Malcolm Baldridge writes: >Funny, I've written a simple program (derived from the Jack "simple_client") >recent to do something similar. That sounds impressive. Someone correct me if I am wrong, but Jack requires X windows for just about everything. As a computer user who is blind, X is just not quite ready to productively use yet. My program uses the raw /dev/dsp PCM audio device. Without any IOCTL directives, this device reads and writes a 8 thousand sample-per-second stream of 8-bit audio. It is great for communications audio and no good for anything else.:-) My program idles by reading the samples and looking for any that are a given value above or below 0X80 which is the value one gets from the A/D converter under silence. If there is a swing through 0 to the other side of the cycle, a flag gets set. I make sure that several 0 crossings go by to avoid transient trips and then I set the VOX delay timer which tells the rest of the program to store samples in the output file. There is a buffer between the input and output so as to preserve the wave form and not chop it off. I burn roughly 25 megs for each hour of captured audio. I don't see anything wrong with making a new file for each recording, but I think there is a limit to the number of files one can have in a directory. That is the only pitfall I can see. There is one more bell to this program. If the sample read is 0 or 1 at one extreme or 0Xfe or 0Xff at the other, I send the bell character to warn that the audio is probably going in to clipping and to reduce the input level. The warning functions like a peak indicator. >What it does (for now, I'm sure I'll be adding more to it) is: > >1) Monitor the command-line specified input port for a sound above the >squelch level. > >2) Apply a configurable DC Bias adjustment [squelch comparison is performed >after this] > >3) Keep track of the peak samples processed to pass a "scaling value" to >normalise the sound data. [This is also post-DC Bias adjustment.] > >3a) I'm also looking at various dynamic compression [gain reduction] strategie
