[linux-audio-user] format conversion question (long)

Hi, I have a few questions about audio format conversion. After reading a description of the purpose of this list, and reading the list itself for about 10 days, I think this is an acceptable place to be asking. If, in fact, my questions are best asked someplace else, please let me know, and my apologies. I have quite a few recordings that were made from a RealPlayer 8 live stream. As saved by vsound (.au format), they are about 500 Megabytes each! Seeing as RealPlayer reports the (original) stream/broadcast as 12.4 Kbps, and the recordings are about 3.5 hours long, I am quite sure they are being saved to disk with much higher quality then needed. :-) My basic need is to reduce their size. I am not an expert in audio processing, and I would prefer not to become an expert in order to make the correct choices for this conversion. Hence, I hope that this is an easy question for somebody(s) reading this list to answer. I don't need to conserve every possible megabyte of disk space, indeed I would prefer to be conservative, and not lose any quality. The recording is of low AM radio quality as it is... I have sox installed on my system, so I am trying to use that. I read through the man page. I don't feel a need to have stereo, so I took a wild guess as to what rate would be appropriate and did the following. My attempt was to produce a mono recording at 8000 samples per second. marit@chipmunk:/var/tmp$ sox -V test.au -c 1 -r 8000 test.wav polyphase sox: Detected file format type: au sox: Found Sun/NeXT magic word sox: Input file test.au: using sample rate 11025 size shorts, encoding signed (2's complement), 2 channels sox: Input file test.au: comment "test.au" sox: Writing Wave file: Microsoft PCM format, 1 channel, 8000 samp/sec sox: 16000 byte/sec, 2 block align, 16 bits/samp sox: Output file test.wav: using sample rate 8000 size shorts, encoding signed (2's complement), 1 channel sox: Output file: comment "test.au" ******* The resulting file sizes are then: -r--r--r-- 1 marit marit 527881224 Jan 6 15:43 test.au -rw-r--r-- 1 marit marit 191521568 Jan 7 19:13 test.wav I am open to any suggestions. I wasn't expecting 3.5 hours of low-quality audio to be 200 MB, but maybe I am naive. Am I using the wrong tool? As a separate question: How much space would I save using mp3 or ogg encoding? Thanks in advance, Ben Blout