[linux-audio-dev] Hi, is it possible to record multi channel speech audio and down sample it 2 stereo channels BUT with horizontal audio positioning of each audio channel ie. like dolby surround effect. I'm not looking to make multi channel podcast, just a plain stere

[Steve Harris]

On 13 Mar 2007, at 09:15, Valent Turkovic wrote:

> Hi,
> is it possible to record multi channel speech audio and down sample it
> 2 stereo channels BUT with horizontal audio positioning of each audio
> channel ie. like dolby surround effect.

Sure, but you might be disappointed by the results, Pro Logic is not  
very sophisticated (eg. there's no separate rear left and right  
channel, and the bandwidth is limited). Also the only free software  
implementation that I know of is not state of the art, partly due to  
patent problems, and partly due to lack of interest.

There's a LADSPA plugin: http://plugin.org.uk/ladspa-swh/docs/ladspa- 
swh.html#id1401
which does Pro Logic matrix encoding, you will need some other  
software to mix your independent streams into LCR channels (you can  
do it by ear with a 3+ variable send bus mixer), but once you have  
that you can feed it to the plugin and get a pro logic compatible  
stream out.

PS ignore the documentation, it has been tested, and it does work,  
just not brilliantly. You will get better results if you EQ the mics  
a bit to cut the level of the highs and lows a bit, especially in the  
rear channel.

You would get much better results with an ambisonic stream, but I  
don't /think/ you can make stereo-compatible ambisonic streams, and  
not many people have ambisonic decoders. Other people on this list  
know a lot more about ambisonics though.

- Steve