DH-IPC-HDW4431C-A audio problems

[tygger]

Just got mine today and when I view it through the cam's UI, I'm getting a loud hum. Doesn't matter what codec I select or enabling/disabling the noise filter. Tried adjusting the microphone input volume and it didn't help either. If I turn it down, it barely picks up audio. [FONT=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif]
[/FONT]
[FONT=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif]When I view it through Blueiris, it sounds like morse code in static.


The cam is powered via POE. Any ideas?
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[cor35vet]

Turn off the noise filter in the audio settings, the implementation of that seems to be garbage.
There's barely any noise for me anyways.

You can also always watch the main RTSP stream in a video player like mpv or VLC.
rtsp://admin:admin@192.168.1.108:554/cam/realmonitor?channel=1&subtype=0

I'm using AAC btw. I believe that should be the best out of the available codecs.

 

[tygger]

I turned the noise filter off and it doesn't make a difference.

Here's the response from the seller:

1,please set your computer to a fixed IP address !
2. Clear your browser history and cookies !
2. Lower the camera MIC volume and the volume of external speakers of your computer!
3,please use dahua pc software or NVR connect the camera!then test sound!
if you use webpage test sound ,the sound will be affected by the speed of your computer and browser running speed effect!

How would setting my computer to a fixed IP and clearing my browser's history/cache make a difference? I'll try it tomorrow evening for kicks.

Lowering the mic level and speaker volume doesn't help. If I turn the volume down, the hum goes away, but so does any audio.

 

[cor35vet]

Do you hear anything change when you tap/knock against the camera or is it only a humming noise at all times?
Because if you don't then the mic isn't connected or broken.

OH, here's another thing (only if the mic still works/eg. you hear your tapping/knocking).
Connect the camera to a 12V car battery and connect the ethernet port straight to a battery powered laptop.
Set a static IP on the camera (default settings 192.168.1.108) and a static IP on your laptop (192.168.1.100 / subnet mask 255.255.255.0)
It might be that you have some problems with your POE switch/power supply or your home electric wiring which can cause this.

I'm pretty sure doing the things the seller suggested will change nothing...
Could try doing a factory reset for the giggles.

 

[tygger]

Had a little time to play with it today.

So the hum is only there when I'm viewing the live feed with audio enabled. It's not a constant. It starts out low and gets louder. If I'm not viewing the live feed, it appears to record audio fine. Not sure where the interference in coming from. I've disconnected all of the other ports from the POE+ switch, I've tested different cables, and I've also tried moving it away further away from the wifi router.

So maybe what the seller is stating could be plausible. I'll have more time to test tomorrow evening.

 

[wasabi]

Have you tried using shielded cables for the audio run ? this might cause the issue.

 

[tygger]

Haven't tried shielded cables. I tested on a 3ft cat6 cable and a 10ft cat5e cable. I don't understand why there's audio interference during live view, but not during a recording when live view was off. However, If I record while playing live view w/ audio, the interference would also be recorded.

The seller said to try the dahua software. I guess it was on the disc provided, but it isn't working so I've asked for a download.

 

[Fastb]

tygger,

I have a IPC-HDBW4421E-AS. It doesn't have an internal mic. I use an external powered mic.
I use an NVR, not BI

Let's eliminate the obvious. (I don't mean to insult you!)

Could feedback be a factor? ie:
1) Recorded audio/video doesn't have hum. (when viewing using playback)
Tells me shielding isn't root cause.
Tells me mic is functional

2) Live audio/video has hum. It starts out low and gets louder.
Maybe the audio out (from your BI PC?) might be reaching the mic on the cam?
How close is the camera to your audio out location?
Maybe do a test with audio output going to earbuds?

3) If I understand, Recording is fine (confirmed through Playback)
Tells me the POE switch, cables, and proximity to your WiFi router are not root cause.
Listening live, and recording while listening live has the hum problem.

This was posted on another thread:
"In the other thread it is mentioned that only after switching to MPEG the microphone audio was ok."
Thread:
[h=1]IPC-HDW4431C-A Discussion[/h]Good luck. I've run out of ideas....

Fastb

 

[tygger]

Fastb, I appreciate the feedback. You're helping narrow down the issue.

Here's what I know so far:

- The mic is definitely functional.

- The hum is being introduced by the Klipsch 2.1 system. When I used earbuds as you suggested, the hum doesn't occur. I noticed that when I have the 2.1 system hooked up, the hum usually comes right after I adjust the volume up. I also tried hooking up a 3.5mm passive ground noise isolator when using the 2.1 system and it didn't make a difference.

- The AAC codec works better than the MPEG codec for me.

- New Discovery: When viewing the recording, if I use earbuds, it sounds fine... when I hook up the speakers and view the same recording, the hum comes back. So it definitely has something to do with my speakers. Very odd.

Good news is I now know it's not a camera issue.

 

[Fastb]

Tygger,

Progress!

You state "The hum is being introduced by the Klipsch 2.1 system. When I used earbuds as you suggested, the hum doesn't occur."

Maybe impedance mismatch?
The output and input impedance should be identical, says my EE schooling background.

I've never had a mismatch problem in the audio realm, personally, that I know of.
Usually I just hooked pre-amp outputs to pre-amp inputs, and everything worked fine.

Another idea: Grounding.
A ground difference of a few volts can cause problems.
I know from theory. And practice.
If you're old enough to have used turntables, you probably know the hum noise that would occur if you didn't hook up the ground wire between the turntable and amplifier.
That ground wire made sure both systems were at the same ground potential. Zero volt difference.
If not zero, ground currents travel along the ground conductors inside the audio cable itself. Leading to hum.
So you might try clip leads to ground the enclosures together, to reduce/eliminate the ground currents in your audio cable.

Good luck!

Fastb

 

[Fastb]

Another thought:

Is the hum 60 Hz (or 120Hz)?
ie: is it a low frequency hum, related to the frequency of AC power?

If so, that's an important clue.

Listen to 60 Hz hum here: https://en.wikipedia.org/wiki/Mains_hum

Scroll down to the player.
If you're outside the US, maybe you have 50Hz power.

 

[Kawboy12R]

Computer speakers and sound cards or chips are generally the cheapest of the cheap and can have weird sound and hum issues, Klipsch or not.