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View partial (new) events whilst they're still recording (MP4/H264 storager)

Posted: Mon Jul 01, 2019 11:53 am
by MarkH
Unless this is already possible - it would be great to be able to view events whilst they're recording, when using the MP4 storage. I don't know if this is possible with JPEG storage but presume it is.

Only, with 10 minute event lengths (on continuous recording) it makes it impossible to view an event that occurred just a few seconds ago. I've considered dropping the event lengths to 1 minute but it doesn't entirely remove the problem.

Re: View partial (new) events whilst they're still recording (MP4/H264 storager)

Posted: Fri Jul 12, 2019 2:22 am
by pavlo
Yes, that's how it works with JPEG storage.

I was experimenting with H264 storage the other day and the lack of this ability was the only showstopper. I really don't know how it would be done though, the MP4 file format is such that crucial details required by the player/viewer don't get written until you close the file. Maybe record as MTS files instead...

I almost salivate at the potential space savings and possible quality boost from not having to transcode to a JPEG image sequence, currently some 30MB/s on average is written to the camera storage, about 120 writes a second with an average request size of 250KB.

Re: View partial (new) events whilst they're still recording (MP4/H264 storager)

Posted: Fri Aug 02, 2019 12:32 pm
by MarkH
Thanks for your thoughts. Yes, I've had to move from JPEG storage for quite a few reasons (a couple of cameras required audio recording; mostly, though, the underlying storage we're using struggles massively with millions of deletes in short succession, so at 10 - 15 million JPEG's recorded per day, this caused many lock-ups!).

So... I get that the index can be placed at the end of an H264 file (I thought it could also be at the beginning?) but - despite ZM not doing any actual 'encoding' - it must be doing some manipulation of the stream in order to split the 'file'/source stream into multiple output H264 fully-contained files. Does it have the information required to produce a suitable index at the beginning? Alternatively, like you suggested, perhaps a different container entirely...

I'm going to try 1 minute recordings for a while and see if I lose any data between segment boundaries (or if the filesize just increases slightly)...