[alsa-devel] pcm_rate API question

Clemens Ladisch clemens at ladisch.de
Mon Sep 30 16:16:58 CEST 2013

Rob Sykes wrote:
>>> Typically there is some buffering/delay within a resampler -- how
>>> does the pcm_rate API allow for this?
>> The API itself does not allow for this.  Your code must generate
>> dst_frames samples.
>> At startup, prefix the output with zero samples.
> this situation can apparently occur at any time: "after that first
> call all subsequent calls will probably get you about 2000 samples out
> for every 1000 samples you put in" — only "probably", not "always";
> occurring after the start, this will likely cause audible distortion.

You must know your resampling algorithm.  If it introduces delays, you
need to buffer more samples.


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