Two way audio at the Dahua cam - Am I dreaming?

[Fastb]

All,

I'm making a job site security system for General Contractors (GC) who do single family residential projects that last 3 to 12 months. Stolen equipment is common. Breaking down the site and locking up equipment every evening is expensive. And then the next day, setting it up again.

Objective: A combo camera/security system. I'm using laser trip lines and Bosch Tri-Tech detectors (PIR + Radar) to detect intruders. GC and crew will self-monitor the site at night. If intruder is detected, SMS and email sent. One deterrence method is two way audio, after the GC surfs in remotely. Eg:
"You're being recorded. Your license plate is 123-xyz. I'm calling 911. Get the hell out".
Two way audio would be best for this conversation.

Non-Issue #1, Audio-in at cams works great:
When I remotely view cameras, the connected mics provide great audio. And the audio is recorded with the video, for later playback.

Issue #2, Audio-out at cams doesn't work:
I connected a powered speaker to "audio out", and don't get anything when I use the "mic" feature in iGDMSS or the laptop connected to the NVR.

Issue #3, the major issue:

Based on my reading, Dahua doesn't support true two-way audio. Instead, it's like a walkie-talkie with push-to-talk. Ie: one-way, half duplex comm.
GC: "I see you and hear you. Over"
Thief: "I don't care. Over"
GC: "I'm calling police. What do you have to say? Over"
You get the idea.

Worse yet, this walkie-talkie exchange is only supported at the NVR using the mic-in and speaker-out RCA jack.
Not supported at the camera.

Q: What's the camera's audio out line for?


Conclusion:
The only two-way audio using Dahua seems to be;
- Use the audio in jacks, camera-by-camera, for good audio surveillance.
- Use the NVR audio out jack, and a really loud speaker to cover the whole job site.
- Half duplex, like a walkie-talkie
- And with delays for live viewing remotely. This ain't VOIP!

Any ideas?

Thanks in advance,
Fastb

 

[nayr]

The Camera's audio output is just a signal, it has to drive an amplifier to power a speaker..

but you nailed all the rest, its not a full duplex voip solution.. not suitable for decent 2-way communications, no IP Camera is.. if you want a digital intercom system then you need to forget about security cameras and go to VoIP Phones.

 

[Fastb]

@nayr,

Thanks, as always, for the reply.

Good hunch. But the camera's audio out was going to an amplified speaker. There is no audio on the "Audio Out" line in the camera pigtail.

But I noticed some funny behavior that tells me the Camera's audio out is, at the least, designed for a different purpose.

Data point #1: Audio out at NVR.
The amplified spkr, plugged into "Audio Out" on the NVR backpanel, mutes itself when I select "Start Talk" in the browser interface for the NVR. My hunch: The NVR want to avoid feedback from having audio in (mic) and audio out (spkr) enabled simultaneously. So it half-duplex audio is implemented.

Data point #2: Audio out at Camera
With music playing near the NVR mic, and in "Start Talk" mode, I checked for audio out at the camera, hoping to hear music. Nothing.
But when I reviewed the recorded video, I noticed the mic at the camera was still active and recorded my colorful language.

Hunch: The camera's mic input was active when I was checking for the camera's audio out.
But an active mic is a situation ripe for feedback problems. And not the "half-duplex" audio implementation I mentioned earlier.

Conclusion: The "audio out" signal from the camera does not support audio coming from 1) the audio in jack on the NVR back panel or 2) audio from a laptop connected to the NVR through a web browser, or 3) audio from a cell phone running iGDMSS

The above was performed with the Camera on input channel 3.
The Dahua manual touts "1-ch bidirectional talk output"
Maybe that means "1-camera channel bidirectional talk output"
(and doesn't mean mono, as vs two channel stereo)

Nayr, have you ever used an audio out signal from the camera?

Thanks,
Fastb

 

[nayr]

I dont have any audio outputs, I use voip.. try disabling the mic and seeing if the speaker works, you are right in that you can only have one or the other enabled at once..

 

[Zeddy]

Have you tried seeing if 2 way audio works directly from the cameras web interface rather than the DVR? It would help narrow down the problem.

I had a look at the Dahua API, section 13.2.1 mentions that the audio codec must be G.711 a-law, it would be worth checking what the DVR is configured to.

ftp://ftp.asm.cz/Dahua/kamerove_systemy/_SDK&API/HTTP API/DAHUA_HTTP_API_FOR_DVR_V1.29.pdf

Also you've not mentioned what cameras and firmware you're running?

Oh and also it might be work running a wireshark capture of traffic between the camera and NVR.

 

[smoothie]

Hey @nayr are there resources you can recommend for getting started with a home voip setup ?

I would imagine that @Fastb and I are in a similar situation which is: Wanting 2 way full duplex audio. I know that I am open to a voip system but I don't really know much about them and perhaps @Fastb would also be interested exploring a voip based system to achieve his goal. I could be wrong but I would think that myself and other members of this forum would have interest in this sort of system.

