- change AO_ALSA_PERIOD_TIME back to 0 so its calculated by default.

- apply patch from clemens (at) ladisch.de (fixes:612)

The attached patch makes various enhancements to libao's ALSA plugin:

* it isn't necessary to use a separate snd_pcm_access_mask_t variable to set the access mask;

* add a sample rate check (similar to the OSS plugin);

* return the correct error code when calling snd_pcm_prepare() after an underrun;

* set the start_threshold to a positive value – using zero can result in an immediate underrun when the first write is very small;

* various comments were wrong or misleading.




git-svn-id: http://svn.xiph.org/trunk/ao@9570 0101bb08-14d6-0310-b084-bc0e0c8e3800