Direct-to-Disk questions

[Thixotropic]

I've read the BI manual including the part about Direct-to-Disk recording, and I'm still not 100% sure I understand it.

(I'm referring to the Video Compression section in the dialog box under the Video File Format & Compression button in the Record tab for each camera. If that's not the right setting, please let me know.)

Anyway, I'm wondering if I should be doing Direct-to-Disk recording? What's the benefit or advantage?

My system records both the New and Stored clips to a NAS on my network, and it's storing them as .BVR files.

Any suggestions or recommendations would be welcome.

[HeneryH]

In D2D mode, the original stream as provided by the camera is written to disk.

The CPU only needs to decode the stream in order to perform its motion detection and other tasks, then it can discard the uncompressed data. It does NOT re-encode the video stream again before writing it to disk.

The upside is that it saved perhaps half the CPU horsepower by "decoding only" versus "decoding then re-encoding."

The downside is that any overlays generated by BI such as motion boxes or timestamps are not saved onto the recorded streams. Trigger flags on the timeline are retained in both modes as they are database flags and not really part of the video stream.

Many of us use our cameras to put timestamps on the video (the timestamp is part of the input stream) rather than BI so we get around that limitation.

[Thixotropic]

I've got all my cameras set so that they do the time-stamping instead of having BI do it, and I disable overlays in BI so that BI doesn't have to decode/recode the stream. I was told that doing this this should reduce the workload on the PC quite a bit when using multiple cameras.

When recording direct-to-disk, what format do the videos get saved in? Is it dependent on the camera?

Based on what little I've been able to puzzle out it sounds like maybe I should record direct-to-disk. Is this primarily a CPU/workload issue that this is meant to help with? Also, is it an issue recording to a NAS on the network when doing direct-to-disk?

In D2D mode, the original stream as provided by the camera is written to disk.

The CPU only needs to decode the stream in order to perform its motion detection and other tasks, then it can discard the uncompressed data. It does NOT re-encode the video stream again before writing it to disk.

The upside is that it saved perhaps half the CPU horsepower by "decoding only" versus "decoding then re-encoding."

The downside is that any overlays generated by BI such as motion boxes or timestamps are not saved onto the recorded streams. Trigger flags on the timeline are retained in both modes as they are database flags and not really part of the video stream.

Many of us use our cameras to put timestamps on the video (the timestamp is part of the input stream) rather than BI so we get around that limitation.

[HeneryH]

Is this primarily a CPU/workload issue that this is meant to help with?

Yes, if you can do without BI generated overlays D2D can cut your CPU usage but a significant amount.

Also, is it an issue recording to a NAS on the network when doing direct-to-disk?

D2D is unrelated to any problems or non-problems NAS that might occur. A more accurate questions would be "are there any NAS recording problems?" to which I cannot speak to. D2D won't matter.

[Thixotropic]

D2D is unrelated to any problems or non-problems NAS that might occur. A more accurate questions would be "are there any NAS recording problems?" to which I cannot speak to. D2D won't matter.

I asked because if BI is writing DTD to a local disk then it should be pretty fast (basically the speed of a SATA connection), but if it has to send everything over the network to a NAS, perhaps that might be an issue if the network wasn't robust.

Maybe I should switch the "New" directory back to the local disk and just put the "Stored" directory on the NAS. (??)

[HeneryH]

My point is... it has to write to the disk regardless of whether or not you are using D2D.

[Thixotropic]

My point is... it has to write to the disk regardless of whether or not you are using D2D.

Yup, I get that, but wouldn't writing to a local disk be faster and impose less of a CPU workload than writing to a disk over the network?

[HeneryH]

Yes, but that it not related at all to D2D. it is a separate discussion. The use or lack of use of D2D has zero impact on the NAS discussion.

[TimG]

Maybe I should switch the "New" directory back to the local disk and just put the "Stored" directory on the NAS. (??)

I would do that. My setup has "New" and the BI db on a separate internal SSD. After that, I don't think it matters where your storage goes to. The only problem would be if Windows "lost" the NAS.

[Thixotropic]

I changed the "New" dir to record to a local 1TB drive and the Stored will go to the NAS.

I set the max size for "New" to a 30GB and 3-day retention.

I'm wondering if I should set the max size for "New" to be bigger (50~100GB?) and retention time to 12 or 24 hours so that clips won't stay on the local drive for very long. I'd like everything to end up on the NAS sooner rather than later.