On 24/10/2019 07:27, Roland Perry wrote:
In message , at 20:37:27 on Wed, 23 Oct
2019, Recliner remarked:
Roland Perry wrote:
In message , at 19:05:11 on Wed, 23 Oct
2019, remarked:
On Wed, 23 Oct 2019 09:34:49 +0100
Roland Perry wrote:
In message , at 07:41:34 on Wed, 23 Oct
2019, remarked:

I wonder if dashcams storing low/uncompressed video is so it can
accurately
capture very fast movement - eg just before an accident - which
most video
compression systems are not particularly good at.

I think it's because they don't want to have the silicon|dollars|power
budget of compressing the video. They externalise it to users
having to
buy stupidly big SD cards.

My previous dashcam gobbled through 1.2GB for each ten minute file.

There must be more to it than that. Even cheap smartphones can do
realtime
video compression.

They produce files in MP4 format, but not very much compressed. My phone
produces typically 150MB per minute (1920 x 1080 pixels).

So, Full HD video.

Like my dashcam (I presume the camera is essentially the same as that in
a phone).

The hardware is probably commodity by now.

My whole dashcam only cost about £30.

That doesn't leave much budget for the lens.

The lens is quite large (1.5cm), and wide angle (170 degrees). And yes,
it's probably one of the more expensive components.

But I run my dashcam at the lower setting of 720p, so that the SD card
fills up slower, which results in video a bit like this *after* it's
been cropped and re-compressed by video editing software to 30MB/min
@720p, and reprocessed by YouTube to 144-720p depending on the view you
select.

https://www.youtube.com/watch?v=F4aHaSyBHvE

(Rail-related content)

Nice view of the sky, you need to pan the camera down a bit to see more
of the road.

--
Graeme Wall
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