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SRT - Dropped packets
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Hi all
Question
Are dropped SRT packets re-sent or just dropped like UDP?
What percentage of dropped packets would be considered acceptable for good quality video transfer?
Using starlink and I would guess some dropped packets are part of a wireless connection
Thanks
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They are re-sent. This is why the second configuration option for an SRT source is latency. You are supposed to set the latency to 3x your average round-trip time in milliseconds. That will normally give enough time for any missed, or out-of-order packets to arrive and keep a smooth stream.
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Originally Posted by: BARP ![Go to Quoted Post Go to Quoted Post](/Themes/yafpro/icon_latest_reply.gif) They are re-sent. This is why the second configuration option for an SRT source is latency. You are supposed to set the latency to 3x your average round-trip time in milliseconds. That will normally give enough time for any missed, or out-of-order packets to arrive and keep a smooth stream. Thanks for this information
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From the vmix online manual Quote:Secure Reliable Transport is an open source video transport protocol. It optimises streaming performance across unpredictable networks, such as the Internet, by dynamically adapting to the real-time network conditions. Quote:Latency Specify the latency of the connection in milliseconds to adapt to network congestion. The higher this value, the better SRT can handle difficult network conditions. As a general rule this should be set to at least 4x the ping time destination IP. So 20ms would require a latency setting of at least 80 This must be set to the same value on both ends. So the question is: How can we tell if the internet connection is not good enough for a stable video transfer via SRT? I was using dropped packets as an indication of a good connection. It appears that dropped packets are ok to a point. But where is that point?
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Rank: Member
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Joined: 10/14/2022(UTC) Posts: 12 ![United States United States](/Content/images/flags/US.png) Thanks: 2 times Was thanked: 1 time(s) in 1 post(s)
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In my opinion that's a bit of a trick question. In this day and age, if you are getting more than 2% packet loss from your ISP, you should get a new ISP. Even Starlink peaks around 1.2% loss on its worst days. That being said, I have been in situations where all we had was cellular hotspots with nearly 30% packet loss (about an hour outside the nearest city) and turning up the latency to 5,000ms (5 seconds) was enough to get a stable stream.
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Rank: Advanced Member
Groups: Registered
Joined: 6/8/2017(UTC) Posts: 73
Thanks: 8 times Was thanked: 2 time(s) in 2 post(s)
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Originally Posted by: BARP ![Go to Quoted Post Go to Quoted Post](/Themes/yafpro/icon_latest_reply.gif) In my opinion that's a bit of a trick question. In this day and age, if you are getting more than 2% packet loss from your ISP, you should get a new ISP. Even Starlink peaks around 1.2% loss on its worst days. That being said, I have been in situations where all we had was cellular hotspots with nearly 30% packet loss (about an hour outside the nearest city) and turning up the latency to 5,000ms (5 seconds) was enough to get a stable stream. Thank you for this insight
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