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RTSP - Why is this so unstable?
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Joined: 6/9/2020(UTC) Posts: 13 Location: Michigan
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Why are RTSP streams so unstable in VMix? I have had so many problems with various devices I've been testing not working well with this program. Some devices won't work at all, some at only certain bitrates, and other oddities. For example, the CAMON app works well on every device except the Pixel 4 which will not show a picture. I have a TBS2603 that connects but won't show a picture. I have a TBS2603SE that only works for certain bit rates. Everything works fine with VLAN, so I know it isn't the devices (per se) or the network.
One more oddity: the other day I had a system with 3 RTSP streams in and YouTube and Facebook streams out and everything was great until I started to record. Then my main camera stream using the TBS2603SE started glitching. I had to reduce the bitrate to below 3Mbs to keep it stable. Perhaps it was just a coincidence, but the system was working great and was well tested for hours including sending the 2 output streams using hardware encoding (RTX2060 Dell G5 laptop). Once I started recording to the internal NVMe using software, that one stream went south. The other two were still working fine. CPU usage was typically 60% - 80%. Never in the 90s.
This has been really frustrating. Any solutions until NDI encoders start showing up again for purchase?
Robert
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Joined: 1/13/2010(UTC) Posts: 5,208 Location: Gold Coast, Australia Was thanked: 4290 time(s) in 1520 post(s)
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Hi Robert,
RTSP is a very broad ranging protocol with many quirks and oddities in how encoders use it which may make it incompatible with vMix. It works in VLC because most of these encoders check for compatibility there.
This is why we added the VLC dropdown option for Add Stream Input to ensure compatibility for all unusual encoders that work in VLC.
Regards,
Martin vMix
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1 user thanked admin for this useful post.
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Rank: Member
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Joined: 6/9/2020(UTC) Posts: 13 Location: Michigan
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Thanks for the response Martin. Yes, I've tried the VLC option but the latency is just terrible. I have one NDI encoder on its way now, thank goodness. Doesn't look like I will get a complete NDI solution until sometime next month, unfortunately.
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Joined: 6/11/2020(UTC) Posts: 1
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Hello,
We want to build a sreaming system in our church with 3 cameras. We have ptz ip cameras with rtsp stream, an analog audio mixer and we wanted to use the OBS program for streaming, but we noticed that the videos from the cameras are in delay, compared to each other, and also compared to the audio from the analog audio mixer. In the OBS we can adjust the audio and also the video delay parameters, but we noticed that each time we restart the OBS, the 3 video feeds and the audio feed are delayed in a random way, so the previously adjusted delay compensation parameters are not covering the actual delay situation. The builders of the system said that maybe using vMix instead of OBS will solve the problem. So my question is: have you had any experiences like this and did you managed to solve it somehow with vMix?
Thank you in advance! Zoltán
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Rank: Member
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Joined: 6/9/2020(UTC) Posts: 13 Location: Michigan
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Originally Posted by: nadasizoltan Hello,
We want to build a sreaming system in our church with 3 cameras. We have ptz ip cameras with rtsp stream, an analog audio mixer and we wanted to use the OBS program for streaming, but we noticed that the videos from the cameras are in delay, compared to each other, and also compared to the audio from the analog audio mixer. In the OBS we can adjust the audio and also the video delay parameters, but we noticed that each time we restart the OBS, the 3 video feeds and the audio feed are delayed in a random way, so the previously adjusted delay compensation parameters are not covering the actual delay situation. The builders of the system said that maybe using vMix instead of OBS will solve the problem. So my question is: have you had any experiences like this and did you managed to solve it somehow with vMix?
Thank you in advance! Zoltán Well, vMix does allow you to delay audio and video streams independently and that works as expected. If you are getting random amounts of latency, my recommendation is to try and force the cameras to stream at whatever frame rate you are delivering and do so strictly - Constant vs Variable. That will go a long way to reducing any variations you may be seeing. Keeping the bitrate between cameras consistent wouldn't hurt either. I personally have given up trying to deal with multiple sources using RTSP as there are just too many things that go wrong. I've ordered a couple NDI converters that I'm quite certain will solve all sorts of issues, not the least of which is stability. This is the direction I would recommend to anyone looking for an IP based distribution of multiple video sources. Good Luck!
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Joined: 3/20/2014(UTC) Posts: 2,721 Location: Bordeaux, France Thanks: 243 times Was thanked: 794 time(s) in 589 post(s)
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Quote:did you manage to solve it somehow with vMix VMix can do a great job with such issues however the real problem is RTSP itself... It is not a professional protocol for video "production". It's designed mostly for security cameras where latency and sync between multiple cameras is not a problem. If you are concerned about production value and getting your work look pro, don't go for RTSP... This forum is full of users reporting sync issues, artefacts, variable latency, bad lips sync between audio and video... If you want to stick to IP Video over the network, I'd say NDI (full NDI - not NDI-HX) is the bare minimum for quality multicam work. That's more money but at least it's not a waste of money... But for less money, SDI is still the best solution offering the best image quality and the less trouble...
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The last major event I streamed, I had the main camera as a PTZ optics 12x gen 2 running rtsp to vmix. I haven't had problems with it in the past, but that weekend it decided to continuously grey-out and show static. Was extremely annoying and unusuable.
Thankfully, the quality camera that I was recording video clips with was plugged into an NDI converter as a backup/secondary camera angle for the stream and I wound up just using that angle for the whole thing (4 days of streaming, 16hrs a day). PLus it looked a lot better :)
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Originally Posted by: DWAM VMix can do a great job with such issues however the real problem is RTSP itself...
Some companies claim that they can deliver super low latency H264 IP streaming that is faster than NDI and as fast as SDI. For example: this company A H264 IP stream from camera to monitor takes only 100ms. How is it possible that they can provide such a stable feed without buffering? Software like BlueIris (CCTV) can also deliver a very low latenccy and stable H264 IP feed, are they using other protocols than RTSP/RTMP?
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That company claims that it achieve NDI results with RTSP because they use better decoders than eg VLC. Are there better decoders that can be used in vMix as well? Is converting RTSP into NDI an option?
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Rank: Advanced Member
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It's not only the decoder that is important, but also the camera encoder.
I have seen a RTSP streaming test with one of their PTZ cameras (vMix RTSP setting: RTSP over UDP, 0ms buffer, low latency) There is really no noticiable latency relative to SDI and the image is smooth.
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