This is merely a historical archive of years 2008-2021, before the migration to mailman3.
A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/OpenBSC@lists.osmocom.org/.
Alexander Chemeris alexander.chemeris at gmail.comOn Jun 1, 2016 9:37 PM, "Holger Freyther" <holger at freyther.de> wrote: > > > > On 01 Jun 2016, at 17:18, Max <msuraev at sysmocom.de> wrote: > > > > Hi. > > > > > Right now in osmobts when sending/receiving frames with osmo_rtp_* it's > > assumed that no frame is lost and timestamp is always advanced in 160ms > > steps. In practice (especially when DTX is in place) frames do get lost > > so we have to adjust the step to compensate. > > > > > > However the result sound not much better than using hardcoded value > > which suggest that I might be doing FN -> ms conversion (or smth else) > > wrong. Any ideas/advices? > > Don't do it. I don't find the relevant spec within the time frame I had but I think I recently saw a piece of documentation that SQN (and timestamp) should only be incremented if data is being sent. > > Either in the RTP RFC, RTP AMR RFC or the A over IP spec.. I think I saw it while going through the documents Harald had pointed while I introduced my ideas for the SIP connector. > It's in the RTP RFC. Sequence number is incremented by 1 with every packet, even if the packet is sent after a long pause (due to DTX). This way you know when you miss a packet. Timestamp is measured in samples and this is incremented by a number of samples since the last packet. This way you know when to start playing the packet in case of DTX. A proper RTP library or rather a jitter buffer should handle this automatically, but I'm not sure how does ortp handle it. Please excuse typos. Written with a touchscreen keyboard. -- Regards, Alexander Chemeris CEO Fairwaves, Inc. https://fairwaves.co -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/openbsc/attachments/20160601/37b1ddc5/attachment.htm>