No Audio In Saved / Downloaded Video

H

helmanfrow

n3wb
Nov 26, 2023
5
1
Toronto
Hi, all.
First-time reader; first time poster.

I've been struggling to extract footage from a Hikvision DS-7732NI-K4 with audio intact.

So far I've tried:
  • Downloading clips to a computer using iVMS
  • Downloading files to a computer using the web browser UI
  • Saving footage to a USB flash drive directly from NVR
All of these methods produce a video file devoid of audio.

I have played the footage in VLC and other media players.
I have checked the video file metadata in MediaInfo and Handbrake.
There is no audio stream.

The NVR is running firmware V4.72.107 build 220914

I'm basically at the end of my wits at this point and would be grateful for some insight.

Thanks.
 
Last edited:
Perhaps I wasn't clear.
The NVR is recording audio.
I can hear the audio when streaming footage in IVMS and on the browser app.

The problem is that the files it creates when exporting footage do not contain the recorded audio.
 
Unfortunately, I live in a state which requires two party consent on audio recording. So each separate video file that contains audio is a separate 3rd degree felony if two party consent was not received. So if a crime were committed in view of my exterior video cameras, and I was subpoenaed to provide video evidence which contained audio, not only would the video be inadmissible in court as evidence and possibly result in charges getting dismissed, I might find myself in court defending myself for committing multiple 3rd degree felonies.

My understanding is live un-recorded audio does not require two party consent. One might be able to argue that consent is implied when a person presses a doorbell video camera, but I am not willing to take that chance. All my video cameras/doorbells have the ability to disable recorded audio.

Some cameras/NVRs intentionally disable audio recording based on location or country code, or by default and give you a warning message to check your local laws before enabling recorded audio. Perhaps your NVR intentionally strips off the audio when exporting to save yourself from committing a felony, but then that in of itself might be considered altered video, thus inadmissible as evidence.

You might want to check the laws in your country/jurisdiction before you find yourself on the wrong side.



IMG_2122.jpeg
 
Last edited:
elvisimprsntr said:
Unfortunately, I live in a state which requires two party consent on audio recording. So each separate video file that contains audio is a separate 3rd degree felony if two party consent was not received. So if a crime were committed in view of my exterior video cameras, and I was subpoenaed to provide video evidence which contained audio, not only would the video be inadmissible in court as evidence and possibly result in charges getting dismissed, I might find myself in court defending myself for committing multiple 3rd degree felonies.

My understanding is live un-recorded audio does not require two party consent. One might be able to argue that consent is implied when a person presses a doorbell video camera, but I am not willing to take that chance. All my video cameras/doorbells have the ability to disable recorded audio.

Some cameras/NVRs intentionally disable audio recording based on location or country code, or by default and give you a warning message to check your local laws before enabling recorded audio. Perhaps your NVR intentionally strips off the audio when exporting to save yourself from committing a felony, but then that in of itself might be considered altered video, thus inadmissible as evidence.

You might want to check the laws in your country/jurisdiction before you find yourself on the wrong side.



View attachment 178755
Click to expand...
Regulations require us to record audio on certain cameras in the facility.
This is one of those cameras.
 
helmanfrow said:
The NVR is recording audio.
I can hear the audio when streaming footage in IVMS and on the browser app.
Click to expand...
Is this when you are using Playback?

alastairstevenson said:
Is this via 'clip' in Playback, or the Download page in Playback?
Can you share a small sample to examine?
Click to expand...
A small sample via the clipping tool might be useful.
It might just be a codec mismatch with whatever you are using to play the downloaded video.
 
alastairstevenson said:
Is this via 'clip' in Playback, or the Download page in Playback?
Can you share a small sample to examine?
Click to expand...
Unfortunately I'm not at liberty to share CCTV footage.

I think I've got a leg up on the problem, however.

The audio-enabled cameras are all set to encode audio with the default G.711 μLaw.
Testing the files with ffprobe confirms this:

1701293188423.png

I was using VLC to play back the files on my computer.
Normally VLC has no issues with μLaw-encoded audio but for some reason in this case it simply ignores the embedded stream and plays just the video.
I learned that Hikvision developed their own player app, but I have not downloaded it because it turns out that Media Player classic plays the files back just fine.

This solves half of the problem.
The other half is that some files were saved without an audio stream at all.
I have to find an hour to sit and figure out exactly what kind of export creates these files.
Maybe those cameras have audio disabled.
I'm not sure yet.

In the meantime I can just issue a notice that we must use MPC to play back camera footage and not VLC.
 
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As an aside, I find it kind of ridiculous that Hikvision would use an ancient, crunchy-sounding telecom codec to encode audio when the market is absolutely rife with high-quality, open-source options.
This is not to say that I find it surprising. It's actually right in line with my expectation for Hikvision given all the ridiculous issues I've had using their hardware and software for the last 4 months.
 
The audio is most likely contained in the downloaded file. It just that the player apps are not able to play the encoded audio. Install the Hikvision Windows "Panoramic Player" Tool, from Tools. It will play the audio contained in the *.mp4 encoded file.
 
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