Re: Quality resampling code for libasound

[Jean-Marc Valin <jean-marc.valin@usherbrooke.ca>]

> Don't hurry up.  We are still in a long rc phase :)
> Let's check with the latest 1.0.14rc3 and see the performance.
> Making it as default is so easy to add one line to /etc/alsa.conf (or
> ~/.asoundrc) as found in the documentation.

OK, hopefully that can happen for 1.1.14... Did you actually test my
plugin yet to see whether it works as expected?

>> OK, did a bit of search/replace on samplerate.txt and attached the
>> result. As you can see, it's fairly similar. So far, I'm also including
>> 3 levels of quality that match the libsamplerate levels, but I can
>> change that depending on what people want.
> 
> Thanks.  I guess the title should be changed (I already took the fixed
> version on my local tree).

Oops :-)

>> The Speex resampler offers
>> quality settings that range from 0 to 10, so I can expose them all (is
>> there a way to pass a quality parameter to the resampler instead of
>> having to create lots of symbolic links?).
> 
> We can extend the rate plugin API so that the plugin code can refers
> the config parameters.  But this would require an ABI extension /
> incompatibility.  So I'd like to avoid this as much as possible.
> 
> I don't think we need to expose all 11 ranges.  Three should be
> enough, normally...

I think we can live with 3 settings, at least for now. The libsamplerate
plugin had 5 settings, of which only 3 were useful (I used equivalent
quality to those) -- the other 2 were zero-order hold and linear
interpolation, which nobody in their right mind would want to use!

One last thing, what happened to the other patch I sent for doing
rounding-to-nearest (instead of rounding down) when doing sample format
conversion?

	Jean-Marc

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