+ * least PA 0.9.8. It is ignored on older servers.
+ *
+ * When creating streams with pa_stream_new_extended(), this flag has no
+ * effect. If you specify a format with PCM encoding, and you want the
+ * server to choose the channel count and/or channel map, then you should
+ * leave the channels and/or the channel map unspecified in the
+ * pa_format_info object. This also means that you can't use
+ * pa_format_info_from_sample_spec(), because that function always sets
+ * the channel count (but if you only want to leave the channel map
+ * unspecified, then pa_format_info_from_sample_spec() works, because it
+ * accepts a NULL channel map).
+ *
+ * \since 0.9.8 */