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commit 0c5948e98a6a8535c89b7bcab13017d7732181c6 Author: Hui Wang hui.wang@canonical.com Date: Fri Oct 23 16:47:10 2020 +0800

aplay: try to use 16-bit format to increase capture quality

Recently users reported a bug, I tested it and found it is a common
issue on Laptop or Desktop machines.

The issue is users plug a headset and use "arecord test.wav" to
record a sound with default input volume, the recorded sound has
poor quality and nearly can't distinguish it is the sound we want
to record.

This is because the input volume is low and the default format is U8.
The driver records sound with 16bit, because the input volume is low,
most of samples are within (-256,+256), when converting 16bit to U8,
those samples will be 0x7f. This is called quantization noise and we
could only workaround it by increase the input volume or adding -f to
arecord.

But users want to record a better quality sound with default input
volume (after installing a new OS, the volume is the default volume),
and they don't want to add parameters to the arecord because most of
new linux users just use "arecord test.wav".

So this patch tries to change the default format from U8 to S16_LE/BE.
If the machine doesn't support S16_LE/BE, it still uses U8 as default
format.

Signed-off-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

This brought a slight concern about the compatibility, as the tool is very old and used in many places. But a right usage is always with the proper option, so maybe this won't break too many things (hopefully).

Though, this change made me wonder why we don't have any default configuration for aplay/arecord. With that, you can adjust it per user or per distro. Would it bring more benefit?

thanks,

Takashi