Yi Ultra Dash Camera

c4rc4m

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#81
He doesn't hide the fact that he posts affiliate links, it's mentioned on his website

AFFLIATED LINKS NOTICE

TECHMOAN.COM is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to AMAZON.COM & AMAZON.CO.UK.


He also mentions that not all products are purchased, some stuff has been pre release
That's changed then. :(
 
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Dash Cam
DOD LS360W, YI Ultra Dash Cam
#83
Actually this concerns me from a quality perspective. At night, or in lower light eg a dull day, why would you reduce the data rate? In theory at night you can see less, so less detail, so you might be tempted but there maybe a lot of detail there in the form of noise, and as the encoder presumably can't tell the difference between it and a genuine pixel, presumably that detail can in turn cause compression artefacts where high compression is used (low bit rate) due to the high level of detail being compressed - just a guess but seems logical). However, at night, the quality looks much lower in the above examples and when it's dull in the day it looks lower as well. When it's dull I can't see any justification for reducing the bit rate as the detail is still there and visible.

It seems to me that reducing the data rate according to the light conditions is just an anal way of saving SD card space and adversely affects quality. Why not simply set a data rate and leave it the same bright light, dull light and night? People will miss quality far more than an extra minutes recording space! Maybe someone needs to revisit the parameters of the VBR and up the minimum level considerably or switch it to CBR.
I agree... Using VBR, I would've thought at lower light levels it would be a higher bit rate than bright days... The opposite of what the camera is actually doing.
So for now I have switched back to H.264 codec where the bit rate is constant..... Maybe another firmware will fix this...

But at least by using @wacko911 modified app we can play around with it and have the choice of either codec......
 

c4rc4m

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#85
The camera should be varying the bit rate according to the detail yes. Although it doesn't necessarily follow there's substantially less detail at night (due to noise) or low day light (due to the fact that on a dull day you can see pretty much the same as on a bright day in the absence of mist, just not as brightly!) Ultimately the parameters of max and minimum bit rate are set by the programmer. You can find the settings in any video encoder when processing your own video in post. The hard encoder must have similar settings. My best guess would be the minimum bit rate setting is way to low to maintain the quality. There could be other causes though. I wouldn't claim to be a professional or to have an answer that's fact. I can only give my opinion on a possible cause.

At programming level I'd be unsure if there are also threshold settings for various levels of reduction such as if there's some kind of curve profile used of bit rate vs light level with threshold points added to control the shape of the curve. If so, maybe there are some issues here as well. I'm guessing you'd know the answer on that one Jokin being a manufacturer.
 
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Dash Cam
DOD LS360W, YI Ultra Dash Cam
#86
The camera should be varying the bit rate according to the detail yes. Although it doesn't necessarily follow there's substantially less detail at night (due to noise) or low day light (due to the fact that on a dull day you can see pretty much the same as on a bright day in the absence of mist, just not as brightly!) Ultimately the parameters of max and minimum bit rate are set by the programmer. You can find the settings in any video encoder when processing your own video in post. The hard encoder must have similar settings. My best guess would be the minimum bit rate setting is way to low to maintain the quality. There could be other causes though. I wouldn't claim to be a professional or to have an answer that's fact. I can only give my opinion on a possible cause.

At programming level I'd be unsure if there are also threshold settings for various levels of reduction such as if there's some kind of curve profile used of bit rate vs light level with threshold points added to control the shape of the curve. If so, maybe there are some issues here as well. I'm guessing you'd know the answer on that one Jokin being a manufacturer.
There seems to be a few variables when using VBR... (clues in the name, lol) so it would be a lot easier if the firmware could just be changed to CBR @ 13mb/s..... Halve of that of H.264. But I guess that would need the programmer to set that.. With this camera being able to take 128gb cards, trying to reduce file sizes too much is not necessary now.....
 

c4rc4m

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#87
There seems to be a few variables when using VBR... (clues in the name, lol) so it would be a lot easier if the firmware could just be changed to CBR @ 13mb/s..... Halve of that of H.264. But I guess that would need the programmer to set that.. With this camera being able to take 128gb cards, trying to reduce file sizes too much is not necessary now.....
Personally if going own that route I'd suggest just have it CBR at the same rate as for h.264 and have increased quality in any event. There's no loss of storage space if the amount of data stored is the same as for h264, and if that much storage was acceptable for h264 then why not use it fully for h265?
 
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Dash Cam
DOD LS360W, YI Ultra Dash Cam
#88
Personally if going own that route I'd suggest just have it CBR at the same rate as for h.264 and have increased quality in any event. There's no loss of storage space if the amount of data stored is the same as for h264, and if that much storage was acceptable for h264 then why not use it fully for h265?
True and what with H.265 being a better codec anyhow, it would be a win win from both sides....
 
Last edited:

Bruuuz

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Dash Cam
Mobius, Yi Ultra Dashcam
#89
Did you know, that a 43mm CPL Filter fits out of the box on the Yi Ultra dashcam? There is no step up adapter needed compared to the other yi dashcam like here Xiaomi Yi Car DVR - Easy CPL filter !
The ayex MRC CPL Filter-43mm Multicoated Polfilter Slim needs no extra modification.


Pictures and recordings will be available the next days.

Sorry guys, it was early evening and i mounted it the wrong side, but the polarization only works one direction. Next filter with 46mm will be delivered on thursday.
 
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wacko911

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#90
Just to confirm the stuttering issues I was having with h.265 recording was due to using the stock SD card. Replaced with Samsung as suggested and both cams working fine.
 

wacko911

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#92
I'll give it a week and check. Looked about the same quality to my untrained eye at half the filesize
 

jchantw

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#93
Nice comparision to Viofo A119 (with beta HDR firmware)

Hi guys, I'm currently using Viofo A119 and the pics are sharp.. in the above pics, the A119 seems to be sharper significantly more than the Yi Ultra Dash cam... and the A119 has lower resolution than the Ultra... so does anyone have real life usage experience of these 2 dash cams and is the Yi Ultra really shaper (in day and night) due to its higher resolution? Thanks a lot for your advice..... cheers!