerger useful here? It's default behavior, upon receiving two
> stereo streams is to output a stereo stream. (No docs on that
> AUMerger, seemingly, so I'm a little lost on that one.)
There are a couple of new audio units for splitting and merging, but I
haven't tried those out yet. I just use the Matrix Mixer for this. You
can configure the matrix mixer to have an arbitrary number of input
buses or output buses, which can each have an arbitrary number of
channels. You can use this combine multiple streams together or take
them apart.
> E.g., let's say the user is playing six sound files. Three are mixed
> down to stereo using the stereo mixer, three more are mixed down with
> a second stereo mixer. I want to be able to merge those two stereo
> streams into a single four channel stream.
I'd use the Matrix Mixer with two stereo input buses and one quad
output bus.
> 2) Multi-channel sound files. So, let's say I have a four-channel
> sound file. And I would like the user to manipulate each of these
> channels as individual mono streams. How do I pull those channels
> apart for individual processing, and the recombine them to send them
> to the output device
Matrix Mixer with one quad input bus and four mono output buses.
> 3) It also seems that some AU's don't want to accept mono inputs. Do
> I need to use a format converter to convert the mono to stereo, and
> then back again after the output?
Assuming you want to process the above sound file, use a matrix mixer
with one quad input and four *stereo* output buses.
Maybe someone from Apple can comment on whether using the
AUSplitter/AUMerger can make better use of resources, but I've found
matrix mixer to be very efficient and fast.
- sekhar
--
C. Ramakrishnan email@hidden
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