Ticket #11334 (new defect)
XO-1.75 audio sounds terrible in some configurations
|Reported by:||dsd||Owned by:||saadia|
|Component:||kernel||Version:||Development source as of this date|
|Deployments affected:||Blocked By:|
Mitch suggested " the codec does not have digital antialiasing, so, while it can play at numerous rates, anything lower than 48000 will be subject to "stairstepping", which results in analog domain aliasing that sounds awful"
However, after we made that change, so that the driver would only offer 48k and so that alsa-lib would be forced to resample anything that came in at other rates, we found that sounds (like those which come in Scratch) now sound bad. They are 11025Hz, and sound fine if sent to the hardware like that, but sound terrible when resampled by ALSA.
With a kernel that advertises the full set of rates, the horrible audio (which is presumably the analog domain aliasing referred to by mitch) can be reproduced with:
gst-launch audiotestsrc ! audio/x-raw-int,rate=44100,channels=1
but interestingly, if you run it with 2 channels, it sounds fine. I confirmed that the parameters being sent to the hardware do not differ in anything but the obvious in these 2 cases - with 2 channels a larger buffer is used, and it is configured as 2 channels, but the rest is fine.
I've experimented with the full range of rate and channels values, results are:
"BAD" means that the sound was crackly. "WRONG TONE" means that the sound was not crackly but the test produced a different audible tone from the norm.