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BUG: Recording black video even though there is a camera input
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Joined: 8/2/2013(UTC) Posts: 462
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Hello
has anyone else experienced this problem:
Sometimes when I create an instant replay channel with 4 input and stop/restart the recording, stop/restart one camera or unplug and plug camera input back in it only shows black on that instant replay input. I have to either restart Vmix or delete the instant replay input and create a new one to get the video source back in the replay channel.
And yes, the original camera input always works and shows no black screen.
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Joined: 11/28/2015(UTC) Posts: 183
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Hello I have also experienced this problem during my productions in March and April 2016 with version 16. The only solution was to remove the instant replay input and add it again. I only had three cameras configured. See here, topic "Problems": http://forums.vmix.com/d....aspx?g=posts&t=6433Three weeks ago the new season started again and we did the first two productions with version 17 (108). Once, I lost one camera in instant replay. Start/stop the replay recording didn't help. At the end the camera came back after doing this: stop the recording, setting all replay cameras to "none", close the replay settings dialog, reopen the settings dialog, configure all cameras and start recording again. After these steps the "lost camera" was still black, but after approx. one minute it came back. There were some changes in 17.0.0.110 regarding replay (http://forums.vmix.com/default.aspx?g=posts&t=6142), which goes in the direction we experienced. Regards, Patrick
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Joined: 1/13/2010(UTC) Posts: 5,186 Location: Gold Coast, Australia Was thanked: 4223 time(s) in 1508 post(s)
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Hi,
As a general rule, replay assumes that all cameras will remain permanently plugged in throughout the session with the same format. This is important for a number of reasons, as having cameras randomly disconnect can cause sync issues with the replay.
vMix 17.0.0.110 makes this a bit easier to deal with in that if you have a camera unexpectedly disconnect then you can stop recording, click the cog icon and click ok again to have vMix search through all the cameras and configure them again.
Regards,
Martin vMix
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Rank: Administration
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Joined: 1/13/2010(UTC) Posts: 5,186 Location: Gold Coast, Australia Was thanked: 4223 time(s) in 1508 post(s)
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vMix doesn't use FFMPEG for most things such as cameras. It does low level access to whatever the capture card has available such as the AJA, Blackmagic or Magewell APIs. These APIs may offer an alternate signal such as colour bars (I believe Magewell does on some models).
How important is it for vMix replay to cater for "unreliable" cameras? Should vMix have a mode where the recording stops automatically if one camera angle drops out for a second or more?
Possible hardware solutions include something like the Decimator MD-HX. When it is configured in scaling/frame rate conversion mode (even if converting an identical signal) it can be configured to insert a frame when signal is lost and thus can be used as a reliable source in vMix where the camera may not be.
Regards,
Martin vMix
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Rank: Advanced Member
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Joined: 8/2/2013(UTC) Posts: 462
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Could this be a problem that came up with the update where you made Vmix recognize the input video sources and resolutions on itself?
I dont think that I ever had an issue with that last year.
And no...the recording shouldn't stop, it should record black as long there is no video source, but it should recognize new and changed video inputs on itself (if it has the same resolution and framerate as the configured instant replay input) and show it once it's plugged back in.
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Rank: Administration
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Joined: 1/13/2010(UTC) Posts: 5,186 Location: Gold Coast, Australia Was thanked: 4223 time(s) in 1508 post(s)
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Not sure what you mean sorry, what capture card are you using with replay?
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Rank: Administration
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Joined: 1/13/2010(UTC) Posts: 5,186 Location: Gold Coast, Australia Was thanked: 4223 time(s) in 1508 post(s)
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We built the entire replay system from scratch, so it doesn't use any open source code from FFMPEG and the like.
Anyway, I think I have worked out the best way to deal with this. It will involve checking each stream for gaps longer than half a second or for discontinuities where the capture card resets the timestamps. Then it will create a new recording segment at the current time just for that stream without interrupting the others.
This approach will avoid needing to fill in blank frames, improving performance, while also hopefully making the recording more robust to unreliable sources or from network sources like NDI.
If this sounds good, I will try and get this added to the vMix 18 beta due any day now.
Regards,
Martin vMix
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1 user thanked admin for this useful post.
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Rank: Advanced Member
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Joined: 11/28/2015(UTC) Posts: 183
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Hi Martin
Sounds good to me. Especially if you have in mind that people are using network sources (RTSP in my case).
Regards, Patrick
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Rank: Advanced Member
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Joined: 8/2/2013(UTC) Posts: 462
Thanks: 38 times Was thanked: 39 time(s) in 35 post(s)
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What I meant was that there is a build in auto detect for camera inputs since Vmix 17 (i think). When I create an 1080i camera input and plug a cable with a 720p input in, it automatically detects the 720p source and converts the once 1080i input to an 720p input. Could this be the source of the problem?
Im using Blackmagics Decklink Quad (1)
And I don't really understand how your solution prevents recording a black screen, would I have to go to the cog and press ok to have the video source again in the instant replay input or will it also be automatically detected?
Let's say a camera guy turns off his camera unbeknownst during the break and the second half of a football match starts. Something happens and I want to create an event from that camera angle, but it's only black because A: I didn't know the camera was turned off for a short time (maybe it was only a couple of seconds), B: I didn't see that the input was black, because the instant replay channels won't show all instant replays channels live input. I can only see the "normal" live camera input and those work just fine, because they automatically detect the signal and won't have a problem when the source is unplugged or turned off for a second.
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Joined: 2/2/2015(UTC) Posts: 166 Location: NL
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I know this is a (really) old thread, but unfortunately the issue described is still happening. Is there any news on this? 5 camera irp, all 1080p50, all NDI. All wired. 4x Full NDI, 2x NDI HX. Connections to the camera's are stable.
Still, several replay events have only black 'video' on some of the camera angles. .log files shows: StreamDiscontinuity - Start / Stop and
DueToCPUOrDisk: 0 on all cams A few frames / samples dropped, due to SourceTooSlow
Hoping that I can have more replay events without angles being black.
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Rank: Administration
Groups: Administrators
Joined: 1/13/2010(UTC) Posts: 5,186 Location: Gold Coast, Australia Was thanked: 4223 time(s) in 1508 post(s)
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Rank: Advanced Member
Groups: Registered
Joined: 2/2/2015(UTC) Posts: 166 Location: NL
Thanks: 164 times Was thanked: 19 time(s) in 16 post(s)
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