On Fri, 27 Jul 2007, stan wrote: > I really want to avoid rate resampling if I can, while format > conversion has to occur somewhere in order to match the hardware in > most cases. I assume that any format conversion alsa does > is at least as good as one I would do myself. While the rate Not really. If application knows all things, the final code might be much more optimized. Alsa-lib has all plugins universal (thus mostly unoptimized). For example - attenuation + sample conversion can be implemented together, but alsa-lib has two plugins - it means two iteration over same data. > resampling can introduce throughput issues and inaccuracies in the > sound stream. I answered this numerous times on this list. We have a function to notify the plugins that resampling should be avoided - it's snd_pcm_hw_params_set_rate_resample(). hw:x,y,z - native device without any conversions plughw:x,y,z - device trying to do all conversions for applications default - default device with all conversions (mostly pointing to plughw:x,y,z) And yes, plugin doing all conversions is named "plug". So anywhere where "plug" plugin is used, other plugins - including the rate plugin - can be dynamically inserted to satisfy application requirements. Jaroslav ----- Jaroslav Kysela <perex@xxxxxxx> Linux Kernel Sound Maintainer ALSA Project, SUSE Labs _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
