[alsa-devel] Question about Conversion to S24_LE from S24_3LE

[Tan, Seng Kai]

Thanks Clemens

Tan, Seng Kai wrote:
>> I am facing similar problem like this issue, hope to get your advice.
>> http://mailman.alsa-project.org/pipermail/alsa-devel/2012-August/05424
>> 1.html

>And the answer is the same.

>> I try to turn on S24_LE support for HDMI Audio using below patch.
>Your hardware does not support S24_LE.
>24-bit samples use the S32_LE format (unless you have very exotic hardware, but HDA isn't).
We have another I2S hardware which is able to support S24L_LE and S32_LE format, 
when I use -Dplughw to play S24_3LE format the same things happen. It pad the 0 in MSB
the whole data is shift to right and the audio volume is lower. Is this the problem for alsa plugins?

>> Back end  S24_LE :  0x00123456(in 4bytes, MSB 0 padding)
>This is how S24_LE works.
S24_LE in wav file supposed to be in format  0x00123456 ( 0 pad MSB) or
0x12345600 ( 0 pad LSB) which one is correct? I am a bit confuse here, because 
When I open file with 0x12345600 ( 0 pad LSB) using audacity, it is able to view the file
But not for 0x00123456 ( 0 pad MSB).

>> Can you advice how to tell the alsa plugin to pad in LSB instead of MSB?
>Use S32_LE.
Question: is all HDMI support 24 bit must have 32bit support? My concern is it don't
And we want to maximize the quality to 24bit. 

Regards,
Seng Kai