CP850 - Sound not synced with image

[Abdulaziz Saleh]

Hi ,

Im facing an Issue with one of aud, i have BARCO L45- series, with atmos,
last month we had 3 cases where the sound will be delayed a little bit, rebooting the whole sound rack is the only thing will solve the Issue.

Action taken,
Update the CP850
Tried to play a bit with player time from barco.

Log of CP850 showed Dolby Atmos content play as PCM same error repeated 183 times.
The thing is the Issue is not continuously happening.

[Leo Enticknap]

So the CP850 is also randomly dropping from Atmos to regular AES?

Sounds like it could be a networking issue to me, and specifically related to switch configuration.

[Abdulaziz Saleh]

I have rested the Ethernet cables today hopefully it goes back to normal the only concern is the syncing of sound with image, guests have commented on it

[Pete Naples]

Do you have a TMS, and if so, which one?

[Abdulaziz Saleh]

Yes I have TMS of Unique X ( RosettaBridge)

[Harold Hallikainen]

Ideally the logs will tell you something. Audio sync requires proper decoding of the FSK sync signal on AES channel 14. It also requires that the CP850 be able to prefetch the IAB data from the server before it is needed. Ideally a log entry would show the loss of the FSK sync or a buffer underflow on the IAB data fetch. As I recall, there can also be a different AES key on each reel, so perhaps there's an issue there (a switch from IAB to PCM on a reel change might be an indication of that. Note also that there is a discontinuity in the FSK sync signal on a reel change also).

Good luck!

[Pete Naples]

Yes I have TMS of Unique X ( RosettaBridge)

I have a feeling you were going to say that.

The RB has a naughty habit of polling equipment for status rather too often, IIRC the default results in something like 36 requests per second, to every piece of kit it knows about.

Because most Atmos installs are putting Atmos data down the management network, and don't have a dedicated Atmos data port, that polling can result in the Atmos data getting buffered/out of sync, to the point the CP850 will decided it's bogues and drop out of Atmos, reverting to 7.1/5.1

Ask Unique to reduce the polling frequency to every five seconds.

I do this as a matter of course with RB TMS now, the excess polling can upset even CP950 without Atmos.

[Ioannis Syrogiannis]

Apart from that (I have seen series 1 projectors to execute cues with a delay of more than a minute, because of excessive polling), I would make sure that Alchemy has the latest software.
The issue of loss of sync after a pause is almost, if not completely, gone since the last update. I don't say that that is the reason, but you better cover all bases.

[Harold Hallikainen]

I recall a GDC server was polling captioning equipment (SMPTE ST430-10) nearly continuously keeping ithe captioning equipment from doing anything else. On the captioning side, I dealt with it by not responding more than 10 times a second or something like that. The standard allows for a response delay of two seconds, as I recall.

[Marco Giustini]

36 times a second? Why on earth someone would need that amount of data???

[Harold Hallikainen]

I don't think they need to poll that often, it was just easier to code a loop without a timer. Again, I slowed down the GDC server by delaying the response so it would not flood the network with requests. With SMPTE ST430-10, you cannot send another request until you have received a response or timed out (2 seconds). So, that worked out well!

Harold

[Frank Cox]

I wonder why they need to poll at all.

In a cinema application the unit was present a second ago it's present now and it will still be present in ten minutes.

Enumerate the devices when you boot up or start the show, and call it good. Why keep it cranking for no good reason?

Cinema isn't sms messaging or something where a device can suddenly disappear.

[Harold Hallikainen]

I think that with regard to the TMS, they want the display of the various servers to be up to date. I suspect a once per second poll would be good enough. On captioning, ST430-10 recommends a TimelineUpdate request be sent at least once a minute. There is also a lease that is set by the server. Each request/response pair resets the lease timer. The GetNewLease request uses a 32 bit unsigned integer to set the lease timeout. Recent Sony server software sets the lease timeout to 0xffffffff seconds. The GDC very fast poll was requesting the status of the captioning equipment. Again, once a second should be fine.

[Pete Naples]

I guess, it means the timeline display on the TMS is accurate, as is readout of fader and format for audio processors.

Buit it's excessive. I have also known it crash Barco ICMP.

Running the Unique TMS in P-Player mode helps, in that mode it send content, SPL and schedule to the SMS then leaves it alone to get on with running to schedule.

Whereas in A-Autop mode, my understanding is that it sends content and drives the SPL from the TMS, playing every clip and firing every cue as a separate instruction.

[Leo Enticknap]

Because most Atmos installs are putting Atmos data down the management network, and don't have a dedicated Atmos data port, that polling can result in the Atmos data getting buffered/out of sync, to the point the CP850 will decided it's bogues and drop out of Atmos, reverting to 7.1/5.1

If the server is a GDC you have no choice, because it only has two network cards in it. Same for an IMS3000 with a NAS as the primary storage. Management communication for an iCMP can go through the projector's IP address, thereby freeing up one of the two NICs on the ICMP itself for IAB data. But as soon as you have to pass IAB data through either the management or media LANs, that opens up a world of pain and complication making sure that speeds, switch configurations, etc. are all OK.

Thanks for the heads up about RosettaBridge. The GDC TMS (which accounts for almost all the TMS systems I install, now that the DolReMi TMS has been discontinued) has its faults, but thankfully, excessive polling isn't one of them. In fact, I've noticed that if I change a projector macro or audio processor fader, it sometimes takes 3-5 seconds for the TMS to register. I did the training for RB a couple of years ago in preparation for an install that in the event didn't happen (never was told why), but I have yet to install an actual system.