nils/shairport-sync
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Clean up the statistics output to make it provide information for the stream type. Parameterise it so that it's a bit easier to manage.

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This commit is contained in:
Mike Brady
2021-06-02 17:17:54 +01:00
parent 5b8d76cfbe
commit 8bee92a4e6
2 changed files with 161 additions and 138 deletions
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rtp.c
+34 -14
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@@ -290,8 +290,8 @@ void *rtp_control_receiver(void *arg) {
obfp += 2;
};
*obfp = 0;
// get raw timestamp information
// I think that a good way to understand these timestamps is that
// (1) the rtlt below is the timestamp of the frame that should be playing at the
@@ -302,19 +302,19 @@ void *rtp_control_receiver(void *arg) {
// Thus, (3) the latency can be calculated by subtracting the second from the
// first.
// There must be more to it -- there something missing.
// In addition, it seems that if the value of the short represented by the second
// pair of bytes in the packet is 7
// then an extra time lag is expected to be added, presumably by
// the AirPort Express.
// Best guess is that this delay is 11,025 frames.
uint32_t rtlt = nctohl(&packet[4]); // raw timestamp less latency
uint32_t rt = nctohl(&packet[16]); // raw timestamp
uint32_t fl = nctohs(&packet[2]); //
debug(1,"Sync Packet of %d bytes received: \"%s\", flags: %d, timestamps %u and %u,
giving a latency of %d frames.",plen,obf,fl,rt,rtlt,rt-rtlt);
//debug(1,"Monotonic timestamps are: %" PRId64 " and %" PRId64 "
@@ -1327,16 +1327,36 @@ int get_ptp_anchor_local_time_info(rtsp_conn_info *conn, uint32_t *anchorRTP,
// we know its local time, so we use the new clocks's offset to
// calculate what time that must be on the new clock
// but if the master clock has become equal to the actual anchor clock
// then we can reinstate it all
// first, calculate the cumulative offset after swapping all the clocks...
conn->anchor_time = conn->last_anchor_local_time + actual_offset;
// we can check how much of a deviation there was going from clock to clock and bakc around to the master clock
// Now, the thing is that while the anchor clock and master clock for a
// buffered session starts off the same,
// the master clock can change without the anchor clock changing.
// SPS allows the new master clock time to settle down and then
// calculates the appropriate offset to it by
// calculating back from the local anchor information and the new clock's
// advertised offset. Of course, small errors will occur.
// More importantly, the new master clock(s) and the original one will
// drift at different rates. So, after all this, if the original master
// clock becomes the master again, then there could be quite a difference
// in the time information that was calculated through all the clock
// changes and the actual master clock's time information.
// What do we do? We can hardly ignore this new and reliable information
// so we'll take it. Maybe we should add code to slowly correct towards it
// but at present, we just take it.
// So, if the master clock has again become equal to the actual anchor clock
// then we can reinstate it all.
// first, let us calculate the cumulative offset after swapping all the clocks...
conn->anchor_time = conn->last_anchor_local_time + actual_offset;
// we can check how much of a deviation there was going from clock to clock and back
// around to the master clock
if (actual_clock_id == conn->actual_anchor_clock) {
int64_t cumulative_deviation = conn->actual_anchor_time - conn->anchor_time;
debug(1, "Master clock has become equal to the anchor clock. The actual clock is %f ms ahead/behind (+/-) the calculated clock.", 0.000001 * cumulative_deviation);
int64_t cumulative_deviation = conn->anchor_time - conn->actual_anchor_time;
debug(1,
"Master clock has become equal to the anchor clock. The estimated clock time "
"was %f ms ahead(+) or behind (-) the real clock time.",
0.000001 * cumulative_deviation);
conn->anchor_clock = conn->actual_anchor_clock;
conn->anchor_time = conn->actual_anchor_time;
conn->anchor_rtptime = conn->actual_anchor_rtptime;