Re: [ecasound] -z:psr? -z:nopsr?

Hi,

On Sun, 25 Jan 2009, Linux Media wrote:

> I can't find any information about what -z:psr or -z:nopsr is/does.
> Could someone shed some light on this option?
>
> The man page says "'-z:psr' enables the precise-sample-rates mode for
> OSS-devices". Does this mean it has no effect when running jack+alsa?

yes, this impacts usage with the OSS audio hw interface only. With
'-z:psr', opening an OSS device will fail, unless the device supports the
exact requested sampling rate.

Back in 1999 (when this feature was added), some popular soundcards (and
their OSS drivers) would accept e.g. rate 44100, but they would report
that the actual rate is +/-1% of the nominal 44.1kHz rate. With -z:nopsr,
ecasound would ignore this small difference -> you'd get the +/-1% error
in playback speed, but OTOH, you didn't need to apply resampling to the
stream. If you instead wanted to use the exact rate, and resample to let's
say 44102, you'd use -z:psr.

With ALSA and JACK this has no impact, although with ALSA this setting
could be utilized when setting up the device params. In fact, current ALSA
code in ecasound is implemented like -z:nopsr
(the snd_pcm_hw_params_set_rate_near() ALSA interface is used, which picks
a rate equal or near the requested one).

------------------------------------------------------------------------------
This SF.net email is sponsored by:
SourcForge Community
SourceForge wants to tell your story.
http://p.sf.net/sfu/sf-spreadtheword
_______________________________________________
Ecasound-list mailing list
Ecasound-list@email-addr-hidden
https://lists.sourceforge.net/lists/listinfo/ecasound-list
Received on Sun Jan 25 20:15:05 2009