Re: [ecasound] Resampling in realtime / resampling quality problem

On Sat, 19 Feb 2005, Kamil Wencel wrote:

> Kai, Aaron tell me something please :
[...]
> What is the differnece between these lines ? I am still not really
> certain what effects these changes have

Let's see...

> ecasound -f:16,2,96000 -i resample-hq,44100,foo.wav -f:24,2,96000 -o alsa, spdif96
> ecasound -f:24,2,96000 -i resample-hq,44100,foo.wav -f:24,2,96000 -o alsa, spdif96
> ecasound -f:32,2,96000 -i resample-hq,44100,foo.wav -f:24,2,96000 -o alsa, spdif96

These will produce identical results. The -f option is used to set the
"requested audio parameters". If an input object has fixed parameters (for
example wav-file headers contains the exacts parameters), then those will
be used and the -f option ignored. But in many cases -f has an effect:

 - when opening ALSA or any other device (the device supports
   multipe audio param combinatios so you have to pick one with -f)
 - raw and other audio files for which audio parameters are open; -f
   is needed to interpret the audio data in the correct way
 - when opening new wav/etc files: many audio params combinations
   are possibly, so -f is needed

It's also good to note that -f is sticky. You don't have to add a separate
-f option before each audio object, only if you want to change the
"requested audio parameters" (audio objects are parsed in the order they
are given on the command line).

> whatever I change in the first -f: it always comes to this result :
[...]
> (eca-chainsetup) 'rt' buffering mode selected.
> (eca-chainsetup) Audio object "uninitialized", mode "read".
> (audio-io) Format: s16_le, channels 2, srate 96000, interleaved.

As is should be, the s16_le-2ch-96kHz params are read from the wav-file
header.

> I can also give my go for the resampling issue. I had some time this
> morning so I fetched the snapshot from
> 12.10.2004 and build it from scratch. Aaron's tests with sinewaves were
> very good for comparison but I like
> to trust my ears. NO hearable distortions whatever. The clearly hearable
> noise is gone as well.
[...]
> I have both ecasound versions installed parallel so I tried them both.
> THIS is clearly a BIG improvement. Therefore

That is very good to hear. :) Thanks again for testing!

-- 
 http://www.eca.cx
 Audio software for Linux!
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