Is there a forum, website, or perhaps basic equipment you can suggest that would get us started in the right direction. I have heard you talk about your setup in the past which sounds fantastic, and depending on costs I would very much like to get to a similar level myself in the future, but I am unsure of where to start with the subject.

I also realize that given your extensive knowledge of the subject this might actually be a difficult question for you to answer since from your perspective it might be too simple, if that is the case perhaps enumerating a few makes and models of equipment you use or have considered might help shed some light on where we should be looking ourselves. For myself I would like to find some kind of IP PBX (if that is even the right piece of equipment) that can use my AT&T U-verse voice line for outbound/inbound calls but would also have the ability to allow for future expansion to include IP phones around my home (not more than 6 of them) plus the two way front door ability and perhaps cool tech implementations I haven't even considered yet.

I am a bit on the fence if this post would count as contributory to this discussion or more of a thread hijack. I am hoping it is contributory as that is my intention but if it isn't, mods please feel free to remove this post.

 

[nayr]

I do it the hard way, but I hear FreePBX is good: https://www.freepbx.org/

Basically for what you guys are wanting, you need a VoIP Speakerphone that can do auto-anwser from your VoIP Server.. how you dial that phone, you can either do a VoIP to VoIP call, which means putting a VoIP Server on the internet and configuring a number like: sip://frontdoorphone@yourVoIPDomain.com, you'd need a VoIP softphone on your tablet/computers/etc to call it (ie, sip://mytablet@yourVoIPDomain.com <-> frontdoorphone@yourVoIPDomain.com)

All my Cisco VoIP Desk phones are PoE powered and have microphone input/outputs, you could install one of those inside and run the mic/speaker outside and completely hide the normal looking phone.. I can set a phone up to auto-call a number when the receiver is picked up so someone at the door could just push a button and call me.. or inverse, have the phone auto-answer when called from a whitelist of numbers.

I have an intercom system using the VoIP phones.. basically I have a conference room on my VoIP Server and a script will call every phone in the house and have it auto answer with mute enabled (avoid feedback from all the phones with active mics) and drop it into the conference room.. takes about a second then you can make an announcement to the entire house, and anyone can walk up to a phone and unmute it to return conversate.. a have a special extension I can trigger from my phones that will allow me to use the intercom remotely.. its most usefull when someone is sick/injured, they can lie in bed and use cell phone to ask for help without screaming through the house.

or you can get a SIP Trunk provider and get a normal telephone number, and any device can call from anywhere.. I use flowroute.com for my SIP Trunk provider.

lots of stuff on the internet, your going to need a fairly good technical background and self teaching skills to get it off the ground with no idea where to start.

 

[tangent]

Issue #3, the major issue:

Based on my reading, Dahua doesn't support true two-way audio. Instead, it's like a walkie-talkie with push-to-talk. Ie: one-way, half duplex comm.
GC: "I see you and hear you. Over"
Thief: "I don't care. Over"
GC: "I'm calling police. What do you have to say? Over"
You get the idea.

Worse yet, this walkie-talkie exchange is only supported at the NVR using the mic-in and speaker-out RCA jack.
Not supported at the camera.

Do you really want/need to have a conversation with the thief?
Allow me to continue your conversation for you...
Thief: Watch me light the place on fire and piss and shit everywhere... better send the fire department too.

Now, if you hear 2 thieves talking and can address them by name / read their license plate that will scare them. I understand wanting to hear what's going on (full duplex), but I fail to see the point of having a conversation with a thief.

 

[Fastb]

@tangent,

Not everyone on the job site, without the knowledge of the GC, is a thief.
Maybe it's the homeowner, or the homeowner asked someone to bid on a piece of work.
Bidirectional talk:
GC: "Who are you?"
X: "I'm Joe Smith.. Homeowner Harry asked me to bid on wrapping the fireplace with tile"

Maybe the new sheetrock installer arrived early.
Maybe a member of the crew returned for his coat.

Yes, just video might be sufficient. If bidirectional talk was easy, it might be a helpful freebie.
- The iGDMSS app supports talk.
- The NVR and cameras appear to support it.
- It's just I can't get it to work.

The GC imagines he'd use bidirectional like this;
"Hey, you in the red hoody! Get the hell out. You're being recorded."
"I've called 911 with your description, and the make/model of that crappy blue chevy pickup"
(not quite a "conversation")

Thieves aren't the smartest, usually. But they'd have to be pretty stupid to stay, piss & shit everywhere, etc.

After the shootings in Dallas, I read that "Facebook Live" was used by some. It streams live cell phone video to a FB page. Real Time.

Maybe 911 operators have internet access? Maybe when the GC calls 911, he'd share a FB url, and 911 could watch live video. The GC would have his camera trained on his home computer, with job site video up on the screen. And sound.

Maybe too hi-tech and tricky for a typical GC....

Fastb

 

[tangent]

Thieves aren't the smartest, usually. But they'd have to be pretty stupid to stay, piss & shit everywhere, etc.

