storage savings with privacy masks?

[Schuft]

Hi wise ipcamtalk forum,

I have a couple of Dahua IPC-HDW5442TM-ASE / EmpireTech IPC-T54IR-AS-S3 running with some having large black privacy masks (due to privacy laws in my country).


I observed that those privacy mask DO NOT impact the bandwith and storage used.
My thinking was: Black areas without changes must be more easy to compress = saving storage space.

I learned that this is not automatically true like chatgpt explained me: ChatGPT - Privacy Masks and Bandwidth

So I tried get the saving out there nevertheless by:
* creating "region of interest" on the no-black areas to allow the cam to maybe compress the black areas harder
* using AI-Coding to let the cam maybe update the black parts less in the stream.
* changing vom CBR to VBR

Those actions did only bring like 2-4% reduction - on a nearly 50% blacked out stream which I created for tests.

I use H.265 2688x1520 at 20/1 FPS, use RTSP to save the stream unchanged via frigate.

Do you have some ideas what else I can try take advantage of the blacked out areas to save storage space?

 

[weigle2]

You will not get any storage space savings, using 'blacked out' or privacy masks. A better way is to lower FPS from 20 to 10, as for security cam purposes 10 FPS is more than adequate. Some have found issues with using H.265 compression because of how it works, and instead use H.264/H.264H. I also would not rely on ChatGPT as a reliable source of info regarding storage space savings.

 

[bigredfish]

I’ll leave it to others with far more technical knowledge but as far as the implementation on Dahua cameras, I’ve found that there is little to be gained and plenty to lose with H.265/AI encoding/ VBR

Storage us relatively cheap and I have too many other things to keep me busy to spend a lot of time and effort on seeing how much I can degrade the quality of my video in the name of saving a few bytes

If you really must, as mentioned above, cut FPS to the most annoying value and nudge it up a bit from there, and do the same with bitrate.

Those will produce real savings if that’s a priority.

I’ll add a bigger hard drive, get great quality video, and work on my screened in porch project

 

[Schuft]

Thank you both for your answers.

Yes, I know reducing FPS will lower storage requirements - clear.
I asked ChatGPT to get an overview about the topic - I know that answers can be hallucinational.
Is the technical explenation of ChatGPT right? "Many IP cameras implement privacy masks as an overlay on the final encoded video stream (i.e., post-encoding)"

Its fine for me if there's no savings possible - but as someone who whants the reduce things where possible this idea was nagging me

 

[bigredfish]

I don’t know if that’s technically correct but yeah that’s the end affect

 

[StevenFromTexas]

Storage us relatively cheap and I have too many other things to keep me busy to spend a lot of time and effort on seeing how much I can degrade the quality of my video in the name of saving a few bytes

I’ll add a bigger hard drive, get great quality video, and work on my screened in porch project

I'll skip the porch project, but I agree 100% with the rest.