If I understand correctly, based on implementation, if VoIP support silence detection (which most of the codec support it), it will not constantly sending packets; that might be the reason for bad quality. Wey-Yi Guy Intel Corporation 2111 N.E. 25th Avenue M/S JF3-308 Hillsboro OR 97124-5961 USA Work Phone: 503-264-6023 (OR) Cell Phone: 503-329-8410 Email: wey-yi.w.guy@xxxxxxxxx -----Original Message----- From: Kalle Valo [mailto:kalle.valo@xxxxxxxxx] On Behalf Of Kalle Valo Sent: Wednesday, April 01, 2009 4:13 AM To: Johannes Berg Cc: Dan Williams; Guy, Wey-Yi W; linux-wireless; Matthew Garrett; Marcel Holtmann Subject: Re: more thoughts on power saving (was: wireless powersaving (in NM?)) Johannes Berg <johannes@xxxxxxxxxxxxxxxx> writes: > Hi, > > So I had a few more thoughts. > > Let me start with a story :) > > I use my N810 device for landline calls via SIP these days. > Every time I'm in a call, audio is very choppy and I can barely > understand the person I'm talking to -- my fix is to "ping -i > 0.05" the device to disable its powersaving... > > > Now, why is audio choppy? I was blaming it on the wireless powersaving, > and disabling that clearly fixes it. But is the problem really just > there? I think it might also be the application -- its playback buffer > is smaller than the networking latency I am experiencing due to > wireless. I think I could probably tolerate an additional audio latency > of 150ms (my beacon interval being 102.4ms) or so, if audio wasn't > choppy. What's the DTIM count in your AP? N810 wakes up only for DTIM beacons, that might increase the latency. > That means the application (telepathy sofiasip I guess) would have > to have 150ms or so playback buffer to make the playback smooth with > delay. [1] [...] > [1] I don't quite see why this doesn't happen automatically, it seems it > must discard packets that don't fit into its idea of the stream timing N810 only disables the power save when there's a frame to transmit. I guess the SIP connection isn't constantly sending anything and that's why you get bad quality. -- Kalle Valo -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
