Gap between file segments

dashcam.br

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I have some class 4 cards that I bought for my old fake SD camera. The cards were cheap and the camera didn't create noticeable gaps between files when the cards were empty, but the DVR-027 does not behave like this - gaps between files is the main problem of this camera. It seems that the 207 model does not create noticeable gaps, but I wonder how this model behaves when the card is full.

Anyway, I wanted to check how to minimize the gaps, so here is a little experiment with file sizes (I was bored): starting with an empty card, I left the chronometer on my phone running (so I can record tenths of a second), set the camera to record segments of 15 minutes and recorded my phone for a little more than 45 minutes (so I have at least 3 complete segments and 3 gaps). Repeated the experiment with 5 minutes segments (recording a little more than 15 minutes) and again with 2 minutes segments (recording a little more than 6 minutes). Then I repeated everything with a full card (I filled it with 2 segment files and then run the 5 and 15 minute tests). Here are the results:

DVR-027, class 4 card formatted with FAT 32 and 64 kB clusters

Empty card
- 2 min segments: average recording time: 1 min 59.4 S, average gap: 2.5 S (misses 2.1%) best
- 5 min segments: average recording time: 4 min 59.1 S, average gap: 3.0 S (misses 1.0%)
- 15 min segments: average recording time: 14 min 58.9 S, average gap: 4.1 S (misses 0.5%) best

Full card
- 2 min segments: average recording time: 1 min 58.9 S, average gap: 2.7 S (misses 2.2%)
- 5 min segments: average recording time: 4 min 59.2 S, average gap: 4.6 S (misses 1.5%) worst
- 15 min segments: average recording time: 14 min 59.2 S, average gap: 4.0 S (misses 0.5%)

Here are some comments from the History of a new Scottish DVR-007 owner... (Huge post) topic:
rjgscotland said:
Others of course include the 2-3 second gap between videos that everyone knows about. I currently have the camera on 5 min clips and use a class 10 SD card. I have observed less delay between clips at two minutes, but it begs the question - what's worse? Losing a second every two minutes or losing 3 seconds every 5 minutes. One increases the possibility of a file change happening during something "interesting", but losing less, the other decreases the chance but at the risk of losing more recording should it happen.
And an interesting comment on how the internal camera buffer is affected by slow cards:
mariomart said:
I would never recommend using anything lower than Class 6 with a DVR, Class 10 being the preferred option. It would appear that with the slower class cards there is a very high potential for large gaps between file saves (over 4 second gaps) as the on-board DVR memory (not the SD card) can only buffer a small amount of video whilst the write action is occurring on the SD card. The longer it takes to finalize the write action on the slower class cards the higher likely hood of extended gaps occurring between finalized/saved videos.
You can minimize the chances of missing something with 15 minute segments (you will miss only 0.5% of the record time). If you want the smallest gap possible, you will miss more than 4 times that with 2 minute segments. But then, if something happens, I expect the need to record just a few seconds, so the smaller gap is also important.

I think I'll leave mine with the 15 minute segments for the smaller chance to miss something. The smaller gap with 2 minutes is also an option, but the 5 minute segments seem to be the worst choice.

Any comments on your preference?
 
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DashCamMan

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Thanks dashcam.br for performing this test. Most of the anecdotal evidence indicates shorter clips are better. But your test it appears 15 minute clips worked best. This is eye opening. I will update the DVR-027 FAQ to indicate shorter clips may not be best. Much appreciated!
 
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dashcam.br

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Thanks. I'm happy to share.
 
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