My Theory on the 27 & 207 image sensor

BobDiaz

BobDiaz

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This is my first post on this forum and by way of introduction I'm looking at several possible choices in a car cam.

In looking at the DVR 27 and DVR 207 the image seems soft and falls short of the true 1280x720 resolution. In an experiment I covered some of the 1280x720 YouTube videos from the 27 & 207 to 852x480. After the conversion, the image looked sharp at the lower resolution. This led me to wonder if the units really have a 852x480 EDTV image sensor, rather than a true 1280x720 HD image sensor.

IF they put the lower resolution sensor, it would cost less and they could generate an up-converted 1280x720 for recording. Magnifying the image by 1.5x would not give any more detail and would result in a fuzzy 1280x720 picture.

I notice in the specifications that the camera does have a 848x480 recording mode. I assume that they chose 848 rather than 854 because 848 is evenly divisible by 8, something important in the compression process.

If my theory is correct, there should be no difference in sharpness between an 848x480 recording stretched to 1280x720 and a recording at 1280x720. Just wondering if anyone would like to try the experiment and post their results or if anyone agrees or disagrees with my theory.


Thanks,

Bob Diaz
 
I think for some of the 720p solutions out there you're possibly correct, there's some very cheap products about claiming to do 720p but delivering very poor results
 
The biggest problem I see out there is there are so many fake versions of the camera (DVR 207) this makes it really hard to sort it out. This forum is a gold mind because there are so many user reports on so many cameras and so many user reports on sellers, it makes it easier to sort things out.

Right now I'm torn between just a basic DVR 207 or going for the Mobius. The Mobius appears to be a wonderful camera, but heat is an issue. Excessive heat is really hard on electronics and even harder on batteries. So far I think it's been about 2 or 3 months that the Mobius has been out so it's hard to say what the long term impact will be. Still at the same time changes to the Mobius are coming. I read that a replacement capacitor is coming in a few months, that would solve the battery issue.

At the other end, the DVR 207 is a solution that appears to do the job as expected and it has been out for a while. I look at it as the no frills solution. However, the biggest issue is avoiding all the cheap fakes.


Bob Diaz
 
I believe this theory may be true. The 720p quality on my DVR-207GS isn't quite what I would call 720p, even in optimal lighting conditions. I bought mine from SpyTec in the USA so I believe I have the real deal. For only a 70$ dashcam, I wouldn't be surprised if the 720p isn't a true 720p, rather a magnified image/video.
 
Thanks Chris,

For $70 having EDTV (854x480) resolution is still good. If you get a chance record the same shot at 848x480 and 1280x720 and see if you can pick out any more detail in the higher resolution shot.

I'm also a bit confused, you said you got a DVR 207GS, but the SpyTec web page only shows the DVR 207. Are they shipping an updated model?


Thanks,

Bob Diaz
 
I have a DVR 027 and a Mobius. No comparison really. Yes heat will be an issue with any camera that has an internal battery, so I'm waiting for a Mobius with a pair of super capacitors. OTOH you could always run the Mobius without the internal battery, which means no date stamp of course. Apart from the potential internal battery issue, the external heat sinks on the Mobius seem to do the job they're supposed to.
 
Gurkha9 said:
I have a DVR 027 and a Mobius. No comparison really. Yes heat will be an issue with any camera that has an internal battery, so I'm waiting for a Mobius with a pair of super capacitors. OTOH you could always run the Mobius without the internal battery, which means no date stamp of course. Apart from the potential internal battery issue, the external heat sinks on the Mobius seem to do the job they're supposed to.
Click to expand...

I've been torn between the Mobius and the DVR 207. One one hand the Mobius is VERY cool, but on the other hand, the DVR 207 does exactly what I'd want it to do anyway, so why bother selecting a unit with extra features.

Putting an external heat sink on the Mobius seems like a logical thing to do and if I go with the Mobius, I'd do just that. The Mobius does get very hot and that's what worries me. Excessive heat is the enemy of electronics and is a killer of batteries. Excessive heat shortens the life of electronics and batteries.

The DVR 207, while it lacks the resolution of the Mobius, it is a proven technology and the battery is a breeze to replace. I'm still bouncing back and forth... I may have to hold off until January 2014 to see what changes occur with the Mobius.


Bob Diaz
 
BobDiaz said:
I've been torn between the Mobius and the DVR 207. One one hand the Mobius is VERY cool, but on the other hand, the DVR 207 does exactly what I'd want it to do anyway, so why bother selecting a unit with extra features.

