[alsa-devel] [PATCH] pcm: softvol: add support for S24_LE

[Clemens Ladisch]

Jörg Krause wrote:
> The i.MX6UL has a Synchronous Audio Interface (SAI), where the data in
> the FIFO can be aligned anywhere within the 32-bit wide register
> through the use of the First Bit Shifted configuration field. In the
> corresponding Linux SAI driver the FBS field is set the way that data
> alignment for 24-bit data is:
>
> 31 30 29 28 | 27 26 25 24 | 23 22 21 20 | .. | 3 2 1 0
> ## ## ## ##   ## ## ## ## [           DATA[23:0]       ]

This indeed is S24_LE.

Which is an extremely uncommon format.  If possible, the driver should
be changed to align to the sample's MSB to the memory word's MSB, and
then label it as S32_LE.

>> S24_LE cannot be handled with the same algorithm as S32_LE.

To be precise: the sign in bit 23 must be preserved.


Regards,
Clemens