Hi,I have implemented/ported USB device driver on the custom platform(ARM processor).I am trying to read and write audio data through to USB headphone.These are my questions? 1) USB isochronous read is an asynchronous call, how can I read data from the mic and send immediatly to speaker(just to make echo), 2) How much data needs to be read from the mic and send to speaker without loosing audio quality?(is it every frames (1msec data) or more buffering can be done) Basically, how can I read from mic and send to speaker continuously without loosing data? Thanks in advance for your answers.Raj  Basavaraj Hiremath