[EMAIL PROTECTED] wrote: > Hi all, > > I'm currently hacking around in kmix to add at least basic OSS4 support. I've > got an usb device with a output.vol control with a value range of 0 - 37. I > of course get values much higher than that when reading from the mixer > device. The normal procedure as shown in the doc and in the ossmix source is > to clamp (is that the right word?) with a bitmask. > > According to the documentation the value is a 31 bit positive integer, > therefore the bitmask should be 0xFFFFFFFE - but that would be wrong, because > I'd get values of about 9k, whereas I need 0 - 37, which I get when using the > bitmask 0xFF and AND the value with it. > What's wrong here, me or the documentation? >
If control is graduated in centibels required range is probably 0 to 370 whereas kmix is probably 0 to 100 so you will have to apply a scaling factor (kmix * 37 / 10 = ossmix). Ideally mixer should read max. value and scale accordingly. Bit masking should be used depending on the type of control to separate the channels. MIXT_STEREOSLIDER is 8 bits per channel whereas MIXT_STEREOSLIDER16 is 16 bits per channel ie maxvalue is 0x01720172 so masking with 0x0000FFFF would select just the left channel. Shift and mask for the other channel. regards, Clive _______________________________________________ oss-devel mailing list oss-devel@mailman.opensound.com http://mailman.opensound.com/mailman/listinfo/oss-devel
