Hi Tufan,
your text confuses me a bit: "But we need to record only local video not remote audio.".
Are you aware of the tc-console? The c40 has some limitations in comparison to the c90 and c60.
http://developer.cisco.com/web/telepresence-developer/tools/integrators/tc-console
I never tried it wwith a c40 but maybe you can at least use tc console to learn about the api commands used on
the bigger codecs to set a specific layout and sound setting which suits your requirements.
The developer forum might be a good sport to ask further questions:
http://developer.cisco.com/web/telepresence-developer/forum/-/message_boards/category/5354383
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