Re: more sample formats? too little place left.

["Martijn Sipkema" <msipkema@sipkema-digital.com>]

> > > it seems that USB audio supports 24 bit sample in 3 bytes format.
> > > and additionally i've found there are 20bit and 18bit sample formats.
> > > the world is large...
> > >
> > > an arising problem is that the number of formats is limited to 32.
> > > already 26 format types are used.  the rest are only 6, and not enough
> > > if we put BE/LE and signed/unsigned for new formats, too.
> > >
> > > how can we solve this?  extend to 64bit?  no, it has too overhead.
> > > add a new field for special formats?
> > >
> > > perhaps we don't need all of them for such special formats.
> > > there are no unsigned types for such formats.
> > > but anyway the left resource is too small.
> >
> > are formats currently a bit in a 'supported formats' flag?
>
> yes.
>
> the problem is that the bitmask is defined as unsigned int, und
> limitied to 31 bits.
>
> if it's only in alsa driver, then it wouldn't be serious.
> but apparently alsa-lib defines also mask as an integer.
> theoretically, redefining this type won't cause any compatibility
> problems, though, as long as you link alsa-lib dynamically.
> (it's an obvious advantage of "complicated" alsa api :)

perhaps not using a bitmask, but having two ioctls, one giving
the number of supported formats, the other returning the format
description taking an index argument, not unlike the EASI interface
, might be better.

--martijn




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