Indeed. I know of a small mountain town with a lot of seasonal vacation properties where there was a string of burglaries where the thieves smeared their shit on people's kitchen counters and sometimes the walls and upholstery too as a calling card of sorts. This was before the CSI tv show. They also lowered their 3 year old down through broken windows and had them unlock doors in some cases.

2 way audio makes a lot more sense for other applications as you described. But I'm inclined to think you won't get the performance you want out of anything less than some sort of voip set up. There is a legal issue... if this is remodel and not new construction, legally the homeowner has a reasonable expectation of privacy inside their own home and recording either audio or video could be a problem.

 

[wasabi]

Hi all,

It seems like this is a restriction on the Dahua NVR end, I hope the new firmware can fix this issue.

I have this same problem with my setup.

I have 8 IP cams connected to the NVR, each camera have a powered audio-in mic connected next to the camera and powered speakers connected via audio-out. The only way for me to speak to the individual cameras is via the NVR web interface. From the mobile app, it only sends the audio to the Mic-out port from the NVR, not the individual cameras.

 

[Fastb]

wasabi,

Please let me know what you find.
Root cause of "NVR firmware" is intriguing.

Similar problem: My problem is similar, is different. You can "speak to the individual cameras is via the NVR web interface." I can't even do that. I have never succeeded in getting audio out from the cameras. (yes, I used powered speakers)

Same problem: gDMSS andoid app only provides audio using the NVR audio out (mic out) RCA jack on the back of the NVR.

So maybe NVR f/w is the cause?

Regards,
Fastb

 

[wasabi]

Have you tried to modify some settings within the NVR audio settings? From memory, there should be some boxes you can select for the audio, have a look around and test.

Some options are: 1. update firmware from place of purchase. Don't even think about contacting dahua in China, they are so difficult to deal with. 2. Change cameras and test. 3. Change NVR ?

 

[nayr]

Setup GDMSS to connect directly to the camera and not the NVR..

 

[wasabi]

Setup GDMSS to connect directly to the camera and not the NVR..

Hi mate,
thanks for this.
its helped me.

 

[Kawboy12R]

Nayr's on hiatus wasabi. I don't use DMSS so I can't help. Someone else on here might be able to though.

 

[tangent]

cameras connected to the nvr's PoE switch aren't directly accessible form the NVR's lan port.

 

[Kinchyle]

I've been on a quest for the same scenario but have some hybrid use cases for the two way. It's a cost overhead and a little silly but I have Dahua NVR and cameras for monitoring and email to phone status alerts then I have Reolink Argus and C2 next to some of my Dahua cameras for the two way (yes a little embarrassing to advertise such a solution)....
Two way I use when I'm watching my kids playing outside or in the pool and I might be inside and we need to talk to them (come inside, don't do that....). I did have in mind the "talk to thief" but more as a proactive deterrent not as much a conversation with being able to say "cops are coming, it will be recorded if you continue(assuming a good head shot already occurred to not tip them off)..". Hoping they wouldn't spend more time looking around and maybe think "I don't want to mess around in here...".
The inside one (upstairs/downstairs) is used as a conference type scenario. Sometimes we use it remotely to get the pets off the couch.... I thought about setting a IVS alert to make a loud recording with "bad dog, get off the couch!!".... The Reolink C2 I was able to get working with the Dahua NVR with ONVIF. Pan/Tilt, motion sensing recording work but not the "start talk" button. What I do though is monitor with Dahua then if I need to talk I use my mobile Reolink app where I can see/talk and switch between the cameras. I can also switch between Dahua gMSS mobile app and Reolink. The Argus doesn't have ONVIF so I just use it for the two/way audio and a slightly different camera angle but it's next to my Dahua starlight.
I use OpenVPN connection from phone (button click) if I need to connect to gDMSS or Reolink app for two way and I'm remote or got an email/status alarm on my phone from the NVR.

If someone finds a two way audio Dahua camera that works with the NVR "talk button" on live preview and gDMSS mobile app and is also a good starlight camera that has IVS, Face Detection, etc. please let me know....

 

[wasabi]

When your cameras are directly connected to the NVR, 2-way audio will work but you must have speakers connected to the NVR’s rear audio-out and then connect to amp/speakers.

If you have amp/speakers connected from the camera’s audio-out, you MUST connect directly to the camera and NOT the NVR for 2-way to work.

 

[Kinchyle]

So the dahua "talk button" on the live preview will go out speakers connected to the NVR?

Connecting to each camera individually seems against best practice when you should be segmenting your network from core network and NVR. I guess you could put another "jump" router on your camera and vpn to it. Then the gdmss mobile app you could setup direct connections. If someone designed this on purpose where nvr can't use the two audio and requires direct connection what is the best way to manage conversations after a triggered event from nvr?
You go to nvr or alert see the camera then load up another app? If its using voip I wonder if they could integrate that functionality into nvr(not sure if voip use open integrations like onvif.