Intermittent low quality on substream clips from timeline

[ultradianguy]

Hi - I've got several cameras set up in Blue Iris, using Dual Streams, continuous recording. When triggered the recordings switch to the Main Stream and the quality is excellent, as I would expect. However, when I look at the recorded video during untriggered periods, the quality of the video is intermittently much worse than I would expect given the substream settings. All my cameras have the substream set to D1 or VGA as available, using VBR, quality Better, max rate around 768 k.


When I watch the recording, the quality seems to keep shifting in and out. Is there some setting I'm missing ? Here's an example from one of them showing the variation I see over a minute or two - this is from a Empire Tech IPC-T5442T-ZE, zoomed out to its widest. I'm not sure if what I'm seeing is a focus shift - and if it is, why this is happening.

 

[sebastiantombs]

What are you sub stream settings, Format and bit rate? I run, usually 720P with a bit rate of 2048 and that looks pretty good while still saving tons of disk space.

 

[wittaj]

If you set up to record as continuous + alerts or continuous + triggered, then you will get substream quality during the non-triggered times.

So either change recording to continuous and then get less recording because it is all mainstream, or get off of VBR and change to CBR and run a higher bitrate.

See this thread as it relates to D1. If you run a higher bitrate it is darn good and uses minimal CPU increase.

How much resolution is really needed for LPR

We have folks come here all the time thinking that more MP is better, whether it be for general purposes or for LPR. Those of us that have been around long enough know that sensor size is more important than MP. Those that have been here awhile know that I share a representative sample of...

ipcamtalk.com

 

[ultradianguy]

What are you sub stream settings, Format and bit rate? I run, usually 720P with a bit rate of 2048 and that looks pretty good while still saving tons of disk space.

Changing from VBR to CBR and using a higher bitrate (1280) seems to have helped a lot.
Would you all recommend not using VBR on the main stream as well? This particular camera also has options for smart codec and AI codec on the mainstream - not sure what those do exactly.

 

[wittaj]

The problem with VBR is that in some field of views the bitrate will drop tremendously and then can't ramp up quick enough when there is motion.

When I tested it, I would set my my bitrate to 8192, but with CBR and no motion, it would drop to 100 or so. Then there is motion and it can't ramp up quick enough and then it looks like a substream.

Smart codec is if you use SMD and AI codec is if you use IVS rules.

 

[ultradianguy]

The problem with VBR is that in some field of views the bitrate will drop tremendously and then can't ramp up quick enough when there is motion.

When I tested it, I would set my my bitrate to 8192, but with CBR and no motion, it would drop to 100 or so. Then there is motion and it can't ramp up quick enough and then it looks like a substream.

Smart codec is if you use SMD and AI codec is if you use IVS rules.

Thanks.
Not sure I understand about the codecs - those are on the video settings screen and they change the bit rates.
Are you saying that if I'm using IVS rules I should choose AI Codec on the video settings page?

 

[wittaj]

The changing of the bitrates is simply the camera going to preset bitrate considerations. Most of us run higher than the recommended bitrate.

In theory yes you should use AI codec if using IVS rules. But reality is I didn't see a difference.

 

[bp2008]

Changing from VBR to CBR and using a higher bitrate (1280) seems to have helped a lot.
Would you all recommend not using VBR on the main stream as well?

VBR can be kind of unpredictable, so you sometimes need to tune it on a camera-by-camera basis. On a lot of my cams I will use VBR quality 3 or 4 with a very low bit rate, 256-512 Kbps and the video looks fine when it is scaled down a bit. On my latest PTZ though, the video looks like trash unless I set it to quality 6 and more than a 1000 Kbps limit. Same D1 resolution and 30 fps as other sub streams.