[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Linphone-developers] ortp: jitter buffer timestamp correction problem
From: |
Petr Kuba |
Subject: |
[Linphone-developers] ortp: jitter buffer timestamp correction problem |
Date: |
Fri, 05 Mar 2010 17:04:19 +0100 |
User-agent: |
Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.8) Gecko/20100216 Thunderbird/3.0.2 |
Hi all,
could someone (probably Simon?) explain me how the "corrective_slide"
and timestamp correction mechanism in ortp works?
My idea was that the goal of this mechanism is to make the incoming
stream timestamps correspond to the local time. Am I right?
However, I'm experiencing the following situation. I use ortp with
adaptive jitter buffer and then I compare two packets of the same
incoming stream (values provided by ortp):
1) ts=2529404960, seq=22032, ssrc=0xd1824425
received at time 54652488 ms
2) ts=2534100160, seq=51371, ssrc=0xd1824425
received at time 55239064 ms
I'm using ulaw audio format where packets has 160bytes, which means 20ms.
And now:
- the difference between the times these packets were received is 586576
ms. This corresponds to 29329 packets.
- we received 29339 packets (seq difference)
- the difference between the timestamps is 4695200. This corresponds to
586900 ms, i.e. 29345 packets. Note that the timestamp values are
modified by the ortp adaptive jitter buffer.
I would expect the timestamp difference to correspond to the delivery
time difference but it seems to represent 586900 - 586576 = 324ms more.
So it looks like after 586576 ms of audio we received 324ms more than we
should. This causes us serious problems in synchronization of streams.
Do I miss something or is there anything wrong?
Thanks for help,
Petr Kuba
- [Linphone-developers] ortp: jitter buffer timestamp correction problem,
Petr Kuba <=