[linux-audio-user] Commandline tools for some audio operations?

Hello, This time I am encoding from a cassette with a rather low noise level. And I'd like to do several things automatically, from the command line, rather than call up Audacity and GWC and do some manual selection. So, which command line tools(if they are available, of course) will: - Do lowpass filtering? - Cut off the silence in the beginning and the end? - Split a file into songs based on long periods of silence in betweeh them? For the latter two points, the silence is not absolute, there is some noise at about -40 db. The tool I want would take a "noise level" value in db as a parameter. The REALLY good tool would leave about a second of "silence" before/after a song intact, because it may contain the beginning or end that are below the threshold. The PERFECT tool would also be able to look at a file with just noise and give me that db value, but it may be too much to ask, so I can find out in Audacity as well. So - are these tools available? Or am I out of luck? Of course, I can use GWC to split a file into songs and Audacity to cut out the silence manually, but that's quite a lot of mouse-dragging for an operation that could be automatic. Yours, Mikhail Ramendik