Suspicious code in rtp_send_frame ( libtrau/rtp_proxy.c )

Hi, At each event since like 27c3 (or maybe even 26c3), we comment out a part of the rtp_send_frame method to solve some audio issues (glitch and sometime progressively increasing delay). This is the piece of code in question: { struct timeval tv, tv_diff; long int usec_diff, frame_diff; gettimeofday(&tv, NULL); tv_difference(&tv_diff, &rs->transmit.last_tv, &tv); rs->transmit.last_tv = tv; usec_diff = tv_diff.tv_sec * 1000000 + tv_diff.tv_usec; frame_diff = (usec_diff / 20000); if (abs(frame_diff) > 1) { long int frame_diff_excess = frame_diff - 1; LOGP(DLMUX, LOGL_NOTICE, "Correcting frame difference of %ld frames\n", frame_diff_excess); rs->transmit.sequence += frame_diff_excess; rs->transmit.timestamp += frame_diff_excess * duration; } } introduced by : commit 392736d38bf9dae29800bde630c9ceee8a3914f3 Author: Harald Welte <laforge(a)netfilter.org> Date: Sun Dec 20 13:16:14 2009 +0100 RTP Proxy: Fix RTP sequence number and timestamp in case of dropped frames During handover, we will not send RTP frames for quite some time. However, the way the rtp_send code is structured, it will increment the timestamp with a fixed amount every time we send a frame, independent how much wallclock time has actually passed. This code is a hack to update the sequence number and timestamp in case it seems to be wrong. It makes handover much more reliable. Does this speak to anyone ? Cheers, Sylvain