[asterisk-users] different format in asterisk

[Nikhil]

Hi
  In asterisk channel ,I so number of variable regarding the Codec ,Can 
anyone explain what are those variable variable means.Below are the 
variables

     1. chan->readformat

     2. chan->writeformat

     3. chan ->rawreadformat

     4. chan ->rawwriteformat

     5. chan->nativeformats

Thanks
Nikhil