[pulseaudio-discuss] WMM protocol

Oscar oscar at j-lux.dyndns.org
Sun Feb 27 04:02:57 PST 2011

Hi all,

A while back I submitted a ticket about some heavy stuttering when
streaming via WiFi on my LAN http://pulseaudio.org/ticket/889 but got
adviced to post here instead.

To summarize I got a massive "Tx excessive retries" while streaming
which resulted in mentioned stuttering. Later I discovered the WMM QoS
in my router and played around with the settings. When WMM, which is
supposed to prioritize things like VoIP, was turned off the stuttering
disappeared until something else put load on the network, like i.e. http
requests (this is exactly what WMM is supposed to rectify). When WMM was
off anytime a site was loaded or youtube video streamed from anywhere
else on the LAN, PA failed with heavy stuttering or sometimes no sound
at all.

This all seems to me like WMM is doing what it should but PA is not
taking advantage of the WMM protocol. I did a quick research and found
that to support 802.1p (WMM) a prioritize bit has to be set in layer 2
header of the packets. This is briefly explained here:
http://msdn.microsoft.com/en-us/library/aa916767.aspx . I believe there
is more information to find.

My suggestion is that this protocol is added to PA, at least to test if
things can be improved as I've seen several postings around the net
about stuttering while streaming over WiFi. If this has already been
suggested or tested I apologize.

Best regards,

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