Project Weevil

Steve Roome steve at
Wed Jun 1 10:06:46 PDT 2005

Julian Elischer wrote:
> * streams to have multiple channels.

I've been thinking about this sort of thing for a while, in terms of
wanting something like audio netgraph, (audiograph perhaps?)...

For example...

record /dev/audio_mic_left | stereo-guitar-amp-sim | play 

So, amp-sim would just be a program that takes in a mono audio stream
and outputs, with some (hopefully very small) delay a stereo,
chorused, grungified or whatever version of the sound.

So, assuming one could write a program: "pitch-up" that takes a
"stream" as stdin (i.e. multiple multiplexed channels in one
datastream) and I can apply that filter to all the audio channels
contained in the stream and then output it through some program "play"
that will sensibly downmix to whatever output format I've got set
as default, something like:

record /dev/audio_mic_stereo | pitch-up 5semitones | play

But the same program could do the same (in the same invocation) for
n-channel sound if the right framework was in place. I'd like that,
but it might be way off where sound is headed.

> * channels might include subchannels
>     (e.g an audio channel may have 5.1 subchannels)

The nomenclature is confusing, I think an audio channel is one mono
stream of audio, and anything else is a multiplexed "bundle" (?) of
channels, I don't understand what you mean by subchannels, but I
might be alone in my confusion on this one.

> * sources and sinks to be either sync or async.  An async sink (sic)
>  might be recording the data do disk and doesn't care if it gets it in 
> bursts or
>  if it gets it at twice normal speed. A sync client wants th e data 
> deliverred at
>  a specific rate, or wants to be able to deliver it at a specific 
> rate). Audio must be keyed
>  to the video by some mechanism to be deliverable in the same way.

A reliable way of multiplexing audio/video signals together with
timing pulses included sounds like the first step, but only in that
it would be really handy for the user to have that provided.

I've no idea how much extra work this would require, or how far this
is from what you envisage, but I've wanted it for a while now!

        Steve Roome        

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