[alsa-devel] Sample format coversion bug?

Alexander E. Patrakov patrakov at ums.usu.ru
Mon Oct 29 12:01:12 CET 2007

Takashi Iwai wrote:
> Well, apparently something wrong with mmap, then.

Do you mean "something is wrong with the kernel driver" or "plug really 
expects mmap access to the card to be available"?

>   Does the device really support 24bit format?

No, it doesn't - that's the whole point of the test. I expected "plug" 
to guess that the device supports a 16-bit format, record 16-bit samples 
from the hardware, multiply all recorded samples by 256, and return the 
result as 32-bit words (so that the result is a set of valid S24_LE 
samples, even though the least significant byte is always zero).

>   S24_LE isn't 3bytes format but packed
> into the lower 3 bytes in 4 byte frames.

Yes, I know.

Alexander E. Patrakov

More information about the Alsa-devel mailing list