[alsa-devel] S24_LE Mode for USB Driver

[Takashi Iwai]

At Thu, 07 Aug 2008 16:25:50 -0400,
Charles Eidsness wrote:
> 
> Hi All,
> 
> It looks like the parse_audio_format_i_type function at line 2369 of usbaudio.c 
> (linux v2.6.23) doesn't support the case where  bSubframeSize (fmt[5]) = 4 bytes 
> and  bBitResolution (fmt[6]) = 24 bits, which should correspond to a S24_LE (or 
> BE) type. I'm developing a new USD DAC which supports this mode (24-bit sample 
> in a 4 byte package). Right now Linux sends me S32_LE formated data, which is 
> wrong. Would it be possible to expand this function to support S24_LE/BE? It 
> would only require adding a few lines of code.

Yes, it's possible, of course.

BTW, is this behavior strictly defined?  I fail to find in the
usb-audio spec that bBitResolution specifies the lower bits, not the
higher bits...


thanks,

Takashi