speech frame loss compensation

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Holger Freyther holger at freyther.de
Wed Jun 1 18:37:47 UTC 2016


> 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.

holger


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