Putting an external heat sink on the Mobius seems like a logical thing to do and if I go with the Mobius, I'd do just that. The Mobius does get very hot and that's what worries me. Excessive heat is the enemy of electronics and is a killer of batteries. Excessive heat shortens the life of electronics and batteries.

The DVR 207, while it lacks the resolution of the Mobius, it is a proven technology and the battery is a breeze to replace. I'm still bouncing back and forth... I may have to hold off until January 2014 to see what changes occur with the Mobius.
Click to expand...

Just to be clear, the Mobius already HAS a built in heat sink, there's no need to add one. It works and gets quite warm doing it's job.
The form factor, image quality, Firmware support and reliability (so far) of the Mobius far outweigh the DVR 027/207 IMHO.
For almost the same price, I'd take the Mobius any day, but don't take my word for it - get both and try them out :)
 
I understand that the Mobius has a built in heat sink, but adding additional surface area allows for increased heat transfer for cooling. Additional cooling can not hurt, but can help. I can get heat sinks for 45 cents each (with the thermal compound), so it won't break the bank to buy them and put them on.

The biggest issue with heat is the battery, excessive heat really shortens the life of the battery. I understand in about 2 months they'll have a capacitor for the Mobius, that would solve the battery issue.



Bob Diaz
 
While the Mobius is much more discreet, has better video quality and good support from the manufacturer, I am not 100% convinced it can withstand the heat.

See this video posted yesterday...

Probably a good idea not to use this camera when parked on hot days. May want to ensure it does not receive direct sunlight as well.
 
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a bit lacking in detail but I have to say any camera that has an internal battery is going to be a liability if left running in a parked car, the bigger the battery the bigger the liability also
 
Hey Bob!

We met on the SmartCarOfAmerica forum.
http://www.smartcarofamerica.com/forums ... post594593

You're still researching DashCam's eh?

Stay away from the 27/207, I bought one I was totally unsatisfied. It's just way too fuzzy looking! Price was right, but spend $20 more! ($80-$110 is the sweet spot)

I was interested in the Mobius but the field of view is not wide enough, and it didn't have GPS. (plus it's not good with heat I'm reading) yes it's the right "size" but the mount really isn't that stealthy, and it's annoying not having a screen to fine tune things.

For $86 you can get the Mini 0801 on AliExpress from Givoe.
Latest firmware is H.264 .MOV @ 11MBps, 1080P, with mini screen + tiny 10 minute battery with outstanding daylight video, and ok/good night video.

http://dashcamtalk.com/mini-0801/ (see "where should I buy" link, and pick Givoe)

http://dashcamtalk.com/mini-0801-faq-added/ (link to discussions etc)

It fits perfectly behind the smart car mirror. You can't see a thing! (totally stealth/hidden from line of sight)

I know you were looking at the DR32 too, but I didin't like how low it hangs.
 
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My Mobius stays in the car all the time. I use a windshield shade and park in the shade when I can. So far no problems at all.
If I lived in a really hot climate, then I'd choose a camera with a super capacitor.
 
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JazJon said:
Hey Bob!

We met on the SmartCarOfAmerica forum.
http://www.smartcarofamerica.com/forums ... post594593

You're still researching DashCam's eh?

Stay away from the 27/207, I bought one I was totally unsatisfied. It's just way too fuzzy looking! Price was right, but spend $20 more! ($80-$110 is the sweet spot)

...
Click to expand...

Hi JazJon, Yes I'm still researching them. :D

The more I look at the video of the DVR 207, the more I see that it's not a true 1280x720 camera. To me it looks like the video sensor is 854x480 and is up converted to 1280x720. Once I take a YouTube 1280x720 video from the camera and convert it back to 854x480, it looks sharp. While the DVR 207 is NOT a true HD camera, it does do the job intended, just not in HD. Also, given that it's been out for a while, it has a known reputation and the battery is a standard cell phone battery that's easy to replace. Overall, the unit is not great, but it does the job.


The Mobius is small, offers true HD, and has a lot of support. Looking at the videos, I wish the lens were a bit wider, BUT it is close enough to work. The heat issue is the biggest thing for me, I'm worried that the camera would work in the short term, but die in the long term. By the way, I would only record when driving, so "parking mode" is not an issue for me. I could put extra heat sinks on the unit to keep it cooler; the heat sinks are dirt cheap:

http://www.allelectronics.com/make-a-st ... INK/1.html


The Mini 0801 looks interesting. I do wish that they used a socket, rather than solder the battery leads in place on the 0801. I still need to research that one more...



Bob Diaz
 
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