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| Best uMPX settings for unreliable IP link? https://forums.stereotool.com/viewtopic.php?t=30714 |
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| Author: | radiohead [ Thu Jun 03, 2021 4:22 pm ] |
| Post subject: | Best uMPX settings for unreliable IP link? |
We are using public internet to both our TX's. It's working fairly well, but there are the odd missing packets and silence gaps from fractions to several seconds. Although internet in UK is generally good, we must expect congestion in busy periods, so I'd like to setup the error corrrection really conservatively in an attempt to minimise or eliminate drops. I don't care about delay/latency, I only care about reliability! The encoder is an i7 and is only running less than 20% with all/most features enabled. I find the error correction settings a bit confusing - so I'd appreciate any help/advice to improve. I've recently moved from 128/16 to 255/32 which I "think" might help with longer packet losses that you get on the internet. My settings are: Encoder: Keyframe ineterval 0.5 Span 255 Overhead 32 Limit rate below 461 Decoder: Delay 6 seconds Multicast NIC Automatic (whatever that is!) Is there anuything else I can do to make things more robust against packet loos or short connection drops? Thanks |
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| Author: | hvz [ Fri Jun 04, 2021 8:29 pm ] |
| Post subject: | Re: Best uMPX settings for unreliable IP link? |
Ah, Span and OVerhead together must be below 256! So Span of 256 won't work. Try 128 instead, for example. 128/32 will in most cases work about equally well as 64/32 (but using half the overhead), because in both cases upto 32 lost packets can be recovered, and if they occur in bursts those two are about equal. You could for example go to 192/48 for the same amount of overhead but the ability to handle twice as long dropouts. Note that the error messages in the decoder will tell you how many packets were lost, so you can use that number to determine what your overhead value needs to be. A delay of 6 seconds is more than you should ever need, 128 packets (the span) takes about 1.5 seconds (94 packets per second), with some margin, you would need at least 2 (maybe use 2.5 to be safe) seconds. You're not using multicast I assume - so the multicast NIC doesn't matter. |
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| Author: | radiohead [ Mon Jun 07, 2021 1:30 pm ] |
| Post subject: | Re: Best uMPX settings for unreliable IP link? |
Thanks. I've adjusted the error correction down, but will leave it a while before stepping the delay down. Would extra delay help mitigate internet congestion, or is it just pointless delay? We don't mind extra delay if it helps reliability. |
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| Author: | radiohead [ Mon Jun 07, 2021 1:38 pm ] |
| Post subject: | Re: Best uMPX settings for unreliable IP link? |
By the way, on this subject, as I mentioned in another thread, "Synchronise input to output sound cards" set to "on" seems to help, especially when I increased "Relative Adjust" to 1.5%. I don't really understand why though, because as far as I was aware there is no feedback from Micro MPX remote TX back to encoder in processor in studio? |
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| Author: | hvz [ Tue Jun 08, 2021 4:27 pm ] |
| Post subject: | Re: Best uMPX settings for unreliable IP link? |
Quote:
By the way, on this subject, as I mentioned in another thread, "Synchronise input to output sound cards" set to "on" seems to help, especially when I increased "Relative Adjust" to 1.5%. I don't really understand why though, because as far as I was aware there is no feedback from Micro MPX remote TX back to encoder in processor in studio?
That would indicate a (rather big) problem with your input sound card's clock. And if that's the problem, you wouldn't get messages about missing packets on the decoder end, but about the buffer being too full or too empty.Longer delay doesn't really do much, long enough is long enough, basically. If you get errors about packets arriving too late, you have to increase it. |
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