william estrada wrote: > I think I have found a problem with the USB sound driver? It appears > that the current drive returns a x'81' for silence but it should be a > x'7f'. The USB audio driver returns whatever data is sent by the device > When I use my laptop's sound device and record without a mic, I get > a file full of x'7f's. If I do the same with my cheap-o USB device > I get a file full of x'81's. For unsigned 8-bit samples, silence is x'80'. Apparently, both devices have some DC offset and are quite noisy. > I have written a recording program that I have a 'silence' filter > that filters out segments of dead air. It works with the laptop's > sound device but not the USB device. The filter works by remove > x'7f's after allowing a selectable amount. Your filter should be able to detect silence even when noise is present. > Sorry for the multiple posting, not sure where is should have gone. The the linux-audio-dev list, of course. ;-) Regards, Clemens _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
