Dahua IPC-HDW5442TM-AS VBR looks terrible

howardtopher

howardtopher

n3wb
Feb 25, 2019
6
2
Chattanooga, TN
I've searched the forums for an answer to this and haven't found one. Apologies if I missed it.

I have three IPC-HDW5442TM-AS. One of them I've had for a few months, the other two I just installed last weekend. I also have one IPC-HDW5831R-ZE. I've always used CBR and only recorded when motion was detected. I've decided to change to recording all the time and only sending an email when motion is detected. I feel this will help ensure I don't miss recording something (it has before). In an attempt to save disk space, I switched to VBR.

After one full day of VBR, I've noticed that video quality is terrible on the 5442, but still looks ok on the 5831. Is this possibly a software issue or is it a configuration issue? Any other ideas? If I go back to CBR it's perfect.


Camera video settings are below. All of the settings in the "conditions" section are still default.

Encode Mode: H.264H
Smart Codec: Off
Resolution: 2688*1520(2688x1520)
Frame Rate: 15
Bit Rate Type: VBR
Quality: 5
Max Bit Rate: 4096
IFrame Interval: 15
SVC: off

Sample picture straight from the camera's web interface (looks identical in blue iris):
20200611_200318.png
 
Try raising the maximum bit rate to 8192.
 
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Raise the max bit rate even higher then. I had a similar problem with a TM-AS and ended up using CBR at 8192. Rock solid, non pixelating,video now.
 
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Have you tried raising your I-Frame interval? I've noticed that things look real "blocky" when I lower the I-Frame below 40 or so. Here is what my settings look like on the same camera with VBR and I'm not having any of your issues:



Screenshot from 2020-06-12 07-49-24.pngScreenshot from 2020-06-12 07-57-18.png
 
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I gave mine the same encoding settings as you did, and got the same awful looking result.

The biggest cause is your i-frame interval being so short. Low i-frame intervals cause poor compression ratios and if you can't set the bit rate a lot higher to compensate, then you see noticeable image quality problems. In this case however I think the effect is a little too much which suggests Dahua's encoder might not be handling it very well. Dahua's default is for i-frame interval to be 2x the frame rate (15 FPS, 30 i-frame) and for me that makes the video drastically better.

You can set the i-frame interval even higher (I'd consider as much as 4x the frame rate) but there are diminishing returns, and higher i-frame intervals do have somewhat annoying effects in Blue Iris (which all boil down to needing to begin decoding at an i-frame).
 
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That's odd. I noticed the exact reverse. The camera is set to 15FPS and with an iframe rate of 30 it pixelates in BI pretty badly. I dropped the iframe rate to 15, matching FPS, and it works fine with CBR at 8192. I do think there's a problem with the encoding in the firmware and have been waiting for an update that might fix it. I'd much rather use VBR and a lower bit rate.
 
CBR has been perfect for me no matter what, even at 4096 bit rate. It's the VBR that's doing this.

So I tried changing the iframe interval, going up in multiples of the frame rate. At 60 it's much better, but occasionally still gets blocky and then clears up. The iframe definitely appears to be at least a good part, if not most, of the cause.

I paid attention to it a little closer last night, and at night time when the IR lights are on, it doesn't do this at all even at an iframe interval of 15 with VBR.
 
Do you have any other IPC-HDW5442TM-AS to test at this place? If that camera is working ok, then this camera have to do warranty. Ask your supplier to make the warranty.
 
I reported the same pixelated “noisy” video on mine to @EMPIRETECANDY but will try the frame rate/CBR changes next with mine.
 
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EMPIRETECANDY said:
Do you have any other IPC-HDW5442TM-AS to test at this place? If that camera is working ok, then this camera have to do warranty. Ask your supplier to make the warranty.
Click to expand...

I don't think it's a problem with the camera that would require replacement. I have three of this model. One has been installed for about 9 months now, the other two I just installed last weekend. The original one was always running in CBR, which works fine, so I never noticed anything. But with my personal change from motion triggered recording to constant recording I wanted to reduce disk usage and switched all three of them to VBR. All three cameras behave identically when changing the settings. Also @bp2008 said in a previous reply that they used the same settings I posted and got the same bad video.
 
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I know I'm somewhat necro'ing an old post.. but THANK YOU!
I recently replaced my 2mp starlights with the new 4mp (HDW5442TM) and had the exact same issue.
VBR 15fps 15 i-frame and it just looked like trash.

Doubled the i-frame to 30 and IT IS SO MUCH BETTER!
Might still have some tweaking to do, but I was so worried that these were lemons (installed 2 of the 4 already and both had this issue).

Thanks again!
DeadEnd
 
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It depends.

With CBR (constant bit rate), you tell the camera to encode at a fixed bit rate. The quality will vary based on scene complexity. It will use a predictable amount of network bandwidth and storage space.

With VBR (variable bit rate), you tell the camera to encode at a fixed quality level. The bit rate (and therefore storage requirements) will vary based on scene complexity. This is mostly useful if you don't set the quality target very high, as this allows the camera to really reduce the bit rate a lot when the scene is idle. If you set the quality target too high, then VBR often ends up working the same as CBR.

I usually use VBR and set the quality one level below the highest, and then set the bit rate limit somewhere around 4 Mbps for a 1080p camera or 6-8 Mbps for a 4K camera. Then depending on the scene, the camera will usually encode at a bit rate that is substantially below the maximum I have set. But when the scene gets temporarily more complex, the bit rate will rise temporarily to try to keep the quality the same.

But VBR is a compromise. You start off saying "okay camera, quality 5 out of 6 is good enough. never go higher than quality 5". If I want the absolute maximum quality possible, then I use CBR and set the bit rate as high as the camera allows. This is more like saying "okay camera, don't compromise on quality at all. use all the space you can."
 
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Today I installed a HDW5442TM-ASE with the same problem as the TS.
I ended up in a constant bit rate of 6144Kbps and an I-frame of 25 with a FPS of 25. (encode mode H.264H)

The picture is clear now, but with VBR it's going from a high bit rate to a very low bit rate which makes the picture awful.
 
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Every time I tried VBR I eventually went back to CBR. No controlled testing to offer in defense of this, just quick judgments on which looked better.
 
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In all of my Dahua's VBR hasn't been the best, on some it improved after a firmware upgrade but is never as clear as CBR.
As others have said with VBR need to really up the Bit rate as high as it goes and iFrame around 3x frame rate (be aware BI direct to disk recording starts on the next iFrame), something to consider if you record motion only, so need to adjust your pre-recording buffer accordingly.
 
bigredfish said:
I set every Dahua I have at 8192 (or higher), CBR, 30fps and 30 Iframe and rarely have a problem. I have had multiple image issues with their VBR
Click to expand...
Similar experience except I use a lower frame rate. The thing is though 8192 at CBR is well what it says, that's a lot of disk space, compared to a Hikvision running VBR no problems. (Disk savings are huge, especially at night) :(
 
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