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rtpjitterbuffer: Fix calculation of RFC7273 RTP time period start

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This has to be based directly on the current estimated clock time and
has to allow for negative period starts.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2655>
This commit is contained in:
Sebastian Dröge 2022-06-24 13:32:34 +03:00 committed by GStreamer Marge Bot
parent 5386a426f3
commit eb0746ba97
1 changed files with 50 additions and 21 deletions
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71
subprojects/gst-plugins-good/gst/rtpmanager/rtpjitterbuffer.c
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@ -877,6 +877,7 @@ rtp_jitter_buffer_calculate_pts (RTPJitterBuffer * jbuf, GstClockTime dts,
GstClockTime internal, external;
GstClockTime rate_num, rate_denom;
GstClockTime ntprtptime_period_start;
gboolean negative_ntprtptime_period_start;
/* Don't do any of the dts related adjustments further down */
dts = -1;
@ -890,23 +891,31 @@ rtp_jitter_buffer_calculate_pts (RTPJitterBuffer * jbuf, GstClockTime dts,
/* Current NTP clock estimation */
ntptime = gst_clock_get_internal_time (media_clock);
/* Current RTP time based on the estimated NTP clock */
ntprtptime = gst_util_uint64_scale (ntptime, jbuf->clock_rate, GST_SECOND);
/* Current RTP time based on the estimated NTP clock and the corresponding
* RTP time period start */
ntprtptime = ntprtptime_period_start =
gst_util_uint64_scale (ntptime, jbuf->clock_rate, GST_SECOND);
ntprtptime += media_clock_offset;
ntprtptime &= 0xffffffff;
/* If we're in the first period then the start of the period might be
* before the clock epoch */
if (ntprtptime_period_start >= ntprtptime) {
ntprtptime_period_start = ntprtptime_period_start - ntprtptime;
negative_ntprtptime_period_start = FALSE;
} else {
ntprtptime_period_start = ntprtptime - ntprtptime_period_start;
negative_ntprtptime_period_start = TRUE;
}
GST_TRACE ("Current NTP time %" GST_TIME_FORMAT " (RTP: %" G_GUINT64_FORMAT
")", GST_TIME_ARGS (ntptime), ntprtptime);
/* Start RTP time of the current RTP time period we are in */
ntprtptime_period_start = ntprtptime & 0xffffffff00000000;
/* Current RTP timestamp in this RTP time period */
ntprtptime &= 0xffffffff;
GST_TRACE ("Current NTP RTP time period start %" GST_TIME_FORMAT " (RTP: %"
G_GUINT64_FORMAT ")",
GST_TRACE ("Current NTP RTP time period start %c%" GST_TIME_FORMAT
" (RTP: %c%" G_GUINT64_FORMAT ")",
negative_ntprtptime_period_start ? '-' : '+',
GST_TIME_ARGS (gst_util_uint64_scale (ntprtptime_period_start,
GST_SECOND, jbuf->clock_rate)), ntprtptime_period_start);
GST_SECOND, jbuf->clock_rate)),
negative_ntprtptime_period_start ? '-' : '+', ntprtptime_period_start);
GST_TRACE ("Current NTP RTP time related to period start %" GST_TIME_FORMAT
" (RTP: %" G_GUINT64_FORMAT ")",
GST_TIME_ARGS (gst_util_uint64_scale (ntprtptime, GST_SECOND,
@ -928,24 +937,44 @@ rtp_jitter_buffer_calculate_pts (RTPJitterBuffer * jbuf, GstClockTime dts,
*
*/
if (ntprtptime > rtptime && ntprtptime - rtptime >= 0x80000000) {
ntprtptime_period_start += 0x100000000;
if (negative_ntprtptime_period_start) {
negative_ntprtptime_period_start = FALSE;
g_assert (ntprtptime_period_start <= 0x100000000);
ntprtptime_period_start = 0x100000000 - ntprtptime_period_start;
} else {
ntprtptime_period_start += 0x100000000;
}
} else if (rtptime > ntprtptime && rtptime - ntprtptime >= 0x80000000) {
/* If there was not a full RTP time period yet then assume we're
* actually that far away. This can only really happen if the epoch of
* the clock is very close to now. */
if (ntprtptime_period_start >= 0x100000000)
if (negative_ntprtptime_period_start) {
ntprtptime_period_start += 0x100000000;
} else if (ntprtptime_period_start < 0x100000000) {
negative_ntprtptime_period_start = TRUE;
ntprtptime_period_start = 0x100000000 - ntprtptime_period_start;
} else {
ntprtptime_period_start -= 0x100000000;
}
}
GST_TRACE ("Wraparound adjusted NTP RTP time period start %" GST_TIME_FORMAT
" (RTP: %" G_GUINT64_FORMAT ")",
GST_TRACE ("Wraparound adjusted NTP RTP time period start %c%"
GST_TIME_FORMAT " (RTP: %c%" G_GUINT64_FORMAT ")",
negative_ntprtptime_period_start ? '-' : '+',
GST_TIME_ARGS (gst_util_uint64_scale (ntprtptime_period_start,
GST_SECOND, jbuf->clock_rate)), ntprtptime_period_start);
GST_SECOND, jbuf->clock_rate)),
negative_ntprtptime_period_start ? '-' : '+', ntprtptime_period_start);
/* Packet timestamp according to the NTP clock in RTP time units.
* Note that this does not include any inaccuracy caused by the estimation
* of the NTP clock unless it is more than 2**31 RTP time units off. */
ntprtptime = ntprtptime_period_start + rtptime;
if (negative_ntprtptime_period_start) {
if (rtptime >= ntprtptime_period_start) {
ntprtptime = rtptime - ntprtptime_period_start;
} else {
/* Packet is timestamped before the NTP clock epoch! */
ntprtptime = 0;
}
} else {
ntprtptime = ntprtptime_period_start + rtptime;
}
/* Packet timestamp in nanoseconds according to the NTP clock. */
ntptime = gst_util_uint64_scale (ntprtptime, GST_SECOND, jbuf->clock_rate);