Re: Quality resampling code for libasound

From: Takashi Iwai <tiwai@suse.de>
To: Jean-Marc Valin <jean-marc.valin@usherbrooke.ca>
Cc: alsa-devel@lists.sourceforge.net,
	James Courtier-Dutton <James@superbug.co.uk>
Subject: Re: Quality resampling code for libasound
Date: Wed, 07 Mar 2007 23:25:19 +0100	[thread overview]
Message-ID: <s5hhcswbsj4.wl%tiwai@suse.de> (raw)
In-Reply-To: <45E4E4A5.6020405@usherbrooke.ca>

At Wed, 28 Feb 2007 13:10:45 +1100,
Jean-Marc Valin wrote:
> 
> > Yes.  I'll apply your current version to the HG tree now, then.
> 
> Thanks. Now, what are the requirements to have it enabled as the default
> resampler?

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.

> >> What kind of document do you want? I can't find anything about the other
> >> sample rate converters, so I'm not sure what it should look like.
> > 
> > A brief instruction how to set up would be enough.
> > See alsa-plugins/doc/samplerate.txt, for example.
> >
> > Although it's planned to be merged in future, a documentation is
> > always nice to have :)
> >
> 
> 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).

> 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...

Takashi

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