[pulseaudio-discuss] How does automatic output resampling in Pulseaudio work?

Erich Boleyn erich at uruk.org
Mon Feb 18 11:56:05 PST 2008

Greetings all,

I'm using higher-quality 24-bit/96-khz PCM to avoid resampling and
dynamic range artifacts in my sound setup, even though most of my sources
start out at 16-bit/44.1-khz.

In trying to keep the audio in the higher-quality format as long as
possible, a question arises:

When Pulseaudio converts from one format to another at the sound output
(say for an ostensibly 16-bit/48-khz DAC) *and* performs the automatic
output resampling (due to the normal output hardware clock imperfection
issues), which one more accurately represents the real chain of events:

  A)    24-bit/96-khz PCM  --(resampled)-->  16-bit/48-khz
                           --(resampled)-->  16-bit/near-48-khz-real-freq

  B)    24-bit/96-khz PCM  --(resampled)-->  16-bit/near-48-khz-real-freq

I.e. is it resampled once to get to the "output format" and again at
the final hardware matching stage, or is it resampled once directly to
the hardware matching frequency?


    Erich Stefan Boleyn     <erich at uruk.org>     http://www.uruk.org/
"Reality is truly stranger than fiction; Probably why fiction is so popular"

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